Copy of Untitled Notebook (1) (1)-compressed (1).pdf - Enzymes are proteins that catalyze chemical reactions. They bind to substrates at their active

Copy of Untitled Notebook (1) (1)-compressed (1).pdf

- Enzymes are proteins that catalyze chemical reactions. They bind to substrates at their active sites and lower

the activation energy, speeding up the reaction process.

- The active site of an enzyme binds to the substrate through weak interactions such as hydrogen bonds and

ionic bonds.

- Enzymes undergo an induced fit mechanism, where the enzyme changes its shape to accommodate the

substrate in the active site.

- Enzymes have specific catalytic groups that contribute to catalysis, including general acid-base catalysis,

covalent catalysis, and metal ion catalysis.

- Factors such as temperature and pH can affect enzyme activity. Each enzyme has an optimal temperature and

pH range for its function.

- The Michaelis-Menten kinetics equation describes the relationship between substrate concentration, reaction

velocity, and the Michaelis constant (Km).

- Exergonic reactions release energy, whereas endergonic reactions absorb energy.

- Living cells require energy from external sources to generate ATP for cellular work, which is essential for

life processes.

- Redox reactions involve the transfer of electrons between reactants, where oxidation refers to the loss of

electrons, and reduction refers to the gain of electrons.

- Cellular respiration is a process where organic molecules are oxidized, and oxygen is reduced, leading to the

production of ATP.

- Glycolysis is the initial stage of cellular respiration, breaking down glucose into pyruvate through a series of

enzymatic reactions.

- The Warburg effect is a phenomenon in cancer cells where they rely more on glycolysis for energy

production even in the presence of oxygen.- Tumor cells have glycolytic rates 200 times higher than normal

cells due to reasons such as a low-oxygen environment, tumor-associated enzymes, and damage to

mitochondria

- Diagnosis of tumors can be done using 18F-labeled substrate hexokinase PET scanning

- Michaelis-Menten kinetics equation: vo = Vmax[S] / (Km + [S])

- Cofactors are non-protein enzyme helpers that can be inorganic or organic, with vitamins being a type of

coenzyme

- Enzyme inhibitors can block activity through competitive or non-competitive mechanisms

- Allosteric regulation of enzymes can either inhibit or stimulate enzyme activity

- Feedback inhibition can shut down a metabolic pathway by the end product of the pathway

- Examples of enzyme inhibitors include toxins, poisons, pesticides, and antibiotics

- Allosteric regulators can be potential drug candidates for enzyme regulation

- The citric acid cycle, also known as the Krebs cycle, takes place in the mitochondrial matrix and generates

ATP, NADH, and FADH2

- The electron transport chain in the mitochondria generates ATP via oxidative phosphorylation by passing

electrons from NADH and FADH2 to oxygen

- Chemiosmosis couples electron transport to ATP synthesis through the movement of H+ ions across the

inner mitochondrial membrane

- ATP synthase is a nanomachine that uses the energy of the H+ gradient to drive the phosphorylation of ADP

to ATP- The F0F1 ATPase structure of mammalian cells was studied in a publication from November 2020 in

the journal Nat Struct Mol Biol. It is involved in ATP synthesis.

- An article on Sheep ATP synthase was published in Science in June 2019, detailing its role in energy

production.

- The energy stored in the H+ gradient across membranes is crucial for coupling redox reactions in the electron

transport chain to ATP synthesis.

- The H+ gradient, also known as the proton-motive force, powers the ATP synthase protein complex,

generating ATP from ADP and Pi.

- Cellular respiration involves a sequence of events starting from glucose breakdown to ATP production

through the electron transport chain and chemiosmosis, with about 35% efficiency in energy harvest from

glucose.

- Bacteria lack membrane-bound organelles like mitochondria, yet they engage in aerobic metabolism through

two cellular membranes.

- Fermentation and anaerobic respiration are alternate pathways for ATP production when oxygen is limited or

absent, using electron carriers.

- Fermentation pathways, such as alcohol fermentation and lactic acid fermentation, are essential for

generating ATP without oxygen.

- Glycolysis, the citric acid cycle, and pathways like beta-oxidation connect various catabolic and anabolic

pathways in metabolism.- Feedback mechanisms, including feedback inhibition, regulate cellular respiration to maintain ATP levels.

- Hibernation and the Warburg effect are examples of uncoupling glycolysis from aerobic metabolism for

specific physiological needs.

- Cellular respiration and photosynthesis involve redox reactions, where electrons are transferred to generate

ATP or store energy in bonds of sugars, respectively.- In chloroplast, the photosynthetic electron transport

chain acidifies the thylakoid space.

- Puncturing the thylakoid membrane would affect processes like splitting water, the flow of electrons in

Photosystem II and Photosystem I, synthesis of ATP, and reduction of NADP+.

