TCA and Glycolysis

Question 1

Why do eukaryotic cells physically separate glycolysis and TCA while in prokaryotes it all takes place in the cytoplasm?

Question 2

What is a mitochondria?

Answer 2

Believed to derive from symbiotic bacteria

Question 3

5 similarities between bacteria and mitochondria

Answer 3

1. Size and shape - bacillus rod shape (1-10 microns in length)
2. Replicate by fission
3. Type of DNA - contain circular DNA plasmids
4. Ribosome and protein synthesis (mitochondria have own ribosomes which are more similar to bacterial ribosomes than eukaryotic)
5. Membranes - have both inner and outer membranes (outer containing similar proteins e.g. porins)

Question 4

In the absence of oxygen, what does pyruvate have to do? Why? What happens in the presence of oxygen?

Answer 4

Has to convert to either lactate or ethanol.

So the NAD+/NADH cycle can be maintained in order to keep making ATP via glycolysis

In the presence of oxygen, the NADH can be oxidized back to NAD+ by the electron transport chain. Then, pyruvate is free to enter the TCA cycle which will eventually be broken down to CO2 and H2O while releasing energy.

Question 5

What’s the difference between a prosthetic group and a Cofactor?

Answer 5

Prosthetic groups are molecules that are tightly bound to an enzyme or protein (e.g porphyrin ring in haemoglobin)

Prosthetic groups are held much more tightly by the protein (can’t really take it out)

Question 6

Why do enzyme complexes exist?

Answer 6

1. Speeds up reactions
2. Products produces can be highly reactive (bad!), therefore enzyme complexes can take these products to protect the overall system

Question 7

What do kinases phosphorylate?

Answer 7

Serine, Threonine, Tyrosine