Unit 1: cells and proteins KA 1.5: protein control of cell division Flashcards
What is the cytoskeleton made of?
A polymer called microtubules. These are composed of protein monomer called tubulin.
name the structure microtubules form during cell division
spindle fibres
name the monomer that forms microtubules
tublin monomer
where do the microtubules radiate from in the cell?
Microtubule organising centre (MTOC) also known as the centrosome
The cell cycle can be divided into two parts what are their names?
interphase and mitotic (M) phase
Function of mitosis
provides new cells for growth repair of damaged tissues and replacement of dead or damaged cells.
It also maintains the cells diploid chromosome complement.
function of interphase
growth and DNA synthesis including-
G1-a growth phase
S phase-during which DNA is replicated and
G2-a further growth phase
what is the acronym for the mitotic phase?
PMAT
What happens in prophase?
DNA condenses into chromosomes each consisting of two sister chromatids
nuclear membrane breaks down
spindle microtubules extend from the MTOC by polymerisation and attaches to chromosomes kineticore in the centromere region
what happens in metaphase?
Chromosomes are aligned at the metaphase plate (equator of the cell)
what happen anaphase?
A spindle microtubules shortened by T polymerisation chromatids are separated and chromosomes are pulled apart to the opposite poles
what happens in Telophase?
The chromosomes decondense and the nuclear membrane are formed around them
What happens in cytokinesis?
The cytoplasm is separated into two daughter cells
what is checked for at the G1 checkpoint?
DNA damage, growth factors and nutrients
what is checked for at the G2 checkpoint?
DNA replication and cell size
what is checked for at the M (metaphase) checkpoint?
chromosomes are properly attached to spindle fibres and aligned the equator/metaphase stage
what can P53 do
stimulate DNA repair arrest the cell cycle or cause cell death (apoptosis) and is also a tumour suppressor
what accumulates during the G1 growth phase?
cyclins
which proteins act as tumour suppressors in the cell cycle?
P53 and retinoblastoma
which molecule inhibits RB and how does this occur?
Phosphate. Phosphate group added by the activated CDKs (cyclin dependent kinases)
What does a decrease in cell division cause?
Degenerative disease diseases such as Alzheimer’s
What does an increase in cell division cause?
tumour formation, i.e. cancer
define the term proto-oncogene
A proto-oncogene is a normal gene usually involved in the control of cell growth or division which can mutate to form a tumour promoting oncogene
What is an internal signal that begins the process of apoptosis?
DNA damage (checked for mostly in G2)
What are 2 external signal that begins the process of apoptosis?
production of death signal molecules from lymphocytes or lack of growth factors
what are two types of signals that can trigger apoptosis?
Internal and external
What protein cascade leads to the breakdown of cellular organelles?
caspade cascade
where does an external signalling molecule bind to?
Extra cellular membrane receptor
What protein is activated when an internal signal is received?
Caspases
where can external death signals originate from?
lymphocytes
