Test 3 - Lecture 25 Flashcards
Mitochondria -
Mitochondrial DNA can be _______ by mutations
altered
Mitochondria -
Almost all of the mitochondria of fertilized eggs are contributed by the ______, so germ - line mutations are transmitted to the next generation by the ______
oocyte
mother
Mitochondria -
True/False
Mutations in mitochondrial genes are associcated with several dieseases
True
Mitochondria -
______ hereditary ______ _______, which leads to blindness, is caused by mutations in mitochondrial genes that encode components of the ______ transport chain
Leber’s
optic
neuropathy
electron
Mitochondria -
1. Mammalian mitochondria genomes encode only __ proteins but contain about _____ different proteins encoded by the nuclear genome
13
1500
Mitochondria -
2. Proteins encoded by nuclear genes include:
Proteins needed for _______ and ________ of mitochondrial DNA
Most Proteins needed for _______ ________
All the ______ involved in _________ metabolism
replication expression oxidative phosphorylation enzymes mitochondrial
Mitochondria -
3. Most of the proteins are synthesized of ____ ribosomes and imported as complete ________
free
polypeptides
Mitochondria -
1. Because of the _____ - ______ structure of mitochondria, import of proteins is complex
double - membrane
Mitochondria -
Proteins are targeted to the matrix by _____ - _______ sequences (presequences) that are removes by proteolytic cleavage after import
amino - terminal
Mitochondria -
2. _______ bind to receptors on the mitochondria that are part of a ______ complex (translocase of the outer membrane, or ____ complex)
Presequences
protein
Tom
Mitochondria -
3. Proteins are then transferred to another complex in the inner membrane (translocase of the inner membrane , or ____ complex)
Tim
Mitochondria -
Some proteins cross the matrix via ____ ; others exit laterally and are inserted into the inner membrane
Tim23
Mitochondria -
Protein translocation requires the ________ potential across the inner membrane during _______ transport
electrochemical
electron
Mitochondria -
Proteins must be _____ and require _____ chaperones
unfolded
Hsp70
Mitochondria -
Presequences are cleaved by ______ processing _______ (MPP) and the polypeptide is bound by other Hsp70 chaperones that facilitate ______
matrix
peptidase
folding
Mitochondria -
Some proteins with multiple trans- membrane domains have ______ import ______ instead of presuequences
internal
signals
Mitochondria -
After translocation across the outer membrane, they are bound by mobile _____ - ______ chaperones, which bring them to _____. The protein is transferred ______ to the _____ membrane
Tim9 - Tim10
Tim22
laterally
inner
Mitochondria -
1. Somme inner membrane proteins are encoded by the ________ _______
They are synthesized on ______ in the mitochondrial matrix and targeted to the ____ _________ in the inner membrane
The exit Oxa laterally to insert into the inner membrane
mitochondrial genome
ribosomes
Oxa translocase
Mitochondria -
2. Proteins designed for the outer membrane or ________ space also pass through the Tom complex
Proteins with ______ transmembrane domains are inserted via the outer membrane protein ______
intermembrane
single
Mim1
Mitochondria -
3. _____ - ______ proteins pass through Tom, are bound by Tim9 - Tim10 and carried to another translocon called the ____ (soting and assembly machinery)
SAM mediates their insertion into the outer membrane
Beta - barrel
SAM
Mitochondria -
Mitochondria catalyze synthesis of the _______ cardiolipin
phospholipid
Mitochondria -
Cardiolipin improves _______ of oxidative phosphorylation by _______ proton flow across the membrane
efficiency
restricting
Mitochondria -
Lipid transfer between Er and mitochondria is mediated by _______ ______ _______
phospholipid transfer proteins
Mitochondria -
The lipids are transported through the _______ and released at a new _______, such as that of mitochondria
cytosol
membrane
Mitochondria -
Many small molecules, such as ATP, ADP, and Pi must be ______ __ and _____ of the mitochondria
moved in and out
Mitochondria -
Energy is provided by the electrochemical gradient generated by _____ pumping across the inner mitochondrial membrane during oxidative phophorylation
proton
Mitochondria -
1. Transport of ___ and ____ is mediated by an integral membrane protein, the _____ nucleotide translocator
One molecule of ADP moves into the _______ in exchange for ___ molecule of ATP transferred to the cytosol
ATP carries a more ______ charge than ADP (-4 compared to -3), so exchange is driven by the _______ component of the electrochemical gradient
ATP ADP adenine mitochondrion one negative voltage
Mitochondria -
2. Pi is brought in as ______ (H2PO4-) in exchange for hydroxyl ions (OH-)
This exchange is ______ ______, but is driven by the proton concentration gradient
phosphate
electrically
neutral
Mitochondria -
3. Higher pH within mitochondria corresponds to a ______ concentration of hydroxyl ions, favoring their trasnlocation to the ______
higher
outside
Chloroplasts -
1. Chloroplasts:
the organelles responsible for photosynthesis.
