Class 5

Eukaryotic cells- protein trafficking, transmembrane transport, cell signaling, cell cycle

all transcription takes place in the

nucleus

all translation begins in the

cytosol

if you are a cytosolic protein, you finish translation in the

cytosol

if you are a secreted protein, transmembrane protein, or a lysosomal protein, then you will finish translation in the

rough ER

What about a signal sequence allows it to bind to ER so well

its hydrophobicity

signal sequence:


1. one of the first amino acids translated
2. removed at the end of translation

secreted protein

lysosomal protein

signal sequence:


1. can be anywhere in the amino acid sequence
2. appears several times in the amino acid sequence
3. remains as a transmembrane domain in the protein

membrane bound protein

there are more than one signal sequence for

membrane bound proteins

(parts in lumen, part in cytosol)

What would happen if you cleaved the signal sequence on a membrane bound protein?

it would cleave the protein in half

What proteins need the signal sequence cleaved?

secreted proteins and lysosomal proteins

What are the components of the cell membrane?

1. phospolipids
2. cholesterol
3. proteins
4. carbohydrates

act as a barrier between the outside and inside of the cell, but the bilayer also has to be able to allow substances to move in and out to allow for signal transduction

phospholipid bilayer

phospholipid head

polar

phospholipid tail

nonpolar

stabilizes the membrane by stabilizing the nearby phosphate heads, also keeps the membrane fluid by preventing tails from packing together. helps disrupt the membrane that maintains homeostasis within the membrane.

cholesterol

can shift around in the membrane freely, but cannot flip over. stick in and out of the membrane. Have a hydrophilic and hydrophobic regions.

proteins

transmembrane domain

The signal sequence remains as a

increase receptor specificity

Ex: glycolipids and glycoproteins

carbohydrates

properties that depend on the number of solute particles but no on their identity.

colligative properties

What are the four colligative properties?

1. freezing point
2. vapor pressure
3. boiling point
4. osmotic pressure

free ions in a solution produced as a result of dissolving ionic substances

electrolytes

How many ions if put in water would NaCl produced?

2 ions

Na+ Cl-

How many ions if put in water would CaCl2 produce?

3 ions

the number of particles produced per molecule of a substance when it dissolves in water

Van’t Hoff factor

For glucose, what is the Van’t Hoff factor?

1

What is the Van’t Hoff factor of NaCl?

2

What is the Van’t Hoff factor of CaCl2?

3

freezing is the orderly arrangement of solvent molecules.

particles in the solution interfere with the solvent molecules arranging orderly, prevent crystallization (freezing)

Thus, the solution must be made even colder to force freezing

freezing point (FP) depression

FP of 1 kg of H2O is:

0 degrees Celsius

FP of 1 kg of H2O with 1 mole of glucose is:

\-1.9 degrees Celcius

What is the freezing point constant?

1\.9 degrees Celcius

pressure that the gas particles exert on the surface of the liquid from which they evaporated

vapor pressure (VP) depression

higher volatility, __________ vapor pressure

higher

particles in solution, act as IMF anchors on the solvent molecules, preventing evaporation

vapor pressure depression

solute particles act as IMF anchors on the solvent molecules, preventing boiling

boiling point (BP) depression

BP of 1 kg of H2O

100 degrees Celcius

BP 1 kg H2O + 1 mol glucose

0\.5(1)(1)= 0.5 degrees Celcius

BP of 1 kg of H2O + 2 mol CaCl2

molality of 2

100 =

103 C

movement of particles from high concentration area to low concentration area

moving down a gradient

diffusion

movement of water

water moves from ITS high concentration area to ITS low concentration area

osmosis

has more particles than

hypertonic

has fewer particles than

hypotonic

has the same number of particles as

isotonic

osmosis will occur until

isotonicity is reached

A will become more diluted and B will become more concentrated

the pressure required to resist the movement of water by osmosis, resisting pressure that prevents osmosis from occurring

osmotic pressure

What does osmotic pressure follow?

