General info on chromosomes and mitosis Flashcards
name of long arm on a chromosome
q
what is the nucleoid
central region without a membrane where DNA is stored in prokaryote (only eukaryotes have a nucleus)
where is the centromere
at the middle of chromosome, links all 4 legs together
define a chromosome
highly organized and compacted chromatin
what is the haploid number
number of different chromosomes
tip of the chromosome
telomere
how many chromatids are in a single straded chromosome
0; chromatids are only in ds chromosomes
definition and examples of ploidy levels
number of homologous chromosomes
ex; haploid (n) diploid (n)
name of short arm on a chromosome
p
what is the genome
all the genes of a cell
steps in cell cycle
interphase = G1, S, G2 mitotic phase (mitosis)
what are homologous chromosomes
same size, same shape, same genes
steps of mitosis
prophase, prometaphase, metaphase, anaphase, telophase
what is translocation
there is an extra piece of chromosome
what happens in G2
preparation for mitosis, growth (right after DNA replication)
what is cytokinesis
division of cytoplasm (starts in early anaphase and ends after telophase)
what does g stand for in G1 and G2
growth or gap
how are anomalies notated
2n + 1 (trisomy), this is a 2n organism with 1 extra chromosome
when does cytokinesis occur in animal cells
is starts at anaphase and ends after telophase
How does mitosis work for prokaryotes?
there is no mitosis, it is binary fission
What happens in G1?
cell growth, size increase, gene expansion (protein synthesis)
functions of cell division
growth: formation of new cells
repair: new cells replace old damaged cells
asexual reproduction
aging because limited divisions are possible
what is the nucleolus
round body in nucleus that makes ribosomes
what is the period with most cell activity
G1
what kind of cells undergo mitosis
somatic cells (anything no reproductive`)
what is cancer
uncontrolled cell growth
what is S phase
synthesis, DNA is replicated ss become ds
what happens in prophase
DNA condenses, organisms and chromosomes appear (chromatin condenses), nucleolus disappears as well as nuclear membrane, spindle fibers appear
what does MPF initiate
M-phase promoting factor;
mitosis may begin
what happens in prometaphase
spindle fibers (made of microtubules) attach to chromosomes (to kinetochore which is attached to the centromere)
ploidy level of each phase of mitosis
all 2n except for anaphase when chromosomes are separated but nuclear membrane is not there yet
how many chromosomes in a human cell
23 pairs of homologous chromosomes (46 total)
what is SPF
s phase promoting factor
what happens in metaphase
chromosomes align
when does the nuclear membrane disappear
starts to disappear in prophase and ends in prometaphase
G1/S checkpoint (at end of G1)
stopping point in cell cycle: cell checks:
for cell double in size,
growth rate adequate
presence on growth factors
if cues present then SPF (s phase promoting factor) will be produced
if not cell falls in G0 (just does its job, no division)
what happens in telophase
opposite of prophase: nuclear membrane reappears, nucleoli reappear, spindle fiber disappear
when does cytokinesis occur in plant cells
after mitosis; cell plate forms and this becomes cell wall
What is mitotic spindle check point
cell waits until all kinetochores are attached, is its okay APC activated
what happens once SPF is activated
start of s phase:
DNA replication occurs
what is APC
allows chromatids to separate, inactivates MPF: spindle breakdown chromosomes decondense (telophase)
when are spindle fibers present
they appear in prophase and disappear in telophase
G2/M check point after G2
another pause in cycle: check for:
mass or growth rate or time
and complete replication
if check point completed MPF activated (metaphase promoting factor), mitosis may begin
What is the kinetichore
protein attached to centromere (one on each sister chromatid) that will connect to spindel fibers
what are centrosomes made of
2 centrioles (the 2 cylinders composed of microtubials)
When does cytokinesis start
early anaphase
When are organelles replicated
In G1 (before DNA is replicated; they don’t want to replicate DNA for nothing, it is done last)
