Q2 - Vitellogenesis

Question 1

What is the main role of very low density lipoprotein (VLDL)?

Answer 1

Provides nourishment to developing embryo

Question 2

VLDL is the principle component of egg yolks. What percentage of yolk solids does this make up in chicken eggs?

Answer 2

60-70%

Question 3

VLDL is the principle component of egg yolks. What percentage of yolk solids does this make up in crocodilian eggs?

Answer 3

30%

Question 4

VLDL is the principle component of egg yolks. What percentage of yolk solids does this make up in lizard eggs?

Answer 4

It is not present in lizard eggs, they don’t produce infertile eggs

Question 5

What two main nutrients is VLDL composed of? What are their percentages by mass?

Answer 5

Protein - 12.5%

The rest is lipid

Question 6

What types of lipids make up VLDL?

Answer 6

Triglycerides, cholesterol, phospholipids etc.

Question 7

What is the importance of lipid as an energy source?

Answer 7

It is more energy dense than other nutrients, allowing more energy to be packed into a smaller volume

Question 8

What two molecules make up the protein portion of VLDL?

Answer 8

Apolipoprotein B and Apo-VLDL II

Question 9

When is apolipoprotein B produced?

Answer 9

It is a normal component of plasma, but increased synthesis is stimulated by oestrogen

Question 10

When is apo-VLDL II produced?

Answer 10

Only during egg laying

Question 11

What organ is VLDL synthesised in?

Answer 11

Liver

Question 12

How is VLDL formed?

Answer 12

It forms in hepatocyte endoplasmic reticulum from newly synthesised lipids

Question 13

How is VLDL deposited in the ovum?

Answer 13

Oocyte receptors, specific for apolipoprotein B, facilitate endocytosis