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The Role of a Concierge in Modern Hospitality
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THE SOAR SYSTEM A solar system is a group of planets and other celestial bodies that revolve around a star. A solar nebula- a vast cloud of gas and dust, mostly hydrogen and helium. How the Solar System Form • COLLAPSE AND SPINNING DISK FORMATION - Gravity pulls material inward. The cloud flattens into a spinning disk due to conservation of angular momentum. • PROTOSTAR FORMATION- (BIRTH OF THE SUN). Material collects at the center, and begun to heat up. When it reaches to 10 million KELVIN, nuclear fusion begins. thus, SUN is born. • PLANETESIMALS AND PROTOPLANETS. Dust and gas in the disk stick together via static and gravitational forces. These form planetesimals, which grow into protoplanets collision and accretion. • PLANET FORMATION. Inner disk: too hot for gas rocky planets form Mercury, Venus, Earth, Mars. • PLANET FORMATION. Outer disk: gas and ice giants. Jupiter, Saturn, Uranus, Neptune • LEFTOVER DEBRIS. Remaining materials forms moon, asteroids, comets and dwarf planets. DIFFERENT HYPOTHESIS IN THE FORMATION OF SOLAR SYSTEM. 1. NEBULAR HYPOTHESIS- The Solar system formed from a rotating cloud of Gas and Dust (solar nebula). As it rotates conservation of angular momentum caused the cloud to flatten into a disk. the Sun formed at the center (DISK) while planets formed from the surrounding materials through acceleration. thus, it explains the coplanar and nearly circular orbit of the planets all planets orbits around the sun on the same flat, disk shaped plane. Proposed by Immanuel Kant in 1755 and Modified by Pierre Simon Laplace in 1756. PROTOPLANET HYPOTHESIS. The Solar system formed from a rotating cloud of Gas and Dust (solar nebula). As it rotates conservation of angular momentum caused the cloud to flatten into a disk. 2. Protoplanet hypothesis. Builds on the nebular model but focuses more on the role of planetesimals which then form into full planets. PROCESS: - Small solid particles stick together through collisions. As collisions takes place, it grows into kilometer-sized planetesimals. Gravitational interactions lead to the formation of planets. Lead to formation of steroids belts and varying planet sizes 3. Encounter hypothesis. States that the sun encountered a rogue star. The encounter led to the removal of hot gas from both stars due to their gravitational interaction. The hot gas then accumulated and formed the planets. The materials from the less dense rogue star formed the other planets, while that from the sun formed the inner planets. 4. TIDAL HYPOTHESIS. (also called the Tidal Theory) is an early scientific idea about how the solar system might have formed. Proposed by James Jeans and Harold Jeffreys. A massive star passed very close to the early Sun. The hot gas then accumulated and formed the planets. The materials from the less dense rogue star formed the other planets, while that from the sun formed the inner planets. Streams of hot gas were drawn out from the Sun in elongated shape. These streams eventually condensed and cooled, forming planets, moons, and other bodies in the solar system. 5. Not accepted theory. Later studies showed the streams of hot gas would disperse too quickly into space instead of condensing into planets. The theory also couldn’t explain the specific orbital patterns and compositions we see today. Modern science favors the Nebular Hypothesis, which explains solar system formation through the collapse of a rotating gas cloud. Earth as the only habitable planet 1. Right Distance from the Sun (The Goldilocks Zone). Not too hot, not too cold — just right for liquid water to exist. 2. Atmosphere with Oxygen. Earth has a mix of gases, especially oxygen, which most living things need to survive. 3. Liquid Water. Earth has oceans, rivers, and rain — water is essential for all life. 4. Magnetic Field. Earth’s magnetic field protects us from harmful solar radiation. 5. Stable Climate. The atmosphere and natural cycles keep temperatures and weather mostly stable over time. 6. Rich Resources. Earth has soil for growing food, minerals, and energy sources that support life and technology. Solar explorations 1. AUGUST 6, 2014. First space craft to orbit a comet (ROSETTA PROBE). Captures the comet photograph. -Comets have coma and tail as it approaches to the sun. 2. JULY 14, 2015. NASA’s New Horizons spacecraft made history by becoming the first spacecraft to fly by Pluto, giving us our first close-up look at the dwarf planet. First time visiting Pluto. Before this, Pluto was just a blurry dot in telescope images. Revealed a surprising world New Horizons showed mountains of ice, smooth plains, and a heart-shaped region called Tombaugh Regio. Changed what we knew. Scientists thought Pluto would be dull and frozen — instead, it turned out to be geologically active and incredibly complex. 