T4M1- The cell cycle

Question 1

What type of material is distributed among daughter cells

Answer 1

Genetically identical

Question 2

Define binary fission

Answer 2

A form of asexual reproduction

Question 3

Where does binary fission occur?

Answer 3

Prokaryotes

Question 4

What happens as the chromosome replicates during binary fission?

Answer 4

Cells elongate and new DNA is anchored to plasma membrane

Question 5

When do cells stop elongating during binary fission?

Answer 5

Until two DNA attachment sites are at opposite ends of elongated cells

Question 6

How do you know when replication is complete in binary fission?

Answer 6

Bacterium is double its size

Question 7

Where does the cell constrict when replication is complete?

Answer 7

Along the midpoint of the cell

Question 8

What is synthesised during binary fission?

Answer 8

Synthesis of cell membrane and cell wall

Question 9

What happens during cell division?

Answer 9

Unicellular fertilized egg becomes multicellular complex organism

Question 10

What are two functions of cell division?

Answer 10

Repair and renewal

Question 11

Can adult stem cells give rise to all cell types?

Answer 11

No- can only replace non reproducing specialised cells

Question 12

What are quiescent cells

Answer 12

Non dividing satellite stem cells

Question 13

What can happen to quiescent cells in muscle cells

Answer 13

Become activated and divide to enable muscle regeneration

Question 14

What does the activation of muscle stem cells lead to?

Answer 14

Proliferation, differentiation and fusion of muscle precurser cells

Question 15

What are muscle precursor cells called?

Answer 15

Myoblasts

Question 16

What do myoblasts form and what are they?

Answer 16

Myofibers- mature muscle cells

Question 17

List some differences between eukaryotic and prokaryotic reproduction?

Answer 17

• eukaryotes larger
• eukaryotic DNA packed into nucleus
• eukaryotes organized into linear chromosomes
• eukaryotes require more regulated control

Question 18

What two main phases does mitosis contain?

Answer 18

Interphase and M phase

Question 19

What does interphase consist of?

Answer 19

S phase, two gap growth phases G1 and G2

Question 20

What does the M phase consist of?

Answer 20

Mitosis and cytokinesis

Question 21

What is the purpose of interphase?

Answer 21

Preparation for cell division

Question 22

What occurs during the s phase?

Answer 22

• replication of DNA in the nucleus
• increase in cell size

Question 23

What does G1 phase prepare for? When does it occur?

Answer 23

DNA synthesis
Before S phase

Question 24

What does G2 phase prepare for? When does it occur?

Answer 24

Mitosis- after S phase

Question 25

When do cells pause?

Answer 25

In G0 phase- between M and S phase

Question 26

How long do cells pause for?

Answer 26

Can be days or years

Question 27

What type of cells enter G0 phase?

Answer 27

Eye lens, muscle cells, nerve cells

Question 28

What do quiescent cells do upon injury?

Answer 28

Activated from dormant phase and re-enter cell cycle

Question 29

Who discovered the 5 phases of mitosis and how?

Answer 29

Walther Flemming in 1882 by staining salamander embryos to analyze chromosomes of dividing cells

Question 30

What must happen to chromosomes prior to mitosis

Answer 30

Duplication and condensing

Question 31

In what form are chromosomes during interphase

Answer 31

long and thin chromatin fibres

Question 32

What happens to sister chromatids as the M phase progresses?

Answer 32

Sister chromatids of each duplicated chromosome separate and move to 2 new cells

Question 33

What marks the beginning of M phase?

Answer 33

End of interphase G2 phase

Question 34

Can chromosomes be identified during interphase?

Answer 34

No

Question 35

What happens to duplicated chromosomes as the cell transitions from G2 to M phase?

Answer 35

Condense and become visible

Question 36

First stage of mitosis?

Answer 36

Prophase

Question 37

How do chromosomes appear in prophase?

Answer 37

Identical sister chromatids joined at centromeres

Question 38

What do centromeres do in prophase?

Answer 38

Radiate long microtubules forming mitotic spindles

Question 39

What follows prophase in mitosis?

Answer 39

Prometaphase

Question 40

What is the defining feature of prometaphase?

Answer 40

Fragmentation of nuclear envelope

Question 41

What happens to microtubules as a result of nuclear envelope fragmentation? and where?

Answer 41

Microtubules attach to kinetochores in prometaphase

Question 42

Define kinetochore

Answer 42

Specialised protein structure that associate with each one of sister chromatids on each side of centromere

Question 43

Why do microtubules attach to kinetochore regions?

Answer 43

Essential to pull chromosomes to pole of cell

Question 44

What comes after prometaphase in mitosis?

Answer 44

Metaphase

Question 45

What marks metaphase?

