Studied by 19 people
plasma membrane
double layered structure with phospholipids and proteins
semi permeable
only small, hydrophobic molecules like O2 and CO2 can pass through without help
integral proteins
firmly bound to plasma membrane
transmembrane proteins
intregral proteins that extend all the way through the membrane
fluid mosaic model
each layer of phospholipids is flexible
adhesion proteins
form junctions between adjacent cells
receptor proteins (hormones)
docking sites for things that arrive at the cell
transport proteins
make pumps to actively transport solutes across the membrane with ATP
channel proteins
make channels that selectively allow for the passage of certain ions/molecules
cell-surface markers (glycoproteins)
exposed on surface -- cell recognition and adhesion
carb side chains
on the surface of some proteins; stabilize fluidity of membranes in animal cells (cholesterol)
nucleus
directs what happens in the cell and is responsible for the cell’s reproduction ability
what is the largest organelle
nucleus
chromosomes
what DNA is organized into
nucleolus
where rRNA is made and where ribosomes are assembled
ribosomes
carry out protein synthesis
what are ribosomes made out of?
rRNA and protiens
where are ribosomes located?
free floating in the cell or attached to the ER
rough endoplasmic reticulum
proteins made here are trafficked to/across membrane, used to build golgi bodies. lysosomes, or ER, compartmentalize
where is the rough endoplasmic reticulum located?
attached to nucleus and has ribosomes attached
smooth endoplasmic reticulum
makes lipids, hormones, steroids, detoxification of waste
golgi bodies
helps process pollutants by modifying/processing/sorting products after RER synthesizes them; packaging/distribution for stuff meant to be discarded from the cell; produce lysosomes
vesicles
carry products to the plasma membrane
mitochondria
convert energy from organic molecules into energy for the cell (ATP)
where does most ATP production happen?
cristae
lysosomes
have digestive enzymes to break down unwanted/dead/old stuff in the cell, intracellular digestion
hydrolytic enzymes
found inside lysosomes; only work at a certain pH -- essential during apoptosis
centrioles
make microtubules to pull replicated chromosomes to opposite ends of the cell during cell division
vacuoles
fluid-filled sacs that store water, food, wastes, salts, pigments
peroxisomes
detoxify stuff to make H2O2 via enzymes
what makes up the cytoskeleton
microtubules and microfilaments
microtubules
made up of protein tubulin; help control cellular division and movement
microfilaments
help with movement; made from protein actin that can be joined together and broken down to help microfilaments grow and shrink
cilia and flagella
help with movement in single-celled organisms
cellulose
makes up cell wall
what are cell walls found in
plant cells, protists, fungi, bacteria
chloroplasts
have chlorophyll and make plants green :)
central vacuole
large vacuole that takes up much of a plant’s cytoplasm
what does a full vacuole indicate about a plant?
it’s not dehydrated
what does a not full vacuole indicate about a plant?
it’s dehydrated
what charge of things can cross the lipid bilayer
hydrophobic
facilitated transport
uses protein channels as tunnels through membranes
aquaporins
a type of facilitated diffusion for water; water can’t cross without it
passive transport/diffusion
high → concentration
simple diffusion
small, polar molecules can go right through without assistance
facilitated diffusion
when assistance from a channel-type protein is required
passive trasnport
when soemthing is moving by diffusion; no energy needed
osmosis
when the molecule that’s diffusing is water
what happens if a cell membrane loses H2O in a plant cell?
shrinks away from the wall
what happens if a cell membrane takes in H2O in a plant cell?
expands and goes against it
hypertonic
more dissolved solutes/less solvent
hypotonic
fewer dissolved solutes/more solvent
water potential
measures potential energy in water; how much potential it has to diffuse -- how eager it is to go from low to high
in what direction does water potential go?
high to low ALWAYS.
what is water potential affected by
pressure potential and solute potential
how does adding a solute affect water potential?
water potential is lowered; water is less likely to leave the solution and more likely to enter
active transport
movement against natural flow (low → high)
sodium-potassium pump
pushes out 3 Na+ ions and brings in 2 K+ ions across the membrane
secondary active transport
something is actively transported using energy from movement of another substance going down its concentration gradient
endocytosis
when larger pieces want to enter the cell, a piece of the membrane engulfs it, forms a pocket, and makes a vacuole/vesicle
pinocytosis
cell ingests liquids
phagocytosis
cell igests solids
receptor mediated endocytosis
when a ligand bonds to a receptor, it’s brought into the cell by folding in the membrane, making a vesicle around the ligand
bulk flow
fluids moving in one direction due to pressure
exocytosis
large particles transported out of the cell
why are cells small?
moving things in and out is harder the larger the cell
what leads to a more efficient cell?
a higher ratio of SA:V (12/1 is higher than 6/1)
what happens as cells increase in volume?
relative SA decreases and the demand for internal resources increases → more complex structures needed to sustain the cell
when do phospholipids form a bi-layer in an aqueous environment?
spontaneously
embedded proteins
hydrophilic or hydrophobic, loosely bound to membrane surface
what happens when embedded proteins are hydrophilic?
charged and polar side groups
what are the purposes of embedded proteins?
transport, cell-cell recognition, enzymatic activity, signal transduction, enzymatic activity, signal transduction, intercellular joining, attachment for extracellular matrix or cytoskeleton
how is cholesterol distributed in the bilayer?
randomly between phospholipids
what does cholesterol do for the bilayer?
regulates fluidity under different environmental conditions
plasmodesmata
small holes between plant cells that allows the transfer of nutrients, waste, plants
what complex carbs do plants have?
cellulose
what complex carb do fungi have?
chitin
what complex carb do prokaryotes have>
peptidoglycan
what does exocytosis require energy for?
to move large molecules out of the cell
what does active transport do?
establishes and maintains concentration gradients
cotransport
uses energy from an electrochemical gradient to transport two different ions across the membrane through a protein
symport
two different ions are transported in the same direction
antiport
two different ions are transported in opposite directions
electrochemical gradient
relies on an electrochemiccal difference across a membrane (membrane potential)
osmolarity
total solute concentration in a solution
solute
substance being dissolved
solvent
a substance that dissolves
how are water concentration and solute concentration related?
inversely
environmental hypertonicity
less cellular solute and more cellular water (water leaves); plasmolysis
environmental hypotonicity
more cellular solute and less cellular water (water enters); turgid
what does osmoregulation allow for in animal cells
maintains water balance and allows control of internal solute composition/water potential
what do plasma membranes allow cells to do
establish and maintain different internal and external envrionments
what do cellular compartments allow for
various metabolic processes and specific enzymatic reactions to occur simultaneously, increasing cell efficiency
what do prokaryotic cells have in terms of compartmentalization
internal region, nucleoid region with genetic material
what do eukaryotic cells have in terms of compartmentalization
additional inner membranes and membrane bound orgnalles
endosymbiosis
a free living anaerobic prokaryote was engulfed and didn’t get digested → over time, lost some functionality and became mitochondria
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