Cell Membrane, Membrane Transport, Etc. Flashcards by Christian Fenton

What are the functions of the plasma membrane?

Separate cytoplasm from ECF
Regulate exchange between ECF and Cytoplasm
Communicate with other cells
Provide structural attachments between cells or between cell and extracellular matrix

How well did you know this?

Not at all

Perfectly

What is the structure of the plasma membrane?

Described by the Fluid Mosaic Model

How well did you know this?

Not at all

Perfectly

What are the four molecules that make up the plasma membrane?

Phospholipids
Steroids
Proteins
Carbohydrates

How well did you know this?

Not at all

Perfectly

What is the consistency of the plasma membrane at body temperature?

Thick oil

How well did you know this?

Not at all

Perfectly

What is the structure of a phospholipid?

Amphipathic

How well did you know this?

Not at all

Perfectly

How are phospholipids organized in a plasma membrane?

Bilayer

How well did you know this?

Not at all

Perfectly

What are the functions of phospholipids in a plasma membrane?

Creates barrier

How well did you know this?

Not at all

Perfectly

What can pass through a pure phospholipid bilayer?

Hydrophobic substances - Small, nonpolar molecules
Ex. (Gases (O2, CO2), Fatty acids, steroids
Lipophilic substances
Ex. Ethanol
Water

How well did you know this?

Not at all

Perfectly

What cannot pass through a pure phospholipid bilayer?

Larger molecules
Polar molecules
Charged substances
Ex.
Glucose
Ions
Amino acids
Proteins

How well did you know this?

Not at all

Perfectly

What is the purpose of cholesterol in a plasma membrane?

Help keep membrane fluid over a wide range of temperatures
Help to make membrane water tight

How well did you know this?

Not at all

Perfectly

What determines the function of proteins?

Shape

How well did you know this?

Not at all

Perfectly

What do mutations alter?

Primary structure

How well did you know this?

Not at all

Perfectly

What does denaturation alter?

Secondary, tertiary, and quartenary structure

How well did you know this?

Not at all

Perfectly

What can cause denaturation?

pH, T, Osm

How well did you know this?

Not at all

Perfectly

What does Covalent/Allosteric Modular change?

Secondary, tertiary, and quartenary structure

How well did you know this?

Not at all

Perfectly

What are the structural classifications of plasma membrane proteins?

Transmembrane
Integral
Peripheral

How well did you know this?

Not at all

Perfectly

What do receptor proteins do?

Bind to specific chemical signals (ligands) and transmit that information to the cytoplasm

How well did you know this?

Not at all

Perfectly

What are the properties of receptor proteins?

Specificity
Saturation
Competition

How well did you know this?

Not at all

Perfectly

What is specificity of a receptor protein?

Shape of the binding site determines what will bind.
Each type of protein, in general, will interact with only one type of substance or class of substances

How well did you know this?

Not at all

Perfectly

What is saturation of a receptor protein?

refers to the fraction of total binding sites that are occupied at any given time

How well did you know this?

Not at all

Perfectly

What does saturation depend on?

on [protein] and the [substance]

How well did you know this?

Not at all

Perfectly

Within solutions of the body there are a set number of what and a set number or what?

Proteins and binding sites

How well did you know this?

Not at all

Perfectly

What is the transport rate proportional to?

Substrate concentration UNTIL carriers are saturated

How well did you know this?

Not at all

Perfectly

What is a competitive inhibitor?

is a chemical substance (exogenous ligand) that binds to the active site of the protein and blocks the endogenous ligand from binding

How well did you know this?

Not at all

Perfectly

When bound, what does a competitor do?

Does not produce an effect

What is level of inhibition depend on for a competitive inhibitor?

[protein], [endogenous ligand], and [competitive inhibitor].

Response of a cell to a chemical signal is mediated by what?

Receptor mediated, not signal mediated

What happens when one ligand binds to two different receptors?

Two different responses

What is receptor affinity?

Strength/Ease of ligand-receptor binding

Affinity is directly proportional to the number of ligands...

bound to receptors at any given [ligand]

If there is a high number of ligands bound to the receptor the affinity is...

high

Affinity is inversely proportional to...

What is Kd?

[Ligand] where ½ receptor occupied

What does Vm stand for?

Voltage to the membrane

What is membrane potential?

Charge difference across the plasma membrane

What creates the membrane potential?

unequal distribution of anions and cations across the cell membrane

What is the source of energy in a membrane potential?

Charge separation

What is resting membrane potential?

the charge difference across the plasma membrane when the cell is at rest.

