DAT Bootcamp High-Yield Biology Notes PDF

 “How Do I Get a Good Bio Score on the DAT?” Bootcamp has multiple ways to study bio based on how you learn best. We have High-Yield Bio Notes, Biology Videos, Bio Bites, question banks, and more. For content review: If you like reading, use these notes. They serve as a concise refer...

 “How Do I Get a Good Bio Score on the DAT?” Bootcamp has multiple ways to study bio based on how you learn best. We have High-Yield Bio Notes, Biology Videos, Bio Bites, question banks, and more. For content review: If you like reading, use these notes. They serve as a concise reference to everything you need to know for the DAT. If you prefer videos, watch the Bio Videos. They cover the same info and incorporate practice questions. Most importantly, you have to practice what you’ve learned. You can practice with the Bio Question Bank and Bio Bites as you progress through biology. The bio practice tests will tie everything together and the performance page will identify areas where you need further studying. If you’re short on time, my #1 recommendation is finishing and reviewing all the DAT Bootcamp practice tests 1-10 and focusing on learning from the explanations. These are the most representative and high-yield questions you’re likely to see on the DAT. Be sure to learn everything in the explanations in the practice tests before you take your DAT. Lastly, I want DAT Bootcamp to be perfect for you. If you have any feedback or questions, please email us at [email protected]! Your feedback is invaluable to improving these notes for future generations of students. Happy studying! 😃 -Dr. Ari and the DAT Bootcamp team © 2024 Bootcamp.com 2  Table of Contents Chapter 1: Molecules and Fundamentals of Biology Chapter 2: Cells and Organelles Chapter 3: Cellular Energy Chapter 4: Photosynthesis Chapter 5: Cell Division Chapter 6: Molecular Genetics Chapter 7: Heredity Chapter 8: Microscopy & Lab Techniques Chapter 9: Diversity of Life Chapter 10: Plants Chapter 11.1: Circulatory System Chapter 11.2: Respiratory System Chapter 11.3: Immune System Chapter 11.4: Nervous System Chapter 11.5: Muscular System Chapter 11.6: Skeletal System Chapter 11.7: Endocrine System Chapter 11.8: Digestive System Chapter 11.9: Excretory System Chapter 11.10: Integumentary System Chapter 12: Reproduction and Developmental Biology Chapter 13: Evolution Chapter 14: Ecology Chapter 15: Animal Behavior © 2024 Bootcamp.com 3 Ch. 1: Molecules and Monosaccharides are carbohydrate monomers with an empirical formula of (CH2O)n. “n” represents the Fundamentals of Biology number of carbons. Ribose: A five carbon monosaccharide. Table of Contents Fructose: A six carbon monosaccharide. Glucose: A six carbon monosaccharide. Biological Chemistry Carbohydrates Glucose and fructose are isomers of each other (same Proteins chemical formula, different arrangement of atoms). Lipids Nucleic Acids Disaccharides contain two monosaccharides joined Biological Hypotheses and Theories together by a glycosidic bond. It is the result of a dehydration (condensation) reaction, where a Biological Chemistry water molecule leaves and a covalent bond forms. A hydrolysis reaction is the opposite, through which a Matter: Anything that takes up space and has covalent bond is broken by the addition of water. mass. Element: A pure substance that has specific Sucrose: Disaccharide made of glucose + fructose. physical/chemical properties and can’t be broken Lactose: Disaccharide made of galactose + down into a simpler substance. glucose. Atom: The smallest unit of matter that still retains Maltose: Disaccharide made of glucose + glucose. the chemical properties of the element. Molecule: Two or more atoms joined together. Polysaccharides contain multiple monosaccharides Intramolecular forces: Attractive forces that act connected by glycosidic bonds to form long polymers. on atoms within a molecule. Intermolecular forces: Forces that exist between Starch: Form of energy storage for plants. molecules and affect physical properties of the Glycogen: Form of energy storage in animals. substance. Monomers: Single molecules that can Proteins polymerize, or bond with one another. Polymers: Substances made up of many Proteins contain carbon, hydrogen, oxygen, and monomers joined together in chains. nitrogen atoms (CHON). These atoms combine to form Dehydration (condensation) reaction: When amino acids, which link together to build monomers bond with each other to form polypeptides (or proteins). A proteome refers to all polymers, releasing water. the proteins expressed by one type of cell under one Hydrolysis: When polymer bonds are broken set of conditions. using water. Amino acids are the monomers of proteins and have Carbohydrates the structure shown below. There are twenty different kinds of amino acids, each with a different “R-group”. Carbohydrates are used as fuel and structural support. They contain carbon, hydrogen, and oxygen atoms (CHO). They can come in the form of Amino Acid Structure monosaccharides, disaccharides, and polysaccharides. Amino Carboxyl © 2024 Bootcamp.com R-group side chain 4 Polypeptides are polymers of amino acids and are Protein Function Description joined by peptide bonds through dehydration (condensation) reactions. Hydrolysis reactions Storage Reserve of amino acids break peptide bonds. The polypeptide becomes an Signaling molecules that amino acid chain that contains two end terminals on regulate physiological Hormones opposite sides. processes The N-terminus (amino terminus) of a polypeptide Proteins in cell is the side that ends with the last amino acid’s amino Receptors membranes which bind to signal molecules group. Provide strength and The C-terminus (carboxyl terminus) of a polypeptide Structure support to tissues (hair, is the side that ends with the last amino acid’s spider silk) carboxyl group. Antibodies that protect Immunity against foreign substances Conjugated proteins are proteins that are composed of amino acids and non-protein components. These Regulate rate of chemical Enzymes include: reactions Metalloproteins (e.g., hemoglobin): Proteins Levels of Protein Structure that contain a metal ion cofactor. Glycoprotein (e.g., mucin): Proteins that contain Amino acids Peptide bonds a carbohydrate group. Protein structure: 1. Primary structure: Sequence of amino acids Alpha helix Beta pleated sheet connected through peptide bonds. 2. Secondary structure: Intermolecular forces between the polypeptide backbone (not R-groups) due to hydrogen bonding. Forms α-helices or Hydrogen bonds β-pleated sheets. 