Answer 45

Alignment of chromosomes down the centre of the cell - metaphase plate

Question 46

What facilitates the metaphase plate?

Answer 46

kinetochore microtubules attached to centromere

Question 47

What follows metaphase?

Answer 47

Anaphase

Question 48

What occurs during anaphase?

Answer 48

Kinetochore microtubules shorten - sister chromatids separate into individual chromosomes pulled into opposite spindle poles of cell

Question 49

What elongates cell in anaphase?

Answer 49

Polar microtubules pull against each other

Question 50

What marks the end of anaphase?

Answer 50

Both ends of cell will have complete set of chromosomes

Question 51

What comes after anaphase?

Answer 51

Telophase

Question 52

What marks telophase?

Answer 52

Two new daughter nuclei forming

Question 53

What happens to nuclear envelope during telophase?

Answer 53

reforms around chromosome at opposite poles of dividing cells

Question 54

what happens to chromosomes and microtubules in telophase

Answer 54

decondense and spindle microtubules depolymerise (break down)

Question 55

How does cytokinesis occur in animals?

Answer 55

Begin with formation of contractile ring made of motor proteins with bundles of actin fibres

Question 56

what forms to separate daughter cells during cytokinesis

Answer 56

cleavage furrow

Question 57

what do plants form during cytokinesis

Answer 57

lie down new cell wall along cell plate- dividing middle of cell

Question 58

when is cytokinesis completed in plant cell?

Answer 58

when cell wall fuses with existing wall

Question 59

What was thought to allow the transition of G2 to M phase in 1970s?

Answer 59

Mitosis promoting factor

Question 60

What did Tim Hunt do in the 1980's?

Answer 60

Measured protein level changes in urchin embryos

Question 61

What did Tim Hunt add to the urchin eggs

Answer 61

Methionine and thought they would be incorporated into new proteins in embryos

Question 62

How did Tim Hunt measure samples of protein

Answer 62

Used gel electrophoresis every 10 mins to visualise changes in protein

Question 63

What happened to the protein in Tim Hunt's experiment

Answer 63

Became darker

Question 64

What happened to one specific protein and its intensity in Hunt's experiment?

Answer 64

The cyclin protein band oscillated in intensity - suspected had something to do with cell cycle progression

Question 65

What does the mitosis promoting factor consist of

Answer 65

Cyclin protein and cyclin dependent kinase (CDK)

Question 66

Define the role of kinases

Answer 66

Phosphorylate key amino acid

Question 67

what is the activity of kinase dependent on?

Answer 67

Being attached to cyclin

Question 68

What does cyclin-CDK complex do

Answer 68

trigger changes by phosphorylation of target proteins

Question 69

What does the G1/S cyclin CDK complex do?

Answer 69

Needed for transition from G1 to S phase and prepares for DNA replication

Question 70

What does S cyclin CDK complex do?

Answer 70

Initiate DNA synthesis

Question 71

What does M cyclin CDK do?

Answer 71

Prepare cell for mitosis

Question 72

What is sthe purpose of checkpoints?

Answer 72

- serve as cellular surveillance - block cyclin CDK if anything goes wrong - can pause cell division until next step - allow cells to be repaired

Question 73

What does G1 phase check for?

Answer 73

DNA damage checkpoint

Question 74

What does G2 pase check for?

Answer 74

DNA replication checkpoint

Question 75

What is the M checkpoint?

Answer 75

Spindle assembly checkpoint at the end of anaphase

Question 76

what happens when damage occurs in a cell?

Answer 76

kinase phosphorylates P53 - used turn on genes that inhibit cell cycle - tumor cell that suppresses growth

Question 77

What does p53 produce

Answer 77

CDK inhibitor protein which pauses cell cycle in G1 phase

Question 78

What can regulatory proteins monitor as early as prometaphase

Answer 78

The degree to which sister chromatids are attached to spindle microtubules at the kinetochore regions

Question 79

What happens if there are unattached kinetochore regions

Answer 79

Create wait signal which leads to recruitment of spindle assembly protein

Question 80

How is the recruitment of spindle assembly protein detected

Answer 80

Lack of tension in centromere area

Question 81

what enzyme breaks sister chromatids

Answer 81

separase

Question 82

what is the function of kinetochore microtubules

Answer 82

assist with movement of chromosomes

Question 83

what is the function of nonkinetochore microtubules

Answer 83

forms cage like network which facilitates the activities of cell cycle - assists in elongating the entire cell during anaphase

Question 84

what happens to the binding proteins between the sister chromatids during anaphase

Answer 84

break down

Question 85

describe disjunctional segregation

Answer 85

centromeres of sister chromatids disjoin and segregate

Question 86

when do chromatids become chromosomes

Answer 86

anaphase