3. SEPTEMBER 8, 2016. NASA launched OSIRIS-REx, the first U.S. mission to collect a sample from an asteroid and return it to Earth. Changed what we knew. Scientists thought Pluto would be dull and frozen — instead, it turned out to be geologically active and incredibly complex. OSIRIS-REx stands for: Origins, Spectral Interpretation, Resource Identification, Security–Regolith Explorer It was sent to study the asteroid Bennu, a near-Earth asteroid about 500 meters wide. Mission Goals: Collect a sample of surface material from Bennu Study the asteroid’s omposition, structure, and history. Mission Goals: Help scientists understand the origins of the solar system. Learn more about asteroids that could impact Earth. 4. August 12, 2018: Launch of NASA’s Parker Solar Probe, the first spacecraft to "touch" the Sun by flying through its outer atmosphere, called the corona. Mission Goal: To study the Sun up close and help scientists understand: How the solar wind (a stream of charged particles) is formed. Why the Sun’s corona is hotter than its surface. What causes solar storms that can affect Earth’s satellites and power grids. 5. November 26, 2018: NASA’s Insight Lander Touches Down on Mars. Its mission was focused on studying the interior of the Red Planet (crust, mantle, and core of the planet). Why the Sun’s corona is hotter than its surface. What causes solar storms that can affect Earth’s satellites and power grids 6. November 26, 2018: NASA’s Insight Lander Touches Down on Mars. Its mission was focused on studying the interior of the Red Planet (crust, mantle, and core of the planet) 7. JULY 30, 2020 PERSEVERANCE PROBE. Perseverance rover as part of the Mars 2020 mission aboard an Atlas V-541 rocket This marked a major step in Mars exploration. 8. DECEMBER 25, 2021-JAMES WEBB SPACE TELESCOPE. Investigate exoplanets’ atmospheres for signs of habitability. Observe the first galaxies formed after the Big Bang. Study the formation of stars and planetary systems. Look deeper into the infrared universe than ever before. RESULTS OF EXPLORATION • Evidence of Ancient Life-friendly Environment. • Sedimentary rocks formed in water-rich environments. • Signs of clay and carbonate minerals, which can preserve biosignatures (traces of past life). • Evidence of Ancient Life-friendly Environment. • Sedimentary rocks formed in water-rich environments. • Signs of clay and carbonate minerals, which can preserve biosignatures (traces of past life). • Evidence of Ancient Life-friendly Environment. • Sedimentary rocks formed in water-rich environments. • Signs of clay and carbonate minerals, which can preserve biosignatures (traces of past life).THE STRATEGIC PLAN OF RICHARD BLAND COLLEGE OF WILLIAM & MARY 2020-2025 “The dogmas of the quiet past are inadequate to the stormy present. The occasion is piled high with difficulty, and we must rise with the occasion. As our case is new, so we must think anew and act anew.” – Abraham Lincoln What is the role of a selective, two-year, residential, liberal arts transfer institution within the higher education landscape of the Commonwealth of Virginia? This is a key question that must be answered to ensure the success of Richard Bland College (RBC) and the constituency that the College serves. The 2020 RBC strategic plan’s primary objective is to answer that very question so that the College, the community and the Commonwealth can engage successfully within this identity and purpose to the benefit of all. RBC has long been identified as the hidden gem of higher education in Virginia. The hidden adjective is based both on its relative obscurity—few are aware of RBC outside the Tri-Cities region—and its rural setting featuring 750+ acres of wetlands, bucolic forest, and the state’s oldest and largest pecan grove. Additionally, on average, a student of Richard Bland College travels a mere 36 miles to campus. This keeps the knowledge of RBC in a tightly focused radius. The gem moniker refers both to the College’s reputation for excellence and the undeniable sensation that the campus often elicits in its students, visitors, faculty and staff, the feeling of a warm and palpable embrace of care, compassion and support. That sensation is where we start. According the State Council of Higher Education for Virginia (SCHEV), 99% of the 11.5 million new jobs created since the great recession require workers to have more than a high-school education. Students with a bachelor’s degree have an earning potential almost double that of people with only a high school education, and yet only 17% of residents in the Petersburg area have a bachelor’s degree, 15% below the national average. The obstacles in the way of education have been exhaustively researched and include financial challenges, academic under-preparedness, low self-esteem, slow college assimilation and immature levels of self-efficacy. To combat this growing problem, Richard Bland College initiated a pilot program to determine the viability of a data-driven approach to improve retention and graduation rates. The program ultimately effected