Reproduction Flashcards
diploid
2n
contain two copies of each chromosome
i.e. autosomal cells
haploid
n
contain only one copy of each chromosome
i.e. germ cells
cell cycle
specific series of phases during which a cell grows, synthesizes DNA, and divides
derangements can lead to unchecked cell division and may be responsible for the formation of cancer
four stages: G1, S, G2, M
interphase
G1, S, G2 collectively
longest part of the cell cycle
chromatin
G0 stage
cell is simply living and serving its function, without any preparation for division
chromatin
less condensed form of chromosomes
allows for DNA to be available to RNA polymerase so genes can be transcribed
G1 stage
cells create organelles for energy and protein production (mitochondria, ribosomes, and ER), while also increasing size
restriction point
governs passage into S (synthesis) stage
criteria (i.e. containing the proper complement of DNA) must be met
S stage
cell replicates its genetic material so that each daughter cell will have identical copies
after replication, each chromosome consists of two identical chromatids bound together at specialized region known as centromere
G2 stage
cell phases through another quality checkpoint
DNA already duplicated
cell checks to ensure that there are enough organelles and cytoplasm to divide between two daughter cells
makes sure DNA replication proceeded correctly to avoid passing on error to daughter cells that may further replicate error to progeny
M stage
consists of mitosis itself along with cytokinesis
divided into four phases: prophase, metaphase, anaphase, telophase
p53
main protein in control of checking at restriction point (between G1/S) as well as at G2/M checkpoint to ensure that there is no damage to the DNA and that the cell has achieved adequate size and organelles have been properly replicated to support two daughter cells
cyclin-dependent kinases (CDK)
responsible for the cell cycle
require presence of right cyclins
conc’s of various cyclins increase/decrease during specific stages
cyclins bind to these creating an activated complex, which can then phosphorylate transcription factors
transcription factors
promote transcription of genes required for the next stage of the cell cycle
cancer
results when cell cycle control becomes deranged and damaged cells are allowed to undergo mitosis
one of the most common mutations found is of gene that produces p53 (TP53)
- cell cycle is not stopped to repair damaged DNA which allows for mutations to accumulate
tumors
created when cancer cells undergo rapid cell division
metastasis
if cancer cell begins to produce the right factors, the damaged cells are then able to reach other tissues
distant spread of cancerous cells through the bloodstream or lymphatic systems
mitosis
process by which two identical daughter cells are created from a single cell
four phases: prophase, metaphase, anaphase, telophase
occurs in somatic cells–cells not involved in sexual reproduction
finite number of divisions before programmed death: 20-50 for human somatic cells
prophase
first phase in mitosis
condensation of the chromatin into chromosomes
centriole pairs separate and move toward opposite poles of the cell
centrioles form spindle fibers made of microtubules, which radiate outward
nuclear membrane dissolves, allowing spindle fibers to contact the chromosomes
nucleoli become less distinct, may disappear completely
kinetochores appear at the centromere
centriole pairs
cylindrical organelles located outside the nucleus in centrosome region
responsible for the correct division of DNA
asters
formed from microtubules
anchor the centrioles to the cell membrane
kinetochores
protein structures located on the centromeres that serve as attachment points for specific fibers of the spindle apparatus
metaphase
centriole pairs are now at opposite ends of the cell
kinetochore fibers interact with the fibers of the spindle apparatus to align chromosomes at the metaphase plate
metaphase plate
equatorial plate
equidistant between the two poles of the cell