BIOL 221 Lecture Exam 2 UWEC

Hemochromatosis

iron accumulation in the liver

The phospholipid bilayer is _____

semi-fluid

Cholesterol is _____ & _____

amphipathic; hydrophobic

Lipids can rotate _____ the plane of the phospholipid bilayer, (within/between) leaflets

within; within

Lipids can move laterally (in their own/between) leaflets

in their own

Movement between leaflets requires the _____ enzyme

flippase

contain carb groups attached to fatty acid tails that don't have many C=O, so they aren't kinked

glycosphingolipids

Lipid rafts are involved in

endocytosis and cell signaling

Transmembrane proteins allow movement

across leaflets

Transmembrane proteins contain

nonpolar amino acids

Lipid-anchored proteins have _____ covalently attached to an ________ side chain

lipids; amino acid

In lipid-anchored proteins, _____ insert into the hydrophobic portion of the membrane

fatty acid tails

In peripheral membrane proteins, (covalent/non-covalent) bonds form with either transmembrane proteins or with ______

non-covalent; phospholipid polar heads

Cell adhesion in membrane proteins: proteins in the ________ of adjacent cells hold the cells together

plasma membrane

Membrane transport in membrane proteins: _____ in the plasma membrane allow the transport of substances in and out of cells

proteins

Cell signaling in membrane proteins: an ___________ binds to a receptor that activates a ______, leading to a _______

extracellular signal; signal cascade; cellular response

Membrane protein functions

-cell adhesion

-cell signaling

-membrane transport

Protein movement is (more/less) restricted than lipid movement in the membrane

more

Transmembrane proteins are much (larger/smaller) than phospholipids, so they move much more (fast/slowly)

larger; slowly

What affects membrane fluidity?

-phospholipid composition

-presence of cholesterol

only some ions and molecules can move through the plasma membrane

selective permeability

Diffusion; movement of a solute (down/up) its gradient

down

Diffusion; transport protein (is/isn't) needed

isn't

Diffusion is a type of (active/passive) transport

passive

What are the four characteristics that determine whether molecules can cross the membrane by DIFFUSION?

-size

-polarity

-charge

-concentration

Diffusion (Size); smaller molecules tend to diffuse (faster/slower), and are (more/less) likely to be able to diffuse

faster; more

Diffusion (Polarity); nonpolar molecules are (faster/slower) and are (more/less) likely to be able to diffuse

faster; more

Diffusion (Charge); neutral molecules are (more/less) likely to diffuse

more

Diffusion (Concentration); the rate of movement is (faster/slower) when solute concentration is higher on one side of the membrane versus the other

faster

Facilitated diffusion; movement (up/down) gradient

down

Facilitated diffusion; transport protein (is/isn't) necessary

is

Facilitated diffusion is a type of (active/passive) transport

passive

Active transport; movement (with/against) a gradient

against

Active transport occurs (with/without) the help of a transport protein

with

Active transport can be shut down by

limiting ATP access

In a concentration gradient, the concentration of a solute is...

higher on one side of the membrane than the other

Na+ moves (in/out) of the cell

in

K+ moves (in/out) of the cell

out

Movement of water is dependent on _______

solute concentrations

Osmosis; when the outside is isotonic to the inside, there will be ____

no net movement of water across the membrane

Osmosis; when the outside is hypertonic to the inside, there will be _____

movement of the water toward the outside

Osmosis; when the outside is hypotonic to the inside, there will be _____

movement of the water toward the inside

Water moves from (higher/lower) concentration to a region with (higher/lower) concentration

higher; lower

Osmosis; crenation means

shrinkage

Osmosis; osmotic lysis means

rupture

Osmosis; when placed in a hypertonic solution, cells will

shrink

Osmosis; when placed in a hypotonic solution, cells will

rupture

Lipid rafts usually have a high amount of

cholesterol

When lipids have shorter tails, they are (more/less) likely to interact with one another, making the membrane (more/less) fluid

less;more

More double bonds means (more/less) fluidity

more

The presence of cholesterol stabilizes the membrane because it is

short and rigid

During osmosis, water moves (up/down) its concentration gradient

down

Water channels in the plasma membrane that allow faster movement of water

aquaporins

Transmembrane proteins that form a pore or passageway through the membrane

channels

Channels (can/cannot) open and close

can

Channels; the movement of a substance (does/doesn't) require the channel to change confirmation

doesn't

Channels are (fast/slow)

fast

Channels always move substances (down/up) the gradient

down

Specific binding pockets for the molecule(s) being transferred

transporters

Transporters (do/don't) have to change confirmation

do

When a molecule is moved across the membrane via a transporter, the transporter must undergo a series of _____

conformational changes

Transporters are (slow/fast)

slow

A carrier protein that transports a single molecule across the plasma membrane.