a cultural, organizational and operational shift at RBC, resulting in a personalized model of student support, the Exceptional Student Experience (ESE@RBC). Originally many of the practices that RBC used as the basis of ESE@RBC were adapted from the four key principles found in the American Association of Community Colleges (AACC) Pathways Project: 1) map pathways to student end goals; 2) help students choose and enter a program pathway; 3) keep students on path; and 4) ensure that students are learning. Unfortunately, limited resources made it necessary to skip some primary elements of guided pathways and instead to focus on a specific, high-priority project that was immediately available for implementation, dedicated student support. This strategic framework reimagines the way that RBC serves students, faculty and staff within the context of our existing culture, the principles of guided pathways and a hybrid work-college experience. Rather than thinking of a two-year college as a pipeline to a four-year university, this vision describes a more expansive menu of well-defined pathways to high-demand fields, all radiating from a curriculum constructed around the development of soft skills that define the liberal arts experience: critical thinking, written communication, analytical reasoning, civic engagement and oral communication. Furthermore, the impact of meaningful work is a resonating theme, providing avenues to participate in career-focused internships and jobs that develop important life & work skills, confidence, and character. Richard Bland has tested its entrepreneurial mettle and its capacity for transformation in recent years. The College was among a select few Competency-Based Education sites established by the U.S. Department of Education. We were ahead of the curve using predictive analytics to improve student retention and success rates, and online enrollment now makes up nearly 20 percent of course offerings. It may be counter-intuitive, but these and other deep-level institutional changes still to come will ensure that Richard Bland College remains true to its original mission. We prepare our students for a lifetime of endless potential. SYI-1.D: Describe the structure and/ or function of subcellular components and organelles. ★ SYI-1.E: Explain how subcellular components and organelles contribute to the function of the cell. ★ SYI-1.F: Describe the structural features of a cell that allow organisms to capture, store, and use energy. ★ ENE-1.B: Explain the effect of surface area-to-volume ratios on the exchange of materials between cells or organisms and the environment. ★ ENE-1.C: Explain how specialized structures and strategies are used for the efficient exchange of molecules to the environment. ★ ENE-2.A: Describe the roles of each of the components of the cell membrane in maintaining the internal environment of the cell. ★ ENE-2.B: Describe the Fluid Mosaic Model of cell membranes. ★ ENE-2.C: Explain how the structure of biological membranes influences selective permeability. ★ ENE-2.D: Describe the role of the cell wall in maintaining cell structure and function. ★ ENE-2.E: Describe the mechanisms that organisms use to maintain solute and water balance. ★ ENE-2.F: Describe the mechanisms that organisms use to transport large molecules across the plasma membrane. ★ ENE-2.G: Explain how the structure of a molecule affects its ability to pass through the plasma membrane. ★ ENE-2.H: Explain how concentration gradients affect the ★ movement of molecules across membranes. ★ ENE-2.I: Explain how osmoregulatory mechanisms contribute to the health and survival of organisms. ★ ENE-2.J: Describe the processes that allow ions and other molecules to move across membranes. ★ ENE-2.K: Describe the membrane-bound structures of the eukaryotic cell. ★ ENE-2.L: Explain how internal membranes and membrane- bound organelles contribute to compartmentalization of eukaryotic cell functions. ★ EVO-1.A: Describe similarities and/or differences in compartmentalization between prokaryotic and eukaryotic cells. ★ EVO-1.B: Describe the relationship between the functions of endosymbiotic organelles and their free-living ancestral counterpartsInstructions: Please answer the following questions to test your understanding of aptitudes and interests. 