- Autotrophs are able to produce their own food through photosynthesis, while heterotrophs rely on consuming

other organisms for nutrition.

- Photosynthetic organisms convert light energy into chemical energy through the light reactions of

photosynthesis.

photosynthetic organisms use the products of light reactions to make sugar.

Untitled Notebook (1) (1)-compressed (1).pdf

- Class 14 on Photosynthesis (Calvin-Benson Cycle) is on Friday, February 21st with guiding questions

focusing on the conversion of light reactions into sugars and how photosynthetic organisms adapt to hot and

arid climates.

- Two practice questions are provided: one about NADP+ in photosynthesis and the other about the products

of the light reactions.

- The Calvin-Benson Cycle involves two stages: light reactions in the thylakoids and the Calvin-Benson Cycle

in the stroma, broken down into three phases.

- Alternative mechanisms like C4 plants and CAM plants have evolved to deal with hot and arid climates by

optimizing the Calvin cycle and minimizing photorespiration.

- The lecture covers various aspects of photosynthesis, including the two stages, the Calvin Cycle broken

down into three phases, and alternative mechanisms for plants in hot, arid climates.

- Biological membranes and bonds are discussed, including different types of chemical bonds and the factors

that determine whether a molecule is polar or non-polar.

- Factors such as electronegativity determine how evenly atoms share electrons in covalent bonds, leading to

polarity in molecules like water.

- The structure of water is related to its function through hydrogen bonds and the specific heat capacity of

water, which moderates temperature changes.

- Acids, bases, and buffers are defined, with explanations of their roles in maintaining the pH balance in living

organisms.

- A practice question on calculating pH from hydrogen ion concentration is provided to reinforce

understanding.- In the alveolus, CO2 is exchanged for O2 to facilitate the process of respiration.

- Fused basement membranes help maintain the structure and integrity of tissues in the body.

- CO2 dissolved in plasma can combine with water to form carbonic acid (H2CO3) through the action of

carbonic anhydrase.

- The chloride shift, facilitated by transport proteins, helps maintain the ionic balance in red blood cells during

gas exchange.

- Carbon is considered the backbone of life due to its ability to form complex structures with its four unpaired

electrons in the outer valence shell, allowing it to form 4 covalent bonds with other atoms.

- The polarity of molecules is determined by the arrangement of atoms and their electronegativities,

influencing their functions in biological systems.

- Carbohydrates, lipids, proteins, and nucleic acids are the four major classes of biological macromolecules

that make up all living organisms.

- Monosaccharides, disaccharides, and polysaccharides are different forms of sugars that serve as fuel and

building materials for cells.

- Fats, phospholipids, and steroids are important types of lipids that play various roles in cellular function,

such as energy storage and membrane structure.

- Proteins are essential macromolecules that perform a wide range of functions in the body, including

catalyzing reactions, providing structural support, and aiding in communication between cells.

- Nucleic acids, including DNA and RNA, store and transmit genetic information through the sequences of

nucleotides they contain.- Nucleic acids are made up of nucleotides that have a 3' end and a 5' end

- The nitrogenous bases in nucleic acids include pyrimidines (Cytosine, Thymine, Uracil) and purines

(Adenine, Guanine)

- Sugars in nucleic acids include Deoxyribose in DNA and Ribose in RNA

- Phospholipids and proteins make up cellular membranes, which are fluid mosaics

- The fluid mosaic model describes the membrane structure as fluid with various embedded proteins

- Membrane proteins serve various functions such as transport, enzymatic activity, signal transduction,

cell-cell recognition, intercellular joining, and attachment to cytoskeleton and extracellular matrix

- Membranes have distinct inside and outside faces with asymmetrical distribution of proteins, lipids, and

associated carbohydrates

- Passive transport includes diffusion and osmosis, while active transport requires energy

- Osmosis is the diffusion of water across a selectively permeable membrane

- The concept of tonicity affects the movement of water into or out of a cell

- Transport proteins aid in the passage of hydrophilic substances across the membrane

- Membrane potential is maintained by ion pumps, such as the sodium-potassium pump

- Bulk transport mechanisms include exocytosis and endocytosis for moving large molecules across the

membrane

- Cell fractionation enables scientists to separate organelles for studying their functions

- Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both

- Common organelles in eukaryotic cells include the endoplasmic reticulum, flagella, centrosomes, and

cytoskeleton- Eukaryotic cells have membrane-bound organelles and a nucleus bounded by a membranousnuclear envelope

- The nucleus contains the cell's genes and is surrounded by a double membrane called the nuclear envelope

- The nuclear membrane is composed of a lipid bilayer and contains pores that regulate the entry and exit of

molecules

- The nuclear lamina, composed of protein, helps maintain the shape of the nucleus

