Quiz 3

Lipid bilayer

membrane made up of phospholipids

Lipid bilayer function

separate the cell from the outside environment; allow intake/output of components

Driving force of lipid bilayer formation

hydrophobic effect; self healing

What allows biomolecule transportation across the membrane?

channels, pumps, carriers

What do membranes have that pick up signals from the outside and cause internal change?

signal receptors

Why is the membrane a bilyar?

polar head towards the outside and nonpolar tail towards the inside

Shape of lipid bilayer

ball layer

The outer leaflet of phospholipid heads are ... than the inner leaflet phospholipid heads

larger

The membrane is ... when there is more saturated lipids

rigid

The membrane is ... when there is more unsaturated lipids

fluid

What is it called if the membrane components are not fixed are have fluidity?

Lateral diffusion

What keeps the membrane asymmetrical, with different components on each side?

transverse diffusion

What moves lipids from the exoplasmic to the cytosolic face? (outside to inside)

Flippases

What moves lipids from the cytosolic face to the exoplasmic? (inside to outside)

Floppases

greater than 20 hydrocarbon tails and saturated fatty acids

Tighter membranes

What adds to membrane rigidity?

cholesterol; due to van der waals forces

Areas where cholesterol joins with saturated fatty acids and other proteins and lipids

lipid rafts

Thin layer of actin meshwork under the plasma membrane and connects to the cytoskeleton; found in the inner face of the plasma membrane

cell cortex

Cell cortex function

supports the plasma membrane

cytoskeletal protein that lines intracellular side of the plasma membrane in eukaryotic cells

spectrin

How does spectrin attach to the cell membrane?

transmembrane proteins

Dysfunction of spectrin for Red Blood Cells

shape can't be maintained; membranes breakdown

Regions in membrane where proteins must reside

membrane domain

How can membrane domains be set?

1. attach to something on the exterior membrane

2. attach to something on the interior membrane

3. prevent proteins from moving out (tight junctions)

outermost exterior membrane covered with carbohydrates

carbohydrate layer (glycocalyx)

What is the glycocalyx made of?

glycolipids and glycoproteins

Function of the glycoclayx

lubrication; layer of protection; allows adherence to other cells and surfaces; signal reception

Lectin functions for carbohydrate layer

recruitment and agglutination of cells

Proteins embedded into the membrane; span the entire membrane or part of it

Integral Proteins

On surface of membrane

Peripheral Proteins

Types of transport proteins

transporters/carriers, channels

Protein has a conformational change to allow molecule to pass; can go with or against the concentration gradient

Transporters/ Carriers

Protein shape stays the same; allows molecules through following the concentration gradient

Channels

small molecules follow concentration gradient without proteins

simple diffusion

Ions pass through membrane using membrane protein

facilitated diffusion

Facilitated diffusion where ions follow concentration gradient

passive transport

Facilitated diffusion where ions go against the concentration gradient; requires energy

active transport

Uses energy from ATP to pump molecules

primary active transport

Uses the energy of a molecule going along the concentration gradient to transport another molecule with it

secondary active transport

transport a single species across a membrane without energy

uniporter

couple the downhill flow of one species to the uphill flow of another in an opposite direction

antiporter

couple the downhill flow of one species to drive the flow of another in the same direction

symporter

Can charged ions easily pass through the membrane?

No; the need exclusive transport proteins

What types of molecules can pass through a channel?

correct size and charge; needs no energy

How can molecules can pass through a carrier protein?

it must bind to the protein and cause a conformational change; needs energy

Transport proteins that work against concentration gradient

proton pump

How does glucose into cells?

glucose transporter proteins

Gradient of electrochemical potential for an ion to move across a membrane

electrochemical gradient

Ways to move ions across an opposing electrical gradient?

coupled transport; ATP driven pump

couple the flow of one molecule to the flow of another to facilitate movement

coupled transport

hydrolyzes ATP to ADP and uses the energy to pump molecules against the gradient

ATP driven pumps

Na+/K+ pump

3 Na+ out, 2 K+ in

difference in electrical potential between internal and external cell

membrane potential; without it there will be an electrical imbalance

Voltage sensor measures the membrane potential causing channel to open/close

Voltage gated ion channel

ligand binds to the channel causing it to open/close

ligand gated ion channel

physical pressure in shape causes it to open/close

stress gated ion channel

Arachidonic acids is generated by ...

phospholipase A2

Which enzyme converts Arachidonic acid into protasglandins

Prostaglandin H2 synthase

Enzyme that is a peripheral protein bound to the ER with just an alpha helix in the hydrophobic portion

Prostaglandin H2 synthase

Arachidonic acid prefer ... regions

hydrophobic

blocks arachidonic acid from getting to the enzyme by blocking hydrophobic channel; causes conformation change

Aspirin mechanism

Resting membrane potential

-70 mV

What allows potassium to leave the cell?

Leaky potassium channels

What allows sodium to easily enter the cell?

Leaky sodium channels

Change in the membrane potential

Graded membrane potential

membrane potential becomes less negative (more positive)

depolarize

membrane potential becomes more negative

hyperpolarize

level the membrane potential must be depolarized for an action potential to occur; -50 mV

threshold potential

What causes depolarization?

sodium entering the cell

What causes hyperpolarization (-100 mV)?

potassium leaving the cell

Membrane potential voltage during depolarization?

-70 mV to -50 mV to +40 mV

Depolarization (-50 mV) opens voltage gated sodium channels causing ...

sodium to enter the cell and increase the voltage to +40 mV

When the cell is +40 mV, it opens...

voltage gated calcium channels, allowing calcium into the cell

What does calcium do vesicles?

brings vesicles containing neurotransmitters to cell membrane via V snares

At what potential do voltage gated potassium channels open and allow potassium to leave?

+40 mV

What happens when potassium leaves the cell?

potential goes from +40 to -100 mV

What happens to the voltage gated calcium channels when the potential is -100 mV?

They close

Kinesin moves from dendrite to axon terminal

anterograde

Dynein moves from axon terminal to dendrite

Retrograde

cold sores; rash of the skin and mucous membrane

Herpes Labialis

What happens to the herpes virus?

travels along cytoskeleton; remains in trigeminal nerve ganglion

Acyclovir

Guanosine analog; virus incorporate into the DNA; can't be translated

Anesthetic

Blocks sodium entry; prevents depolarization and release of neurotransmitters

process where body changes food to energy

metabolism

Breaking large molecules to subunits; releases energy; oxidative

catabolism

building large molecules from smaller molecules; needs energy; reductive

anabolism

ultimate electron acceptor

oxygen

ADP to ATP

stores energy

ATP to ADP

releases energy

reactions that are linked via products or reactants; links unfavorable reactions with favorable reactions

coupled reactions

role a coenzyme plays to get a reaction to occur; ex: Coenzyme A (CoA)

Activation

breakdown of glucose by enzymes, releasing energy and producing 2 pyruvate molecules

glycolysis

enzymes that add phosphoryl group

kinases

enzymes that remove phosphoryl groups

phosphatases

rearrangement of groups on the substrate making a different molecule structure

isomerization

cleavage or splitting of bonds

fission

donating or accepting electrons

redox

remove two hydrogens and one oxygen; forms water and new bonds

dehydration reaction

location of glycolysis

cytosol

First step of glycolysis

glucose to glucose-6-phosphate