1. What are Core Drivers (Talents) in the context of aptitudes and interests? a) Abilities that are developed through education b) Natural gifts that predict job effectiveness and contentment c) Interests that change over time d) Personality traits 2. Determine how effective and satisfied you'll be doing a particular kind of work. a) Visual Comparison Speed b) Numerical Reasoning c) Spatial Visualization d) Sequential Reasoning 3. Which Core Driver is associated with the knack for organizing things in a sequential and systematic manner? a) Visual Comparison Speed b) Numerical Reasoning c) Spatial Visualization d) Sequential Reasoning 4. What is the primary role of Space Planners in careers? a) They are responsible for interior design b) They read maps and blueprints c) They generate creative ideas d) They manage financial accounts 5. Which Core Driver relates to the ability to mentally translate two-dimensional images into three-dimensions? a) Visual Comparison Speed b) Numerical Reasoning c) Spatial Visualization d) Sequential Reasoning 6. What type of individuals are known as 3D Visualizers? a) Those who excel in visual art b) People who can quickly process numerical data c) Individuals who can mentally create 3D models from 2D representations d) Creative writers 7. How do Brainstormers differ from Concentrated & Focused individuals in terms of generating ideas? a) Brainstormers generate more ideas b) Concentrated & Focused individuals generate more ideas c) They generate ideas at the same rate d) Both groups struggle to generate ideas 8. What is the primary advantage of having high Visual Comparison Speed? a) It helps in artistic endeavors b) It is useful in complex mathematical problems c) It aids in tasks requiring clerical detail and accuracy d) It enhances spatial visualization 9. Which career is NOT associated with the Core Driver: Visual Comparison Speed? a) Fire Inspector b) Astronomer c) Creative Writer d) Orthoptist 10. What is the main focus of Numerical Reasoning? a) Identifying numerical patterns and trends b) Analyzing historical data c) Solving abstract problems d) Communicating effectively 11. Which Core Driver involves the ability to rapidly draw conclusions from seemingly unrelated pieces of information? a) Numerical Reasoning b) Idea Generation c) Spatial Visualization d) Inductive Reasoning 12. What is the primary characteristic of Diagnostic Problem Solvers? a) They follow a logical step-by-step method of problem-solving b) They rely on specific information and observed experience c) They intuitively leap to conclusions based on limited information d) They are meticulous and deliberate in decision-making 13. What is the role of Fact Checkers in the problem-solving process? a) They intuitively provide solutions b) They rely on specific information and observed experience c) They enjoy acquiring new information and learning d) They make conclusions based on limited facts 14. In what type of role are Abstract Thinkers most comfortable? a) Counseling b) Law c) Marketing d) Construction 15. How can understanding your Core Drivers benefit collaborative work? a) It allows individuals with similar aptitudes to work together more effectively b) It creates conflicts within the team c) It doesn't affect collaborative work d) It makes collaboration more challenging 16. Which Core Driver is associated with processing complex mathematical problems logically? a) Visual Comparison Speed b) Numerical Reasoning c) Sequential Reasoning d) Idea Generation 17. What are Collaborative Planners more likely to do in a team project? a) Lead the team b) Create individual pieces of a project c) Solve abstract problems d) Generate creative ideas 18. How can understanding your aptitudes and interests help you make informed career choices? a) It guarantees job satisfaction b) It allows you to align your career with your strengths c) It helps you choose any career at random d) It has no impact on career decisions 19. Which Core Driver affects whether your thoughts go in several directions at once or follow single ideas more readily? a) Visual Comparison Speed b) Numerical Reasoning c) Idea Generation d) Inductive Reasoning 20. What is the primary characteristic of Idea Contributors? a) They generate creative ideas b) They discuss the big picture and next steps c) They are highly focused and detailed d) They follow a logical step-by-step approach 21. What is the role of Space Planners in the problem-solving process? a) They intuitively provide solutions b) They rely on specific information and observed experience c) They quickly organize information d) They create abstract plans 22. Which Core Driver is linked to the ability to see relationships in seemingly unrelated pieces of information? a) Spatial Visualization b) Inductive Reasoning c) Idea Generation d) Visual Comparison Speed 23. Which career is NOT associated with the Core Driver: Numerical Reasoning? a) Statistician b) Survey Researcher c) Chef d) Actuary 24. What are Core Drivers, and why are they important in the context of aptitudes and interests? a) They are educational qualifications b) They are interests that change over time c) They are natural gifts that predict job effectiveness and contentment d) They are personality traits 25. How can understanding your Core Drivers benefit collaborative work? a) It allows individuals with similar aptitudes to work together more effectively b) It creates conflicts within the team c) It doesn't affect collaborative work d) It makes collaboration more challenging Answers: b) Natural gifts that predict job effectiveness and contentment a) Visual Comparison Speed d) Sequential Reasoning b) They read maps and blueprints c) Spatial Visualization