cell bio and organelles Flashcards
which are the double membrane organelles?
mitochondria, nucleus
rough vs smooth ER
rough synthesizes/modifies secretory and membrane bound proteins; smooth performs detoxification and glycogen breakdown in the liver; steroid synthesis in the gonads
The ER is also joined to the nuclear membrane
lysosomes vs peroxisomes
lysosomes have hydrolases for digesting substances; peroxisomes metabolize lipids and toxins specifically with H2O2
nuclear matrix
kind of like a cytoskeleton for nucleus; DNA is attached to the matrix at certain sites so it has a role in gene regulation
what organelle made in nucleolus
ribosome. Nucleolus is the site where RNA pol I makes rRNA too. Translation within nucleus prevented bc ribosomes not fully assembled here
nuclear localization sequence
proteins with this sequence are imported into nucleus by specific transport mechanisms (too large for pores)
endosymbiotic theory
mitochondria were once independent prokaryotes
maternal inheritance
applies to mitochondria only
N-terminus signal
sequence on N terminus of proteins that is recognized by SIGNAL RECOGNITION PARTICLE which takes the peptide and ribosome to the RER. This sequence is cleaved, after which it leaves. This is the pathway for secretory proteins (ones which leave cell)
The sequence has hydrophobic AAs
transmembrane domains
sequences of hydrophobic AAs that anchor it in membrane. These exist in integral membrane proteins
targeting signals
sequence on protein that takes otherwise secretory proteins (those made in RER) to another organelle first
localization signals
sequence on protein that takes cytoplasmically made protein (not RER) to certain organelles
Golgi
proteins move from cis > medial > trans. Proteins come from ER to the cis portion
constitutive secretory pathway
proteins sent from RER > golgi > cell surface; whereas REGULATED SECRETORY PATHWAY is when secretory proteins are kept in vesicles and released upon signal
What proteins follow this pathway? Integral, organelle membrane-bound, and secreted
acid hydrolases
enzymes found in lysosome, only function at pH 5
catalase
enzyme that breaks down H2O2, found in peroxisome because H2O2 is byproduct of some reactions inside
colligative properties
set of properties depending only on number of solute particles. Identity of particle is not important. 4 examples: vapor-pressure depression, bp elevation, freezing point depression, osmotic pressure
vapor pressure depression
when a liquid gets solute dissolved in it, vapor pressure lowers, bc ions increase IMF
bp elevation
presence of solute in a liquid raises bp. The equation
rise in bp = kim, where k is a constant for each solvent, i is the solute’s van’t Hoff factor, and m is molality
freezing point depression
presence of solute will lower its freezing point, because it interferes with lattice formation. Again, drop in fp = kim
osmotic pressure equation
P = MiRT, M = molarity i = van't hoff factor R = ideal gas constant T = temperature in K
facilitated diffusion kinetics
reaches a plateau, when all transport proteins are saturated. However simple diffusion increases linearly with concentration
Na/K ATPase
pumps out 3 Na and takes in 2 K. Thus, it establishes a negative RMP inside cell
** apparently, all active transporters are reversible, so it could theoretically run backward
clathrins
proteins that coat pits in membrane, alongside the receptors important for receptor-mediated endocytosis (used in transport of cholesterol)
GPCR pathway
ligand binds to GPCR
This causes the GDP in G protein to be swapped for GTP and so beta and gamma dissociate
The activated G protein activates AC
AC makes cAMP
cAMP binds to protein kinase to activate it
Meanwhile, intrinsic GTPase activity of alpha subunit makes beta and gamma subunits join back
cytoskeleton composed of
microtubules < intermediate filaments < microfilaments of actin
microtubule
composed of alpha tubulin and beta tubulin, which dimerize. one end of microtubule is connected to MTOC, near nucleus
Within MTOC is pair of centrioles.
Used for: flagella, centrioles, cilia, spindle fibers
mitotic spindle
consists of centriole and the polar fibers (microtubules that connect to chromosomes)
are centrioles essential for mitosis?
no
flagellum
only human cell that has it is sperm. Both flagella and cilia have 9 + 2 structure
remember that prokaryote flagella are different
dynein
contractile protein that permits microtubules to move past each other
basal body
same structure as centriole (a ring of nine triplets of microtubules), that anchors cilia and flagella
microfilaments
polymers of actin, involved in amoeboid movement. It is these that are responsible for cleavage furrow during anaphase, as well as cytokinesis
intermediate filaments
btw microtubule and microfilament in thickness
Found in: cytoskeleton
tight junctions
form seals btw adjacent cells, e.g. in intestinal epithelia
desmosomes
anchored to cells by keratin plaque, glue cells together
gap junctions
make two cells’ cytoplasm continuous
phases of mitosis?
interphase, prophase, metaphase, anaphase, telophase
prophase
chromatin condenses; nucleus dissolves
metaphase
all chromosomes lined up in center, spindle fibers attached to kinetochores
anaphase
chromosomes pulled away. A cleavage furrow begins to form
telophase
new nuclear membrane forms around chromosomes
what phase karyotype taken in ?
metaphase
oncogenes
genes that normally provide regulation of cell cycle (protooncogenes), but cause cancer when mutated
tumor suppressor genes
can either detect genetic damage and halt cell cycle until repair, or trigger apoptosis
caspase
carries out apoptosis. Initiator caspases activate other caspases upon death signal; effector caspases cleave proteins to trigger apoptosis
apoptosis sequence of events
cell shrinks away from its fellows, disassembly of cytoskeleton, nuclear envelope breakdown, DNA breakdown, different cell surface proteins emerge (to signal macrophages)
where is cell cycle most tightly regulated
between G1 and S phases
which amino acids most likely to be phosphorylated?
Ser, Thr, Tyr, and also His in plants
Go phase of cell cycle
the resting quiescent stage, where cell is not growing or dividing. Exists outside of cell cycle
protists
one of the eukarya kingdoms; have mitochondria and nucleus but no cell wall. Ameoba are one type
3 layers of embryonic tissue?
ectoderm: nervous system, epidermis,
mesoderm: muscle, connective tissue, bones, heart
endoderm: organs