Your particle concentration (osmotic pressure concentration)

red blood cell in a beaker of pure water

hypertonic to the beaker, water will want to swell up with water, the cell will swell and lyse

Typical NaCl (salt) concentration in our cells is what?

Think saline in the hospital

0\.9%

20% NaCl

shrink and shrivels the cell

1% NaCl

red blood cell is going to slightly shrivel up

no energy needed

relies on concentration gradient to drive movement

passive transport

What are the two types of passive transport?

simple diffusion

facilitated diffusion

works well for small hydrophobic molecules

simple diffusion

O2, CO2, lipids, steroid hormones

simple diffusion

still moves down gradient

small hydrophobic molecules, needs a helper protein

facilitated diffusion

H2O, ions, glucose, amino acids

facilitated diffusion

All amino acids have a c and n-terminus that are charged. All amino acids at their core are

hydrophilic

helper proteins

pores

channels

porters

non-specific, size-dependent holes in the membrane

found intracellularly

Ex: aquaporin in nuclear membrane

pores

highly specific, regulated holes in the membrane

Ex: Na+ channels

channels

undergo a conformational shape change to push the molecule across

“shape shifter’s”

porters

requires energy

moves molecules against their concentration gradients

active transport

what are the two types of active transport?

requires energy

moves molecules against their concentration gradients

primary active transport

uses ATP indirectly

“Piggybacks” off of primary active transport

secondary active transport

sodium potassium ATPase

consumes ATP on the inside of a cell, able to shuttle 2 Na out of the cell for every 2 K it pumps in.

accumulation of Na outside of the cell.

accumulation of K in the cell.

cell has an overall negative charge

resting membrane potential

maintains osmotic balance

establishes electrical gradient (RMP= approx. -70mV)

Na/K ATPase

relies on gradient set up by primary active transport, uses ATP indirectly

secondary active transport

Na+ in the kidney and bloodstream (connective tissue)

Na/K ATPase

pumping sodium out of your cells

glucose gets naturally filtered out into

the lumen

glucose is used

as energy

have sodium in the urine because the cell wants to get rid of it to create a

proton gradient

involved in cell recognition and communication processes

G protein coupled receptors

to activate the G protein coupled receptor, the

ligand has to bind

What raises intracellular levels of cAMP?

adenylyl cyclase

cAMP leads to the activation of

proteins kinases

2nd messenger systems

cAMP

signal amplification

\-ligand itself= 1 signal

\-activated many cAMPs= many signals

fast and temporary

\-flipping molecule structures

\

phospholipase C

These act as important second messengers

IP3

DAG

What does DAG do?

activates kinases

change enzyme activity

What does IP3 do?

increase intracellular calcium

What three types of filament make up the cytoskeleton?

microtubule

microfilament

intermediate filament

has alpha and beta tubulin

large diameter

Uses:

mitotic spindle

intracellular transport

cilia and flagella

microtubule

How are microtubules arranged?

9+2

contractile protein present in cilia and flagella

when it contracts, it moves the cilia and flagella side to side

dynein

actin

small diameter

uses: muscle contraction

pseudopod formation

cytokinesis

microfilament

several different protein types

medium

structural roles

intermediate filament

these are general adhesive junctions found in between cells, hook cells together

like glue

Ex: digestive tract

desmosomes

seal lumens

separate environments

tight junctions

allow for cell to cell communication

allow for particles to cross from one cell to another

gap junctions

Cell cycle can be broken into two parts

interphase and mitosis

clone the cell you had before

go from one cell to two cells

mitosis

in between the m-phases

G1

S

G2

interphase

where normal cell growth happens

where normal cell activity takes place

G1

cells spend most of their time in the

G1 phase

do not divide

G0 cells

nondividing cells

always in G1

neurons and muscle cells

barrier between G1 and S is very heavily regulated

DNA replication

S-phase