Unit 5 Test - Cell Transport

polar; hydrophilic; glycerol; functional groups

Phospholipid Heads:

• _______

• _________________

• constructed of _____________ and phosphate _________________________

nonpolar; hydrophobic; saturated; monounsaturated

Phospholipid Tails:

• ____________

• ____________________

• Constructed of 1 __________________ fatty acid and 1 ___________________________ fatty acid

amphipathic molecule

A molecule that had both hydrophilic and hydrophobic ends

Phospholipid bilayer

A double layer of phospholipids, with hydrophilic heads facing outward and hydrophobic tails facing inward.

selectively permeable

allows certain molecules to pass through but not others; controls the flow of substances in or out of the cell (homeostasis)

size, polarity, charge

Factors that affect permeability

small; nonpolar

____________ & _________________ substances pass through the bilayer easily (ex: O2 and CO2)

larger; polar

__________ & ____________ particles do not pass through easily

fluid mosaic

the cell membrane is made of many different molecules that are free-floating through the membrane

cholesterol, carbohydrates, protein

Membranes contain

cholesterol

helps strengthen the flexible membrane

Carbohydrates

aids in cellular identification

glycoproteins

membrane proteins with carbohydrate chain attached

glycolipids

phospholipids with carbohydrates attached by a glycosidic bond

receptor proteins

proteins that function as receptors for chemical messages from other cells

receptors

proteins that detect a signal molecule and perform an action in response

channel proteins

proteins with tube-like openings that allow specific substances to enter/exit freely

aquaporins

channel proteins that allow water to pass freely

ion-gated protein

channels that open or close in response to a stimuli

carrier proteins

proteins that bind to molecules or ions and carry them to the other side of the membrane

10-50 mm; period

Plant/animal cells

• about _____________

• 1/500 the size of a _______ in the textbook

0.2 mm

Bacteria cells are about _________, which is 50-250x smaller than plant/animal cells

surface area

total space in contact with extracellular environment

cell membrane; rate; good

Surface Area:

• includes all of ________________________

• available surface area determines ______ materials can pass into/out of cell

• high surface area = _________

volume

total space within the cell

cytosol; organelles; within; bad

Volume:

• includes all of ________ and ______________

• cell volume determines rate at which materials move _____________ the cell

• high volume = _______

maintain homeostasis

cells want a high surface area compared to their volume to ________________________

smaller

the ______________ the cell, the higher the SA:V ratio

concentration gradient

difference in amount of molecules across a sapce

high; low

Molecules move from __________ concentration to _____ concentration

equilibrium

when there is an equal concentration of molecules dispersed throughout a solution

passive transport

any movement of molecules that does not require energy

down; equilibrium

Passive Transport:

• always moves molecules __________ the concentration gradient

• molecules eventually reach _______________

diffusion

the movement of molecules from an area of high concentration to an area of low concentration

heat energy and collisions

Factors that cause molecules to move

heat energy

causes molecules to move randomly

higher; faster

the __________ the temperature, the ___________ the rate of diffusion

collision

__________ with other molecules changes trajectory and spreads molecules out

facilitated diffusion

molecules move passively across a membrane through a protein

channel or carrier proteins

___________________________ or ion channels may facilitate diffusion of solutes across membranes

polar; do not

many kinds of ___________ molecules __________ diffuse freely across membranes and need channel proteins

osmosis

the diffusion of WATER across a semipermeable membrane

lower; higher

In osmosis, water travels from a solution of ____________ solute concentration to _____________ solute concentration

tonicity

the measure of the osmotic pressure gradient

isotonic

concentration of solute is the same on both sides of the cell membrane

stays the same

a cell ___________________ in an isotonic solution

best

an isotonic solution is the _____ environment for an animal cell

homeostasis

when an animal cells is in an isotonic solution, it is at _________________

okay

an isotonic solution is an _____ environment for a plant cell

flaccid

when a plant cell is in an isotonic solution, it is _________________

hypertonic

a solution with a greater concentration of solute compared to a cell

leave; shrink

If a cell were placed in a hypertonic solution, water would __________ the cell and the cell would ________

crenated

Animal cell: cells shrivel and shrink due to dehydration (hypertonic)

plasmolysis

Plant cell: when the cell membrane pulls away from the cell wall; wilts (hypertonic)

hypotonic

a solution with a lower concentration of solute compared to a cell

rush; expand

If a cell were placed in a hypotonic solution, water would ________ into the cell and the cell would _________

cytolysis

Animal cell: when a cell bursts because of osmotic pressure (hypotonic)

turgor pressure

Plant cell: pressure created when the cell membrane pushes against the cell wall; homeostasis (hypotonic)

protists

Have contractile vacuoles to actively pump water out to prevent bursting

contractile vacuole

protists use ______________________ to actively pump water out to prevent bursting (osmosis)

salt water fish

have specialized gills to pump out excess salt water from blood to prevent dehydration

specialized gills

salt water fish have _____________________ to pump out excess salt water from blood to prevent dehydration (osmosis)

plants

have cell wall to prevent bursting when in hypotonic state

cell wall

plants have a ________________ to prevent bursting when in hypotonic state (osmosis)

active transport

any movement of molecules that requires energy from the cell

up; prevented

in active transport, molecules move _______ the concentration gradient and are _____________ from reaching equilibrium

atp

powers nearly all forms of cellular work

phosphorylation

transfers a phosphate group from ATP to another molecule because of a hydrolysis reaction

released; created

in phosphorylation, energy is ___________ and ADP (adenosine diphosphate; low energy molecule) is __________

sodium potassium pump

uses ATP phosphorylation to actively pump Na+ and K+ ions across the cell membrane

electrical current

in a sodium potassium pump, these charged ions build up an ________________________ for nerve cell impulses

3 Na+

1. Sodium Potassium Pump: ________ ions load from the inside of the cell

ATP

2. Sodium Potassium Pump: ______ phosphorylates the protein causing it to change shape

Na+

3. Sodium Potassium Pump: _____ ions are released to the outside of the cell

2 K+

4. Sodium Potassium Pump: _____ ions load into the protein from the outside

dephosphorylated

5. Sodium Potassium Pump: the protein is ___________________

2 K+

6. Sodium Potassium Pump: _______ ions are released to the inside

exocytosis

large molecules are released from the cell

vesicle, ATP; large molecules

Exocytosis:

• a __________ fuses with the membrane and expels its contents

• requires ____ to move vesicles

• used to move _______________ or large amounts of liquids

hormones, waste, enzymes

exocytosis removes large molecules like ______________________________

endocytosis

large molecules are brought into the cell

membranes; ATP

Exocytosis:

• ___________ fold inward to bring in large molecules by forming a vesicle

• requires _____ to move vesicles

phagocytosis and pinocytosis

two types of endocytosis

phagocytosis

type of endocytosis; “cell eating”; incoming substance is a solid

pinocytosis

type of endocytosis; “cell drinking”; incoming substance is a liquid