cell theory
1. All things are made of cells |
2. Cells are the basic units of structure and function in all living things |
3. All cells come from pre-existing cells |
endosymbiotic theory
Mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells, may have gained entry as undigested prey or parasites. |
all eukaryotic cells came from bacterial cells that lived together |
proof:all chloroplasts and mitochondria have own DNA and are autonomous (existing and functioning as an independent organism) |
cell surface area to volume
smaller cell is faster and more efficient at supplying materials and removing waste than larger cell |
once volume becomes too great for area of cell membrane, pathway is triggered and cell divides |
water potential - def and vid
osmotic potential
potential of water molecules to move from a hypotonic solution (more water, less solutes) to a hypertonic solution (less water, more solutes) across a semi permeable membrane |
tonicity
- turgor pressure - pressure that water molecules exert against cell wall (considered normal GOOD)
- plasmolysis - cells shrinking away from cell wall
- cytolysis - same as lyse
diabetes
type 1 |
insulin isn't produced, beta pancreatic cells damaged |
type 2 |
insulin/glucose receptors not working |
Hyperglycemia (high blood sugar), hypoglycemia (low blood sugar). Antagonist to insulin is glucagon.
prokaryotic cells
unicellular bacteria |
nucleoid region: DNA floating in cytoplasm, no true nucleus or nuclear membrane |
considered first form of life - were most likely anaerobic |
cell membrane: regulates transport; selective permeability |
cell wall: protective layer external to cell membrane |
*does not contain phospholipid or transport proteins |
*peptidoglycan? |
bacterial cell wall is often target for antibiotic treatment |
DNA exists freely in cytoplasm as closed loop |
ribosomes: protein synthesis location |
capsule: outside of cell wall; made of carbohydrate |
* limit the ability of phagocytes to engulf the bacteria |
* cannot be washed off easily |
pathogenic (causes disease) |
pills make it stick and can't wash off |
prokaryotes vs eukaryotes
pro |
euk |
No Membrane-Bound Organelles |
Membrane-Bound Organelles |
No Nucleus (single Circular DNA) |
Multiple Linear DNA |
Free Ribosomes and cell wall |
Histones on DNA |
endomembrane system
all the different membranes within a eukaryotic cell’s cytoplasm |
divide the cell into compartments (organelles!) |
nuclear membrane |
double membrane that encloses the cell nucleus |
er |
connected to the nucleus; allows for reactions, membraneous; |
rer |
proteins, has a lot of ribosomes |
ser |
lipids, responsible for the detoxification of harmful chemicals |
golgi body |
packaging in membrane and signals for export |
lysosomes |
used for intracellular digestion and apoptosis, also to fuse w another vesicle to break down using its hydrolytic enzymes |
vesicles |
may carry hormones that help w body regulation, merges w plasma membrane, releases contents into the external envi, lysosome is a type of vesicle |
vacuoles |
water and solutes; large and central in plants |
cell membrane: regulates transport; selective permeability |
modifications for cell specificity : |
muscle cell has more rer bc of its need for protein |
liver cell has more ser bc of its role in detoxification |
rest of organelles
nucleus |
holds DNA and nucleolus (where ribosomal subunits are made) |
mitochondria |
double membrane; outer is smooth and inside is folded with enzymes to make ATP (site of cellular respiration) |
ribosomes |
site of translation-protein synthesis; made of rRNA and protein |
cytoskeleton |
Microfilaments-contractile protein, gives shape, movement within cells; Microtubules-centrioles, cilia, flagella, spindle fibers |
ANIMAL |
lysosomes |
contain enzymes; used for intracellular digestion and apoptosis |
Centrioles |
used in cell division |
plants |
Chloroplast |
double membrane; site of photosynthesis |
Cell wall |
middle lamella-pectin; primary cell wall-cellulose; secondary cell wall- lignin |
nervous system
Function; sensory input, motor function, regulation |
Structure; neuron, axon, dendrites, synapse |
Polarized neuron; Na+ outside, K+ and Cl- inside |
Depolarization moves Na+ into the neuron, generating an action potential |
Repolarization exchanges Na+ and K+ through the sodium-potassium pump |
At the synapse, calcium channels open to allow calcium to rush in, stimulating release of neurotransmitters |
Neurotransmitters released into synapse to generate action potential for motor neurons or muscle cells |
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link for signal transduction pathway
cell signaling / signal transduction
reception: when a receptor protein picks up a signaling molecule on the surface in the phospholipid bilayer. are other ways...
