Mitochondria and metabolism Flashcards
Describe the characteristics and properties of mitochondria
- 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
how do mitochondria self repair?
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
Why is DNA only maternal?
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
Why is the rate of mutation in mitochondria higher than average?
Have a different DNA polymerase: gamma which does not proof read
What has to occur for a mutation in mitochondria to be seen?
Have to reach the biochemical threshold which is different for different cell types. A certain amount of the organelles have to have the mutation
What is common to all mitochondrial disorders?
a lack of energy to meet cellular demands
Chloroplasts characteristics and similarities to mitochondria?
Double membrane of the thylakoid, compartmentalised and produce ATP
Perixomes characteristics and similarities to mitochondria?
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
What is the role of Kinases?
To add phosphates: by adding a phosphate it destabilises things such as glucose so easier to split
Why is arsenic poisonous?
Arsenate is similar in structure to phosphate so can substitute in in glycolysis, so only 2 ATP produced so no net gain
What is different about the respiration in erythrocytes?
only anaerobic
Overall products of glycolysis?
net 2 ATP, 2 pyruvate, 2 NADH
Overall products of KREBS for 1 pyruvate?
3 NADH, 1 FADH2, 1 ATP, 1 GTP, 2 CO2
What else can supply krebs other than pyruvate to acetyl coA?
Fat - Fatty acid + glucerol
Polysacharides - glucose and other sugars
Protein - amino acids
Fatty acids can be broken down to produce acetyl coA
What is NADH oxidised to?
NAD+ + H+ + 2e-
What is the role of the electrons in ETC?
Provide energy to pump protons across membrane to create a gradient
Steps in NADH pathway?
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
Difference between NADH and FADH2 pathways?
FADH2 = complex 2,3,4 and produces 1.5 ATP NADH = 1,3,4 and produces 2.5 ATP
Role of ATP synthase?
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
Total production form ETC ?
32 ATP
total ATP from all of cellular respiration?
36
What does the liver metabolise?
fat - making macromolecules + fatty acid and sterols
Brain metabolises?
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
What does muscle metabolise in low and high activity?
low = ketone bodies, glucose, fatty acids High = glycogen in anaerobic respiration producing lactate
What happens to the lactate in anaerobic?
back to liver where converted into glucose by the glycogenic pathway. Using lactate dehydrogenase. can also be converted into pyruvate
Roles of insulin and glucagon in control of glucose?
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
What is type 1 diabetes
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
What is type 2 diabetes
due to over eating refined carbohydrates, body starts to become resistant to insulin so pancreas begin to not be able to produce.
What is the perinucleur space?
gap between to inner and outer membrane of the nucleus
Inner membrane in nucleus’ role?
Has lamina and chromosomes tethered to it, contains the proteins for these to be tethered to it
Outer membrane of nucleus characteristics?
Continuous with the rough ER membrane, studded wit ribosomes
What are NPC’s?
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
What can and cannot diffuse through the NPC’s?
5000 daltons diffuses through freely
the bigger the protein the longer it takes to pass through
60,000 daltons and above cannot pass through
What are nucleus localisation signals??
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.
How can you tell that the transportation through NPS’s is active transport?
at lower than 4 degrees it doesn’t transport RNA
needs ATP
