Cells alive 2- mitochondria Flashcards
describe the structure of mitochondria
- oragnelles bound by a double membrane
- outer membrane
- inner membrane forms invaginations called cristae
- space between membranes is intermembrane space
- inside of mitochondrion is mitochondrial matrix
what are the functions of mitochondria
- generates most of the energy a cell requires
- Most nutrients delivered to cell are broken down in cytoplasm to simple constituents which are transported to the mitochondria
- Constituents are further oxidised producing CO2 and H2O which releases energy as ATP
- Mitochondria often located close to sites of high ATP utilisation
adenosine triphosphate (ATP) energy release is by hydrolysis of what bonds?
phosphoanhydride bonds
Which stages of aerobic respiration occur in the cell cystoplasm?
Glycolysis
Which stages of aerobic respiration occur in the mitochondria?
Link reaction
TCA/Krebs cycle
Oxidative phosphorylation
Describe the metabolism of fatty acids
B oxidation
can be in peroxisome also
2 C removed from hydrocarbon tail at a time
- used to produce acetyl-coA
how is glucose converted to pyruvate?
glycolysis
How and where is pyruvate converted into acetyl coA?
- Link reaction -in mitochondria
- Decarboxylated
*remove a C = CO2
Leaves acetate
*2 C molecule
Actetate combines with coenzyme A = acetyl- CoA
How are amino acids used in aerobic respiration?
- Deamination
*removal of amino group - Leaves a carbon skeleton
- can enter at different points depending on the amino acid it was
What does acetyl coA feed into?
TCA/Krebs/Citric acid cycle
what are the end products of acetyl- CoA oxidation ( Krebs) and how many
3 x NADH
1 x FADH2
what is produced as waste from acetyl-CoA oxidation (Krebs) and how many
2 x CO2
What are NADH and FADH2 needed for?
Carrying electrons to be used in the electron transport chain
What is oxygen’s role in aerobic respiration?
Final electron acceptor in oxidative phosphorylation, it is reduced to H2O
Describe the movement of electrons in the ETC
Move from areas of low affinity to high
3 protein complexes in the mitochondria inner membrane
Each has higher affinity for electron than the previous
Energy released from the movement of electrons in the ETC causes what?
H+ to be pumped from matrix to intermembranal space
Creates an electrochemical gradient across the inner membrane
How does ATP synthase generate ATP in oxidative phosphorylation?
Uses energy from H+ diffusing back into matrix
chemiosmosis - H flow down electrochemical gradient
H+ rotates transmembranous rotor domain stalk attached to ATP synthase
Enzymatic head held still by arm attached to membrane
Mechanical energy generated as stalk grinds against head
Mechanical converted to chemical
ADP + PI -> ATP
Theoretically how many ATP are made in aerobic respiration?
how many are actually produced?
36 -38
glycolysis 2
krebs 2
oxidative phosphorylation - 34
30-32
Some are used for active transport within the mitochondria
How many ATP made per:
NADH
FADH2
NADH - 3
FADH2 - 2
Describe transport in and out of the mitochondria’s outermembrane
- Has porins that are permeable to molecules less that 5kDa
- gases oxygen and carbon dioxide freely diffuse across the membranes down their concentration gradients- no energy or transporters needed
Describe transport in and out of the mitochondria’s innermembrane
- electrochemical gradient
- pyruvate and inorganic phosphate transport driven by H+ gradient, they are co-transported in the same direction- SYMPORTER
- ATP and ADP are co-transported in opposite directions using charge gradient- ANTIPORTER
Where are most mitochondrial proteins encoded and produced?
How do they get to the mitochondria?
Encoded - nucleus
Produced - cytosolic ribosomes
Transported by hsp70 chaperones across cytosol to nucleus
Importance of chaperones?
Keeps mitochondrial protein unfolded
N terminal signal peptides target them to mitochondria
When does transport of mitochondrial proteins occur?
After translation
What mediates the passage into the mitochondria?
Translocases of inner+ outer membranes
(TOM - translocases of the outer)
( TIM - translocases inner mitochondrial )
Are mitochondria maternally or paternally inherited?
Maternally
Role of mitochondria in apoptosis?
Release cyctochrome C from intermembrane space to trigger apoptosis
pH of intermembrane space
7
pH of matrix space
8
Describe mitochondrial DNA
Mitochondria have own genome
Circular
Vary in size and number of genes encoded
Translation and transcription of genes occurs in matrix
With dogs, mitochondrial DNA can be used to..
Determine breed origin
What is endosymbiosis?
Theory that mitochondria were once independent entities
At one point in time became associated with eukaryotic cells
Evidence of endosymbiosis?
Grow and divide by fission
Own genome
Own translation and transcription processes
have own DNA and ribosomes
Mitochondria can act as stores of what mineral?
Calcium
2 things mitochondria help to synthesis (other than ATP)
Haeme
Steroids
What do mitochondria in hepatocytes contain?
Enzymes to detoxify NH3
Examples of TCA inhibitors?
Arsenite
- inhibit pyruvate dehydrogenase
2-fluorocitrate
- irreversibly inhibits aconitase, used in 2nd step TCA
How do rotenone and cyanide inhibit oxidative phosphorylation?
Block electron transfer
Rotenone binds to complex I
Cyanide binds to Fe of complex IV
How does Bongkrekic acid affect mitochondria?
Inhibits the transporter bringing ADP into the mitochondria and ATP out
How does 2,4 DNPH affect mitochondria?
Uncoupling agent
Uncouples electron transport from ATP synthesis
weak acid +lipid soluble
sits in the H+ carrier in the inner membrane
dissipates the electrochemical gradient
Where does FADH2 donate its electrons first?
complex II
Where does NADH donate its electrons first?
complex I
What are mitochondrial respiratory complexes?
electron transport complexes that work together to harness energy
Where are mitochondrial proteins synthesised?
cytoplasm
mitochondrial matrix
