Cell biology

Question 1

Where is RNA synthesized

Answer 1

Nucleolus

Question 2

What is the function of the cell nucleus

Answer 2

Contains cell DNA and facilitate the expression of mRNA hence co-ordinating cell activity

Question 3

Which cells are anuclear

Answer 3

Red blood cells

Question 4

Which cells are multinuclear

Answer 4

Skeletal muscle cells

Fused macrophages = multinucleated giant cells

Question 5

What is the function of the outer mitochondrial membrane

Answer 5

To separate it from the cytoplasm

Question 6

How do small and large molecules enter the mitochondria

Answer 6

Small (<5kDa): pyruvate/amino acids/short-chain fatty acids –> passively via porins

Large(>5kDa): Longer chain fatty acids –> require the carnitine shuffle to cross the membrane

Question 7

What is the function of the intermembranous space

Answer 7

H+ ions are pumped by the protein complexes of the electron transport chain into the intermembranous space to create the H+ conc. gradient necessary for ATP synthesis.

Question 8

What is the function of the inner mitochondrial membrane?

Answer 8

The site of the electron transport chain. Membrane bound proteins participate in redox reactionsresulting in synthesis of ATP

Question 9

What processes occur within the inner mitochondrial matrix?

Answer 9

Citric Acid Cycle
Fatty Avid Metabolism
Urea Cycle

Question 10

Which cells don’t contain mitochondria

Answer 10

RBCs

Question 11

What is endoplasmic reticulum

Answer 11

Protein and lipid synthesizing network of vesicles and tubules occupying much of the cytosol

Question 12

What types of endoplasmic reticulum are there and how do these differ in function

Answer 12

Smooth ER - Steroid and lipid synthesis

Rough ER - Protein synthesis (contains ribosomes)

Question 13

What is the Golgi apparatus and what is its function?

Answer 13

Series of tubules next to the ER - Modification and packaging of proteins in preparation for their secretion.

Question 14

What are lysosomes and in which cells are they found. What is the function of lysosomes?

Answer 14

Vesicles that contain powerful digestive enzymes, acid and free radical species.

Found in all cells but particularly common in phagocytic cells.

Function:

1. Housekeeping (degrading old proteins)
2. Apoptosis
3. Destruction of phagocytosed organisms

Question 15

Tabulate the differences between prokaryotic cells and eukaryotic cells

Answer 15

EUKARYOTES (humans) 
Nucleus - present
Chromosomes - multiple
Mitochondria - present
Golgi apparatus - present
Cell wall - Plant and fungi only
DNA wrapping - Around histones
Ribosomes - Present
Vesicles - Present

PROKARYOTES (bacteria)
Nucleus - absent
Chromosomes/DNA - One plus plasmids
Mitochondria - absent
Golgi apparatus - absent
Cell wall - present
DNA wrapping - Folded/supercoiled
Ribosomes - present
Vesicles - present

Question 16

Give 6 functions of the cell membrane

Answer 16

1. Structure and shape
2. Barrier: physical and chemical
3. Transport (selective permeability)
4. Communication - intercellular (e.g. nerves/receptors)
5. Recognition (‘markers’ –> glycoproteins)
6. Adhesion - intercellular

Question 17

How are cell membrane proteins receptors classified

Answer 17

By there structural relationship to the bi-layer

1. Integral proteins (transmembrane)
2. Peripheral proteins (located outside bilayer)
3. Lipid anchored proteins (lie outside, but linked to molecules within the bilayer)