ap biology

define polarity and hydrogen bonding

polarity is the distribution of electrical charge among the atoms connected by a chemical bond - a hydrogen bond is a specific type of electrostatic attraction between a hydrogen atom and another electronegative atom

describe how polarity and hydrogen bonding affect how water functions biologically

water's polarity and the resulting hydrogen bonding give it unique properties that are crucial for biological functions - these properties include cohesion, adhesion, high surface tension, high specific heat, and excellent solvent properties - these properties allow water to support life in various ways, from regulating body temperature to transporting nutrients and waste

define cohesion, adhesion, and surface tension

cohesion refers to the attraction of molecules for other molecules of the same kind, and water molecules have strong cohesive forces thanks to their ability to form hydrogen bonds with one another - adhesion is the binding of a cell to another cell or a cell to a surface through cell adhesion molecules - the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules

describe why organisms must exchange matter with the environment

organisms must exchange matter with the environment to grow, reproduce and maintain organization

explain what biological molecules carbon is used to build

carbon forms the backbone of all major biological molecules, including carbohydrates, lipids, proteins, and nucleic acids

explain what biological molecules nitrogen is used to build

nitrogen is a key component in building proteins, nucleic acids (DNA and RNA), and amino acids

explain what biological molecules phosphorus is used to build

phosphorus is a key component of several important biological molecules, including DNA, RNA, ATP, and phospholipids

describe the purpose and process of hydrolysis reactions

hydrolysis is a chemical process where water is used to break down large molecules into smaller ones - the purpose of hydrolysis is to break down polymers (like proteins, carbohydrates, and lipids) into their constituent monomers, such as amino acids, glucose, or fatty acids. This process is the reverse of dehydration synthesis, where water is removed to build up larger molecules

describe the purpose and process of dehydration reactions

dehydration reactions, also known as condensation reactions, are chemical reactions where a water molecule is removed from the reactants, forming a larger product - the primary purpose of these reactions is to build up complex organic molecules, such as polymers, from smaller units, called monomers

identify the type of bonds that connect monomers in macromolecules

monomers in macromolecules are connected by covalent bonds

describe the structure of DNA and RNA nucleotides

a nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base

explain how DNA and RNA differ in structure and function

DNA is a double-stranded molecule that stores genetic information, while RNA is a single-stranded molecule that plays various roles in gene expression, including protein synthesis - RNA uses uracil instead of thymine, and its sugar is ribose instead of deoxyribose

describe the structure of amino acids

amino acids all share a basic structure consisting of a central carbon atom attached to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R-group) - the R-group is what distinguishes each of the 20 different amino acids

explain how the R group of an amino acid can be hydrophilic, hydrophobic, or ionic, and what this means for the structure and function of the protein

the R group (side chain) of an amino acid dictates its chemical properties, influencing its interaction with water and other molecules - hydrophobic R groups are non-polar, typically consisting of carbon and hydrogen, and prefer to avoid water, clustering together in the interior of proteins - hydrophilic R groups are polar or charged, readily interacting with water and often found on the protein's surface - ionic R groups carry a permanent charge, enabling them to form strong interactions with oppositely charged groups or water molecules, contributing to protein structure and function

describe the structure of complex carbohydrates

complex carbohydrates are long chains of sugar molecules (monosaccharides) bonded together, also known as polysaccharides - they can be branched or unbranched, and are composed of more than ten monosaccharides

describe the structure of lipids

lipids are a diverse group of biological molecules, largely composed of hydrocarbons, that are insoluble in water

describe how differences in saturation affect the structure and function of lipids

saturated fatty acids, lacking double bonds, are straight and pack tightly together, resulting in more rigid and solid-like lipids, like butter - unsaturated fatty acids, with double bonds, have kinks in their structure, preventing tight packing and leading to more fluid and liquid-like lipids, like olive oil - this difference in structure influences how lipids interact with each other and other molecules, affecting membrane fluidity, lipid solubility, and overall biological functions

describe the different regions of phospholipids

phospholipids have two distinct regions: a hydrophilic "head" and a hydrophobic "tail" - the head is composed of a phosphate group and glycerol, which are attracted to water (hydrophilic), while the tail is made up of two fatty acid chains, which repel water (hydrophobic)

describe the structure of nucleic acids

each nucleic acid contains four of five possible nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U)

explain how nucleotides are added during DNA and RNA synthesis and in what direction

during both DNA and RNA synthesis, nucleotides are added to the 3' end of the growing strand, extending the chain in a 5' to 3' direction - this process is facilitated by enzymes like DNA polymerase (for DNA) and RNA polymerase (for RNA) - the 3' end possesses a free hydroxyl group that interacts with the 5' phosphate group of the incoming nucleotide, forming a phosphodiester bond

