17-09-21 - Cell structure

Question 1

1. Why are the insulin granules surrounded by membrane?
2. Which disease is due to a lack of insulin secreting cells?

Answer 1

• The membrane ensures that when the granule membrane fuses with the plasma membrane, the contents are released into the extracellular space
• The disease is diabetes

Question 2

What causes cystic fibrosis?

Answer 2

• Cystic fibrosis is an inherited disease with a subtype caused by the arrest of a key transport protein in the RER.

Question 3

Explain why the lumen of endomembrane is equivalent to the outside of the cell.

Answer 3

• Fusion of the limiting membrane with the plasma membrane would deliver endomembrane contents to the outside of the cell.

Question 4

What is the reason for the lack of organelles in red blood cells?

Answer 4

• Red blood cell precursors did have organelles but these are jettisoned/degraded during maturation.

Question 5

Which of the following structures can be imaged clearly in conventional histological sections? Ribosomes, haemoglobin molecules, nuclear pores, mRNA, secretory granules of goblet cells.

Answer 5

• Only secretory granules of goblet cells.

Question 6

Complete these questions with the list provided:

• This organelle is the site of membrane synthesis in eukaryotic cells.
• This lumen of this organelle has a strongly acidic pH.
• All the vesicles produced by this organelle are delivered to the Golgi complex.
• The site of ribosome synthesis.
• Forms complexes with myosin to provide contractile forces in cells.
• A secretory form of this organelle is responsible for release of surfactant, which reduces surface tension in the lung.
• Organelles are moved within cells along this structure.
• Without this feature mRNA would not be able to access ribosomes for translation.

Golgi complex

Actin filament

Plasma membrane

Nucleolus

Ribosome

Intermediate filaments

Rough endoplasmic reticulum

Lysosome

Secretory vesicle

Nuclear envelope

Heterochromatin

Microtubule

Nuclear pores

Answer 6

This organelle is the site of membrane synthesis in eukaryotic cells.

Rough endoplasmic reticulum

This lumen of this organelle has a strongly acidic pH.

Lysosome

All the vesicles produced by this organelle are delivered to the Golgi complex.

Rough endoplasmic reticulum

The site of ribosome synthesis.

Nucleolus

Forms complexes with myosin to provide contractile forces in cells.

Actin filament

A secretory form of this organelle is responsible for release of surfactant, which reduces surface tension in the lung.

Lysosome

Organelles are moved within cells along this structure.

Microtubule

Without this feature mRNA would not be able to access ribosomes for translation.

Nuclear pores