AM - Organelles (1 + 2)

Question 1

Cytosol vs Cytoplasm

Answer 1

Cytosol is the aqueous portion of the cytoplasm

Question 2

Name 7 structures of the mitochondria

Answer 2

1. Outer membrane
2. Intermembrane space
3. Inner membrane
4. Electron transport chain
5. Matrix
6. Mitochondrial DNA
7. Granules

Question 3

What are the 2 types of mitochondrial fission?

Answer 3

1. Midzone fission
2. Peripheral fission - can be used to get rid of DAMAGED material

Question 4

What occurs in the Chemiosmotic stages

Answer 4

• High energy electrons are transferred along a series of electron carriers embedded in the membrane
• As the electrons reach each carrier energy is released which acts to pump H+ across the membrane - creating an electrochemical gradient
• Electrons travel down this gradient via ATP synthase
• ADP + Pi –> ATP

Question 5

What is the size (in svedberg units) of prokaryotic ribosomes?

Answer 5

70S
50S large subunit
30S small subunit

Question 6

What is the size (in svedberg units) of eukaryotic ribosomes?

Answer 6

80S
60S large subunit
40S small subunit

Question 7

What are ribosomes made up of?

Answer 7

rRNA
Ribosomal proteins

Question 8

What do Ribosome Inactivating Proteins (RIPs) do?

Answer 8

Toxins which act to irreversibly inhibit protein translation

Question 9

What is the difference between Type I and Type II RIPs?

Answer 9

Type I cannot cross the cell membrane whereas Type II consists of a binding domain which allows entry crossing the plasma membrane

Question 10

What are the main structural features of Peroxisomes?

Answer 10

• Enclosed by a single membrane
• Contain no DNA or ribosomes
• Contain oxidative enzymes

Question 11

What is the general reaction carried out by peroxisomes?

Answer 11

RH2 + O2 –> R’ +2H2O

Question 12

What occurs during peroxisome biogenesis and maturation?

Answer 12

1. Budding of vesicles from the ER
2. Vesicles include import proteins which recruit peroxisome proteins
3. Peroxisomes can undergo fission to replicate

Question 13

What are the main structures of a lysosome?

Answer 13

• Enclosed within a membrane
• Consist of 40 types of soluble hydrolytic enzymes

Question 14

What enzymes are present in lysosomes?

Answer 14

• Proteases
• Nucleases
• Phospholipases
• Phosphatases
• Sulfatases

Question 15

What are Endosomes?

Answer 15

• Endosomes are membrane-bound vesicles
• Act as intracellular sorting organelles and fuse with lysosomes

Question 16

Why does the lysosome not digest itself?

Answer 16

Consists of a modified lipid membrane with highly glycosylated proteins
- Cannot be digested by hydrolytic enzymes

Question 17

What are some functions of VAULT complexes?

Answer 17

• Nuclear pore complex assembly
• mRNA localisation
• Drug resistance
• Cell signalling
• Transport between nucleus and cytoplasm

Question 18

What are the structure and function of Proteasomes?

Answer 18

• Consists of a central hollow cylinder comprising 4 stacked heptameric rings
• Target proteins made up of polyubiquitinylated chains and destroy misfolded proteins

Question 19

What are the structure and function of Vacuoles?

Answer 19

• Fluid-filled membrane-bound organelles
• Contain hydrolytic enzymes
• Act to store nutrients and waste, regulate turgor pressure and regulate pH in the cell