B2.2 - organelles and compartmentalisation

Question 1

metabolite

Answer 1

any substance produced in metabolism

Question 2

poles

Answer 2

opposite ends of a cell

Question 3

organelle

Answer 3

discrete sub-units of a cell that are adapted for a specific function that are mostly surrounded by a membrane

Question 4

what are examples of organelles?

Answer 4

nuclei, vesicles, ribosomes

Question 5

what are non-examples of organelles?

Answer 5

cell wall, plasma membrane, cytoplasm, cytoskeleton

Question 6

when did the study of the function of individual organelles become possible?

Answer 6

when ultracentrifuges had been invented and methods of using them for cell fractionation had been developed

Question 7

fractenation

Answer 7

breaking down a membrane and spinning the sample at high speeds so the heavier components move further down the tube
- allowed different sizes of ribosomes to be detected as the smaller, less dense 70S was found higher in the fraction than the larger, more dense 80S

Question 8

what is an advantage of separation of the nucleus and cytoplasm into separate components?

Answer 8

allows separation of the activities of gene transcription and translation
- post-transcriptional modification of mRNA can occur before it meets ribosomes in the cytoplasm
- not possible in prokaryotes

Question 9

what are advantages of compartmentalisation in the cytoplasm of cells?

Answer 9

• allows accumulation of metabolites and enzymes at high concentrations
• separates incompatible biochemical processes

Question 10

what are 2 examples of compartmentalisation?

Answer 10

lyosomes - contain hydrolytic enzymes and free radicals which digest biological molecules
- prevents useful molecules being digested and cell damage
phagocytic vacuoles - contain pathogen engulfed by endocytosis
- protects cellular contents from damage by the pathogen