identify the DNA nucleotides that base pair together and with how many bonds

in DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C) - these base pairs are held together by hydrogen bonds - A-T pairs are held together by two hydrogen bonds, while G-C pairs are held together by three hydrogen bonds

describe the structure of proteins

proteins have a hierarchical structure, ranging from the linear sequence of amino acids (primary structure) to the overall three-dimensional shape of the protein (tertiary and quaternary structures)

describe the primary, secondary, tertiary, and quaternary structures of proteins

the primary structure is the amino acid sequence - secondary structure involves local folding patterns like alpha helices and beta-pleated sheets - tertiary structure is the overall three-dimensional shape of a single polypeptide chain - quaternary structure refers to the arrangement of multiple polypeptide chains (subunits) in a protein

describe the structure of carbohydrates

carbohydrates are composed of carbon, hydrogen, and oxygen, often with a 1:2:1 ratio (CH2O)n

describe the difference between linear and branched carbohydrate polymers

branched polymers tend to be less dense than similar linear polymers

identify the three major components of DNA and RNA

both DNA and RNA are made from nucleotides, each containing a five-carbon sugar backbone, a phosphate group, and a nitrogen base

explain the basic structural differences between DNA and RNA

DNA is double-stranded, forming a double helix, while RNA is usually single-stranded - the sugar in DNA is deoxyribose, whereas RNA contains ribose

describe the antiparallel nature of nucleic acids

the strands are antiparallel, meaning they run in opposite directions, which is crucial for DNA replication

describe how the structure of a ribosome is related to its function of producing proteins

the structure of a ribosome, consisting of two subunits that bind to mRNA and tRNA, enables it to efficiently synthesize proteins by facilitating the translation of mRNA into polypeptides - the ribosome's structure allows it to hold mRNA and tRNA molecules in the right place and at the right time, ensuring the correct sequence of amino acids is assembled into a protein

explain how ribosomes reflect the common ancestry of all known life

ribosomes, the cellular machinery responsible for protein synthesis, reflect common ancestry because they are universal components found in all known life forms, demonstrating a shared mechanism inherited from a common ancestor

compare and contrast smooth and rough endoplasmic reticulum

the rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) are two interconnected forms of the endoplasmic reticulum (ER), both essential for cell function - the key difference lies in their structure: RER is studded with ribosomes, while SER lacks ribosomes - this structural difference dictates their functions: RER is primarily involved in protein synthesis and modification, while SER is involved in lipid synthesis, detoxification, and other metabolic processes

explain the role of the Golgi complex and what it looks like

a stack of small flat sacs formed by membranes inside the cell's cytoplasm (gel-like fluid) - the Golgi complex prepares proteins and lipid (fat) molecules for use in other places inside and outside the cell

explain the role of the mitochondria and how the double membrane affects their function

mitochondria are the "powerhouses" of the cell, responsible for producing ATP (energy) through cellular respiration - the double membrane structure of mitochondria, with its outer and inner membranes, is crucial for this process by creating compartments and regulating the flow of molecules - the inner membrane folds into cristae, increasing surface area for ATP production

explain the role of lysosomes in the cell

lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself

explain the role of vacuoles in the cell

vacuoles store nutrients and water on which a cell can rely for its survival - they also store the waste from the cell and prevents the cell from contamination

explain the role of chloroplasts in the cell

chloroplasts are the organelles in plant cells responsible for photosynthesis, the process where plants convert light energy into chemical energy (sugars) and release oxygen

explain how the structure of a chloroplast is related to its function

the chloroplast is surrounded by a double membrane, providing a distinct internal environment for photosynthesis to occur - inside, it contains stacks of thylakoids, which are flattened sac-like structures - these thylakoids are where the light-dependent reactions of photosynthesis take place

describe the role of the endoplasmic reticulum in supporting cellular function

the endoplasmic reticulum (ER) plays a vital role in supporting cellular function by acting as a manufacturing, processing, and transport hub for essential cellular components - it's involved in protein synthesis, lipid synthesis, calcium storage, and detoxifying harmful substances

describe the role of the mitochondrial double membrane in supporting cellular function

the mitochondrial double membrane plays a crucial role in supporting cellular function by compartmentalizing the mitochondrion, creating an environment for efficient energy production, and facilitating the movement of molecules - the outer membrane acts as a barrier, while the inner membrane, with its folds (cristae), houses the machinery for ATP synthesis

describe the role of the lysosome’s hydrolytic enzymes

the hydrolytic enzymes within a lysosome are crucial for breaking down large biological molecules into smaller components, a process vital for cellular homeostasis, waste disposal, and the recycling of cellular components