c) Individuals who can mentally create 3D models from 2D representations a) Brainstormers generate more ideas c) It aids in tasks requiring clerical detail and accuracy c) Creative Writer a) Identifying numerical patterns and trends d) Inductive Reasoning c) They intuitively leap to conclusions based on limited information b) They rely on specific information and observed experience b) Law a) It allows individuals with similar aptitudes to work together more effectively b) Numerical Reasoning b) Create individual pieces of a project b) It allows you to align your career with your strengths c) Idea Generation b) They discuss the big picture and next steps c) They quickly organize information b) Inductive Reasoning c) Chef c) They are natural gifts that predict job effectiveness and contentment a) It allows individuals with similar aptitudes to work together more effectively 1. What is the main purpose of including theme and main idea questions in a text? a) To test your reading comprehension skills b) To understand the overall message or lesson of the text c) To practice identifying specific details in the text d) To improve your vocabulary and word knowledge 2. What is the purpose of finding the theme in a text? a) To summarize the main idea of the text in a few words b) To identify the specific details and examples in the text c) To understand the order of events in the text d) To analyze the author's writing style and techniques 3. Which of the following represents the theme of a text? a) A long sentence that describes the setting of the story b) A single word or short phrase that captures the main idea of the text c) A list of characters and their traits d) A detailed description of the plot and conflict in the story 4. How does identifying the main idea of a paragraph help you understand the text? a) It allows you to make connections between different parts of the text b) It helps you identify the author's purpose for writing the text c) It enables you to predict what will happen next in the story d) It helps you remember the specific details and examples in the paragraph 5. Which of the following best describes the main idea of a paragraph? a) The specific details and examples that support the theme of the text b) The order of events and actions in the paragraph c) The overall message or lesson conveyed by the paragraph d) The vocabulary words and their definitions in the paragraph 6. In a short paragraph about dogs, what could be a possible theme? a) Running and playing in the park b) Different breeds of dogs and their characteristics c) The loyalty and companionship dogs provide d) How to train a dog to do tricks 7. What might be the main idea of a paragraph about the importance of recycling? a) Recycling reduces pollution and conserves natural resources b) The process of recycling and how it works c) The different types of materials that can be recycled d) The history of recycling and its impact on society 8. Which of the following could be the theme of a paragraph about the benefits of reading? a) The importance of reading for academic success b) How to choose the right book to read c) The different genres of literature and their characteristics d) The role of libraries in promoting reading 9. If a paragraph discusses the life cycle of a butterfly, what would be the most likely main idea? a) The different colors and patterns of butterfly wings b) The stages of a butterfly's life from egg to adult c) The habitats and environments where butterflies live d) The types of plants that attract butterflies for feeding 10. What is the purpose of including vocabulary words and their meanings in context in a text? a) To test your knowledge of different words and their definitions b) To understand the specific details and examples in the text c) To improve your reading comprehension skills d) To practice using new words in your own writingWhat is a Plant Cell? Plant cells are eukaryotic cells that vary in several fundamental factors from other eukaryotic organisms. Both plant and animal cells contain a nucleus along with similar organelles. One of the distinctive aspects of a plant cell is the presence of a cell wall outside the cell membrane. Plant Cell Structure Just like different organs within the body, plant cell structure includes various components known as cell organelles that perform different functions to sustain itself. These organelles include: Cell Wall It is a rigid layer which is composed of polysaccharides cellulose, pectin and hemicellulose. It is located outside the cell membrane. It also comprises glycoproteins and polymers such as lignin, cutin, or suberin. The primary function of the cell wall is to protect and provide structural support to the cell. The plant cell wall is also involved in protecting the cell against mechanical stress and providing form and structure to the cell. It also filters the molecules passing in and out of it. The formation of the cell wall is guided by microtubules. It consists of three layers, namely, primary, secondary and the middle lamella. The primary cell wall is formed by cellulose laid down by enzymes. Cell membrane It is the semi-permeable membrane that is present within the cell wall. It is composed of a thin layer of protein and fat. The cell membrane plays an important role in regulating the entry and exit of specific substances within the cell. For instance, cell membrane keeps toxins from entering inside, while nutrients and essential minerals are transported across. Nucleus The nucleus is a membrane-bound structure that is present only in eukaryotic cells. The vital function of a nucleus is to store DNA or hereditary information required for cell division, metabolism and growth. 1. Nucleolus: It manufactures cells’ protein-producing structures and ribosomes. 2. Nucleopore: Nuclear membrane is perforated with holes called nucleopore that allow proteins and nucleic acids to pass through. Plastids They are membrane-bound organelles that have their own DNA. They are necessary to store starch and to carry out the process of photosynthesis. It is also used in the synthesis of many molecules, which form the building blocks of the cell. Some of the vital types of plastids and their functions are stated below: Leucoplasts They are found in the non-photosynthetic tissue of plants. They are used for the storage of protein, lipid and starch. Chromoplasts They are heterogeneous, colored plastid which is responsible for pigment synthesis and for storage in photosynthetic eukaryotic organisms. Chromoplasts have red-, orange- and yellow-colored pigments which provide color to all ripe fruits and flowers. Central Vacuole It occupies around 30% of the cell’s volume in a mature plant cell. Tonoplast is a membrane that surrounds the central vacuole. The vital function of the central vacuole apart from storage is to sustain turgor pressure against the cell wall. The central vacuole consists of cell sap. It is a mixture of salts, enzymes and other substances. Golgi Apparatus They are found in all eukaryotic cells, which are involved in distributing synthesized macromolecules to various parts of the cell. Ribosomes They are the smallest membrane-bound organelles which comprise RNA and protein. They are the sites for protein synthesis, hence, also referred to as the protein factories of the cell. Mitochondria They are the double-membraned organelles found in the cytoplasm of all eukaryotic cells. They provide energy by breaking down carbohydrate and sugar molecules, hence they are also referred to as the “Powerhouse of the cell.” Lysosome Lysosomes are called suicidal bags as they hold digestive enzymes in an enclosed membrane. They perform the function of cellular waste disposal by digesting worn-out organelles, food particles and foreign bodies in the cell. In plants, the role of lysosomes is undertaken by the vacuoles. Chloroplasts It is an elongated organelle enclosed by phospholipid membrane. The chloroplast is shaped like a disc and the stroma is the fluid within the chloroplast that comprises a circular DNA. Each chloroplast contains a green colored pigment called chlorophyll required for the process of photosynthesis. The chlorophyll absorbs light energy from the sun and uses it to transform carbon dioxide and water into glucose. Structure of Chloroplast Chloroplasts are found in all higher plants. It is oval or biconvex, found within the mesophyll of the plant cell. The size of the chloroplast usually varies between 4-6 µm in diameter and 1-3 µm in thickness. They are double-membrane organelle with the presence of outer, inner and intermembrane space. There are two distinct regions present inside a chloroplast known as the grana and stroma. • Grana are made up of stacks of disc-shaped structures known as thylakoids or lamellae. The granum of the chloroplast consists of chlorophyll pigments and are the functional units of chloroplasts. • Stroma is the homogenous matrix which contains grana and is similar to the cytoplasm in cells in which all the organelles are embedded. Stroma also contains various enzymes, DNA, ribosomes, and other substances. Stroma lamellae function by connecting the stacks of thylakoid sacs or grana. The chloroplast structure consists of the following parts: Membrane Envelope It comprises inner and outer lipid bilayer membranes. The inner membrane separates the stroma from the intermembrane space. Intermembrane Space The space between inner and outer membranes. Thylakoid System (Lamellae) The system is suspended in the stroma. It is a collection of membranous sacs called thylakoids or lamellae. The green colored pigments called chlorophyll are found in the thylakoid membranes. It is the sight for the process of light-dependent reactions of the photosynthesis process. The thylakoids are arranged in stacks known as grana and each granum contains around 10-20 thylakoids. Stroma It is a colorless, alkaline, aqueous, protein-rich fluid present within the inner membrane of the chloroplast present surrounding the