Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

The Golgi body, rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) are components of the cell’s internal membrane system. These membranes display a fluid mosaic arrangement. Fig. 1.1 shows a transmission electron micrograph of part of a liver cell, with one region containing RER and another containing SER. Mitochondria can also be seen in the image.
(a)[3]

Describe the structural and functional differences between RER and SER.

(b)[2]

Phospholipids are among the principal membrane components. Describe the arrangement of a phospholipid molecule.

(c(i))[2]

A Golgi body and Golgi vesicles cannot be seen in Fig. 1.1. Describe the characteristics, apart from the presence of Golgi vesicles, that would allow you to recognise a Golgi body in a transmission electron micrograph of another part of the same liver cell.

(c(ii))[3]

Some Golgi vesicles carry secretory proteins for export from the cell. Describe the sequence of events from packaging a secretory protein into a Golgi vesicle until its release from the cell.

(c(iii))[1]

Some Golgi vesicles contain glycoproteins or glycolipids that are added to the cell surface membrane. Outline the function of glycolipids in the cell surface membrane.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: RER has ribosomes / SER lacks ribosomes

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI