AP BIO UNIT 2 Flashcards

Question

Endosymbiont Theory

Answer 1

The theory that explains the similarities mitochondria and chloroplasts have to a prokaryote. The theory states that an early eukaryotic cell engulfed a prokaryotic cell. The prokaryotic cell became an endosymbiont (cell that lives in another cell). It then became one functional organism. Evidence for the theory includes double membrane, ribosomes, circular DNA, and being capable of functioning on their own.

Answer 2

Site of cellular respiration. Structure of the double membrane: outer membrane is smooth while the inner membrane has folds called cristae. These membranes divide the mitochondria into two internal compartments and increase surface area. The number of mitochondria in a cell correlates with metabolic activity. Cells with high metabolic activity have more mitochondria.

Answer 3

The space between the inner and outer membrane.

Answer 4

The location for the Krebs cycle. It contains enzymes that catalyze cellular respiration and produce ATP, mitochondrial DNA, and ribosomes.

Answer 5

Specialized organelles in photosynthetic organisms. It is the site of photosynthesis and contains the green pigment, chlorophyll. Inside of its double membrane are thylakoids (membranous sacs that can organize into stacks called grana) and stroma (fluid around the thylakoids). Light dependent reactions occur in grana. Stroma is the location for the Calvin Cycle. They contain chloroplast DNA, ribosomes, and enzymes.

Answer 6

Membranous sacs that can organize into stacks called grana. Light dependent reactions occur in grana.

Answer 7

Fluid around the thylakoids. The location for the Calvin Cycle. It contains chloroplast DNA, ribosomes, and enzymes.

Answer 8

(NOT an organelle). A network of fibers throughout the cytoplasm. They give structural support (especially for animal cells) and mechanical support. They anchor organelles and allow for movement of vesicles and organelles and/or the whole cell. Movement occurs when the cytoskeleton interacts with motor proteins. The three types of fibers in the cytoskeleton include microtubules, microfilaments, and intermediate filaments.

Answer 9

A fiber in the cytoskeleton. Hollow rod-like structures made form the protein tubulin. They grow from the centrosome and assist in microtubule assembly. They serve as structural support (kind of like tracks) for the movement of organelles that are interacting with motor proteins. They assist in the separation of chromosomes during cell division and assist in cell motility (example: cilia and flagella).

Answer 10

Thin solid rods made of the protein actin. They maintain the cell shape and bear tension and assist in muscle contraction and cell motility. Actin works with another protein called myosin to cause a contraction. They also assist in the division of animal cells, causing the contractile ring of the cleavage furrow.

Answer 11

Fibrous proteins made of varying subunits. Permanent structural elements of cells. They maintain cell shape, anchor the nucleus and organelles, and form the nuclear lamina which lines the nuclear envelope.

Answer 12

Cellular metabolism depends on cell size. Cellular waste must leave and thermal energy must dissipate. Nutrients and other resources/chemical materials must enter. At a certain size, it begins to be too difficult for a cell to regulate what comes in and what goes out of the plasma membrane.

Answer 13

The size of a cell will dictate the function. Cells need a high surface area-to-volume ratio to optimize the exchange of material through the plasma membrane.

Answer 14

Total SA = height x width x # of sides x number of boxes Total Volume = height x width x length x # of boxes

Answer 15

SA = 4πr² Total Volume = 4/3πr³

Answer 16

Cells tend to be small. Small cells have high SA: V ratios. This optimizes the exchange of materials through the plasma membrane. Larger cells have a lower SA: V ratio. Because of this, they lose efficiency exchanging materials. The cellular demand for resources increases and the rate of heat exchange decreases.

Answer 17

Separates the internal cell environment from the external environment. Comprised primarily of phospholipids. Phospholipids are amphipathic (hydrophilic head and hydrophobic tails which form a bilayer). Plasma membranes have selective permeability that allows the membrane to regulate the substances that enter and exit the cell.