3. Tertiary structure: Three-dimensional structure due to interactions between R-groups. Can create hydrophobic interactions based on the R-groups. Disulfide linkage Disulfide bonds are created by covalent bonding Hydrogen bond between the R-groups of two cysteine amino acids. Hydrogen bonding and ionic bonding Hydrophobic between R groups also hold together the tertiary interactions structure. Ionic (electrostatic) 4. Quaternary structure: Multiple polypeptide interactions chains come together to form one protein. Protein denaturation describes the loss of protein function and higher order structures. Only the primary structure is unaffected. Proteins will denature as a result of high or low temperatures, pH changes, and salt concentrations. For example, cooking an egg in high heat will disrupt the intermolecular forces in the egg’s proteins, causing it to coagulate. © 2024 Bootcamp.com 5 Catalysts increase reaction rates by lowering the High-yield biological enzymes: activation energy of a reaction. The transition state is the unstable conformation between the reactants Phosphatase: Cleaves a phosphate group off of a and the products. Catalysts reduce the energy of the substrate molecule transition state. Catalysts do not shift a chemical Phosphorylase: Directly adds a phosphate group reaction or affect spontaneity. to a substrate molecule by breaking bonds within a substrate molecule. Enzymes act as biological catalysts by binding to Kinase: Indirectly adds a phosphate group to a substrates (reactants) and converting them into substrate molecule by transferring a phosphate products. group from an ATP molecule. These enzymes do not break bonds to add the phosphate group. Enzymes bind to substrates at an active site, which is specific for the substrate that it acts upon. Feedback regulation of enzymes occurs when the Most enzymes are proteins. end product of an enzyme-catalyzed reaction inhibits The specificity constant measures how efficient the enzyme’s activity by binding to an allosteric site. an enzyme is at binding to the substrate and converting it to a product. Competitive inhibition occurs when a competitive The induced fit theory describes how the active inhibitor competes directly with the substrate for site molds itself and changes shape to fit the active site binding. Competitive inhibitors can be substrate when it binds. The “lock and key” outcompeted by adding more substrate. model is an outdated theory of how substrates bind. Noncompetitive inhibition occurs when the A ribozyme is an RNA molecule that can act as an noncompetitive inhibitor binds to an allosteric site enzyme (a non-protein enzyme). (a location on an enzyme that is different from the A cofactor is a non-protein molecule that helps active site) that modifies the active site. enzymes perform reactions. A coenzyme is an Noncompetitive inhibitors cannot be outcompeted by organic cofactor (i.e., vitamins). Inorganic cofactors adding more substrate. are usually metal ions. Holoenzymes are enzymes that are bound to Types of Enzyme Inhibition their cofactors while apoenzymes are enzymes Uninhibited that are not bound to their cofactors. Enzyme Substrate Prosthetic groups are cofactors that are tightly or covalently bonded to their enzymes. Active Protein enzymes are susceptible to denaturation. site They require optimal temperatures and pH for function. Competitive Enzyme Inhibitor Enzymes catalyze reactions in the following ways: Active Conformational changes that bring reactive site groups closer. Noncompetitive The presence of acidic or basic groups. Inhibitor Enzyme Induced fit of the enzyme-substrate complex. Electrostatic attractions between the enzyme and Active substrate. Allosteric site site © 2024 Bootcamp.com 6  An enzyme kinetics plot can be used to visualize how Lipids inhibitors affect enzymes. Below are a few terms used to describe the plot: Lipids contain carbon, hydrogen, and oxygen atoms (CHO), like carbohydrates. They have long 1. The x-axis represents substrate concentration [X] hydrocarbon tails that make them very hydrophobic. while the y-axis represents reaction rate or velocity (V). Triacylglycerol (triglyceride) is a lipid molecule with 2. Vmax is the maximum reaction velocity. a glycerol backbone (three carbons and three hydroxyl 3. Michaelis Constant (KM) is the substrate groups) and three fatty acids (long hydrocarbon tails). concentration [X] at which the velocity (V) is 50% of Glycerol and the three fatty acids are connected by the maximum reaction velocity (Vmax). ester linkages. 4. Saturation occurs when all active sites are occupied, so the rate of reaction does not increase Saturated fatty acids have no double bonds and as a anymore despite increasing substrate result pack tightly (solid at room temperature). concentration (causes graph plateaus). Unsaturated fatty acids have double bonds. Double Competitive inhibition → KM increases, while Vmax bonds create kinks in the fatty acid chain, preventing stays the same tight packing and increasing membrane fluidity. Enzyme Kinetics: Competitive Inhibition Phospholipids are lipid molecules that have a Normal glycerol backbone, one phosphate group, and two enzyme fatty acid tails. The phosphate group is polar, while the fatty acids are nonpolar. As a result, they are amphipathic (both hydrophobic and hydrophilic). Reaction Furthermore, they spontaneously assemble to form rate lipid bilayers. Competitive inhibitor: ½ Vmax Vmax stays the same while Km increases Cholesterol is an amphipathic lipid molecule that is a component of the cell membranes. It is the most common precursor to steroid hormones (lipids with four hydrocarbon rings). It is also the starting material for vitamin D and bile acids. Km Km [Substrate] Factors that influence membrane fluidity: Noncompetitive inhibition → KM stays the same, while Vmax decreases 1. Temperature: ↑ Temperatures increase fluidity while ↓ temperatures decrease it. Enzyme Kinetics: Noncompetitive Inhibition 2. Cholesterol: Holds membrane together at high Normal temperatures and keeps membrane fluid at low enzyme temperatures. 3. Degrees of unsaturation: Saturated fatty acids pack more tightly than unsaturated fatty acids, Reaction which have double bonds that may introduce rate kinks. ½ Vmax Noncompetitive inhibitor: ½ Vmax Vmax decreases while Km stays the same Km [Substrate] © 2024 Bootcamp.com 7 Lipoproteins allow the transport of lipid molecules in Nucleic acid polymerization proceeds as nucleoside the bloodstream due to an outer coat of triphosphates are added to the 3’ end of the phospholipids, cholesterol, and proteins. sugar-phosphate backbone. Waxes are simple lipids with long fatty acid chains DNA is an antiparallel double helix, in which two connected to alcohols. complementary strands with opposite directionalities (positioning of 5’ ends and 3’ ends) twist around each Carotenoids are lipid derivatives containing long other. carbon chains with double bonds and function mainly as pigments. mRNA is single-stranded after being copied from DNA during transcription. Sphingolipids have a backbone with aliphatic Nucleic Acid Polymerization (non-aromatic) amino alcohols and have important functions in structural support, signal transduction, Phosphate group and cell recognition. Glycolipids are lipids found in the cell membrane with 5’ end Nitrogenous a carbohydrate group attached instead of a phosphate base 5’ group in phospholipids. Like phospholipids, they are amphipathic and contain a polar head and a fatty acid 4’ 1’ chain. 