Unit 2 Test

review notes, labs, handouts, pathways poster

cell theory

1. All living organisms are composed of one or more cells

2. Cells are the basic unit of life

3. All cells arise from pre-existing cells

How does the SA:V ratio affect the size of the cell?

larger SA:V ratio - smaller cell

smaller SA:V ratio - larger cell

What type of SA:V ratio is best?

a large SA:V ratio (high SA, low V)

how does an increase of SA affect the increase in V?

as SA increases (cell gets larger), V increases faster, lowering SA:V ratio

how can a cells increase surface area without increasing the volume?

microvilli (increase SA), flattened cell shape (maximize SA), cellular division (prevent cells from getting too large)

fluid mosaic model

phospholipids drift fluidly, membrane composed of different components arranged randomly

selective permeability

maintains homeostasis by controlling what enters/exits the cell

how does temperature affect the fluidity of the membrane?

higher temperatures make the membrane more fluid and vice versa

how does the fatty acid composition in phospholipids impact membrane fluidity?

more unsaturated fatty acids increase fluidity, and more saturated fatty acids decrease fluidity

cholesterol

stabilizes membrane fluidity at high and low temperatures, only found in animal cells

integral proteins

permanently attached to the membrane; penetrates into the hydrophobic space

transmembrane protein

type of integral protein that spans from one side to the other

peripheral proteins

temporarily attached to the surface of the membrane; play a role in cell signaling

what 6 functions do membrane proteins have?

intercellular joinings, enzymatic activity, transport, cell-cell recognition, anchorage attachment, signal transduction

gap junctions

channels that connect neighboring cells to allow molecules to pass from one cell to another

tight junctions

plasma membrane of neighboring cells tightly press together, bounded by specific proteins to prevent leakage of substance and create separate environments

glycoprotein/glycolipid

carb chain attached to an extracellular protein/lipid, involved in cell-cell communication and recognition

how does the phospholipid bilayer maintain the internal environment of a cell?

selective permeability

how does the membrane of organelles allow for specific processes to take place?

can create special environments tailored to those specific processes

compartmentalization

membrane-bound organelles in eukaryotic cells create specific environment for those specific processes without influencing the rest of the cell

what is the function of inner membrane folding in mitochondria? ER’s folded membrane?

to maximize SA without increasing V

difference between prokaryotic and eukaryotic cells

prokaryotes have no membrane-bound organelles and a nucleoid region, while eukaryotes have a nucleus, are more complex, and compartmentalize

similarities between prokaryotic and eukaryotic cells

cell membrane, has DNA

difference between plant and animal cell

plant cells have a cell wall, chloroplasts, large central vacuole, plasmodesmata; animal cells have lysosomes, centrioles, and can have cilia and flagella

plasmodesmata

channels that allow communication and transport between plant cells

centrioles

play a role in cell division

how is a prokaryotic cell compartmentalized

prokaryotes don’t necessarily compartmentalize like eukaryotes do, but they have different regions that can carry out different functions

how is a eukaryotic cell compartmentalized?

eukaryotic cells have different membrane-bound organelles, which can carry out many different processes

endosymbiotic theory

eukaryotic cells evolved from prokaryotic cells when larger prokaryotes absorbed smaller prokaryotes and became dependent on them for ATP

what evidence supports the endosymbiotic theory?

mitochondria and chloroplasts have their own DNA and are double-membraned

endomembrane system

membraned organelles involved in synthesis, modification, and transport of proteins and lipids

nucleus

permanently stores DNA, hosts DNA replication and transcription

nucleolus

compartment of nucleus that makes ribosomes

nuclear envelope

the nucleus’ double membrane

nuclear pore

located on the nuclear envelope to control what goes in/out the nucleus

rough endoplasmic reticulum

has bounded ribosomes on the surface, involved in secretion protein and plasma membrane protein synthesis

smooth endoplasmic reticulum

involved in detoxification in cells and lipid synthesis

ribosomes

site of translation during protein synthesis, not part of endomembrane system because it doesn’t have a membrane; free floating ribosomes make cytoplasmic proteins

how does the ribosome demonstrate a common ancestry of all known life?

