W2 Mammalian structure and organelles/ Lec 2

Question 1

Nucleus structure and function

Answer 1

Largest organelle of eukaryotic cells
Controls all the cellular activities
Has DNA
Site of DNA replication, RNA synthesis

Question 2

Nuclear envelope structure

Answer 2

Inner and outer nuclear membrane
Both membranes fuse at nuclear pores
Ringlike gates composed of proteins allowing regulated movement between the nucleus and the cytosol

Question 3

Nucleolus function

Answer 3

Synthesis of ribosomal RNA

Question 4

What does the endomembrane system include? (5 organelles)

Answer 4

Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vesicles

Question 5

What is the function of the Smooth Endoplasmic reticulum? (properties)

Answer 5

• Lacks ribosomes
• Production of lipids
• Stores and releases calcium ions
• Detoxification of drugs and alcohol in liver cells

Question 6

What is the function of the Rough Endoplasmic Reticulum?

Answer 6

Has ribosomes
- Protein synthesis
- Protein post-translational modifications, folding and quality assurance
Glycosylation- Disulphide bonds
Protein sorting/trafficking

Question 7

What do transport vesicles do?

Answer 7

They are cell transport mechanisms for proteins:
- From rough ER to Golgi apparatus
- From Golgi apparatus to cell membrane
- From Golgi apparatus to other compartments of the end-membrane system

Question 8

What is the structure of the Golgi Apparatus

Answer 8

Stacks of flattened, membranous sacs
Distinct in 3 main regions (different enzymes)
Cis face- entry side-facing the RE
Medial face- Central layers
Trans face- Exit side towards the plasma membrane

Question 9

What is the function of the Golgi apparatus?

Answer 9

-Protein modification into mature proteins
- Glycosylation (addition/removal of carbohydrates)
- Phosphorylation
- Proteolysis
- Lipid Modification
- Protein sorting or export