Cell Bio Exam 2

Question 1

the ER and golgi are

Answer 1

in contact

Question 2

mitochondria are dynamic

Answer 2

cells compartmentalize
-membranes and proteins change for diff organelles

-mitochondria change shape, dvide and fuse
they can move bidirectionally and where needed
-interact w lipids

Question 3

properties of mitochondria

Answer 3

2 membranes
inner membrane has fold = cristae
contains proteins that carry out oxidative phosphorylation, including the electron transport chain and ATP synthase that makes atp (F- type ATP synthesis_

matrix- space w hundreds of enzymes between folds
enzymes that required for oxidation of pyruvate and fatty acids and citric acid cycle

outer mem- contains large channel- forming proteins (porins) and permeable to all molecules of 5000 daltons or less - most proteins dont get throught

intermembrane space
-space between the two membranes
has several enzymes that use ATP passing out of the matrix to phosphorylate other nucleotides= also contains protiens that are released during apoptosis

Question 4

mitochondria and chloroplasts derived from

Answer 4

ancient prokaryotic symbionts (over 1500 million years ago)

smalll prokaryote-like genomes rRNA, tRNAs and some replicative enzymes and subunits of membrane respiratory chain complexes

nuclear genome encodes 98% mitochondrial proteins

Question 5

comparing the organization of mitochondria and bacteria

Answer 5

circualr small genome - ancestral genome
humans 17000bp , 13 protiens encoded, 2 rRNAs, 22 tRNAs, porins in outer membrane

mitochonria -
outter mem, inner mem, dna, cristae, matrix
some electron transport complex in mitochondrial mem proteins

bacterium-
periplasmic space, dna, inner and outer mem

Question 6

sources of mitochondrial proteins

Answer 6

most proteins encoded from nuclear genome

proteins destined for secretion
-know from the fedex system
marking proteins based on N terminal of amino acids

proteins is translated in cytoplasm but cant enter mitochondria bc too big

–over 600 mit proteins cynthesized in cytoplasm and improted into mit
13 mitochondrial mem proteins
22 trna
2 rrna

*post translational targeting

Question 7

targeting signals that direct proteins synthesized in cytoplasm to organelles (transit sequences)

Answer 7

some for chloroplast

-proteins made on free ribosomes
polypeptide synthesized with chloroplast transit sequence and secondary targeting seq

or polypeptide synthezised with mitochondrial presequence
or w c terminal pts signal

targeting signal is cleaved off before folding into stroma or compartmen

Question 8

getting across inner and outer mem

Answer 8

translocons used by polypeptides to cross mem
tic and toc

Question 9

machinery for importings proteins into mitochondria

Answer 9

signal presequences
tom - tim
translocons
signal peptidase (cuts signal sequence off)
Hsp70 chaperone ( on both sides bc helps unfold proteins and folded back w Hsp70

whehn proteins unfold can sneak through

energy source from electrical potential and atpase chaperone

*big protein donut
complex is fluid once proteins doc on tom

proteins itneract btwn tom and tim = channel that spans both mems

Question 10

mitochondrial protein import

Answer 10

translocon of inner mit mem
TIM 23 complex

TOM complex
sam complex
tim 22, oxa complex

Question 11

import of protiens in to the mitochondrial matrix

Answer 11

translocans made of proteins - all proteins doing diff jobs

made of 8-10 proteins –> make up donuts

proteins doc, bring mems together, (need energy in form of atp), cut off sequence, refold once inside

Question 12

synthesis of mitochondrial proteins

Answer 12

for matrix proteins– transported on free ribosomes

polyribosome- multiple ribosomes reading seq

most proteins in cytoplasm not made as single copies

————————————————————-made on cytoplasmic free ribosomes
-bidng hsp70 for delivery
singal presequence of 10-70 basic and hydrophobic amino acids; usually at N termal end
-interactions w tom 20 and 22 at first
-then interact w tom40 translocon
-unfolded to transit
-then itneract w tim 23, 17, 50
hsp70 helps fold protein in matrix and pull it through translocon