found in all forms of life and doesn’t have a membrane

golgi apparatus/bodies/complex

modifies, sorts, and packages proteins and lipids for storage or transport out of cell

cisternae

flattended sacs found in golgi body

lysosomes

membrane sacs containing hydrolytic enzymes that break down waste materials and cellular debris, only found in animal cells; aids in aptosis

vacuoles

membrane sacs used mostly for storage; plant cells have one large central vacuole, animal cells have multiple small vacuoles

vesicles

small membranous sacs that store/transport/secrete materials into/out cells, made out of lipid bilayer

mitochondria

makes ATP through cellular respiration, has double membrane but not part of the endomembrane system

cristae

inner membrane folds in the mitochondria

chloroplasts

conducts photosynthesis (converts light energy to chemical energy stored in glucose), has double membrane but not part of endomembrane system

thylakoids

where the 1st half of photosynthesis occurs

grana

increase SA in chloroplasts

stroma

where the 2nd half of photosynthesis occurs

cytoskeleton

provides structural support, aids in cell division, cell movement, and intracellular trafficking

parts of cytoskeleton

cilia & flagella (allow for cell motility), motor proteins (uses cytoskeleton as a highway to transport molecules)

peroxisomes

contains enzymes that detoxify harmful substances and break down fatty acids; generates toxic hydrogen peroxide as a byproduct, then converts it into water; membrane-bound but not part of endomembrane system

how does ER provide mechanical support?

it physically provides support and also produces proteins and lipids that enhance the structure of the cell (can form the membrane of the cell, etc.)

how does the lysosome aid in recycling organic cell matter?

once it breaks down a molecule, it sends the organic material back into the cytoplasm to be reused

how does the vacuole provide turgor pressure?

in plant cells, when the large central vacuole fills up with water, it causes the cell membrane to expand and press up against the cell wall, creating turgor pressure

how does the vacuole assist in storage of macromolecules?

it has large empty space to store the molecules, whether it be food or water

what is passive transport?

when a substance diffuses down/with the concentration gradient (high to low); no ATP required

types of passive transport

simple diffusion, facilitated diffusion, osmosis

simple diffusion

small uncharged molecules can pass through the membrane freely

facilitated diffusion

large/charged molecules need proteins to pass through membrane

osmosis

water diffusion

channel proteins

proteins form pores, allowing specific molecules/ions to pass

can water move freely through the membrane?

yes, because it is a small molecule, but since it is polar, it moves across very slowly

example of channel protein

aquaporins assist in osmosis

carrier/gated proteins

protein binds to molecule, changes shape, then releases molecule on the other side

example of carrier/gated protein

sodium-potassium pump

how does size influence rate of diffusion?

larger molecules diffuse slower, while smaller molecules diffuse faster

how does temperature influence rate of diffusion?

hotter temperature diffuses faster, colder temperature diffuses slower

how does state of matter influence rate of diffusion?

gasses diffuse fastest, solids diffuse slowest

how does the steepness of the concentration gradient influence rate of diffusion

the steeper the concentration gradient is, the faster the substance will diffuse

how is the concentration gradient maintained?

cells may utilize active transport to promote cell diffusion

active transport

moves substances up/against its concentration gradient (low to high); requires ATP

examples of active transport

protein pumps, vesicular/bulk transport

protein pumps

activated when they are phosphorylated, causes them to change shape

example of protein pumps

sodium-potassium pump, proton pump

sodium potassium pump

3 Na+ out, 2 K+ in; helps maintain neural cells’ membrane potential

proton pump

creates electrochemical gradient across membrane by moving H+ ions

membrane potential

voltage across membrane

what voltage range does the membrane typically sit at

-40mV to -80 mV

electrochemical gradient

drives direction of ions through a channel; determined by chemical and electrical force

how does the electrochemical gradient influence the directionality/movement of ions?

cations want to move into the cell, anions want to move out of the cell

vesicular/bulk transport

movement of large/large amounts of substances; uses ATP to move and create vesicles

endocytosis

moving substances into the cell

exocytosis

expelling substances out of the cell

phagocytosis

engulfing solid particles

pinocytosis

engulfing liquid particles

receptor-mediated endocytosis

needs specific molecule to bind to receptors on the cell surface in order to form vesicle

primary active transport vs. secondary active transport

primary active transport directly uses ATP, while secondary active transport indirectly uses ATP

secondary active transport

uses electrochemical gradient generated by primary active transport to transport specific molecules across the membrane

what types of cells have a cell wall?

plant, fungi, and prokaryotic cells

what makes up the plant cell wall

cellulose

what makes up the fungi cell wall

chitin

what makes up the prokaryotic cell wall

peptidoglycan

hypertonic solution

higher concentration of solute & lower concentration of solvent outside of the cell; water flows out of the cell

hypotonic solution

lower concentration of solute & higher concentration of solvent outside of the cell; water flows into the cell

isotonic solution

same concentration of solute and solvent outside of the cell; no net change in water

what happens to animal and plant cells in a hypertonic environment?

animal cells crenate and plant cells plasmolyze

what happens to animal and plant cells in a hypotonic environment?

animal cells lyse and plant cells become turgid

what happens to animal and plant cells in an isotonic environment?

animal cells become normal and plant cells become flaccid