grana. Grana Stack of lamellae in plastids is known as grana. These are the sites of conversion of light energy into chemical energy. Chlorophyll It is a green photosynthetic pigment that helps in the process of photosynthesis. Functions of Chloroplast Following are the important chloroplast functions: • The most important function of the chloroplast is to synthesize food by the process of photosynthesis. • Absorbs light energy and converts it into chemical energy. • Chloroplast has a structure called chlorophyll which functions by trapping the solar energy and is used for the synthesis of food in all green plants. • Produces NADPH and molecular oxygen (O 2 ) by photolysis of water. • Produces ATP – Adenosine triphosphate by the process of photosynthesis. • The carbon dioxide (CO2) obtained from the air is used to generate carbon and sugar during the Calvin Cycle or dark reaction of photosynthesis. Mitochondria “Mitochondria are membrane-bound organelles present in the cytoplasm of all eukaryotic cells, that produce adenosine triphosphate (ATP), the main energy molecule used by the cell.” What are Mitochondria? Popularly known as the “Powerhouse of the cell,” mitochondria (singular: mitochondrion) are a double membrane-bound organelle found in most eukaryotic organisms. They are found inside the cytoplasm and essentially function as the cell’s “digestive system.” They play a major role in breaking down nutrients and generating energy-rich molecules for the cell. Many of the biochemical reactions involved in cellular respiration take place within the mitochondria. The term ‘mitochondrion’ is derived from the Greek words “mitos” and “chondrion” which means “thread” and “granules-like”, respectively. It was first described by a German pathologist named Richard Altmann in the year 1890. Structure of Mitochondria • The mitochondrion is a double-membraned, rod-shaped structure found in both plant and animal cell. • Its size ranges from 0.5 to 1.0 micrometers in diameter. • The structure comprises an outer membrane, an inner membrane, and a gel-like material called the matrix. • The outer membrane and the inner membrane are made of proteins and phospholipid layers separated by the intermembrane space. • The outer membrane covers the surface of the mitochondrion and has a large number of special proteins known as porins. Cristae The inner membrane of mitochondria is rather complex in structure. It has many folds that form a layered structure called cristae, and this helps in increasing the surface area inside the organelle. The cristae and the proteins of the inner membrane aid in the production of ATP molecules. The inner mitochondrial membrane is strictly permeable only to oxygen and ATP molecules. A number of chemical reactions take place within the inner membrane of mitochondria. Mitochondrial Matrix The mitochondrial matrix is a viscous fluid that contains a mixture of enzymes and proteins. It also comprises ribosomes, inorganic ions, mitochondrial DNA, nucleotide cofactors, and organic molecules. The enzymes present in the matrix play an important role in the synthesis of ATP molecules. Functions of Mitochondria The most important function of mitochondria is to produce energy through the process of oxidative phosphorylation. It is also involved in the following process: 1. Regulates the metabolic activity of the cell 2. Promotes the growth of new cells and cell multiplication 3. Helps in detoxifying ammonia in the liver cells 4. Plays an important role in apoptosis or programmed cell death 5. Responsible for building certain parts of the blood and various hormones like testosterone and estrogen 6. Helps in maintaining an adequate concentration of calcium ions within the compartments of the cell 7. It is also involved in various cellular activities like cellular differentiation, cell signaling, cell senescence, controlling the cell cycle and in cell growth. Disorders Associated with Mitochondria Any irregularity in the way mitochondria function can directly affect human health, but often, it is difficult to identify because symptoms differ from person to person. Disorders of the mitochondria can be quite severe; in some cases, they can even cause an organ to fail.The plasma membrane (also called the cell membrane) has several functions. For example, it allows only certain molecules to enter or leave the cell. It separates internal metabolic reactions from the external environment. In addition, the plasma membrane allows the cell to excrete wastes and to interact with its environment. Membrane Lipids The plasma membrane, as well as the membranes of cell organelles, is made primarily of phospholipids. Phospholipids have a polar, hydrophilic (“water-loving”) phosphate head and two nonpolar, hydrophobic (“water-fearing”) fatty acid tails. Water molecules sur- round the plasma membrane. The phospholipids line up so that their heads point outward toward the water and their tails point inward, away from water. The result is a double layer called a phospholipid