Question 13

import of adp/atp antiporter into the inner mem

Answer 13

slides out of donut into mem

a- assocation of itnernal targeting seq w tom

b- translocation to itnermem space and association w chaperones

c-translotcation from tim22 translocon into the inner mem

Question 14

[atjways for protein import into chloroplasts

Answer 14

transit sequences are signal sequences in plants; toc-tic translocons

not all mitochondrial proteins go into matrix

high atp inside mitochondrial matrix
adp in and atp out

transmem multipass proteins

Question 15

peroxisome biogenesis

Answer 15

peroxins deliver proteins to peroxisomes

targeing signal pts1 (3aa)

peroxisome contain oxidative enzymes

Question 16

summary of how proteins imported into mitochondria and chloroplasts

Answer 16

use metabolism to make atp

atp sunthesis takes place in another part
encoded in nucleus

-mit genomes encode only a small number of proteins which are subunits of respiratory chain complexes

other subunits are encoded by nuclear genes and must be imported in mit

nuclear encoded proteins are synrh w signal sequence and transproted to organelles in compelxes w chaperone protiens

tom and tim complextes transport unfolded proteins across mem

Question 17

cellular distribution of mit

Answer 17

move along cytoskeletal motors

mitochondria wrap around flagellar axoneme in cardiac muscle

Question 18

compartmentalized biochem

Answer 18

amino acids ahve specific transproters

get in transporters
glycolysis breaking down sugars
citric acid cycle to make acetyl coA

Question 19

cell fractionation

Answer 19

in low osmolarity, influx of water causes the mitochondrion to swell adn the otuer mem to rupture, releasing the contents of the intermem space, the inner mem remains intact

centrifuge leaves contens of itnermem space in the nonsedimenting fraction

transfer to medium of high osmolarity = shrinkage

diff parts sep

density-gradient centrifugation
=innter mem, matrix and outer mem

Question 20

metabolic pathways supplying

Answer 20

energy for oxidative phoshorylation by mitochondria

compartmentalization of reactions

Question 21

compartmenalize rxns

Answer 21

stage 1= electron transport drives pump that pumps protons across mem

stage 3= proton gradient is harnassed by atp synthase to make atp

use electron carriers to pump protons out of mit mem
changes pH oof outside to inside

using for F1 transport ot make atp

Question 22

sunlight and foodstuff together

Answer 22

to high energy electrons

transmem electrochemical prton gradient
-active mem transport
-atp synthesis
-bacterial flagellar rotation

Question 23

citric acid cycle

Answer 23

pumps protons through etc
need adp to make atp
co2
water out
part of cellular respiration

Question 24

pyruvate

Answer 24

needs transporter

Question 25

metabolic pathways driving atp synthesis by mitochondria

Answer 25

nadh, fadgh2, atp, citric acid cylce

Question 26

electron transport chain made by

Answer 26

nadh

w energy conversion processes in membrane

=oxidative phosphorylation, making adp into atp

Question 27

respiratory electron transport and atp synthesis

Answer 27

same as proteins found in bacteria

Question 28

1, 3, 4 complex

Answer 28

nadh dehydrogenase complex, cytochrome bc complex, cytochrome oxidase complex

proton motive force due to pH gradient or mem potential

electrons passed along chain

Question 29

atp synthase

Answer 29

can run in reverse

Question 30

bacteria have own flagella

Answer 30

spins rotor bc of pH gradient - which moves bacteria around

flagella motor rotating at more than 100 revolutions per sec

Question 31

disease causing mutations of mitochondrial proteins

Answer 31

need a lot of energy = lot of ATP

disorders secondary to mutations in mitochondrial dna - encoded proteins

complex III - sporadic myopathy

complex 4 - sporadic anemia, myopathy, encephalomyopathy

complex 5
narp, mils, fbsn

Question 32

photosynthetic machinery of chloroplasts and cyanobacteria

Answer 32

outer mem
inner mem
stroma
thylakoid space
thylakoid mem
grana
DNA
ribosomes
starch granule

Question 33

photosystem I and photosystem II
*** know photosynthesis
–review chloroplast and mitochondrion processes

Answer 33

cyanobacteria, algae, plants