describe the role of the vacuole in supporting cellular function

vacuoles play a crucial role in supporting cellular function by storing water, nutrients, and waste products, as well as maintaining turgor pressure for structural support, especially in plant cells - they also help regulate the cell's internal environment by sequestering harmful substances and controlling the flow of molecules

describe the role of the vacuole in plants

in mature plant cells, vacuoles tend to be very large and are extremely important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth

explain the role of compartmentalization in both mitochondria and chloroplasts

compartmentalization in both mitochondria and chloroplasts is crucial for efficient metabolic processes - it involves creating distinct internal compartments with specific environments that allow for specialized reactions and storage of metabolites - this separation ensures optimal conditions for reactions, protects against toxic byproducts, and enables regulated metabolic control

describe where the different reactions of photosynthesis take place in the chloroplast

in a chloroplast, the light-dependent reactions of photosynthesis occur in the thylakoid membranes, while the light-independent reactions (Calvin cycle) take place in the stroma

describe where the different reactions of cellular respiration take place in the mitochondria

in mitochondria, the Krebs cycle (or Citric Acid Cycle) takes place in the matrix, while the electron transport chain and oxidative phosphorylation occur on the inner mitochondrial membrane - glycolysis, however, takes place in the cytoplasm

explain how surface-area-to-volume ratios affect biological processes

smaller organisms with a higher surface area-to-volume ratio can readily exchange materials through diffusion across their surface, while larger organisms with a lower ratio require specialized systems like circulatory and respiratory systems to facilitate efficient exchange

explain how the relationship between surface area and volume affects biological systems and the efficiency of cells

as a cell's volume increases, its surface area to volume ratio decreases, making nutrient and waste exchange less efficient - small cells have a higher SA/V ratio, allowing for quicker exchange of materials, while larger cells have a lower ratio, potentially limiting their ability to sustain themselves

describe the limitations that affect cell size and shape

cell size and shape are limited by a variety of factors, primarily surface-to-volume ratio, diffusion rates, and the need for cell function and structural integrity

describe the efficient strategies that cells and organisms use to obtain nutrients and eliminate wastes

cells and organisms employ diverse and efficient strategies to obtain nutrients and eliminate waste products - these strategies include specialized organs, systems, and structures that enhance nutrient uptake and waste removal

describe the structure and role of phospholipids in the cell membrane

phospholipid bilayers are critical components of cell membranes - the lipid bilayer acts as a barrier to the passage of molecules and ions into and out of the cell - however, an important function of the cell membrane is to allow selective passage of certain substances into and out of cells

describe the structure and role of embedded proteins in the cell membrane

embedded proteins in the cell membrane, also known as integral proteins, have a structure that allows them to be fully or partially embedded within the phospholipid bilayer, and they play a crucial role in various cell functions like transport, communication, and structural support

describe the structure of the fluid mosaic model of the cell membrane

the fluid mosaic model describes the structure of the plasma membrane as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character

explain how the ability of the plasma membrane to be selectively permeable maintains homeostasis within a cell

the selective permeability of the plasma membrane is crucial for maintaining cellular homeostasis by controlling what enters and exits the cell - this allows the cell to maintain a distinct internal environment, regulate the movement of essential nutrients and ions, and remove waste products - the membrane's selective nature, facilitated by transport proteins, ensures the cell's internal conditions remain stable and suitable for its functions

describe what can move through the phospholipid bilayer of the membrane and explain why these molecules can be transported in these ways

small, nonpolar molecules like oxygen and carbon dioxide can move through the phospholipid bilayer of the membrane via simple diffusion - this is because the hydrophobic interior of the bilayer allows these molecules to dissolve into the lipid matrix and pass through - small polar molecules like water can also pass through, though more slowly, due to their partial charge and the hydrophobic nature of the bilayer

describe what can move through the embedded channel proteins of the membrane and explain why these molecules can be transported in these ways

these molecules are transported through the channel proteins because they are not soluble in the hydrophobic interior of the lipid bilayer and cannot freely diffuse through it - the protein channel provides a hydrophilic passage, allowing these molecules to bypass the hydrophobic core

explain the role of the cell wall in maintaining structure and function

the cell wall plays a crucial role in maintaining cell structure and function by providing support, protection, and shape, as well as regulating interactions between the cell and its environment

compare and contrast different forms of passive transport, including: simple diffusion, facilitated diffusion, and osmosis

simple diffusion involves small, nonpolar molecules moving directly across the membrane, while facilitated diffusion uses membrane proteins to help larger or polar molecules move across - osmosis is a special case of diffusion, specifically referring to the movement of water across a semipermeable membrane