bilayer, as shown in Figure 4-10. The cell membranes of eukaryotes also contain lipids, called sterols, between the tails of the phospho- lipids. The major membrane sterol in animal cells is cholesterol. Sterols in the plasma membrane make the membrane more firm and prevent the membrane from freezing at low temperatures. SECTION 3 OBJECTIVES ● Describe the structure and function of a cell’s plasma membrane. ● Summarize the role of the nucleus. ● List the major organelles found in the cytosol, and describe their roles. ● Identify the characteristics of mitochondria. ● Describe the structure and function of the cytoskeleton. VOCABULARY phospholipid bilayer chromosome nuclear envelope nucleolus ribosome mitochondrion endoplasmic reticulum Golgi apparatus lysosome cytoskeleton microtubule microfilament cilium flagellum centriole Cell membranes are made of a phospholipid bilayer. Each phospholipid molecule has a polar “head” and a two-part nonpolar “tail.” FIGURE 4-10 Copyright © by Holt, Rinehart and Winston. All rights reserved. 78 CHAPTER 4 OUTSIDE OF CELL INSIDE OF CELL 1. Cell-surface marker: Glycoprotein that identifies cell type 3. Enzyme: Assists chemical reactions inside the cell 2. Receptor protein: Recognizes and binds to substances outside the cell 4. Transport protein: Helps substances move across cell membrane Carbohydrate portion Protein portion Phospholipid heads Phospholipid tails Phospholipid Cholesterol bilayer Membrane Proteins Plasma membranes often contain specific proteins embedded within the lipid bilayer. These proteins are called integral proteins. Figure 4-11 shows that some integral proteins, such as cell surface markers, emerge from only one side of the membrane. Others, such as receptor proteins and transport proteins, extend across the plasma membrane and are exposed to both the cell’s interior and exterior environments. Proteins that extend across the plasma membrane are able to detect environmental signals and transmit them to the inside of the cell. Peripheral proteins, such as the enzyme shown in Figure 4-11, lie on only one side of the membrane and are not embedded in it. As Figure 4-11 shows, integral proteins exposed to the cell’s external environment often have carbohydrates attached. These carbohydrates can act as labels on cell surfaces. Some labels help cells recognize each other and stick together. Viruses can use these labels as docks for entering and infecting cells. Integral proteins play important roles in actively transporting molecules into the cell. Some act as channels or pores that allow certain substances to pass. Other integral proteins bind to a mol- ecule on the outside of the cell and then transport it through the membrane. Still others act as sites where chemical messengers such as hormones can attach. Fluid Mosaic Model A cell’s plasma membrane is surprisingly dynamic. Scientists describe the cell membrane as a fluid mosaic. The fluid mosaic model states that the phospholipid bilayer behaves like a fluid more than it behaves like a solid. The membrane’s lipids and pro- teins can move laterally within the bilayer, like a boat on the ocean. As a result of such lateral movement, the pattern, or “mosaic,” of lipids and proteins in the cell membrane constantly changes.A1 Psychological definition of health and ill health, addiction and stress Definitions and characteristics of health and ill health, addiction and stress. Health and ill health: biomedical, biopsychosocial, health as a continuum. Behavioural and physiological addiction: o Griffiths’ six components of addiction: physical and psychological dependence (salience), tolerance, withdrawal, relapse, conflict, mood alteration o stress: definition of a stressor, psychological stress, stress and perceived ability to cope. A2 Psychological approaches to health Biological influences – of genetic predisposition, the roles of neurotransmitter imbalances. Behaviourist approaches – the role of cues, positive reinforcement and negative reinforcement to explain healthy and unhealthy behaviours; using operant conditioning to encourage and incentivise behaviour. Social learning approach – effects of parental and peer role models on healthy and unhealthy behaviours; role models in health education. • Cognitive approach – decisions to engage in behaviours to provide relief from stress, anxiety, boredom or to mitigate impacts of other health problems, resolving cognitive dissonance for behaviour change, professional biases in diagnoses and treatments. A3 Theories of stress, behavioural addiction and physiological addiction Theories: key concepts of psychological theories of stress, behavioural addiction and physiological addiction, to include: Health belief model concepts of perceived seriousness, susceptibility, cost-benefit analysis, how demographic variables such as age, gender, culture and external/internal cues affect behaviour Locus of control: internal and external locus of control, the role of attributions in determining health behaviour