Cell and Organismal Bio. Test 3

How are cell membranes made?

Phospholipids self-assemble into a bilayer due to hydrophilic heads and hydrophobic tails.

What are the two protein sorting pathways?

Cytosolic and Secretory

What proteins are made in secretory pathway?

secreted proteins, membrane proteins, proteins for organelles

What is co-translational translocation?

Protein enters ER while being synthesized by ribosome

What crosses the lipid bilayer easily?

Small nonpolar molecules (O2, CO2)

What crosses lipid bilayer slowly?

Small polar molecules (water)

What cannot cross the lipid bilayer?

Ions and large polar molecules

What is diffusion?

Movement from high to low concentration

What is a concentration gradient?

Difference in concentration across space

What is a permease?

Membrane protein that helps transport substances

ΔG when moving down a gradient?

Negative (spontaneous)

ΔG when moving against gradient?

Positive (requires energy)

What is facilitated diffusion?

Passive transport using proteins

ΔG of facilitated diffusion?

Negative

Two types of permeases?

Channel proteins and carrier proteins

What is active transport?

Movement against gradient using ATP

ΔG of active transport?

Positive

What protein is used?

Protein pump (ATPase)

What is cotransport

One solute moves down a gradient to power another moving up

Types of cotransporters?

Symporters and antiporters

Two factors of electrochemical gradient?

Concentration gradient and electrical gradient

What is an aquaporin?

Water channel protein

Is there a water pump?

no

Endocytosis

Taking material into cell

Exocytosis

Releasing material out of cell

Main component of a plant cell wall?

Cellulose

Function of a cel wall?

Support and protection

Main component of a bacterial cell wall?

Peptidoglycan

Animal ECM main components?

Collagen, proteoglycans, fibronectin.

What anchors ECM to cells?

Integrins

Two main roles of epithelia

Protection and absorption/secretion

What keep membrane regions separate?

Tight junctions

Homeostasis

Maintaining stable internal conditions

Osmosis

Water movement across membrane

Isotonic

Equal solute concentration

Hypotonic

Lower solute outside —> water enters cell

Hypertonic

HIgher solute outside —> water leaves cell

Water potential Ψ

Measure of water movement

Solute potential Ψs

Effect of solutes - always negative

Pressure potential Ψp

Physical pressure on water

Ideal condition for plants

Hypnotic (turgid)

Salt-in method

Accumulate ions

Compatible solutes

Organic molecules (eg. sugars)

Central vacuole function

Stores water, maintains pressure

Stomata

Openings for gas exchange

Guard cells

Control stomata using water pressure

Contractile vacuole

Pumps out excess water

Freshwater protists need osmoreg?

Because water constantly enters cell

Breakdown of amina acids produces..

Ammonia

Three waste types

Ammonia, urea, uric acid

Most toxic waste

Ammonia

least water needed

Uric acid

Filtration in the kidneys occurs in

Bowman’s capsule

Reabsorption is in

Proximal tubule

Loop of Henle

concentrates urine

function of ADH

Increases water absorption —> concentrated urine.