Answer 18

Oriented TOWARDS aqueous environments

Answer 19

Oriented inwards AWAY from aqueous environments

Answer 20

A model to describe the structure of cell membranes. Fluid: membrane is held together by weak hydrophobic interactions and can therefore move and shift. Temperature affects fluidity. Unsaturated hydrocarbon tails help maintain fluidity at low temperatures. The kinked tails prevent the tight packing of phospholipids. Mosaic: comprised of many macromolecules.

Answer 21

Helps maintain fluidity at high and low temperatures. High temperature: reduces movement. Low temperature: reduces tight packing of phospholipids.

Answer 22

Proteins that are embedded into the lipid bilayer. (aka transmembrane proteins). Amphipathic.

Answer 23

Proteins that are not embedded into the lipid bilayer.

Answer 24

Important for cell-to-cell recognition.

Answer 25

Carbohydrates bonded to lipids.

Answer 26

Carbohydrates bonded to proteins. Most abundant.

Answer 27

Plants have a cell wall that cover their plasma membranes. Extracellular structure (not found in animal cells). Provides shape/structure, protection, and regulation of water intake. The cell wall is composed of cellulose. Thicker than plasma membranes and contains plasmodesmata (hole-like structures in the cell wall filled with cytosol that connects adjacent cells).

Answer 28

Some substances can cross the membrane more easily than others.

Answer 29

Small, nonpolar, hydrophobic molecules. (Examples: hydrocarbons, C2, O2, N2)

Answer 30

Hydrophilic, polar molecules, large molecules, ions. (Examples: sugar, water)

Answer 31

Transport of a molecule that does not require energy from the cell because a solutie is moving with its concentration or electrochemical gradient. Involved in the import of materials and export of waste. (Examples: diffusion, osmosis, facilitated diffusion.)

Answer 32

Spontaneous process resulting from the constant motion of molecules. Substances move from a high to a low concentration. Move DOWN the concentration gradient. Molecules diffuse directly across the membrane. Different rates of diffusion for different molecules. *Even with diffusion, the membrane is still selectively permeable.

Answer 33

The diffusion of water down its concentration gradient across a selectively permeable membrane.

Answer 34

Diffusion of molecules through the membrane via transport proteins. Increases rate of diffusion for: small ion, water, and carbohydrates. Two categories of transport proteins: channel and carrier.

Answer 35

Provide a channel for molecules and ions to pass. The channel is hydrophilic. Many are gated channels. They only allow passage when there is a stimulus. (Example: aquaporins - a specific channel protein for water).

Answer 36

Undergo conformational changes for substances to pass.

Answer 37

Transport of a molecule that requires energy because it moves a solute against its concentration gradient. Pumps, cotransport, exocytosis, and endocytosis are all types of active transport. Active transport requires energy.

Answer 38

Energy source used by cells. ATP can transfer the terminal phosphate group to the transport protein, which changes the shape of the transport protein to better move a substance (AKA a conformational change).

Answer 39

Maintains membrane potential.

Answer 40

Unequal concentrations of ions across the membrane results in an electrical charge (electrochemical gradient). The cytoplasm is relatively negative in comparison to the extracellular fluid. Energy is stored in electrochemical gradients.

Answer 41

Proteins that generate voltage across membranes which can be used later as an energy source for cellular processes.

Answer 42

Animal cells will regulate their relative concentrations of Na+ and K+. Animal cells have a relatively high concentration of K+ and low concentration Na+ inside the cell in comparison to outside the cell. When ATP phosphorylates the protein, a conformational change occurs. 3 sodium ions and a molecule of ATP are bound to the sodium-potassium pump. The ATP splits and creates energy to change the shape of the channel, driving the sodium out of the cell. The sodium is released outside the membrane and the new shape of the channel allows two potassium ions to bind. Release of the phosphate allows the channel to revert to its original form, releasing the potassium ions on the inside of the membrane. (3 Na+ out and 2 K+ in)

Answer 43

Integral membrane protein that builds up a proton gradient across the membrane. Used by plants, fungi, and bacteria. Pumps H+ out of the cell.

