met 4

Question 1

What is special about proline as an amino acid

Answer 1

• When proline is joined to a polypeptide chain - the NH group of the amino acid is LOST
• This prevents the side chain from hydrogen bonding with C=O groups of another residue within the helix
• This distorts the helical conformation
• Puts a kink into it

pg 43 (LAz)

Question 2

Describe how proteins forl in general and what can interfer with this and how

Answer 2

• (pg 43 (Folding of Proteins))
• Proteins generally fold into the single conformation of lowest energy
• Chaperones may be involved to make sure that folding occurs in the most energetically favourable way
• By breaking bonds that hold the protein together, we can denature the protein into the original flexible polypeptide
• Common Denaturants used in the lab:
  
  • Urea (breaks hydrogen bonds)
  • 2-mercaptoethanol (breaks disulphide bonds)( (

Question 3

Suggest how mitochondrial respiration may be examined experimentally.

Answer 3

pg 83 ibook, oxygen electrode in mitochondria suspension from tissue, to monitor oxygen concentration, see how ti changes

Question 4

Describe the three principle stages of the synthesis of cholesterol from acetyl CoA and describe where rhey occur

Answer 4

pg 85 (Cholesterol biosynthesis - the numbered bulltet point part) Laz’s notes

The biosynthesis of cholesterol can be split into three main parts:

1. Synthesis of isopentyl pyrophosphate, an activated isoprene unit which serves as a key building block (occurs in cytoplasm).
2. Condensation of six molecules of isopentyl pyrophosphate to form squalene (occurs in cytoplasm).
3. Cyclisation and demethylation of squalene by monooxygenases to give cholesterol (occurs in ER).

Question 5

Name the different types of Lipoproteins, and describe how they are recognised by different cells

Answer 5

pg 91 from (LIPOPROTEINS ARE CATEGORISED ACCORDING TO THEIR DENSITY:) to (Lipoprotein Lipase) Laz’s notes

Question 6

`Explain diseases that can occur as result of problems with post translational modification and quality control in the ER

Answer 6

pg 81 (Cystic Fibrosis Transmembrane-Conductance Regulator (CFTR))

Cystic Fibrosis Transmembrane-Conductance Regulator (CFTR)

• CFTR is an ABC transporter-class chloride channel in epithelial cell plasma membranes.
• Mutations of the CFTR gene affects the functioning of the chloride channels in the membrane which causes Cystic Fibrosis.
• The most common mutation (ΔF508) results from DELETION of three nucleotides, which causes the loss of phenylalanine (Phe) at the 508th position on the protein.
• As a result, the CFTR does not fold properly and is degraded in the ER.
• Small molecule corrector 407882 binds to the cytoplasmic domain of ΔF508 CFTR and enhances its movement to the cell surface, restoring function.

Question 7

Describe the different types of endocytosis

Answer 7

pg 85 Laz’s notes (ENdocytosis)

• Receptor-mediated endocytosis - substances bind to specific receptors and begins to form a vesicle which has a protein coat around it.
• Pinocytosis - fluid drinking - the cell extends it’s membrane and takes in some extracellular fluid.
• Macropinocytosis/Phagocytosis - can take up large particles such as bacteria.

Question 8

Provide a summary of glycolysis and the processes that could ensue s under different conditions in metabolism

Answer 8

pg 97 laz’s notes(Summary of Glycolysis:), which continues a little on pg 98

Question 9

Describe the controllers of the glucose metabolism pathway

Answer 9

Laz’s notes pg 101 AD

The pathway is controlled by:

• Product of the reaction or pathways (the product could be an activator or inhibitor of the enzyme)
• External signalling molecules relaying information from other pathways
• Hormones

Question 10

How is metabolism affected by diabetes across the body

Answer 10

Laz’s notes pg 103(How metabolism is affected)