- Ribosomes are particles made of ribosomal RNA and protein that carry out protein synthesis in the cytosol

and on the outside of the endoplasmic reticulum

- The endomembrane system regulates protein traffic and performs metabolic functions in the cell

- It consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and

plasma membrane

- The endoplasmic reticulum (ER) accounts for half the total membrane in many eukaryotic cells and can be

smooth (lacks ribosomes) or rough (has ribosomes on its surface)

- The Golgi apparatus consists of flattened membranous sacs called cisternae and modifies products from the

ER, manufactures certain macromolecules, and sorts and packages materials into transport vesicles

- Lysosomes are digestive compartments within the cell that use enzymes to recycle the cell's organelles and

macromolecules in a process called autophagy

- Mitochondria and chloroplasts are sites for energy conversion in the cell, generating ATP through cellular

respiration and photosynthesis, respectively

- The cytoskeleton is a network of fibers that organizes the structures and activities of the cell, composed of

microtubules, microfilaments, and intermediate filaments

- The cytoskeleton helps support cell shape, produce motility, and regulate biochemical activities within the

cell

- Cell walls distinguish plant cells from animal cells and protect the plant cell, made of cellulose fibers

embedded in polysaccharides and protein

- Intercellular junctions facilitate contact between neighboring cells and include plasmodesmata, tight

junctions, desmosomes, and gap junctions

- Tight junctions press neighboring cell membranes together to prevent leakage, desmosomes fasten cells

together into strong sheets, and gap junctions provide cytoplasmic communication channels between adjacent

cells- Digestion involves breaking down food particles in the body to extract nutrients

- Storage refers to the process of storing essential molecules and energy reserves

- Waste disposal is the elimination of unnecessary or harmful substances from the body

- Water balance is crucial for maintaining proper hydration levels in cells

- Cell growth involves the expansion and replication of cells to support tissue growth and repair

- Protection includes mechanisms to defend against pathogens and maintain cellular integrity

- Mitochondria and chloroplasts are cell organelles responsible for energy conversion

- Mitochondria are involved in cellular respiration, while chloroplasts perform photosynthesis

- Peroxisomes are specialized compartments that contain enzymes for various metabolic reactions

- Prokaryotic cells lack a nucleus and other membrane-bound organelles, unlike eukaryotic cells

- Free ribosomes are in the cytoplasm, while bound ribosomes are attached to the endoplasmic reticulum

- The smooth endoplasmic reticulum is involved in lipid metabolism, while the rough endoplasmic reticulum

synthesizes proteins

- The endomembrane system includes the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles

- Cytoskeleton provides structural support and facilitates cellular movement and transport

- Microtubules, microfilaments, and intermediate filaments are components of the cytoskeleton with specific

structural and functional roles

- Cilia and flagella are cellular structures involved in movement and sensory functions

- Plant cells have a rigid cell wall composed of cellulose for structural support and protection

- The extracellular matrix in animal cells provides structural support and regulates cell behavior

- Intercellular junctions include tight junctions, desmosomes, gap junctions, and plasmodesmata for cell

communication and adhesion

- Energy in living cells is required for various biochemical reactions to support life processes

- Metabolism involves the transformation of matter and energy within an organism

- Metabolic pathways consist of a series of reactions catalyzed by specific enzymes

- The laws of thermodynamics govern energy transformations in living systems

- The first law states that energy cannot be created or destroyed, only transferred or transformed

- The second law states that with each energy transfer, entropy in the universe increases- Cells utilize enzymes as biological catalysts to speed up chemical reactions

- Enzymes lower the activation energy required for reactions to occur

- Enzymes play a crucial role in various metabolic pathways and cellular functions

- ATP is the energy currency of cells and powers various cellular processes

- Cellular work includes chemical, transport, and mechanical work, all powered by ATP hydrolysis

- ATP is regenerated through the addition of a phosphate group to ADP in energy-releasing reactions.- ATP

molecules are consumed and regenerated per second per cell during metabolic processes.

- Energy is released during catabolism, while energy-consuming processes like anabolic pathways require

energy.

- Enzymes play a critical role in speeding up chemical reactions by reducing the energy barriers.

- Thermodynamics provide information about the rate of processes under specific conditions.

- Enzymes affect the change in free energy (G) of a reaction, leading to an increase in the reaction rate.

- Activation energy is the initial energy required to start a chemical reaction, often supplied in the form of heat

from the surroundings.

- Substrate specificity refers to the ability of enzymes to bind specifically to their substrates.

- Enzymes form an enzyme-substrate complex when the substrate binds to the active site of the enzyme.

- The active site of an enzyme is where the substrate binds and catalyzes the reaction by lowering the

activation energy barrier.

- Enzymes can promote catalysis by orienting substrates correctly, straining substrate bonds, providing a

favorable microenvironment, and covalently bonding with substrates.

- Enzymes bind better to transition states of substrates, facilitating the reaction process.