Answer 44

The coupling of a favorable movement of one substance with an unfavorable movement of another substance. Uses the energy stored in electrochemical gradients (generated by pumps) to move substance against their concentration gradient. Plants use cotransport for sugars and amino acids. Example: sugar-H+ cotransporter.

Answer 45

Downhill diffusion

Answer 46

Uphill transport

Answer 47

Plants use contransport for sugars and amino acids. (Example: sucrose - H+ cotransporter. Sucrose can travel into a plant cell against its concentration gradient ONLY if it's coupled with H+ that is diffusing down its electrochemical gradient).

Answer 48

The secretion of molecules via vesicles that fuse to the plasma membrane. Vesicles can fuse to the membrane by forming a bilayer. Once fused, the contents of the vesicle are released to the extracellular fluid. (Example: nerve cells releasing neurotransmitter).

Answer 49

The uptake of molecules from vesicles fused from the plasma membrane (opposite of exocytosis). Phagocytosis, pinocytosis, receptor-mediated.

Answer 50

When a cell engulfs particles to be later digested by lysosomes. Cell surround particle with pseudopodia. Packages particles into a food vacuole. Food vacuole fuses with a lysosome to be digested.

Answer 51

Nonspecific uptake of extracellular fluid containing dissolved molecules. Cell takes in dissolved molecules in a protein coated vesicle. Protein coat helps to mediate the transport of molecules.

Answer 52

Specific uptake of molecules via solute binding to receptors on the plasma membrane. Allows the cell to take up large quantities of a specific substance. When solutes bind to the receptors, they cluster in a coated vesicle to be taken into the cell.

Answer 53

The ability of an extracellular solution to cause a cell to gain or lose water. Depends on the concentration of solutes that cannot pass through the cell membrane.

Answer 54

Cells must be able to regulate their solute concentrations and maintain water balance. Animal cells will react differently than cells with cell walls, like plants, fungi, & some protists.

Answer 55

Cells immersed in an isotonic solution have no net movement of water. The concentration of nonpenetrating solutes inside the cell is equal to that outside the cell. Water diffuses into the cell at the same rate water moves outside the cell.

Answer 56

Cells immersed in a hypertonic solution lose water to their extracellular surroundings. The concentration of nonpenetrating solutes is higher outside of the cell. Water will move to the extracellular fluid. Cells shrivel and die. Plasmolysis will occur in plant cells: vacuole shrinks and the plasma membrane pulls away from the cell wall.

Answer 57

Vacuole shrinks and the plasma membrane pulls away from the cell wall.

Answer 58

Cells immersed in a hypotonic solution gain water. the concentration of nonpenetrating solutes is lower outside of the cell. the cell will gain water. Animals cells swell and lyse (burst). Plant cells work optimally (the cell wall maintains turgor pressure).

Answer 59

A physical property that predicts the direction water will flow. Includes the effects of solute concentration and physical pressure. Greek letter "psi" represents water potential. Measured in megapascals (mPa) or bars. 1 mPa = 10 bars

Answer 60

1. High water potential to areas of low water potential. 2. Low solute concentration to high solute concentration. 3. High pressure to low pressure.

Answer 61

Ψ = ΨS + ΨP

Answer 62

Also known as osmotic potential. An increase in solutes causes binding to more free water. This reduces water potential. Expressed as a negative #. Pure water is 0 mPa.

Answer 63

The physical pressure on a solution. Can be + or - relative to atmospheric pressure. "Open air" = 0 mPa.

Answer 64

ΨS = -iCRT

Answer 65

Number of particles formed. If no ions are formed, the ionization constant is 1. Example: sucrose.

Answer 66

Represented as C

Answer 67

Pressure Constant 0.0831 liter bars/mol-K 0.00831 liter mPA/mol-K

Answer 68

K = 273 + C 273 + degrees in Celsius