Chloroplasts -
True/False
Chloroplasts are similar to mitochondria
True:
They are similar in many ways:
Both generate metabolic energy
Evolved by endosymbiosis
Contain their own genetic systems
Replicate by divisionChloroplasts -
2. Chloroplasts are
______ and more complex
They convert CO2 to _________; plus synthesize amino acids, fatty acids, and lipid components of their own membranes
______ (NO2-) _______ to ammonia (NH3), essential for incorporation of N into organic compounds, also occurs here
larger
carbohydrates
Nitrite reduction
Chloroplasts -
1. Chloroplasts are bounded by a ______ _________ - the chloroplast envelope
double membrane
Chloroplasts -
2. An internal membrane systems, the ________ ________, forms a network of flattened discs (_______), which are frequently arranged in stacks called _______
thylakoid membrane
thylakoids
grana
Chloroplasts -
1. Chloroplasts have three internal compartments:
_____________ space between the two membranes of the envelope
______ : inside the envelope but outside the thylakoid membrane
_________ ________
Intermembrane
Stroma
Thylakoid lumen
Choroplasts -
2. Chloroplast membranes are ______ similar to those of mitochondria
The _____ membrane contains ______ and is freely permeable to small molecules
The _____ membrane is impermeable to ions and _______, which must move through specific transporters.
functionally outer porins inner metabolites
Chloroplasts -
The _____ is equivalent in function to the _________ matrix
stroma
mitochondrial
Chloroplasts - Stroma
It contains the ______ system and _______ enzymes, including those needed to convert CO2 to carbohydrates during photosynthesis.
genetic
metabolic
Chloroplasts -
Electron transport and __________ generation of ATP takes place in the _______ membrane
chemiosmotic
thylakoid
Chloroplasts -
Protons are pumped across this membrane from the _____ to the ______ lumen
stroma
thylakoid
Chloroplasts -
The thylakoid membrane is thus equivalent to the _____ membrane of the mitocjomdria
inner
Chloroplasts -
1. The chloroplast genetic system reflects the _________ origin from photosynthetic bactria
evolutionary
Chloroplasts -
2. _______ DNA molecules are present in ________ copies, but are larger and more complex than those of mitochondria
Circular
multiple
Chloroplasts -
3. The genes encoded in both _____ and ______ involved gene expression and photosynthesis
RNAs
proteins
Chloroplasts -
4. Chloroplast tRNAs are sufficient to translate all the _____ codons using the _______ genetic code
mRNA
universal
Chloroplasts -
1. One subunit of ______ is encoded by chloroplast DNA
Rubisco _______ addition of CO2 to ribulose - 1, 5 - bisphosphate in the ______ cycle
Rubisco is critical for ________, and it is thought to e the single most abundant ______ on Earth
Rubisco catalyzes Calvin photosynthesis protein
Chloroplasts -
2. Other proteins are _______ on _____ ribosomes and imported into chloroplasts as completed polypeptides
synthesized
free
Chloroplasts -
_ - _____ sequences (transit peptides), direct translocation across the two membranes of the envelope and are then removed by _______cleavage
N - terminal
proteolytic
Chloroplasts -
Transit peptides direct ______ to the translocase of the chloroplast outer membrane (the ___ ______)
proteins
Toc complex
Chloroplasts -
Hsp70 molecules keep the polypeptide in an ________ state. Some also hydrolyze ___), providing energy for translocation
unfolded
GTP
Chloroplasts -
Proteins then enter the Tic complex on the _____ membrane and are transported to the _____, drawn by action of an Hsp93 chaperone
inner
stroma
In the stroma, the transit peptide is cleaved by _______ _______ ________ (SPP)
stromal processing peptidase
Chloroplasts -
Proteins that must cross the thylakoid membrane have a _______ ______ sequence, exposed after cleavage of the transit peptide.
second signal
Chloroplasts -
Proteins are translocated into the thylakoid lumen by two different pathways:
1. _____
2. _____
- Sec pathway
2. Tat (twin - arginine translocation)
Chloroplasts -
1. Sec pathway:
ATP - _______ ; signal sequence is recognized by _____ protein
Protein is translocated as as an ______ protein through the Sec translocon
dependent
SecA
unfolded
Chloroplasts -
2. Tat (twin- arginine translocation):
Proteins have a twin - arginie signal sequence: translocated in fully - ______ state
Energy comes from the _____ _______
Signal sequences are cleaves by ______ ________ ________ (TPP)
folded
proton gradient
thylakoid processing protease
