Reproduction Flashcards
in animals, autosomal cells are said to be _ , which means they contain two copies of _
diploid (2n)
each chromosome
What are the four stages of the cell cycle also known as _
G1, S, G2, and M
interphase
Cells that do not divide spend their time in?
G0
during interphase individual chromosomes are not visible with light microscopy because they are in a less condensed form known as _ . and why
chromatin
bc DNA must be available to RNA polymerase so that genes can be transcribed
Describe the G1 stage
cells create organelles for energy and protein production while increasing their size. passage into the S phase is governed by a restriction point.
Describe the S stage
During the Synthesis phase the cell replicates its genetic material so that each daughter cell will have a copy.
describe the chromosomes During the S stage
replicates to two sister chromatids bound by a centromere
Describe the ploidy and amount of DNA in S stage
ploidy is still diploid. Humans still have 46 chromosomes but DNA is doubled because there are 92 chromatids present
Describe the G2 stage
cells pass through another restriction point making sure there are enough organelles for two daughter cells. And checks DNA replication
Describe the M stage
mitosis and cytokinesis. Mitosis is divided into 4 stages
What is the main protein in control of the G1/S restriction point
p53
What are the molecules responsible for the cell cycle
cyclins and cyclin-dependent kinases (CDK)
How do cyclins and CDKs work
cyclins bind to CDKs creating an activated CDK-cyclin complex. this complex can phosphorylate transcription factors that promote the transcription of genes required for the next stage of the cell cycle
what is metastasis
local invasion and distant spread of cancerous cells through the bloodstream or lymphatic system
What are the 4 phases of mitosis
prophase, metaphase, anaphase, and telophase.
mitosis occurs in _ whereas meiosis occurs in _
somatic cells; gametocytes (germ cells)
Describe prophase
first phase of mitosis;
first step; involves condensation of the chromatin into chromosomes and the centriole pairs separate and move toward opposite poles of the cell.
2nd step; spindle fibers form (made of microtubules), some form asters. the nucleoli become less distinct and may disappear.
where are centriole pairs located
in a region called the centrosome; a region located outside the nucleus
Describe metaphase
the centriole pairs are at opposite sides of the cell. kinetochore fibers interact with spindle fibers and align the chromosomes at the metaphase plate or equatorial plate.
Describe anaphase
sister chromatids separate to opposite sides of the cell
Describe Telophase
reverse of prophase; spindle fibers disappear. nuclear membrane reforms around each set of chromosomes. chromosomes then uncoil resuming interphase form.
Describe cytokinesis
separation of the cytoplasm and organelles
Meiosis results in four nonidentical _
gametes
Meiosis I results in
homologous chromosomes being separated generating haploid daughter cells. (reductional division)
Meiosis II results in
reparation of sister chromatids without change in ploidy (equatorial division)
Whats different in Prophase 1 compared to Prophase
homologous chromosomes come together and intertwine in a process called synapsis. chromatids may break at the point of contact called a chiasma and exchange equivalent pieces of DNA.
importance of the synaptonemal complex
a group of proteins that holds homologous chromosomes together in prophase 1.
Mendel’s second law
the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
What is different in Metaphase 1 compared to Metaphase
in meiosis, homologous chromosomes are lined up at the metaphase plate and held by one spindle fiber. in mitosis they’re held by 2 spindle fibers
What is different in Anaphase 1 compared to Anaphase
In anaphase 1 in meiosis, homologous pairs are separated but sister chromatids stay joined together. In anaphase 1 of mitosis the sister chromatids do separate.
What is different in Telophase 1 compared to Telophase
At the end of Telophase 1 during meiosis, we get a haploid set of chromosomes with complete homologous chromosomes separated at each pole.
At the end of Telophase during Mitosis, we get a haploid set of chromosomes with discrete homologs (sister chromatids) of homologous chromosomes separated at each pole.
What is SRY
sex determining region
Pathway of sperm through the male reproductive system
Seve(n) up Seminiferous tubules epididymis vas deferens ejactulatory duct (nothing) urethra penis
What is the function of the interstitial cells of Leydig
secrete testosterone and androgens
what are androgens
male sex hormones
function and purpose of the ductus deferens
a layer of muscle around the vas deferens that can raise and lower the testis to maintain a proper temperature
Describe the physiology of a mature sperm
compact; consist of a head containing genetic material. a midpiece which generates ATP from fructose, and a flagellum.
What is an acrosome
covers the sperm head and is necessary to penetrate the ovum.
What hormones do the ovaries produce
estrogen and progesterone
fallopian tubes are connected to the muscular _ and are lined with _ that propel the egg foward
uterus; cilia
what are spermatogonia
stem cells that make sperm
primary oocytes versus secondary oocytes; arrested phases
primary oocytes; are 2n, at birth are considered primary, arrested in prophase 1
secondary oocytes; 1 primary oocyte per month will undergo meiosis 1 producing a secondary oocyte; than arrested in metaphase 2 until fertilization (meiosis II)
what layers surround the oocyte and what is their purpose
zona pellucida; glycoprotein layer that protect the oocyte and allow sperm cell binding.
corona radiata; lies outside the zona pellucida, layer of cells that adhere to the oocyte during ovulation.
when is meiosis 2 triggered
when a sperm cell penetrates the layers around the oocyte
Before puberty the hypothalamus restricts production of this hormone, but after releases it in pulses
gonadotropin-releasing hormone (GnRH)
the anterior pituitary gland is triggered by GnRH and releases
follicle-stimulating hormone (FSH)
and luteinizing hormone (LH)
What hormones trigger the production of other sex hormones that develop and maintain the reproductive system
GnRH
FSH
LH
_ leads to the thickening of the lining of the _ or _ each month in preparation for the implantation of a zygote
Estrogen
uterus or endometrium
What secretes progesterone in response to LH
corpus luteum
by the end of the first trimester, progesterone is supplied via the _ and the _ atrophies and ceases to function
placenta
corpus leutem
Explain the follicular phase of the menstrual cycle. including the hormones involved
the follicular phase (preovulatory) begins when the menstrual flow begins. GnRH secretion increases in response to the decreased concentrations of estrogen and progesterone. High [GnRH] cause increased [FSH] and [LH]. FSH and LH work in concert to develop several ovarian follicles. The follicles produce estrogen, which has a negative feedback and causes GnRH, LH, and FSH to level off. Endometrial lining regrows.
Explain the ovulation phase of the menstrual cycle. including the hormones involved
estrogen then begins to act in a positive feedback loop where [LH], [GnRH] , and [FSH] spike. The surge in LH induces ovulation.
Explain the luteal phase of the menstrual cycle. including the hormones involved
after ovulation, LH causes the ruptured follicle to form the corpus luteum. progesterone levels rise while estrogen level remain high. High progesterone causes negative feedback on GnRH, FSH, and LH.
_ helps regenerate the uterine lining, but _ maintains it for implantation
estrogen
progesterone
Assuming implantation doesnt occur; explain hormones in luteal phase
the corpus luteum loses stimulation from LH, and progesterone and estrogen levels decline. GnRH rises and next cycle begins.
a blastocyst will implant in the uterine lining and secrete _
human chorionic gonadotropin (hCG)
Why does menopause occur
ovaries become less sensitive to FSH and LH, causing ovarian atrophy.
Upon ovulation, the oocyte is released into the _ than the _
abdominal cavity; fallopian tube
What is the last point in the meiotic cycle in which the cel has a diploid number of chromosomes
During telophase 1
