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