transduction: series of relay molecules or other protein complexes will usually use ATP to transfer the signal down a signal transduction pathway and activate a response
response: changes in enzyme activity, gene expression, and ion channel activity
inactivation: is when response stops - can be apoptosis or a halt of the response.
transduction
a phosphorylation cascade |
phosphorylation - addition of a phosphate group, generally from ATP to a protein or other organic molecule which turns many protein enzyme son and off |
stp is merely a lot of different molecules being involved and carrying a signal from the original site of reception to then carry out a response |
second messangers
cAMP |
broken down even more is cyclic adenosine monophosphate, intracellular messenger |
calcium ions |
inositol triphosphate |
can occur on nuclear level |
genes turning on or off by activation of proteins called transcription factors in nucleus of cell and will activate or inactivate causing transcription of RNA which is then a messenger and is translated into a protein |
organismal response |
fight or flight response: encounter lion, could fight it or run away, activated by adrenaline |
inactivation |
can occur both in inactivation of simple nuclear responses or can be apoptosis (clean programmed cell death) |
phagocytosis |
one cell eats or breaks down another cell, used both in immune system and apoptosis |
apoptosis |
cells called phagocytes consume cell that have sent out signals that occur because of other complex signals that say they must disintegrate and be consumed |
phagocytes |
cyte (cell), phag (consume) |
intracellular receptors
intracellular receptor proteins occur within one cell |
Is when a hormone or other ligand can go through phospholipid bilayer bc it is hydrophobic |
has a receptor protein inside the cytoplasm of the cell |
this often reacts with that receptor protein creating a hormone receptor complex that can enter into nucleus of cell and create RNA subscription? |
ligand gated ion channel
like a door or portal, when signaling molecule attaches to active site on this "gate" will open, usually involved in ion channels, a lot of ions will pass through creating a concentration gradient, on the way out will create ATP and energy of that will be harnessed by the cell
G protein coupled receptors (gpcr)
involved at the surface of the cell a lot of the time w epinepherine//adreniline, affects the fight or flight respsonse in animals. hromone in the endocrine system and neurotransmitters in the synaptic cells
protein kinases (rtks)
kinase-enzyme that catalyzes transfer of phosphate groups from ATP to ADP when it goes through hydrolysis (water breaking off one phosphate ion from ATP). rtk-receptors that when they receive a signaling molecule at their active site, form an unphosphorylated dimer, makes ATP connect to this tyrosine which is a protein and that activates the rtk and turns it into a phosphorylated dimer. Then inactivated relay proteins attach to the phosphates on the dimer and are activated and result in response
passive transport
no added energy required |
movement of molecules from area of high to low concentration |
concentration gradient |
difference in concen of mlcs across a distance |
diffusion |
carbon dioxide and oxygen can pass through membrane bc small and non polar (soluble in lipids) |
facilitated diffusion |
polar molecules (water) need to pass through pore made by transport protein |
osmosis |
diffusion of water, water moves from high to low, amount of solute needs to be payed attention to |
solute |
solid that is dissolved in a solvent |
solvent |
liquid |
hypertonic |
high amount of solute, low amount of water in SOLUTION |
hypotonic |
low amount of solute, high water |
isotonic |
solute concen inside and outside are the same |
isotonic |
water moves back and forth in equal amounts (no net movement), cell maintains shape |
water moves from high concen of WATER to low concen of WATER |
hypo to hyper |
contractile vacuole |
ex paramecium live in hypotonic, use these to collect excess water and then contract to push water out |
our cells pump solutes out of cytosol to bring outside concen closer to inside |
plants |
take in water through their roots through osmosis |
1. molecule binds to carrier protein, 2. carrier protein changes shape, 3. protein releases the molecule to the outside, 4. protein returns to og shape |
second way of fd: ion channels, membrane proteins that allow only one specific type of ion through |
factors that affect the rate at which mlcs move across membrane:
temp- higher temp
starting concen- extreme diff in starting concen
size of particles- small
all diffuse at a faster rate
active transport
requires added energy (ATP) |
moves from low to high concentration |
up the concentration gradient (sodium potassium pump) |
membrane pumps |
carrier proteins that moves substances from low to high concentration |
endocytosis (vesicle movement) |
brings items into the cell, process b y which cells ingest external fluid, macromolecules or other large particles. Phagocytosis is cell eating and Pino cytosine is cell drinking |
exocytosis (vesicle movement) |
process by which a substance is released from a. cell through a vesicle that transports it to the cell surface and fuses w the cell membrane |
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can fuse bc both made of phospholipids, layers press into each other and phospholipids rearrange a little so can open up their contents to the outside of the cell |
ALL REQUIRES ENERGYYYY |
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cytoskeleton
a complex of mesh protein filaments that extends throughout the cytoplasm |
maintains cell shape |
controls position of organelles within cell by anchoring them to plasma membrane |
cytoplasmic streaming |
flow of cytoplasm |
anchors cell in place by interacting w extracellular elements |
includes microtubules and microfilaments |
microtubules |
hollow tubes made of tubulin protein which makes up cilia flagella and spindle fibers |
microfilaments |
made of actin filaments, support shape of cell |
animal cells form cleavage furrow |
amoeba to move by sending out pseudopods |
skeletal muscles contract as they slide along myosin filaments |
cytoplasm
Separates the internal environment of the cell from the external environmen |
Phospholipid bilayer (selectively permeable; amphipathic) |
Fluid mosaic model (in motion; proteins, cholesterol, glycoproteins, and glycolipids among phospholipids) |
membrane is hydrophilic on the inside and outside, hydrophobic within the membrane |
centriole, centrosome, mtoc
non membranous structures that lie outside NUCLEAR membranes |
organize spindle fibers and give rise to spindle apparatus |
two centrioles make up a centrosome (ANIMALS) |
PLANTS have microtubule organizing center (mtoc) which does the same thing |
cell membrane // proteins
give diff types of membranes their unique props |
help w facilitated diffusion and active transport |
connect cells together |
participate in signal transduction |
act as marker for cell identification |
integral |
permanent part of the membrane |
peripheral |
transiently (not perm) associated w either membrane or integral proteins |
associations can be hydrophobic, electrostatic, or non covalent |
integral monotopic proteins |
attached to only one of two leaflets don't span across membrane |
transmembrane (are amphipathic - hydrophobic and phillic) |
span bilayer, can be bitopic spanning across membrane once or polytonic (more than once) |
lipid anchor proteins |
covalently attached to lipids in the bilayer |
post translational changes to integral and peripheral |
addition of fatty acids, diacylglycerol, phrenyl chain, |
hydrophobic affect |
water molecules want to interact w each other so badly, anything getting in the way of their hydro bonds results in decreased entropy |
detergent will disrupt transmembrane proteins bc r amphipathic and will get them out of the membrane |
2 types of transmembrane proteins |
a helical |
found in all membranes |
b barrel |
only in outer membranes of gram neg bacteria, mitochondria, chloroplasts |
function as gateways allowing specific substances to pass across the membrane |
may undergo conformational changes |
most transmembrane proteins are glycosylated, sugar residues always present on non cytosol leaflet of bilayer |
as a result, cell surface is covered in carbs that form cell coat |
apoptosis // capases
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pathways involving enzymes called capases carry out apoptosis |
apoptosis is similar in single celled yeast and in mammalian cells means mechanism for apoptosis evolved early in the evolution of eukaryotic cells |
long distance signaling
in animals or humans through endocrine system - when specialized endocrine cells withing your glands and lymph nodes and lymphatic system will secrete things and those will travel through you blood and when reach any target cell, that will be effected and give a reaction. hormone ex: oxytocin, epinepherine, it is transported form endocrine system through the circulatroy system
local signaling
paracrine signaling - secreting cells, secrete molecules that diffuse from cell and whenever they hit a target cell w a receptor on surface that fits with molecule then will have an induced effect
synaptic signaling - a motor neuron (efferent-sending signals out) will send some sort of molecule (the effect) across the synapse and will affect a target cell that is stimulated and then has another action potential or response. In muscle contraction, mol would be acetylcholine
communication by direct contact
gap junctions - bet animal cells, junctions that allow molecules to play readily bet adjacent cells w/o crossing the plasma membrane
plasmodesmata - bet plant cells
cell to cell recognition - two animal cells may communicate by interactions bet molecules protruding from their surfaces. protiens or other molecules on the surface of cells jutting out can react w each other. they seem to fit together like a specific protein and a specific substrate
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