Cell cycle Flashcards
not complete
Stages of interphase
G0 (some cells only)
G1
S Phase
G2
Stages of mitosis
Prophase Prometaphase Metaphase Anaphase Telophase
What occurs in G0
phase where there is no active preparation for cell division occurs. eg. in nerve cells, eye cells which do not actively divide
What happens in G1
Increased cell size
Increased protein concentration
Regulatory proteins are made and activated
What happens in S phase
DNA replication
What happens in G2 phase
Preparation for mitosis/cytokinesis
Most common form of replication in bacteria?
Binary fission
What occurs in binary fission?
- Circular bacterial DNA is attached to membrane by protein
- DNA replication begins and proceeds bidirectionally around the circle
- new DNA molecule is also attached to the inner membrane, near the original DNAs attachment site
- Cell elongates, moving attachment sites further away
- New membrane begins to form at the midpoint
- 2 identical daughter cells are produced
Which is more complex? Eukaryotic cell division or Prokaryotic? Why?
Eukaryotic
- Due to large genome size, which must be entirely replicated. this is compared to bacteria which only have a relatively small circular DNA molecule
- in proks, the dna is attached to the membrane and dna can be separated into 2 cells by cellular growth. in euks, dna is in the nucleus and requires the nuc envelope to be broken down and reformed
What does the M phase consist of?
Mitosis
Cytokinesis
How long does M phase typically last?
1 hour for most mammalian cells
What is interphase?
the time between two successive M phases, where the cell undergoes preparation for cell division
How is DNA in eukaryotic cells organised?
DNA is organised with histones and other proteins into chromatin, which are looped and packaged into chromosomes
Karyotype
a standard arrangement of chromosomes,showing the number and shapes of the chromosomes representative of a species
How many chromosomes does the human genome contain
46 chromosomes (23 pairs)
homologous chromosomes
pairs of chromosomes which match in size and appearance. carries the same amount of genes. one is from the mother, one is from the father
ploidy
number of complete sets of chromosomes in a cell
haploid
one complete set of chromosomes
diploid
two complete set of chromosomes
polyploid
some organisms can have 4 or sometimes more sets of chromosomes
sister chromatid
two identical copies of a chromosome produced when DNA is replicating
centromere
part of the chromosome that holds the chromatids together, and are the site of the attachment of the spindle fibres that move the chromosomes
prophase
chromosomes condense
centrosomes radiate microtubules and migrate to opposite poles
prometaphase
microtubules attach to chromosomes
metaphase
chromosomes align in centre of cell
anaphase
sister chromatids separate and are pulled to opposite end of cell
telophase
nuclear envelope reforms and chromosomes condense
mitotic spindle
structure made of microtubules that pull the chromosomes into separate daughter cells
centrosome
structure that is the microtubule organising center for animal cells
what happens to the centrosome in S phase?
centrosome duplicates and each begin to migrate around nucleus, creating opposite poles
kinetochores
site of spindle attachment. located on both sides of centromere
what happens during cytokinesis
it is the phase where the parent cell divides into 2 daughter cell
contractile ring
ring of actin filaments that forms at the equator of the cell perpendicular to the axis of what was the spindle at the beginning of cytokinesis
