Reproduction - Kaplan Flashcards
G1 stage
Active growth: production of organelles and protein synthesis
Main point is that cell grows in size
Checkpoint is the size ratio, making sure the DNA is in good condition for replication in synthesis phase
Number of chromatids present in S phase
92 chromatids
23 pairs with a total of 46 chromosomes
G2 stage of interphase
Growth in size, continued growth
Another check point: Mitosis Promoting factor
Cyclins and CDK (cyclin dependent kinase)
Molecules that make sure the cell cycle functions normally. Cyclins activate CDK, which then phosphorylate transcription factors to promote genes requires for the next stage of the cycle
Chromatin
Uncondensed, loose form of chromosome that exists in interphase in order for easy access by RNA polymerase during S phase
Centriole
Microtubule that’s responsible for the proper segregation of DNA during mitosis
Found in centrosome and moves towards the ends during prophase to be anchored to the cell membrane.
Kinetochores
Attachments points on the centromeres that connect spindle fibers and the chromosomes together
T/F each cell undergoes a finite number of divisions before programmed death
TRUE
Synaptonemal complex
Proteins that hold up the homologous chromosomes exchanging genetic materials (support the tetrad structure).
Chiasma
The point of contact during homologous pairs’ exchange of DNA
Linked genes
Genes that are closer together and likely to be crossed over together (tend to stay together)
Crossing over in in prophase I explains what Mendel’s theory?
Law of independent assortment: inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
Difference in metaphase in mitosis and meiosis
In meiosis, the homologous chromosomes randomly line up and each is held by one spindle fiber whereas in mitosis, the chromosomes are held at both ends with a total of 2 spindle fibers.
Anaphase I of meiosis explains what Mendel’s law?
Law of segregation: during disjunction, each chromosome of paternal origin separates from its homologous of maternal origin and either chromosome can end up in either daughter cell
Segregation in meiosis
Separation of the homologous pair of chromosomes (paternal chromosome separates from the maternal chromosome)
Sex-determining region Y
Testis differentiation –> formation of male gonads
Seminal vesicles
Fructose
Prostate gland
Alkaline properties so sperm can survive in female gonads
Bulbourethral glands
Clear viscous fluids that cleans out remnants of urine and lubricates the urethra during sexual arousal
Sertolli cells
Stimulated by FSH, surround and nurture the spermatocytes and spermatids
Leydig cells
Stimulated by LH, release testosterone upon stimulation
Male diploid stem cell
Spermatogonia
Mature sperm
Spermatozoa
Spermatogenesis results in how many functional sperms for each spermatogonium?
Four
Both spermatogonium and oogonium undergo what first?
Replication of genetic material - S phase
Primary oocytes are arrested in what stage before a girl goes through her period?
Arrested in prophase I
Zina pellucida
Layer secreted by granulosa cells that protect the oocyte and contain compounds necessary for sperm cell binding
Corona radiata
Lies outside zone pellucida, layer of the a cells
Granulosa cells
Cells that surround the oocyte forming zone pellucida (oocyte plus zone pellucida is a primary follicle). It’s converts an androgen secreted by LH into estrogen. The extra step to form sex hormone compared to males
Theca cells
Cells that surround to form corona radiata, forming a secondary follicle. Theca cells are stimulated by LH and produce an androgen which is ultimately converted into estrogen by the granulosa cells.
LH in males
Direct testosterone development
FSH in males
Stimulate sertolli cells to nourish and nurture the sperms
Estrogen
Secreted in response to FSH. LH stimulates theca cells to make androgen which is then converted to estrogen by the granulosa cells
**helps to regenerate the endometrium but not maintaining it
Initial thickening of endometrium
Progesterone
Secreted by the corpus luteum
Development and maintenance of the endometrium; not the initial thickening of it.
By third trimester, progesterone is supplied by the placenta
What hormone does the blastocyst release? What’s special about it?
Human chorionic gonadotropin hCG
Looks similar to LH, so it maintains the corpus luteum. Very critical because estrogen and progesterone are released from the corpus Luteum in the first trimester.
What releases estrogen and progesterone in the first trimester of pregnancy?
Corpus luteum
Menopause
Rise in FSH and LH in the blood because the negative feedback is removed
Ovarian atrophy
