Mitochondria and metabolism

Question 1

Describe the characteristics and properties of mitochondria

Answer 1

• Located and transported along microtubules
• double membrane and inner is highly convoluted into cristae
• Have own DNA from maternal
• circular double strand DNA 37 genes long
• Perforated with porins
• contain lots of enzymes e.g. for lipid synthesis and to phosphorylate
• Cannot be made de novo
• Are symbiotic

Question 2

how do mitochondria self repair?

Answer 2

via fission and fussion, the areas that are damaged due to oxidative processes are cut out. Fission: split into two, one containing damaged material is destroyed by apoptosis and other goes on to replicate

Question 3

Why is DNA only maternal?

Answer 3

Ooytes contain a lot more mitochondria, and in sperm they are in the tail so not transferred. If any re transferred they are tagged as foreign by the egg and destroyed

Question 4

Why is the rate of mutation in mitochondria higher than average?

Answer 4

Have a different DNA polymerase: gamma which does not proof read

Question 5

What has to occur for a mutation in mitochondria to be seen?

Answer 5

Have to reach the biochemical threshold which is different for different cell types. A certain amount of the organelles have to have the mutation

Question 6

What is common to all mitochondrial disorders?

Answer 6

a lack of energy to meet cellular demands

Question 7

Chloroplasts characteristics and similarities to mitochondria?

Answer 7

Double membrane of the thylakoid, compartmentalised and produce ATP

Question 8

Perixomes characteristics and similarities to mitochondria?

Answer 8

ingle membrane, no DNA, or ribosomes, carry out oxidative process in liver to detoxify alcohol. Remove H+ and combine with O2 TO PRODUCE H2O2 then used to produce water

Question 9

What is the role of Kinases?

Answer 9

To add phosphates: by adding a phosphate it destabilises things such as glucose so easier to split

Question 10

Why is arsenic poisonous?

Answer 10

Arsenate is similar in structure to phosphate so can substitute in in glycolysis, so only 2 ATP produced so no net gain

Question 11

What is different about the respiration in erythrocytes?

Answer 11

only anaerobic

Question 12

Overall products of glycolysis?

Answer 12

net 2 ATP, 2 pyruvate, 2 NADH

Question 13

Overall products of KREBS for 1 pyruvate?

Answer 13

3 NADH, 1 FADH2, 1 ATP, 1 GTP, 2 CO2

Question 14

What else can supply krebs other than pyruvate to acetyl coA?

Answer 14

Fat - Fatty acid + glucerol
Polysacharides - glucose and other sugars
Protein - amino acids

Fatty acids can be broken down to produce acetyl coA

Question 15

What is NADH oxidised to?

Answer 15

NAD+ + H+ + 2e-

Question 16

What is the role of the electrons in ETC?

Answer 16

Provide energy to pump protons across membrane to create a gradient

Question 17

Steps in NADH pathway?

Answer 17

Complex 1 = Pumps 4 H+ across membrane as ubiqiunone is produced
Complex 3 = 4 more H+ into intermembraen space as ubiquinone loses 2 and then 2 more
Complex 4 = electrons are passed down a group of cytochrome carriers till it reacts with 1/2 o2 to produce water. 2 more H+ transported across

10 H+ in total transported across membrane from one NADH

Question 18

Difference between NADH and FADH2 pathways?

Answer 18

FADH2 = complex 2,3,4 and produces 1.5 ATP
NADH = 1,3,4 and produces 2.5 ATP

Question 19

Role of ATP synthase?

Answer 19

passes H+ through proton channel down a gradient causing ADP + Pi = ATP. Gain one ATP for every 4 protons. The H+ causes a informational change in the shape of the beta barrel that is ATP synthase causing it to rotate

Question 20

Total production form ETC ?

Answer 20

32 ATP

Question 21

total ATP from all of cellular respiration?

Answer 21

36

Question 22

What does the liver metabolise?

Answer 22

fat - making macromolecules + fatty acid and sterols

Question 23

Brain metabolises?

Answer 23

glucose only !! but if in starvation starts metabolising ketone bodies that are made in the liver from the breakdown of muscle protein (amino acids) and fatty acids in the liver

Question 24

What does muscle metabolise in low and high activity?

Answer 24

low = ketone bodies, glucose, fatty acids
High = glycogen in anaerobic respiration producing lactate

Question 25

What happens to the lactate in anaerobic?

Answer 25

back to liver where converted into glucose by the glycogenic pathway. Using lactate dehydrogenase. can also be converted into pyruvate

Question 26

Roles of insulin and glucagon in control of glucose?

Answer 26

After a meal - increase in glucose in blood, release of insulting to increase uptake of glucose by the cells in the body. And gluconeogenesis
In starvation - stop release of insulin, release glucagon, causes glycogenesis so more glucose to metabolise

Question 27

What is type 1 diabetes

Answer 27

immune system destroy the beta cells in the pancreas so cannot produce insulin so cells do not take it up, constant state of starvation, high blood glucose, high levels of glucagon

Question 28

What is type 2 diabetes

Answer 28

due to over eating refined carbohydrates, body starts to become resistant to insulin so pancreas begin to not be able to produce.

Question 29

What is the perinucleur space?

Answer 29

gap between to inner and outer membrane of the nucleus

Question 30

Inner membrane in nucleus’ role?

Answer 30

Has lamina and chromosomes tethered to it, contains the proteins for these to be tethered to it

Question 31

Outer membrane of nucleus characteristics?

Answer 31

Continuous with the rough ER membrane, studded wit ribosomes

Question 32

What are NPC’s?

Answer 32

nucleur porins in the nuclear envelope that allow protein needed in the organelle in and RNA etc out. Are * fold in the membrane. Made up of 30 nucleoporins and contain aqueous passagways

Question 33

What can and cannot diffuse through the NPC’s?

Answer 33

5000 daltons diffuses through freely
the bigger the protein the longer it takes to pass through
60,000 daltons and above cannot pass through

Question 34

What are nucleus localisation signals??

Answer 34

signals within the amino acid structure of proteins etc that need to pass into nucleus. Wish in Arg and Lys. Signal t the NPC’s to allow them to pass through. specific to the proteins.

Question 35

How can you tell that the transportation through NPS’s is active transport?

Answer 35

at lower than 4 degrees it doesn’t transport RNA

needs ATP