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cell theory
All living organisms are composed of one or more cells
Cells are the basic unit of life
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
transporting solid particles
pinocytosis
transporting 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
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