What is a normal resting Vm?

≈ -70mV, depends on cell

What does the membrane potential create?

electrical gradients for movement of ions into/out of cells

What are some functions of the membrane potential?

Opens or closes gated ion channels. Regulates exocytosis

COME BACK TO What is the electrochemical gradient?

Two gradients for the passive transport of charged substances across the membrane

What is the chemical gradient?

Ions will move passively down concentration gradients

What is the electrical gradient?

Ions will move passively down electrical gradients

What are the two gradients for the passive transport of charged substances across the membrane?

Chemical gradient and electrical gradient

What does the strength of the electrical gradient depend on?

the valence of the ion and the magnitude of the membrane potential

Is the larger gradient more of less powerful of drive for the opposite charge?

More/stronger; causes grated diffusion rate

What happens if there is a divalent ion compared to a single valent ion?

Divalent has more of a diffusion drive

What is equilibrium potential?

Vm that creates an ΔE that is equal in strength but opposite in direction of the ΔC

What is the formula for equilibrium potential?

= 61/Z log ([ion]ECF / [ion]ICF)

What is electrochemical equilibrium?

No net ion movement through channels via facilitated diffusion

What is the equilibrium potential for potassium?

-94 mV

What do transport proteins do?

Move hydrophilic substances across the plasma membrane of cell

What are the 3 types of transport proteins?

Channels Carriers Active transporters

What are channels?

Transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and Cytoplasm

What is the function of channels?

Facilitated diffusion of ions into and out of cell (passive; does not require energy)

Are channels specific?

Yes, somewhat

What are the types of channels?

Open channels, gated channels

What are open channels?

Always open and ions freely flow through via facilitated diffusion

What do open channels create?

Leak currents

What are gated channels?

Spend most of their time in the closed state, and will open only when stimulated

What are the tree types of gated channels?

Chemically gated Mechanically gated Voltage gated

What is allosteric modulation of gated channels?

Ligand-gated (ligand binds to open channel)

What is covalent modulation of gated channels?

Kinase/phosphatase opening or closing channel

What are carrier proteins?

Transmembrane protein that moves hydrophilic building blocks across the plasma membrane via facilitated diffusion

What are the properties of carrier proteins?

Specificity Saturation Competition

What are active transporters?

Transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport

What are the properties of active transporters?

Specificity Saturation Competition

What are structural proteins?

Forms cell to cell attachments that hold adjacent epithelial cells together

What are tight junctions?

Prevents intercellular movement of fluid and dissolved substances

What are the types of cell-to-cell junctions?

Tight junctions, desmosomes, gap junctions

What are desmosomes?

Structural support

What are gap junctions?

Cell to cell communication via ions

What are enzymes?

Integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell

What are the properties of enzymes?

Specificity Saturation Competition

How long does it take for proteins to synthesize?

Approx. 2 hours

Are proteins stored?

Yes, many synthesized in advance and stored in an inactive form, activated when needed

What does storing proteins provide?

A means for immediate protein regulation

What is the Mass Action Model?

P + S = PS; Interaction between substance and protein binding site follows this

Where are carbohydrates on a plasma membrane?

Attached to EC surface of membrane lipids and proteins

What do the carbohydrates on the plasma membrane form?

Glycocalyx

What do carbohydrates do?

Plays important role in enabling cells to identify and interact with each other.

Is sodium high inside or outside the cell?

Outside

Is potassium high inside or outside the cell?

Inside

Is calcium high inside or outside the cell?

Outside

Is magnesium high inside or outside the cell?

Inside

Is chloride high inside or outside the cell?

Outside

Is bicarb high inside or outside the cell?

Outside

Is phosphate high inside or outside the cell?

Inside

Is glucose high inside or outside the cell?

Outside

Are amino acids high inside or outside the cell?

Inside

Is pH higher inside or outside the cell?

outside

Are proteins high inside or outside the cell?

inside

Does passive transport require energy?

Does active transport require energy?

Yes

What are the types of active transport?

Active transporters and bulk transport

What are the types of passive transport?

Diffusion, osmosis, bulk flow

What is random thermal motion?

Molecules in a fluid are continuously and randomly bouncing around

What is the rate of movement proportional to?

Temperature divided mass

What is diffusion?

Movement of substances other than water down a gradient

When does the net movement of diffusion stop?

At equilibrium

When does the random movement of diffusion stop?

Never

Is diffusion substance specific?

Yes

What is the primary goal of passive transport?

Moving the system towards equilibrium

Does an concentration gradient increase or decrease net flux?

Increase