cell bio and organelles

Question 1

which are the double membrane organelles?

Answer 1

mitochondria, nucleus

Question 2

rough vs smooth ER

Answer 2

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

Question 3

lysosomes vs peroxisomes

Answer 3

lysosomes have hydrolases for digesting substances; peroxisomes metabolize lipids and toxins specifically with H2O2

Question 4

nuclear matrix

Answer 4

kind of like a cytoskeleton for nucleus; DNA is attached to the matrix at certain sites so it has a role in gene regulation

Question 5

what organelle made in nucleolus

Answer 5

ribosome. Nucleolus is the site where RNA pol I makes rRNA too. Translation within nucleus prevented bc ribosomes not fully assembled here

Question 6

nuclear localization sequence

Answer 6

proteins with this sequence are imported into nucleus by specific transport mechanisms (too large for pores)

Question 7

endosymbiotic theory

Answer 7

mitochondria were once independent prokaryotes

Question 8

maternal inheritance

Answer 8

applies to mitochondria only

Question 9

N-terminus signal

Answer 9

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

Question 10

transmembrane domains

Answer 10

sequences of hydrophobic AAs that anchor it in membrane. These exist in integral membrane proteins

Question 11

targeting signals

Answer 11

sequence on protein that takes otherwise secretory proteins (those made in RER) to another organelle first

Question 12

localization signals

Answer 12

sequence on protein that takes cytoplasmically made protein (not RER) to certain organelles

Question 13

Golgi

Answer 13

proteins move from cis > medial > trans. Proteins come from ER to the cis portion

Question 14

constitutive secretory pathway

Answer 14

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

Question 15

acid hydrolases

Answer 15

enzymes found in lysosome, only function at pH 5

Question 16

catalase

Answer 16

enzyme that breaks down H2O2, found in peroxisome because H2O2 is byproduct of some reactions inside

Question 17

colligative properties

Answer 17

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

Question 18

vapor pressure depression

Answer 18

when a liquid gets solute dissolved in it, vapor pressure lowers, bc ions increase IMF

Question 19

bp elevation

Answer 19

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

Question 20

freezing point depression

Answer 20

presence of solute will lower its freezing point, because it interferes with lattice formation. Again, drop in fp = kim

Question 21

osmotic pressure equation

Answer 21

P = MiRT, 
M = molarity
i = van't hoff factor
R = ideal gas constant
T = temperature in K

Question 22

facilitated diffusion kinetics

Answer 22

reaches a plateau, when all transport proteins are saturated. However simple diffusion increases linearly with concentration

Question 23

Na/K ATPase

Answer 23

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

Question 24

clathrins

Answer 24

proteins that coat pits in membrane, alongside the receptors important for receptor-mediated endocytosis (used in transport of cholesterol)

Question 25

GPCR pathway

Answer 25

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

Question 26

cytoskeleton composed of

Answer 26

microtubules < intermediate filaments < microfilaments of actin

Question 27

microtubule

Answer 27

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

Question 28

mitotic spindle

Answer 28

consists of centriole and the polar fibers (microtubules that connect to chromosomes)

Question 29

are centrioles essential for mitosis?

Answer 29

no

Question 30

flagellum

Answer 30

only human cell that has it is sperm. Both flagella and cilia have 9 + 2 structure remember that prokaryote flagella are different

Question 31

dynein

Answer 31

contractile protein that permits microtubules to move past each other

Question 32

basal body

Answer 32

same structure as centriole (a ring of nine triplets of microtubules), that anchors cilia and flagella

Question 33

microfilaments

Answer 33

polymers of actin, involved in amoeboid movement. It is these that are responsible for cleavage furrow during anaphase, as well as cytokinesis

Question 34

intermediate filaments

Answer 34

btw microtubule and microfilament in thickness | Found in: cytoskeleton

Question 35

tight junctions

Answer 35

form seals btw adjacent cells, e.g. in intestinal epithelia

Question 36

desmosomes

Answer 36

anchored to cells by keratin plaque, glue cells together

Question 37

gap junctions

Answer 37

make two cells' cytoplasm continuous

Question 38

phases of mitosis?

Answer 38

interphase, prophase, metaphase, anaphase, telophase

Question 39

prophase

Answer 39

chromatin condenses; nucleus dissolves

Question 40

metaphase

Answer 40

all chromosomes lined up in center, spindle fibers attached to kinetochores

Question 41

anaphase

Answer 41

chromosomes pulled away. A cleavage furrow begins to form

Question 42

telophase

Answer 42

new nuclear membrane forms around chromosomes

Question 43

what phase karyotype taken in ?

Answer 43

metaphase

Question 44

oncogenes

Answer 44

genes that normally provide regulation of cell cycle (protooncogenes), but cause cancer when mutated

Question 45

tumor suppressor genes

Answer 45

can either detect genetic damage and halt cell cycle until repair, or trigger apoptosis

Question 46

caspase

Answer 46

carries out apoptosis. Initiator caspases activate other caspases upon death signal; effector caspases cleave proteins to trigger apoptosis

Question 47

apoptosis sequence of events

Answer 47

cell shrinks away from its fellows, disassembly of cytoskeleton, nuclear envelope breakdown, DNA breakdown, different cell surface proteins emerge (to signal macrophages)

Question 48

where is cell cycle most tightly regulated

Answer 48

between G1 and S phases

Question 49

which amino acids most likely to be phosphorylated?

Answer 49

Ser, Thr, Tyr, and also His in plants

Question 50

Go phase of cell cycle

Answer 50

the resting quiescent stage, where cell is not growing or dividing. Exists outside of cell cycle

Question 51

protists

Answer 51

one of the eukarya kingdoms; have mitochondria and nucleus but no cell wall. Ameoba are one type

Question 52

3 layers of embryonic tissue?

Answer 52

ectoderm: nervous system, epidermis, mesoderm: muscle, connective tissue, bones, heart endoderm: organs