Cell cycle, mitosis,meiosis

Question 1

Name the 4 different stages of mitosis

Answer 1

Prophase
Metaphase
Anaphase
Telophase

Question 2

What happens during prophase (mitosis)

Answer 2

• Chromatin condenses to make chromosomes
• nuclear envelope dissolves
• Centrioles move to opposite ends of cell to form spindle fibres

Question 3

What happens during metaphase (mitosis)

Answer 3

• spindle fibres attach to the centromere of chromosomes and line them across the equator of the cell
• Metaphase checkpoint - cell checks all chromosomes attached to spindle fibre before mitosis can continue

Question 4

What happens during anaphase (mitosis)

Answer 4

• centromere divides + spindle fibre shortens pulling chromosome apart with each sister chromatid at opposite ends of the cell.

Question 5

What happens during telophase (mitosis)

Answer 5

• chromosomes uncoil to reform chromatin

- nuclear envelope reforms around each set of chromosomes

Question 6

What happens during cytokinesis

Answer 6

cell cytoplasm divides forming 2 new genetically identical or different daughter cells (depending on meiosis or mitosis)

Question 7

stages of interphase

Answer 7

g1,s,g2

Question 8

what happens during g1

Answer 8

organelles replicate, proteins synthesised, cell increases in size

Question 9

what happens during g2

Answer 9

energy stores increased, the cell continues to grow

Question 10

what happens during s phase

Answer 10

DNA is replicated in the nucleus

Question 11

Why is it important that the cell cycle is regulated/checked during the process

Answer 11

To ensure two identical daughter cells are produced from the parent cell and to ensure that cells don’t divide too fast or too slow and not perform their cellular functions

Question 12

Where are the checkpoints during the cell cycle and their functions

Answer 12

G1 checkpoint - end of g1 phase to ensure cell is well suited to proceed to S phase. If good then goes on to next stage if not then goes to g0.

G2 checkpoint - before mitosis, ensure DNA has been replicated with no error - if good then passes on to next stage

Metapahse checkpoint - occurs after spindle fibres have attached to centromere (metaphase)- makes sure all chromosomes are attached to spindle fibre before next stage occurs

Question 13

What is the role of g0

Answer 13

Cells go here to become differentiated (become specialised and no longer divide)

Damaged cells (etc -DNA replication error) cells enter here to die

Question 14

difference between mitosis and cytokinesis

Answer 14

Cytokinesis refers to that stage at which the cytoplasm divides to form 2 daughter cells, However, MITOSIS IS THE PROCESS OF REPLICATING AND DIVIDING THE GENOME

Question 15

Describe the use of mitosis in plants

Answer 15

Asexual reproduction- production of genetically identical offspring from one parent in multicellular and single called organisms(e.g amoeba, plants)

• growth of roots and shoots
• repair of damaged parts of cell

Question 16

What part of plant cell would be best to observe mitosis and why?

Answer 16

Plant root tips
continually grow at regions called meristems
Meristems are a good source of cells for studying mitosis as they are constantly diving
Plant cells are easy to obtain and prepare for microscopy

Question 17

Difference between cytokinesis in plants and animals cells

Answer 17

Animal cells cleavage furrow forms around middle of cell furrow pulls inwards and fuses (1);

plants cells furrow cannot form due to cell wall vesicle assemble across centre of cell and fuse

Question 18

What cells does mitosis occur in

Answer 18

Somatic cells (body)

Question 19

How would you observe meiosis in plants

Answer 19

Cut anther from flower and prepare a squash slide, stain and observe using a microscope

Question 20

What are the gametes in plants

Answer 20

Pollen & ovules

Question 21

What are homologous pairs

Answer 21

Pair of chromosomes-
Same chromosome- one from mother and other from father - that have the same genes but can have different alleles on each gene

Question 22

Describe how homologous chromosomes exchange genetic material

Answer 22

• homologous chromosomes pair up
  -non-sister chromatids entangle and exchange alleles when they have pulled apart in anaphase- producing new combos of alleles.
  Independent assortment of homologous pairs and chromosomes also contributes as when lined up in the middle of cell each orientates independently before being separated to opposite poles of cells - producing new combos of alleles.

Question 23

2 types of cell that can go through the cell cycle an infinite number of times

Answer 23

• stem cells

- tumour cells

Question 24

what is the term used to describe cells that can go through the cell cycle an infinite number of times

Answer 24

hayflick limit