Cell Cycle Flashcards
What are the stages of mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Roughly how long is each stage of the cell cycle
What happens during the G phase of the cell cycle
The cell decides whether the conditions are favourable for division
What happens in the S phase of the cell cycle
DNA is replicated or else daughter cells will only have half of the required genetic material
Involved the use of DNA polymerase (which is very accurate)
It makes 2 sister chromatids which are held together by cohesion
What happens in the prophase
Chromosomes condense
Spindle fibres begin to form, coordinated by the centrosomes
How does chromosome condensation occur
How do spindle fibres form
At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles. Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle
What is the prometaphase and why is it needed
Nuclear envelope breaks down
Protein in nuclear envelope diffuses out
It’s needed as it provides more space in the cell
What happens during the metaphase
Chromosomes align at the equator
Kinetochores attached to microtubules/kinetochore spindle fibres
Chromosomes are visible
What is a kinetochore
Is the protein complex assembled at the centromere that binds to microtubules of the spindle fibres
What happens in the anaphase
Spindle fibres form
Sister chromatids seperate
Daughter chromosomes migrate to opposite poles
Spindle poles move apart
Explain the process of chromosome migration
What happens during the telophase
Daughter chromosomes arrive at poles and decondense
Nuclear envelope reformation
What happens during cytokinesis
Cytoplasmic separation
Formation and contraction of actin ring
What are the stages of the cell cycle
G1, S, G2, M
What are the 3 major regulatory transitions
What is the role of the cell-cycle control system
What does the cell-cycle control system depend on
Depends on cyclin-dependent protein kinases (Cdks)
What are Cdks and what do they do
What are the 4 classes of cyclins
G1/S cyclins
S-cyclins
M-cyclins
G1-cyclins
What do G1/S cyclins do
activate Cdks in late G1 which helps to trigger progression through ‘Start’ which results in a commitment to cell-cycle entry. The level of these cyclins decrease in the S phase
What is the role of S-cyclins
they bind to Cdks ‘start’ has been completed and help stimulate chromosome duplication. The levels of s-cyclins stay high until mitosis and is involved in the control of some early events in mitosis