compare and contrast passive and active transport and give examples of each

passive transport moves molecules along their concentration gradient (from high to low concentration), requiring no energy, while active transport moves molecules against their concentration gradient (from low to high concentration), requiring energy (ATP) - examples of passive transport include simple diffusion, osmosis, and facilitated diffusion, whereas examples of active transport include the sodium-potassium pump and endocytosis/exocytosis

describe how the selective permeability of cell membranes allows for concentration gradients

by controlling which molecules enter or exit the cell, the cell can establish different concentrations of substances inside and outside of the membrane, resulting in a gradient

compare and contrast endocytosis with exocytosis and give examples of each

endocytosis and exocytosis are both forms of active transport that move materials across the cell membrane using vesicles. However, they do so in opposite directions: endocytosis brings substances into the cell, while exocytosis transports substances out of the cell - both processes require energy (ATP) and are crucial for various cellular functions

describe the role of membrane proteins with respect to facilitated diffusion

in facilitated diffusion, membrane proteins act as facilitators for the movement of molecules across the cell membrane, specifically large or polar molecules that cannot easily cross the lipid bilayer on their own - these proteins, known as channel proteins and carrier proteins, provide pathways or binding sites for specific molecules, allowing them to move down their concentration gradient without requiring energy

describe the role of membrane proteins with respect to active transport

membrane proteins play a crucial role in active transport by acting as pumps that use energy, primarily ATP, to move substances across the cell membrane against their concentration gradient - these proteins bind to specific molecules, undergo conformational changes, and release them on the other side of the membrane - this process allows cells to maintain internal environments that differ from their surroundings and to transport essential nutrients and waste products

compare and contrast the terms hypotonic, hypertonic, and isotonic with respect to cell environments

in cell biology, hypertonic, hypotonic, and isotonic solutions refer to the relative concentrations of solutes (dissolved substances) in a solution compared to the cell's cytoplasm - a hypertonic solution has a higher solute concentration than the cell, causing water to move out of the cell and the cell to shrink - a hypotonic solution has a lower solute concentration than the cell, causing water to move into the cell and the cell to swell - isotonic solutions have the same solute concentration as the cell, resulting in no net movement of water and no change in cell size

explain how water moves through osmosis

water moves through osmosis, a type of passive transport, from areas of high water concentration to areas of low water concentration across a semi-permeable membrane - this movement is driven by the osmotic gradient, where the concentration of solutes (dissolved substances) is higher in the region where water is less concentrated

describe the purpose of osmoregulation

osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body

compare the various transport mechanisms, including: passive transport, active transport, endocytosis, and exocytosis

cell transport mechanisms include passive transport, active transport, endocytosis, and exocytosis - passive transport moves molecules along their concentration gradient, while active transport requires energy to move them against their gradient - endocytosis brings substances into the cell, and exocytosis releases them out

explain why compartmentalization in eukaryotic cells is helpful in maintaining homeostasis

spatial separation of metabolic pathways enables rapid control of metabolite levels and coordination between pathways and the environment - moreover, compartmentalization provides a mechanism by which metabolites function directly as signalling molecules to relay organelle homeostasis from one compartment to another

describe how internal membranes facilitate cellular processes

internal membranes in a cell contribute to compartmentalization, enabling different processes to occur concurrently, and they regulate cellular activities by providing specialized environments and facilitating molecular transport

describe how the functions of endosymbiotic organelles are related to their free-living ancestral counterparts

endosymbiotic organelles like mitochondria and chloroplasts function similarly to their free-living ancestral bacteria, but are specialized for their role within the eukaryotic cell - mitochondria, derived from aerobic bacteria, generate energy through cellular respiration, mirroring their ancestral role - chloroplasts, from photosynthetic bacteria, perform photosynthesis, just like their ancestors

define active site and substrate

in the context of enzymes and biochemical reactions, a substrate is the molecule upon which an enzyme acts - the active site is the specific region on the enzyme where the substrate binds, and where the enzymatic reaction takes place

describe what needs to happen for an enzyme-mediated chemical reaction to occur

for an enzyme-mediated chemical reaction to occur, a substrate must bind to the enzyme's active site, which is a specific region on the enzyme with a complementary shape and charge

explain the purpose of enzymes

their main purpose is to significantly speed up these reactions by lowering the activation energy, which is the energy barrier that reactants must overcome to form products

describe how enzymes specifically facilitate chemical reactions

enzymes facilitate chemical reactions by lowering the activation energy, which is the energy barrier that needs to be overcome for a reaction to proceed - they do this by providing an alternate reaction pathway or by stabilizing the transition state, making it easier for bonds to break and form - enzymes also bring reactants together in the correct orientation to facilitate the reaction