Unit 1: Cell Cycle Flashcards
What are the two phases in the cell cycle called?
Interphase and M phase (mitosis and cytokinesis)
what are the five steps in Mitosis
Prophase, prometaphase metaphase, anaphase and telophase
what is the M phase controlled by
cytoskeleton
what is the order of the cell cycle
G1, S, G2, M, cytokinesis
what is the G1 stage?
the first growth stage where the cell makes new proteins and copies organelles
what is the S phase?
when DNA replication occurs
what is the G2 stage?
second growth stag, more proteins made and copies of organelles for preparation for mitosis
what is interphase?
active period of growth and metabolism
what is prophase?
chromosomes condense and become visible
mitotic spindle assembles between centromeres which have been replicated and have moved to opposite poles
what is prometaphase?
the nuclear membrane breaks down
chromosomes attach to spindle microtubules via structures known as kinetochores (centromeres)
chromosomes start to actively move
what is metaphase?
chromosomes line up along the equator of the cell by spindle fibres
spindle microtubules from each pole attach to the kinetochore of each chromosome
spindle fibre from one pole attaches to one chromatid of each chromosome and a spindle fibre from opposite pole attaches to the other chromatid
what is anaphase?
contraction of spindle fibres cause the centromere of the chromosomes to separate and chromosomes are pulled to opposite ends of the cell
what is telophase?
the chromosomes uncoil and lose visibility and the nuclear envelope toms around each set of chromosomes
what is cytokinesis?
the cytoplasm is constricted by a ring of actin producing a cleavage furrow that pushes the cell into two
what is the mitotic index
the percentage of cells undergoing mitosis in the sample
how do you calculate the mitotic index?
the number of cells undergoing mitosis/ total number of cells in the field
what are mitotic spindle fibres composed of?
microtubules
at what stage in the cycle will there be the most DNA content
after S and before G2
where is the G1 checkpoint and what does it check?
towards the end of the G1 phase and monitors cell size
where is the G2 checkpoint and what does it check?
at the end of G2 phase an checks the success of DNA replication
where is the M checkpoint and what does it check?
during metaphase and and monitors chromosome alignment
what is the p53 gene?
involved in the g1 checkpoint. codes for a protein that checks replicated DNA strands are undamaged
what protein is used at the G2 checkpoint?
Mitosis promoting factor - MPF - mitosis will only be triggered is sufficient MPF is present