uniporter

transporter that carries two different ions or small molecules, both in the same direction

symporter

transporter that carries two ions or small molecules in different directions

antiporter

Channel gating provides a route through the membrane for (hydrophilic/hydrophobic molecules)

hydrophilic

Channel gating is controlled by the binding of _____ like hormones and neurotransmitters

ligands

Some channel gates are controlled by

voltage/mechanical force

Transporters have a binding pocket that is (hydrophobic/hydrophilic) and provide and hydrophilic environment for the ligand to pass through the membrane

hydrophilic

Transporters move things like _____,_____,_____,_____,_____,_____ though the membrane

sugars, amino acids, nucleotides, hormones, neurotransmitters, and waste products

Uniporters bind and move a ______ across the membrane

single molecule

Uniporters; the transport of a molecule is (faster/slower) than had the molecule diffused across the membrane

faster

Uniporters; (up/down) the gradient

down

Uniporters are (reversible/irreversible)

reversible

Symporters move ______ substances across the membrane, in the _____ direction

two or more; same

Symporters use ______ transport

secondary active

Antiporters move ______ substances across the membrane in the _____ direction

two or more; opposite

Antiporters use _______ transport

secondary active

Primary Active Transport uses ___ acquisition of energy from ____

direct; ATP

Pumps in primary active transport bind to ____ and use the energy from hydrolysis of the _________ of ATP to power movement of ions or small molecules (with/against) gradients

ATP, terminal phosphate group, against

Na+/K+-ATPase are located in the ________ of all animal cells

plasma membrane

Na+/K+-ATPase; Step 1; 3Na+ bind from the ________. ATP is ______. ___ is released and _____ is covalently attached to the pump, switching it to the ___ confirmation

cytosol; hydrolyzed; ADP; Pi; E2

Na+/K+-ATPase; Step 2; 3 ___ are released from outside of the cell

Na+

Na+/K+-ATPase; Step 3; 2 __ bind from outside of the cell

K+

Na+/K+-ATPase; Step 4; _____ is released and the pump switches to the __ confirmation. 2 __ are released into the ____. The process repeats

Phosphate; E2; cytosol

Electrochemical Gradients; transport of ions and molecules; symporters and antiporters use H+ and Na+ gradients to _____

take up nutrients and export waste products

Electrochemical Gradients; production of energy intermediates; in the mitochondrion and chloroplast, H+ gradients are used to ____

synthesize ATP

Electrochemical Gradients; osmotic regulation; animal cells control their internal volume by regulating ion gradients between the _____ & _____

cytosol; extracellular fluid

Electrochemical Gradients; neuronal signaling; Na+ & K+ gradients are involved in conducting _____

action potentials

Electrochemical Gradients; muscle contraction; Ca2+ gradients regulate the ability of _______

muscle fibers to contract

Electrochemical Gradients; bacterial swimming; H+ drive the rotation of _______

bacterial flagella

Primary and Secondary Active Transport can be coupled to move ______ against the concentration gradient to a cell

sucrose

Exocytosis; Step 1; A vesicle loaded with cargo is formed as a ________ wraps around it

protein coat

Exocytosis; Step 2; A vesicle is released from the _____ carrying cargo molecules

Golgi

Exocytosis; Step 3; ____

coat is shed

Exocytosis; Step 4; vesicle fuses with ______ and releases cargo outside

plasma membrane

Receptor-Mediated Endocytosis; Step 1; Cargo binds to receptor, receptors aggregate and cause the coat proteins to _________. The plasma membrane ________ as coat proteins cause ______

bind to the membrane; invaginates; a vesicle to form

Receptor-Mediated Endocytosis; Step 2; ____ is released into the cell

vesicle

Receptor-Mediated Endocytosis; Step 3; __

coat is shed

Receptor-Mediated Endocytosis; Step 4; Vesicle fuses with an ________, such as a lysosome

internal organelle