2’ Five-carbon sugar 3’ Phosphodiester bond Nucleic Acids Nitrogenous Nucleic acids contain nucleotide monomers that base build into DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) polymers. Nucleosides contain a five-carbon sugar and a 3’ end nitrogenous base. Nucleotides contain a five-carbon sugar, a Other Types of RNA nitrogenous base, and a phosphate group. miRNA (microRNA): Small RNA molecules that can Deoxyribose sugars (in DNA) have a hydrogen at the silence gene expression by base pairing to 2’ carbon while ribose five-carbon sugars (in RNA) complementary sequences in mRNA. have a hydroxyl group at the 2’ carbon. rRNA (ribosomal RNA): It is formed in the nucleolus Phosphodiester bonds are formed through a of the cell and helps ribosomes translate mRNA. condensation reaction where the phosphate group of one nucleotide (at the 5’ carbon) connects to the dsRNA (double stranded RNA): Some viruses carry hydroxyl group of another nucleotide (at the 3’ their code as double stranded RNA. Pro-tip: dsRNA carbon) and releases a water molecule as a must pair its nucleotides, so it must have equal by-product. amounts of A/U, and C/G. A series of phosphodiester bonds create the tRNA (transfer RNA): Small RNA molecule that sugar-phosphate backbone, with a 5’ end (free participates in protein synthesis. phosphate) and a 3’ end (free hydroxyl). © 2024 Bootcamp.com 8  Biological Hypotheses and Theories The RNA world hypothesis is the theory that early life forms relied on self-replicating RNA both to store The Universe is approximately 13.8 billion years old. genetic information and to catalyze chemical reactions The first cells appeared on Earth approximately 3.5 before the evolution of DNA and proteins. billion years ago. Because RNA is reactive and unstable: Primordial Earth: DNA replaced RNA in how genetic information is 1. Earth’s primordial atmosphere was comprised of stored. inorganic compounds and was a reducing Proteins largely replaced RNA in catalyzing environment (little O2 gas). reactions (ribozymes being a notable exception). 2. As Earth cooled, gases condensed, forming the primordial sea. The endosymbiotic theory states that eukaryotes 3. Simple compounds evolved into more complex developed when aerobic bacteria were internalized as organic compounds. mitochondria while the photosynthetic bacteria 4. Organic monomers linked into polymers. became chloroplasts. Evidence for this theory includes 5. Protobionts emerged as precursors to cells. the similarities between mitochondria and 6. Heterotrophic, obligate anaerobic prokaryotes chloroplasts: developed. 7. Autotrophic prokaryotes, such as cyanobacteria They are similar in size. capable of photosynthesis, formed. This led to They possess their own circular DNA. oxygen production and accumulation, creating an They have ribosomes with a large and small oxidizing environment (high O2 gas). subunit. 8. Primitive eukaryotes emerged, supporting the They reproduce independently of the host cell. endosymbiotic theory where membrane bound They contain a double membrane. organelles (mitochondria, chloroplasts), originally free-living, were engulfed by other prokaryotes, leading to a symbiotic relationship. 9. More complex eukaryotes and multicellular organisms began to evolve. Modern cell theory: 1. All lifeforms have one or more cells. 2. The cell is the basic structural, functional, and organizational unit of life. 3. All cells come from other cells (cell division). 4. Genetic information is stored and passed down through DNA. 5. An organism’s activity is dependent on the total activity of its independent cells. 6. Metabolism and biochemistry (energy flow) occurs within cells, 7. All cells have the same chemical composition within organisms of similar species. The central dogma of genetics states that information is passed from DNA → RNA → proteins. There are a few exceptions to this (e.g., reverse transcriptase and prions). © 2024 Bootcamp.com 9  High-Yield Roots, Prefixes, and Suffixes Prefix Meaning Example Root Meaning Example Suffix Meaning Example Against Antibiotic -adrena- Adrenal Adrenaline -ase Enzyme Amylase Anti- Ecto- Outside Ectoderm -blast- Formative cell Osteoblast -crine Secrete Exocrine Endo- Inside Endocrine -derma- Skin Endodermis -cyte Cell Adipocyte Relating to Epi- Above Epidermis -enter- Intestine Enterocyte -cytosis Transcytosis cells Producing, Exo- Outside Exocytosis -gastr- Stomach Gastrin -gen Immunogen generating Insufficient, Hypo- Hypoglycemia -glyc- Sugar Glycogen -genesis Formation of Angiogenesis low Excessive, -lytic or Destruction, Hyper- Hyperactive -hem- Blood Hemoglobin Hemolysis high -lysis breakdown Hydroxyl group, Resembles, Intra- Within Intracellular -hydroxyl- Hydroxylation -oid Nucleoid alcohol related to Inter- Between Intermolecular -leuk- White Leukocyte -ose Sugar Glucose Fearing, Mono- One Monomer -lip- Fat or lipid Lipid -phobic Hydrophobic repelling Peri- Around Peripheral -myo- Muscle Cardiomyocyte -philic Attracting Hydrophilic Nucleus, central Development, Poly- Many Polysaccharide -nucle- Nucleus -plasia Hyperplasia part formation Below, Examination, Sub- Subunit -peptid- Protein chain Peptidase –scopy Microscopy under inspection Supra- Above Supramolecular -phag- Eating, swallowing Phagocytosis –stasis Stopping Epistasis Ribose (five-carbon Trans- Across Transduction -ribos- Deoxyribose –trophy Growth Hypertrophy sugar) © 2024 Bootcamp.com 10 Ch. 2: Cells and Organelles Integral (transmembrane) proteins traverse the entire bilayer, so they must be amphipathic. Their nonpolar parts lie in the middle of the bilayer while Table of Contents their polar ends extend out into the aqueous environment on the inside and outside of the cell. Cell Membrane Usually assist in cell signaling or transport. Crossing Cell Membranes Organelles Peripheral membrane proteins are found on the Cytoskeleton outside of the bilayer, and they are generally Extracellular Matrix hydrophilic. Below are some possible functions: Cellular Tonicity and Cell Circulation Cellular Adaptations Receptor: Trigger secondary responses within the Cell Tissues cell for signaling. If a receptor protein transmits a signal all the way through the lipid bilayer, it is Cell Membrane considered an integral protein. Cell membranes hold cellular contents and are Drugs that bind to receptors can either be agonists or mainly composed of phospholipids and proteins, with antagonists. Agonists are molecules that bind to small amounts of cholesterol. receptors and functionally activate a target, while antagonists bind and prevent other molecules from 1. Phospholipids: Glycerol backbone, one binding, inhibiting production of a response. phosphate group (hydrophilic), and two fatty acid tails (hydrophobic). Amphipathic because the Adhesion: Attaches cells to other things (e.g., molecules have both polar and nonpolar parts, other cells) and act as anchors for the allowing them to form a lipid bilayer in an cytoskeleton. aqueous environment. Cellular recognition: Proteins which have 2. Cholesterol: Has four fused hydrocarbon rings carbohydrate chains (glycoproteins). Used by and is a precursor to steroid hormones. Also cells to recognize other cells. amphipathic and helps regulate membrane fluidity. The fluid mosaic model describes how the 3. Membrane proteins: Are either integral or components that make up the cell membrane can peripheral membrane proteins. move freely within the membrane (“fluid”). Furthermore, the cell membrane contains many Cell Membrane Components different kinds of structures (“mosaic”). Peripheral proteins Phospholipid The fluidity of the cell membrane can be affected by: Integral proteins Temperature: ↑ temperatures increase fluidity while ↓ temperatures decrease it. Cholesterol: Holds membrane together at high temperatures and keeps membrane fluid at low temperatures. Degrees of unsaturation: Saturated fatty acids pack more tightly than unsaturated fatty acids, which have double bonds that may introduce Cholesterol kinks. Trans-unsaturated fatty acids pack more tightly than cis-unsaturated fatty acids (which have a more severe kink). © 2024 Bootcamp.com 11  Crossing Cell Membranes Cytosis refers to the bulk transport of large, hydrophilic molecules across the cell membrane and Cells must regulate the travel of substances across the requires energy (active transport mechanism). cell membrane. There are three types of transport across the cell membrane: Endocytosis involves the cell membrane wrapping around an extracellular substance, internalizing it into 1. Simple diffusion: Diffusion of small uncharged the cell via a vesicle or vacuole. Below are different molecules (e.g., O2, CO2, H2O) or lipid soluble forms of endocytosis: molecules (steroids) directly across the cell membrane, down their concentration gradient Phagocytosis: Cellular eating around solid (high to low) without using energy. objects. 2. Facilitated transport: Channel proteins allow the Pinocytosis: Cellular drinking around dissolved diffusion of large (e.g., glucose, sucrose) or materials (liquids). charged molecules (e.g., Na+, K+, Cl-) across the cell Receptor-mediated endocytosis: Requires the membrane, down their concentration gradient binding of dissolved molecules to peripheral without using energy. membrane receptor proteins, which initiates 3. Active transport: Substances travel against their endocytosis. concentration gradient and require the consumption of energy by carrier proteins. Clathrin is a protein that aids in receptor mediated Primary active transport uses ATP hydrolysis endocytosis by forming a pit in the membrane that to pump molecules against their concentration pinches off as a coated vesicle. This is known as gradient. For example, the sodium-potassium clathrin mediated endocytosis. (Na+/K+) pump establishes membrane potential (discussed in later chapters). Exocytosis is the opposite of endocytosis, in which Secondary active transport uses free energy material is released to the extracellular environment released when other molecules flow down through vesicle secretion. their concentration gradient (gradient established by primary active transport) to pump the molecule of interest across the membrane. Active Transport Primary Secondary Na+ Glucose Cotransporter High [Na+] (symporter) Low [glucose] Low [Na+] High ADP [glucose] ATP P © 2024 Bootcamp.com 12  Nucleus Organelles Cellular Structures Nuclear envelope Golgi apparatus Centrioles Ribosomes Mitochondria Nucleolus Smooth ER Lysosomes Vacuoles Peroxisomes Cell Nucleolus membrane Rough ER Nucleus Ribosomes are not considered to be organelles; they Organelles are cellular compartments enclosed by work as small factories that carry out translation phospholipid bilayers (membrane bound). They are (mRNA → protein). They are composed of ribosomal located within the cytosol (aqueous intracellular fluid) subunits. and help make up the cytoplasm (cytosol + organelles). Eukaryotic ribosomal subunits (60S and 40S) assemble in the nucleoplasm and are then exported from the Only eukaryotic cells contain membrane-bound nucleus to form the complete ribosome in the cytosol organelles. Prokaryotes do not, but they have other (80S). (S does not refer to mass, but to sedimentation adaptations, such as keeping their genetic material in characteristics.) a region called the nucleoid (more on this in later chapters). Prokaryotic ribosomal subunits (50S and 30S) assemble in the cytosol and also form complete The nucleus primarily functions to protect and house ribosomes (70S) there. DNA. DNA replication and transcription (DNA → mRNA) occurs here. Free-floating ribosomes make proteins that function in the cytosol while ribosomes embedded in the rough Parts of the nucleus: endoplasmic reticulum (rough ER) make proteins that are sent out of the cell or to the cell membrane. The nucleoplasm is the cytoplasm of the nucleus. The nuclear envelope is the membrane of the nucleus. It contains two phospholipid bilayers (one inner, one outer) with a perinuclear space in the middle. Nuclear pores are holes in the nuclear envelope that allow molecules to travel in and out of the nucleus. The nuclear lamina provides structural support to the nucleus, as well as regulating DNA and cell division. The nucleolus is a dense area responsible for producing components of ribosomal subunits including rRNA (ribosomal RNA). © 2024 Bootcamp.com 13 The rough endoplasmic reticulum (rough ER) is Lysosomes are membrane-bound organelles that continuous with the outer membrane of the nuclear break down substances (through hydrolysis) taken in envelope and is “rough” because it has ribosomes through endocytosis. Lysosomes contain acidic embedded in it. Proteins synthesized by the digestive enzymes that function at a low pH. They also embedded ribosomes are sent into the lumen (inside carry out autophagy (the breakdown of the cell’s own of the rough ER) for modifications (e.g., glycosylation). machinery for recycling) and apoptosis (programmed Afterwards, they are either sent out of the cell or cell death). become part of the cell membrane. Rough ER Proteasomes are similar in function to lysosomes. These are protein complexes that degrade unneeded or damaged proteins by proteolysis. Ribosomes Such proteins have a ubiquitin molecule attached, tagging these proteins for degradation. Vacuoles: Transport vacuoles: Transport materials between Interconnected organelles. flattened sacs Food vacuoles: Temporarily hold endocytosed food, and later fuse with lysosomes. The smooth endoplasmic reticulum (smooth ER) is Central vacuoles: Very large in plants and have a an extension of the rough ER. Its main function is to specialized membrane called the tonoplast (helps synthesize lipids, produce steroid hormones, and maintain cell rigidity by exerting turgor). Function detoxify cells. in storage and material breakdown. Smooth ER Storage vacuoles: Store starches, pigments, and toxic substances. Contractile vacuoles: Found in single-celled organisms and works to actively pump out excess Interconnected water. flattened sacs (no ribosomes) The endomembrane system is composed of the different membranes that are suspended in the cytoplasm within a eukaryotic cell. It is a group of The Golgi apparatus stores, modifies, and exports organelles and membranes that work together to proteins that will be secreted from the cell. It is made modify, package, and transport proteins and lipids up of cisternae (flattened sacs) that modify and that are entering or exiting a cell. The components of package substances. Vesicles come from the ER and the endomembrane system include the nucleus, reach the cis face (side closest to ER) of the Golgi rough and smooth ERs, Golgi apparatus, lysosomes, apparatus. Vesicles leave the Golgi apparatus from the vacuoles, and cell membrane. trans face (side closest to cell membrane). The Golgi apparatus has a significant role in the Golgi Apparatus endomembrane system: it receives vesicles from the Cis face ER on the cis face that empty proteins and lipids into the lumen of the Golgi. These proteins/lipids undergo modifications and are then sorted, tagged, packaged, and distributed as secretory products. Flattened sacs Trans face © 2024 Bootcamp.com 14  Peroxisomes perform hydrolysis, break down stored Centrosomes are organelles found in animal cells fatty acids, and help with detoxification. These containing a pair of centrioles. They act as processes generate hydrogen peroxide, which is toxic microtubule organizing centers (MTOCs) during cell since it can produce reactive oxygen species (ROS). division (chapter 5). ROS damage cells through free radicals. Peroxisomes Centrosomes contain an enzyme called catalase, which quickly breaks down hydrogen peroxide into water and oxygen. Mitochondria are the powerhouses of the cell, Two perpendicular producing ATP for energy use through cellular cylinders respiration (chapter 3). Mitochondrial inheritance is maternal, meaning all mitochondrial DNA in humans originates from the mother. Mitochondria Inward folds (cristae) Cytoskeleton The cytoskeleton provides structure and function within the cytoplasm. Microfilaments are the smallest structure of the cytoskeleton, and are composed of a double helix made of two actin filaments. They are mainly involved Chloroplasts are found in plants and some protists. in cell movement and can quickly assemble and They carry out photosynthesis (chapter 4). disassemble. Below are some of their functions: Chloroplasts are a type of plastid. Plastids are 1. Cleavage furrow: During cell division, myosin double-membraned organelles found exclusively motors and actin microfilaments form contractile within plant cells and algae, that function in rings that split the cell. photosynthesis and storage of metabolites. 2. Cyclosis (cytoplasmic streaming): The flow (or stirring) of the cytoplasm inside the cell. It is driven Chloroplast Stacks (granum) by forces via actin (microfilaments) and myosin of flattened movement, in a manner similar to muscle membranes contraction. (thylakoids) 3. Muscle contraction: Actin microfilaments have directionality, allowing myosin motor proteins to pull on them for muscle contraction. Intermediate filaments are between microfilaments and microtubules in size. They are more stable than microfilaments and mainly help with structural support. For example, keratin is an important intermediate filament protein in skin, hair, and nails. Lamins are a type of intermediate filament which helps make up the nuclear lamina, a network of fibrous intermediate filaments that supports the nucleus. © 2024 Bootcamp.com 15  Microtubules are the largest in size and give Cilia and Flagella structural integrity to cells. They are hollow and have walls made of tubulin protein dimers. Microtubules Cilia are small hair-like projections found only in also form centrioles (used in cell division) and are eukaryotes. They line the outside of eukaryotic cells found in cilia and flagella (beating appendages, for and function in locomotion of either the cell itself or example cilia remove debris in the lungs and flagella fluids. There are two types: propel sperm). 1. Motile cilia: Help the cell or fluids move around Cytoskeletal Proteins 2. Non-motile cilia: Act as cellular antennas that Microfilaments receive signals from neighboring cells and environment. Structurally, cilia have microtubules made of tubulin. Intermediate They are produced by a basal body, which is initially filaments formed by the mother centriole (older centriole after S phase replication). Flagella are longer hair-like structures found in both Microtubules prokaryotes and eukaryotes. Like cilia, flagella also function in locomotion of the cell or fluids. Eukaryotic flagella are composed of polymers of tubulin with the same 9+2 array as cilia. Kinesin and dynein are motor proteins that transport Prokaryotic flagella are composed of polymers of cargo along microtubules. flagellin and do not have this 9+2 array (they are not microtubules). Kinesin Eukaryotic flagella move in a bending motion, ATP hydrolysis powered “footsteps” while prokaryotic flagella move in a rotary motion. Cargo Eukaryotic Flagella Prokaryotic Flagella Kinesins Composed of tubulin Composed of flagellin ADP ATP Pi dimers Larger, more complex Smaller, simpler structure structure Microtubule ATP driven Proton driven Bending motion Rotary motion Microtubule organizing centers (MTOCs) are present in eukaryotic cells and help organize Complex sliding filament Rotary motor microtubule extension. system Centrioles are hollow cylinders made of microtubules. Centrosomes contain a pair of centrioles oriented at 90 degree angles to one-another. They replicate during the S phase of the cell cycle so that each daughter cell after cell division has one centrosome. © 2024 Bootcamp.com 16  Extracellular Matrix Cell-cell junctions (connect adjacent cells): The extracellular matrix (ECM) provides extracellular 1. Tight junctions: Form water-tight seals between mechanical support for cells. cells to ensure substances pass through cells and not between them. ECM components: 2. Desmosomes: Provide support against mechanical stress. Connects neighboring cells via Proteoglycan: A type of glycoprotein that has a intermediate filaments. high proportion of carbohydrates. 3. Adherens junctions: Similar in structure and Collagen: The most common structural protein; function to desmosomes, but connects organized into collagen fibrils (fibers of neighboring cells via actin microfilaments. glycosylated collagen secreted by fibroblasts). 4. Gap junctions: Allow passage of ions and small Integrin: A transmembrane protein that facilitates molecules between cells. Formed from ECM adhesion and signals to cells how to respond transmembrane proteins known as connexons. to the extracellular environment (growth, Gap junctions are only present in animal cells. apoptosis, etc.). Fibronectin: A protein that connects integrin to Plant cells contain a few unique cell junctions: ECM and helps with signal transduction. Laminin: Behaves similarly to fibronectin. 1. Middle lamella: Sticky cement similar in function Influences cell differentiation, adhesion, and to tight junctions. movement. It is a major component of the basal 2. Plasmodesmata: Tunnels with tubes between lamina (a layer of the ECM secreted by epithelial plant cells. Allows cytosol fluids to freely travel cells). between plant cells. Cell walls are carbohydrate-based structures that act Intercellular Junctions like a substitute ECM because they provide structural Animal cell junctions Plant cell junctions support to cells that either do not have ECM, or have a Adjacent cell minimal ECM. They are present in plants (cellulose), membranes Cell wall Cell fungi (chitin), bacteria (peptidoglycan), and archaea. Tight and wall junctions Protein membrane of complex of one cell adjacent Peptidoglycan is a polysaccharide with peptide chains. cell This is the primary component of bacterial cell walls. Open The cell wall of archaea is also made of channel polysaccharides, but does not contain peptidoglycan. Gap Closed junctions channel Middle The glycocalyx is a glycolipid/glycoprotein coat found Plasmodesmata lamella Connexon mainly on bacterial and animal epithelial cells. It helps with adhesion, protection, and cell recognition. Plaque Cell-matrix junctions (connect ECM → cytoskeleton): Desmosomes Intermediate 1. Focal adhesions: ECM connects via integrins to filaments actin microfilaments inside the cell. Adherens 2. Hemidesmosomes: ECM connects via integrins to junctions intermediate filaments inside the cell. Actin microfilaments © 2024 Bootcamp.com 17  Cellular Tonicity and Cell Circulation Cellular Adaptations Isotonic solutions have the same solute Cells can undergo a range of adaptations that will concentration as the cells placed in them. ensure their survival due to changes in environmental conditions: Hypertonic solutions have a higher solute concentration than the cells placed in them, causing Atrophy: Decrease in cell size due to reduced water to leave the cell. metabolic activity. Hypertrophy: Increase in cell size due to increased Animal cells shrivel. metabolic activity. Cells that have a cell wall (plants, bacteria, fungi, Hyperplasia: Increase in the number of cells in an etc.) undergo plasmolysis, the process of the organ or tissue that appear normal under a cell’s cytoplasm shrinking away from the cell wall. microscope, often seen in the beginning of cancer. Metaplasia: A somatic cell undergoing Hypotonic solutions have a lower solute transformation into another specialized type of concentration than the cells placed in them, causing somatic cell. water to enter the cell. Dysplasia: Development of phenotypically abnormal cells in a tissue that can lead to Animal cells swell and can burst (lysis). cancerous growth. Plant, bacterial, and fungal cells become turgid (swollen and hard). Cell Tissues Tonicity There are four basic types of tissues: Cell added into 3 different solutions 1. Epithelial tissues are cohesive sheets of cells that line internal organs and cover the body. 2. Connective tissues support the structure of the Hypotonic Isotonic Hypertonic organism. Sparse connective tissue cells are scattered within an extracellular matrix. Cartilage, Lysis Shrivel bone, blood, and adipose (fat) are all types of H2O H2O H2O connective tissue. 3. Muscle tissue is responsible for body movement. Muscle tissue is subdivided into smooth, skeletal, and cardiac muscles. 4. Nervous tissues process and transmit information within the body. Nervous tissue is composed of neurons to send information and various support cells called glial cells. © 2024 Bootcamp.com 18 Ch. 3: Cellular Energy Adenosine Triphosphate (ATP) Phosphate groups Table of Contents Adenine base Biothermodynamics Adenosine Triphosphate (ATP) Ribose Mitochondria sugar Aerobic Cellular Respiration ATP Yield of Aerobic Cellular Respiration Nucleoside Fermentation Nucleotide Alternative Sources of Energy Generation Nucleoside diphosphate Nucleoside triphosphate Biothermodynamics These bonds release energy upon hydrolysis (breaking bonds), resulting in ATP losing a phosphate group and Laws of thermodynamics: becoming adenosine diphosphate (ADP). Because of the additional negatively-charged phosphate group, 1. Energy cannot be created nor destroyed, but can ATP is less stable than ADP. be transformed from one form to another. 2. The entropy (disorder) of the universe is always Reaction coupling is the process of powering an increasing. The combined change in entropy energy-requiring reaction with an energy-releasing (system and surroundings) must be positive. one. It allows an unfavorable reaction to be powered 3. The entropy of a substance at absolute zero is 0. by a favorable reaction, making the net Gibbs free energy negative (-ΔG = exergonic = releases energy + Metabolism refers to all the metabolic pathways spontaneous). (series of chemical reactions) that are happening in a given organism. Catabolic processes involve breaking Mitochondria down larger molecules for energy (less ordered state, increased entropy), while anabolic processes involve Mitochondria are organelles that produce ATP using energy to build larger macromolecules (more through cellular respiration (catabolic process). They ordered state, decreased entropy). have an outer membrane and an inner membrane with many infoldings called cristae. The To break down carbohydrates for energy, cells either intermembrane space is located between the outer utilize aerobic cellular respiration (consumes and inner membranes while the mitochondrial oxygen, more energy produced) or anaerobic cellular matrix is located inside the inner membrane. respiration (no oxygen needed, but less energy produced). Mitochondria Adenosine Triphosphate (ATP) Cytosol Adenosine triphosphate (ATP) is an RNA nucleoside Cristae triphosphate. It contains an adenine nitrogenous base linked to a ribose sugar (RNA nucleoside part), and Mitochondrial three phosphate groups connected to the sugar matrix (triphosphate part). Inner membrane ATP is used as the cellular energy currency because of Inter- the high energy bonds between the phosphate membrane groups. space Outer membrane © 2024 Bootcamp.com 19  Aerobic Cellular Respiration Since 2 ATP are used up in the energy investment phase and 4 ATP are produced in the energy payoff Aerobic cellular respiration is performed to phase, a net of 2 ATP is produced per glucose phosphorylate ADP into ATP by breaking down molecule within glycolysis. glucose and moving electrons around (oxidation and Glycolysis reduction reactions). Aerobic cellular respiration involves four catabolic processes: Glucose 1. Glycolysis ATP 2. Pyruvate oxidation 3. Krebs cycle Hexokinase ADP Energy investment 4. Oxidative phosphorylation Glucose-6-phosphate 1. Glycolysis Isomerase Glucose → 2 ATP + 2 NADH + 2 pyruvate Fructose-6-phosphate Glycolysis takes place in the cytosol and does not ATP require oxygen, so it is also used in fermentation. Phosphofructokinase ADP Substrate-level phosphorylation is the process used Fructose-1,6-bisphosphate to generate ATP in glycolysis by transferring a phosphate group to ADP directly from a phosphorylated compound. G3P G3P Glycolysis has an energy investment phase and an NAD+ NAD+ energy payoff phase: Energy payoff 1. Hexokinase uses one ATP to phosphorylate NADH NADH glucose into glucose-6-phosphate, which cannot ADP ADP leave the cell (it becomes trapped by the phosphorylation). ATP ATP 2. Isomerase modifies glucose-6-phosphate into fructose-6-phosphate. 3. Phosphofructokinase uses a second ATP to Pyruvate Pyruvate phosphorylate fructose-6-phosphate into fructose-1,6-bisphosphate. This is the key regulatory step in glycolysis. 