chromosomes, the cell cycle and cell division Flashcards
unicellular organisms vs multicellular organisms with cell division
unicellular organisms- reproduce
multicellular organisms - cell division for growth and tissue repair
replication
Replication of genetic material (DNA) is important; such that two new cells
have identical genes and complete cell function
segregation
The cell must distribute the DNA to each of the two cells.
.the ori begins to move to opposite ends of the cell. Ori
also binds proteins that hydrolyze ATP. The cytoskeleton may be involved in actively moving DNA along or passively acting as “railroad tracks”
cytokinesis
New materials must be added to the cell membrane (or cell wall for cells
that have them) the process of separating two new cells
.when chromosome replication is finished, cytokinesis
begins. The cell pinches inward and tubulin helps to separate the two cells (tubulin makes up microtubules)
prokaryotes reproduce by what
binary fission
binary fission
The cell grows, replicates its genetic material, and divides into two new cells
how can replication e sped up
more nutrients
chromosome
DNA molecule containing genetic information
. highly compacted
prokaryotes vs eukaryotes
pro :
.one chromosome
.constantly divide
. cytokinesis can only occur following duplication of the entire nucleus
euk :
.cell divides by mitosis or meiosis
.do not constantly divide
.many chromosomes
.distinct nucleus (divide into nuclei )
Gametes
sex cells derived from the organisms’ parents
meiosis
occurs only in cells that produce gametes (only in cells that produce
sperm and egg)
how is eukaryotic cell division controlled ?
reproduce sexually
cell cycle
the events that produce two cells from one
M phase describe it
mitosis and cytokinesis - - cell division occurs there . during mitosis nuclear division occurs
interphase
when the cell is most of their life.
what 2 phases are in the cell cycle
mitosis(M) and interphase
G1
represents the end of mitosis and the
beginning of S phase. G1 or gap phase 1
S phase
DNA synthesis and DNA is replicated
G2
separates the end of S phase and
the beginning of Mitosis
more on G1
this phase varies on cell types. some rapidly dividing cells do not have this phase while some remain in G1 for weeks to years
what is the term used when G1 to S transition
commitment step
during G2 what must happen
cell must synthesize microtubules that will move sister chromatids to opposite ends of the dividing cell
cyclin
dependent kinase or cdks are
proteins that facilitate cell cycle transitions
. cyclin
activates cdk by altering its shape and
exposing the active site. It is the cyclin-cdk
complex that acts as a kinase and triggers
transition from G1 to S phase
what is the key to get through restriction zones
RB
what is RB
protein kinase that normally
inhibits progression of the cell cycle,
however when RB is phosphorylated, RB
is inhibited
p21 what is it
it is made when DNA is damaged
. it can bind to G1 ro prevent action
. breaks down when DNA is prepared
. tumor suppressors
what are the three tumor suppressors
p53 , p21 and RB
Growth factors
If cells are to divide, they must be stimulated by signals called growth
factors
chromatin
Eukaryotic chromosomes have tow gigantic linear double stranded
molecules of DNA complexed around many proteins into dense
material
chromatids
Before S phase there is only one double stranded DNA molecule but
after S phase there are two double strands
sister chromatids
cohesions
DNA is held together by protein complexes
centromere
They stay together until
the cohesion is removed, except in a region
called the centromere
condensins
a second group of protein
.condensins coat the DNA to make it
more compact
The centrosomes double during S
phase to form a pair of
centrosomes
centrioles-
a hollow tube lined with
microtubules
centrioles-
a hollow tube lined with
microtubules
During the G2
M transition the
centrosomes separate and move
to opposite ends of the nuclear
envelope
during interphase what is visible under a light microscope ?
nuclear envelope
