Cell Cycle Flashcards
characteristic that best distinguishes living things from non living things
ability to produce more of their own kind
continuity of life is based on the principle called
cell division
role of cell division in prokaryotic cells
reproducing because it makes new organisms
role of cell division in multicellular eukaryotes
allows each cell to develop from a single cell
important part of the cell cycle
cell division
cell cycle
the life of a cell from the time its formed to its own division into daughter cells
in both prokaryotes and eukaryotes, most cell division involves
distribution of identical genetic material (DNA) to two daughter cells
meiosis can only produce
sperm and egg
genome
all the cell’s DNA (genetic information)
how long is eukaryotic DNA
2 meters per cell
before a cell divides
All the DNA must be copied
what happens to the copies of DNA before the cell division
must be separated so that each daughter cell ends up with a complete genome
the replication and distribution of the DNA is possible by
the DNA molecules being packaged into chromosomes
each chromosome has
a very long and linear DNA molecule
genes
units of information that specifies an organisms inherited traits
DNA molecules carry several hundred to thousand
genes
chromatin
entire complex of DNA and proteins that is the building material of chromosomes
varies in its degree of condensation during the process of cell division
chromatin
somatic cells
all body cells EXCEPT the reproductive cells
have 46 chromosomes
somatic cells
gametes
reproductive cells
have half as many chromosomes as somatic cells
gamets
sperm and eggs are considered
gametes
what is a chromosome like when the cell isn’t dividing
a long, thin chromatin fibre
after DNA replication what happens to the chromosome as the cell divides
they condense and become short and thick
sister chromatids
joined copies of the original chromosome
each sister chromatid has a
centromere
centromere
region made up of repetitive sequences in the chromosomal DNA
where is the centromere attached closer
the sister chromatid
what happens to the sister chromatids later in cell division
will separate and move into two NEW nuclei
what are the sister chromatids called once seperated
individual chromosomes
sister chromatid cohesion
initially attached all along their lengths by protein complexes
arm of the chromatid
portion along either side of the centromere
mitosis
division of the genetic material in the nucleus
mitosis is followed by
cytokinesis
meiosis produces
gametes
the daughter cells produced in meiosis have
half the chromosomes of the parent cells
where does meiosis take placed
special cells in the ovaries and testes (gonads)
what does fertilization do in meiosis
fuses the two games together and the chromosome number returns to 46
phases of the cell cycle
- Mitosis (m) phases
- Interphase
The M phase includes
mitosis and cytokinesis
what is the shortest part of the cell cycle
M phase
phases in Interphase
G1
S phase
G2
G1
cell begins to grow
At what time are different cells the most variable in length
G1 phase
S phases is also called
synthesis
what happens in S phase
duplication of chromosomes and cell continues to grow
describe the chromosomes in S phase
cannot be seen individually because they are not condensed
G2
cell grows more as it prepares to divide
what stage of interphase does the nuclear envelope enclose the nucleus
G2
the nucleus contains one or more
nucleoli
what stage of interphase do the two centrosomes form
G2
function of the centrosomes
organize the microtubules of the spindle
what is happening during interphase
intense metabolic growth
how does a cell grow
by producing proteins and cytoplasmic organelles
6 phases in mitosis
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
what stage of mitosis does this describe?
chromatin fibres become more tightly coiled and condense into discrete chromosomes
prophase
what stage of mitosis does this describe?
nucleoli disappear
prophase
what stage of mitosis does this describe?
each duplicated chromosomes appears as sister chromatids joined at their contromeres
prophase
what stage of mitosis does this describe?
the mitotic spindle begins to form
prophase
what is the mitotic spindle made from
microtubules and the centrosomes
what stage of mitosis does this describe?
centrosomes begin to move away from each other by lengthening of the microtubules
prophase
what stage of mitosis does this describe?
nuclear envelope fragments
prometaphase
what stage of mitosis does this describe?
microtubules can now invade the nuclear area
prometaphase
what stage of mitosis does this describe?
chromosomes have become more condensed
prometaphase
what stage of mitosis does this describe?
kinetochore has now formed at the centromere of each chromatid
prometaphase
what stage of mitosis does this describe?
some microtubules attach to the kinetochores
prometaphase
what stage of mitosis does this describe?
the centrosomes are now at opposite ends of the cell
metaphase
what stage of mitosis does this describe?
the chromosomes have all arrived at the metaphase plate
metaphase
where is the metaphase plate located
equidistant from the spindle at both poles
what stage of mitosis does this describe?
each sister chromatid of the chromosome are attached to the kinetochore-microtubule form opposite poles
metaphase
what stage of mitosis does this describe?
shortest stage of mitosis
anaphase
what stage of mitosis does this describe?
begins with the cohesion proteins cleaved
anaphase
what does having the cohesion proteins cleaved do to the sister chromatids
allows them to seperate
what stage of mitosis does this describe?
two liberated daughter chromosomes move towards opposites poles
anaphase
what stage of mitosis does this describe?
cell elongates as the nokinetochore microtubules length
anaphase