AP Biology Unit 2: Cell Structure and Function

ribosome

• non-membrane

• protein synthesis according to mRNA sequences

• BOTH eukaryotic and prokaryotic

• made of proteins and ribosomal RNA (rRNA)

do ribosomes have a membrane?

no

ribosomes are part of _______ synthesis

protein synthesis

are ribosomes found in prokaryotic or eukaryotic cells? both?

both

free ribosomes are found in the __________

cytosol (in both prokaryotes and eukaryotes)

in ___karyotes, bound ribosomes are found…

eukaryotes; found on the membrane of the rough ER

endoplasmic reticulum

• series of membrane channels

• rough endoplasmic reticulum has ribosomes bound

• smooth endoplasmic reticulum does NOT contain ribosomes and functions in lipid synthesis and detoxification of harmful substances in the cell

endoplasmic reticulum is made up of…

series of membrane channels

endoplasmic reticulum is found in prokaryotes or eukaryotes? both?

eukaryotes

rough ER has

ribosomes bound to its membranes

where does lipid synthesis take place?

smooth ER

where does the detoxification of harmful substances in the cell take place?

smooth ER

golgi body

• stack of flattened membrane sacs (cisternae)

• lumen: interior of each cisternae

• contains enzymes necessary for the golgi body to function

• controls the modification and packaging of proteins for transport

• packages the finished proteins into vesicles

golgi body is made up of…

cisternae (stack of flattened sacs)

lumen

interior of each cisternae of the golgi body

golgi bodies function with the help of ______

enzymes

function of the golgi body

modification and packaging of proteins for transport

packages and finished products from the golgi body are sent into ______

vesicles

lysosomes

• membrane-bound sacs

• contains hydrolytic enzymes

1. digest macromolecules

2. break down worn-out organelles

3. apoptosis

4. destroy bacteria/viruses

lysosomes are made up of…

membrane-bound sacs

four functions of lysosomes

1. digest macromolecules

2. break down worn-out organelles

3. apoptosis

4. destroy bacteria/viruses

vacuole

• membrane bound sac

1. food or water storage

2. water regulation in a cell

3. water storage

• can provide the plant cell with turgor pressure and support

vacuoles are made up of…

membrane-bound sacs

3 functions of vacuole

• water and food storage

• water regulation in a cell

• waste storage

central vacuole

maintains turgor pressure with nutrient and water storage (plant cells)

contractile vacuole

maintains osmoregulation in some single-celled organisms

food vacuole

formed from phagocytosis and fuses with lysosome

mitochondria

• double membranes

• smooth outer membrane, folded inner membrane (increases the SA)

• proton gradients for ATP production

chloroplasts

• in plant cells only

• double-membrane

• liquid membranous sacs called thylakoids that are stacked into structures called grana

  • stroma surrounds grana

centrosome

• in animal cells only

• help microtubules assemble into the spindle fibers needed in cell division

amyloplasts

excess glucose produced by photosynthesis is stored as starch molecules in the amyloplasts

nucleolus

• not membrane-bound

• region in the nucleus where ribosomes are assembled

endosymbiosis hypothesis

prokaryotes were absorbed by other larger prokaryotes

these prokaryotes became interdependent on each other

prokaryotes become membrane-bound organelles, become eukaryotes

advantage of compartmentalization

• allow different parts of the cells to specialize their functions

• allow for greater efficiency within the cell

• allows cell to separate the enzymes in different metabolic processes

• greater surface area

what type of relationship does surface area:volume ratio and radius have: direct or inverse

inverse; as radius INC, SA:vol ratio DEC

is a bigger or smaller SA:vol ratio good

bigger

can folding membranes increase SA:vol ratio

yes

small cell size —> big SA: vol —> ____ rate of diffusion

big

plasma membrane is made up of …

phospholipid bilayer

• hydrophilic polar phosphate heads

• hydrophobic nonpolar fatty acid tails

glycoproteins and glycolipids function

cell recognition

cholesterol steroids in plasma membrane function

adjust membrane fluidity in response to changing environmental conditions

what can pass through plasma membrane

small hydrophobic nonpolar molecules (oxygen, carbon dioxide, nitrogen)

small polar molecules (like water) can pass through in SMALL quanitities

passive transport (diffusion)

• movement of polar/charged molecules from higher to lower concentration

• NO energy needed

facilitated diffusion

channel proteins allow the passive transport of ions (no energy needed)

aquaporins

specialized membrane proteins that allow large quantities of water to move down their concentration gradient (facilitated diffusion)

active transport

move molecules from lower to higher concentration (requires energy)

endocytosis

membrane pinches in to surround a particle or extracellular fluid, creating a vehicle that ENTERS the cell

exocytosis

a vesicle that carries something fuses in the membrane and is dumped outside the cell (EXITS the cell)

hypotonic

lower concentration of solute

higher water potential

a hypotonic cell: water leaves cell, leaving animal cell shriveled (crenation) or plant cell plasmolyzed

hypertonic

higher concentration of solute

lower water potential

hypertonic cell: water enters the cell; cell becomes lysed in animal cell and turgid in plant cell

isotonic

equal amount of solute and solvent; normal in animal cell and flaccid in plant cell

water potential

potential energy of water in a solution; or ability of water to do work

measure of water’s tendency to move from high to low water potential

water moves from hypo→hyper or hyper→ hypo

hypo→ hyper

water potential formula

water potential = solute potential + pressure potential

solute potential formula

solute potential = -iCRT

kelvin formula

temperature (in degrees C) + 273

osmolarity

total concentration of solutes in a solution

contractile vacuole

excess water entering the cell is stored then pumped out of the cell

metabolic rate

amount of energy that an organism expends during a given amount of time

basal metabolic rate

amount of energy consumed by an organism at rest at a comfortable temperature

endotherms

generate body heat internally (metabolically); body temp is regulated at a set point (mammals)

as endotherms get BIGGER their rate of energy use (basal metabolic rate) INC or DEC

INC (an elephant uses a lot more energy than a mouse)

as endotherms get BIGGER their relative metabolic rate (metabolic rate/unit of body mass) INC or DEC

DEC (the smaller the animal, the more energy each gram of tissue requires)

ectotherm

body temperature conforms to external environment temperature

Increased surface area will (increase/decrease) the number of transport proteins that can fit in the membrane

Increase