Reproduction Lec. 1, 2 Flashcards
What other name did he find for meiosis?
Where does meiosis occur?
What does it produce?
Reductive division
Gonads (testes/ovaries)
germ cells/gametes (sperm and ova)
Alternative name for mitotic cell divisions.
Alternative name for gamete.
Duplication division
Germ cell
Autosomal chromosomes:
first 22 homologous chromosomes
Both alleles are expressed. In some rare cases one is inactivated. How does this result? # of genes like this?
One parental allele, either the maternal or paternal is silenced.
100 (out of 25000)
Silencing of a single allele is done how?
Methylation of the cytosine in DNA and acetylation of histone proteins in chromatin.
Genomic imprinting:
epigentic changes in the zygote which result in silencing one parental allele and expression of the other remaining, non-imprinted allele.
How many genes does the X chromosome have?
The Y?
1080
80
To what degree can the X and Y chromosome undergo recombination?
Only the tips containing some 50 genes can recombine.
X-linked genes cause how many diseases?
168 known
Is there any evidence that the y chromosome is still surprisingly active?
Yes, it has a large ratio of euchromatin (extended active DNA)
How might the Y chromosome fix errors in itself?
It has massive palindromes, these may enable gene conversions, which may act as a form of crossing over within the Y and help replace erroneous sequences.
What can provide a useful microscopic test for the chromosomal sex of a person?
The barr body.
Testes determining factor is encoded by what gene?
The SRY (sex determining region Y)
How long are the male and female gonads similar in development?
40 or so days
Where do the cells which will give rise to spermatogonia and oogonia come from?
cells which migrated to the gonads from the yolk sack.
