Cell Cycle

Question 1

What are the four phases of mitosis?

Answer 1

Prophase- sister chromatids visible
Metaphase- sister chromatids align at the equator
Anaphase- sister chromatids separate- pulled to opposite poles of spindle
Telophase- segregated chromosomes packaged into separate nuclei

Question 2

Prophase?

Answer 2

Chromosomes condense into X shapes
Pair up
Membrane dissolves away releasing chromosomes
Mitotic spindle extends across the cell between the centrioles

Question 3

Metaphase?

Answer 3

Chromosomes line up neatly
Centrioles are now at opposie poles with mitotic spindle fibres extending from them
Mitotic spindle fibres attach to each sister chromatid

Question 4

Differences between mitosis & meiosis?

Answer 4

Divisions- one vs two
Independent assortment- no vs yes
Synapsis- no vs yes
Crossing over- no vs yes
Outcome- two cells vs four cells
Ploidy- diploid vs haploid
Use- body cells vs gametes
Genetics- identical vs variation

Question 5

What is cell differentiation?

Answer 5

The development of non-specialised cells into cells with specialised functions

Question 6

What is morphogenesis?

Answer 6

Organs and tissues developing a characteristic form from fertilised egg

Question 7

What controls cell differentiation and morphogenesis?

Answer 7

Gene expression

Question 8

What is interphase?

Answer 8

S phase: DNA duplicated
G1 and G2 phase: gap phases

Question 9

Why do we have gap phases?

Answer 9

Needed to allow for growth
Most cells need much more time to grow and double their mass of proteins and organelles

Question 10

What is the cell cycle?

Answer 10

The whole part.
G1: cell doing its everyday job
S: chromsomes coped
G2: prepares for division, cell grows, produces organelles, proteins, membranes
M: phases of division

Question 11

What is the length of cell cycle?

Answer 11

In human cells interphase is 23 hours and M phase 1 hour

Question 12

What is G0?

Answer 12

A phase a cell may enter if extracellular conditions are unfavourable
Can remain for days, weeks or even years

Question 13

How is this controlled?

Answer 13

3 checkpoints: G1, G2, spindle checkpoint
Checkpoint failures lead ot cancer
Cyclin-dependent protein kinases (CDKs)

Question 14

Why is cell division control necessary?

Answer 14

Unchecked growth would be disastrous

Question 15

What are the 3 types of cell death?

Answer 15

Necrosis, apoptosis, autophagy

Question 16

What is necrosis?

Answer 16

Death due to injury/trauma
Cell swells
Neighbouring cells are affected

Question 17

What is apoptosis?

Answer 17

Programmed cell death
Chromatin condensation, DNA fragmentation, membrane blebbing, number of genertic diseases, pathway long conserved

Question 18

What gene is involved in apoptosis?

Answer 18

Ced-3: protease, kills cells by degrading their protein
Active process

Question 19

What is autophagy?

Answer 19

Self-canabilising
Triggered in response to cellular stress, infections or misfolded proteins
Cell engulfs cytoplasm into ‘autophagosome’ and delivers to lysosome
Pathway conserved in yeast

Question 20

What is the autophagy process?

Answer 20

1. macroautophagy- sequestriation of cytoplasmic substances- phagophore
2. microautophacy- lysosomal invagination: fusing
3. chaperone-mediated autophagy- heat shock machinery