4. Fructose-1,6-bisphosphate is broken into dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P), which are in equilibrium with one another. 5. G3P proceeds to the energy payoff phase so DHAP is constantly converted into G3P to maintain equilibrium. Thus, 1 glucose molecule will produce 2 G3P that continue into the next steps. 6. G3P undergoes a series of redox reactions to produce 4 ATP through substrate-level-phosphorylation, 2 pyruvate and 2 NADH. © 2024 Bootcamp.com 20  2. Pyruvate oxidation 3. Krebs cycle 2 pyruvate → 2 CO2 + 2 NADH + 2 acetyl-CoA 2 acetyl-CoA → 4 CO2 + 6 NADH + 2 FADH2 + 2 ATP Pyruvate dehydrogenase is an enzyme that carries The Krebs cycle is also known as the citric acid cycle out the pyruvate oxidation steps below: or the tricarboxylic acid (TCA) cycle. Like pyruvate oxidation, it also occurs in the mitochondrial matrix 1. Decarboxylation: Pyruvate molecules (3 carbon and the cytosol for prokaryotes. molecule) move from the cytosol into the mitochondrial matrix (stays in the cytosol for 1. Acetyl-CoA joins oxaloacetate (four-carbon) to prokaryotes), where they undergo form citrate (six-carbon). decarboxylation, producing 1 CO2 and one 2. Citrate undergoes rearrangements that produce 2 two-carbon molecule per pyruvate. CO2 and 2 NADH. 2. Oxidation: The two-carbon molecule is converted 3. After the loss of two CO2, the resulting four-carbon into an acetyl group, giving electrons to NAD+ to molecule produces 1 ATP through substrate-level convert it into NADH. phosphorylation. 3. Coenzyme A (CoA): CoA binds to the acetyl group, 4. The molecule will now transfer electrons to 1 FAD, producing acetyl-CoA. which is reduced into 1 FADH2. 5. Lastly, the molecule is converted back into Pyruvate Oxidation oxaloacetate and also gives electrons to produce 1 NADH. 6. Two acetyl-CoA molecules produce 4 CO2 + 6 NADH + 2 FADH2 + 2 ATP. NAD+ NADH Coenzyme A (CoA) Krebs Cycle Acetyl CoA Pyruvate CO2 Acetyl CoA CoA Matrix Oxaloacetate Citrate CO2 NADH Each round of the NAD+ citric acid cycle NADH NAD+ produces: 3 NADH 2 CO2 FADH2 1 FADH2 1 ATP CO2 FAD NAD+ NADH Mitochondria ATP ADP © 2024 Bootcamp.com 21 4. Oxidative phosphorylation Oxidative Phosphorylation Cytoplasm Electron carriers (NADH + FADH2) + O2 → ATP + H2O Outer membrane The electron transport chain (ETC) and chemiosmosis (ions moving down electrochemical gradients) work together to produce ATP in oxidative High [H+] Intermembrane space phosphorylation. Oxygen acts as a final electron H+ H+ H+ acceptor and gets reduced to form water. ETC goal: Regenerate electron carriers and create an IV ATP I III synthase electrochemical gradient to power ATP production. 4e- II The mitochondrial inner membrane is the location of the ETC for eukaryotes while the cell membrane is NADH NAD+ FADH2 FAD 4H+ + O2 + 4e- 2 H2O ADP ATP the location of the ETC for prokaryotes. Low [H+] Mitochondrial matrix Four protein complexes (I-IV) are responsible for Electron transport chain (ETC) Chemiosmosis moving electrons through a series of oxidation-reduction (redox) reactions in the ETC. As ATP Yield of Aerobic Cellular Respiration the series of redox reactions occurs, protons are pumped from the mitochondrial matrix to the Aerobic respiration is exergonic, with a ΔG = -686 intermembrane space, forming an electrochemical kcal/mol glucose. gradient. This is the reason the intermembrane space is highly acidic. NADH produces 3 ATP (NADH from glycolysis produces less)* NADH is more effective than FADH2 and drops electrons off directly at complex-I, regenerating NAD+. *The 2 NADH from glycolysis produce 4-6 ATP because a varying amount of ATP must be used to shuttle FADH2 drops electrons off at protein complex-II, these NADH from the cytosol to the mitochondrial regenerating FAD. However, this results in the matrix. However, prokaryotes do not need to shuttle pumping of fewer protons due to the bypassing of their NADH, so they will produce 6 ATP. complex-I. FADH2 produces 2 ATP. Chemiosmosis goal: Use the proton electrochemical gradient (proton-motive force) to synthesize ATP. Net ATP Stage Net products ATP synthase is a channel protein that provides a yield hydrophilic tunnel to allow protons to flow down their 2 ATP (substrate 2 ATP electrochemical gradient (from the intermembrane level) space back to the mitochondrial matrix). The Glycolysis spontaneous movement of protons generates energy 2 NADH 4-6 ATP that is used to convert ADP + Pi into ATP, a Pyruvate 2 NADH 6 ATP condensation reaction that is endergonic (requires decarboxylation energy + nonspontaneous = +ΔG). 2 ATP 2 ATP Krebs cycle 6 NADH 18 ATP 2 FADH2 4 ATP Total 36-38 ATP © 2024 Bootcamp.com 22  Fermentation Anaerobic Respiration Alcohol fermentation Lactic acid fermentation Fermentation is an anaerobic pathway (no oxygen) that only relies on glycolysis by converting the Glucose Glucose produced pyruvate into different molecules in order to + + 2 NAD 2 ADP 2 NAD 2 ADP oxidize NADH back to NAD+. Regenerating NAD+ Glycolysis means glycolysis can continue to make ATP. 2 NADH 2 ATP 2 NADH 2 ATP Fermentation occurs within the cytosol. The two most common types of fermentation are lactic acid 2 Pyruvate 2 Pyruvate fermentation and alcohol fermentation. 2 CO2 1. Lactic acid fermentation 2 Acetaldehyde Fermentation Lactic acid fermentation uses the 2 NADH from 2 NADH 2 NADH + NAD NAD+ glycolysis to reduce the 2 pyruvate into 2 lactic acid. regeneration regeneration 2 NAD+ 2 NAD+ Thus, NADH is oxidized back to NAD+ so that glycolysis may continue. 2 Ethanol 2 Lactate The Cori cycle is used to help convert lactate back into glucose once oxygen is available again. It Types of organisms based on ability to grow in oxygen: transports the lactate to liver cells, where it can be oxidized back into pyruvate. Pyruvate can then be Obligate aerobes: Only perform aerobic used to form glucose, which can be used for more respiration, so they need the presence of oxygen ideal energy generation. to survive. Obligate anaerobes: Only undergo anaerobic Lactic acid fermentation is used by muscle cells during respiration or fermentation; oxygen is poison to periods of intense exercise, when them. aerobically-produced ATP is quickly depleted and Facultative anaerobes: Can do aerobic there is low oxygen availability. Muscle cells will then respiration, anaerobic respiration, or default to lactic acid fermentation to produce energy fermentation, but prefer aerobic respiration anaerobically to continue to meet demand. because it generates the most ATP. Microaerophiles: Only perform aerobic Additionally, lactic acid fermentation occurs respiration, but high amounts of oxygen are continuously in red blood cells, which lack harmful to them. mitochondria needed for aerobic respiration. Aerotolerant organisms: Only undergo anaerobic respiration or fermentation, but oxygen 2. Alcohol fermentation is not poisonous to them. Alcohol fermentation uses the 2 NADH from Microorganism Oxygen Preferences glycolysis to convert the 2 pyruvate into 2 ethanol. Thus, NADH is oxidized back to NAD+ so that glycolysis may continue. However, this process has an extra step Facultative anaerobe that first involves the decarboxylation of pyruvate into Obligate anaerobe Obligate aerobe Microaerophile acetaldehyde, which is only then reduced by NADH Aerotolerant into ethanol. [O2] © 2024 Bootcamp.com 23  Alternative Sources of Energy Generation Free fatty acids undergo beta-oxidation to be converted into acetyl-CoA. Beta-oxidation occurs in Molecules other than glucose, such as other types of the mitochondrial matrix of eukaryotic cells and carbohydrates, fats, and proteins can be modified to requires an initial investment of ATP; the fatty acid enter cellular respiration at various stages for energy chain is then continuously cleaved to yield two-carbon generation. acetyl-CoA molecules (which can be used in the Krebs cycle for ATP generation) and electron carriers (NADH 1. Other carbohydrates mostly enter during + FADH2 - produces more ATP). glycolysis. Glycogenolysis describes the release of Beta-Oxidation glucose-6-phosphate from glycogen, a highly branched polysaccharide of glucose. Fatty acid Disaccharides can undergo hydrolysis to release ATP Coenzyme A (CoA) two carbohydrate monomers, which can enter ADP glycolysis. Fatty acyl CoA (activated) Glycogenolysis Digestion FADH & NAD+ Acetyl CoA β-oxidation cycle FADH2 & NADH Glycogen Glucose-6-phosphate Krebs Electron transport cycle chain (ETC) Carbohydrates are the preferred energy source since they are easily catabolized and are high yield (4 kcal/gram). Glycogenesis refers to the reverse process - the Fats are harder to catabolize than carbohydrates as conversion of glucose into glycogen to be stored in the they must undergo beta-oxidation and transport away liver when energy and fuel is sufficient. Glycogen is from fat cells. However, per carbon molecule, fats are stored in the liver and muscle cells. the most efficient source of energy containing about ~9 kcal/gram. 2. Fats are mostly present in the body as triglycerides. Lipases are required to first digest 3. Proteins are the least desirable energy source (4 fats into free fatty acids and alcohols through a kcal/gram) because the processes to get them into process called lipolysis. These digested pieces cellular respiration take considerable energy and then can be absorbed by enterocytes in the small proteins are needed for many essential functions intestine and reform triglycerides. in the body. Adipocytes are cells that store fat (triglycerides) and have hormone-sensitive lipase enzymes to help release triglycerides back into circulation as lipoproteins or as free fatty acids bound by a protein called albumin. Chylomicrons are lipoprotein transport structures formed by the fusing of triglycerides with proteins, phospholipids, and cholesterol. They leave enterocytes and enter lacteals, small lymphatic vessels that take fats to the rest of the body. © 2024 Bootcamp.com 24 Ch. 4: Photosynthesis Photosynthesis vs. Cellular Respiration Photosynthesis Table of Contents Net energy input Chloroplast (endergonic) Objective of Photosynthesis Photosynthesis and Cellular Respiration Leaf Structures of Photosynthesis Light Dependent Reactions of Photosynthesis The Calvin Cycle Photorespiration 6 CO2 6 H2O C6H12O6 6 O2 Alternative Photosynthetic Pathways Carbon Water Glucose Oxygen dioxide Objective of Photosynthesis ATP Net energy output Mitochondria While heterotrophs must get energy from the food (exergonic) they eat, autotrophs can make their own food. Cellular respiration Photoautotrophs take light energy and convert it to chemical energy using photosynthesis. This process Leaf Structures of Photosynthesis originally developed in cyanobacteria. Mesophyll cells: Located between the upper and Photosynthesis reduces atmospheric carbon dioxide, lower epidermis of leaves. Facilitate gas movement releases oxygen, and creates chemical energy that can within the leaf. Contain chloroplasts. be transferred through food chains. Photons (light energy) are used to synthesize sugars (glucose) in Chloroplasts: Organelle that carries out photosynthesis. photosynthesis. Found in plants and photosynthetic algae, but not in cyanobacteria. They are similar to Carbon fixation is the process by which inorganic mitochondria and contain the following structures carbon (CO2) is converted into an organic molecule (outermost to innermost): (glucose). Photosynthesis takes electrons released from photolysis (the process of splitting water Structure Description molecules) and excites them using solar energy. These excited electrons are then used to power carbon Outer Outer plasma membrane made fixation. membrane of phospholipid bilayer. Intermembrane Space between the outer and Photosynthesis and Cellular Respiration space inner membranes Photosynthesis and cellular respiration are reverse Inner plasma membrane made Inner membrane processes in terms of their overall reactions: of phospholipid bilayer. Fluid material that fills the area Photosynthesis is non-spontaneous and endergonic, Stroma inside the inner membrane. producing glucose after an input of solar energy. The Calvin cycle occurs here. Cellular respiration is spontaneous and exergonic, A membrane structure within breaking down glucose to generate energy in the form the stroma. Multiple stack up to Thylakoids form a granum. They are the of ATP. site of light dependent reactions. Interior of the thylakoid and H+ Thylakoid lumen ions accumulate here, making it acidic. © 2024 Bootcamp.com 25  Light Dependent Reactions of Photosynthesis 3. The primary electron acceptor sends the excited electrons to the electron transport chain (ETC). The light dependent reactions occur in the During the redox reactions within the ETC, protons thylakoid membrane and harness light energy to are pumped from the stroma to the thylakoid produce ATP and NADPH (an electron carrier) for later lumen. The electrons are then deposited into use in the Calvin cycle. ATP generated in the light photosystem I. dependent reactions is not used to power the cell; it is 4. Photons excite pigments in photosystem I, consumed in the Calvin cycle. energizing the electrons in the reaction center to be passed to another primary electron acceptor. Photosystems contain special pigments, such as 5. The electrons are sent to a short electron chlorophyll, that absorb photons. Chlorophyll transport chain that terminates with NADP+ absorbs red and blue light and reflects green light, reductase, an enzyme then reduces NADP+ into giving plants their green color. NADPH using electrons and protons. 6. The accumulation of protons in the thylakoid The reaction center is a special pair of chlorophyll lumen generates an electrochemical gradient molecules in the center of these proteins. Chlorophyll that is used to produce ATP using an ATP has a porphyrin ring structure with a magnesium synthase, as H+ moves from the thylakoid lumen atom bound in its center. Photosystem II (P680) and back into the stroma. photosystem I (P700) are used in photosynthesis. Cyclic photophosphorylation: Photosystem I returns Non-cyclic photophosphorylation is carried out by its electrons to the first ETC instead of to the NADP+ the light-d