L10 Sex from a Genetic Perspective Flashcards
Sexual reproduction is common in ( eukaryotic / prokaryotic ) organisms
Eukaryotic
Asexual reproduction is theoretically twice as fast, so what is the advantage of sexual reproduction?
Creates genetic variation which enables a population to better respond to changes in the environment
Two main modes of sex determination are (2)…
- Protenor Mode ( XX / XO )
2. Lygaeus Mode ( XX / XY )
In the Protenor mode sex is determined by the…
Presence or absence of the X chromosome in the male gametes
The homogametic sex produces…
Only one kind of gamete (e.g. XX)
The heterogametic sex produces…
Varying gametes (e.g. XX or XY)
In moths, butterflies and most birds (such as chickens) males are the…
Homogametic sex
In species where the female is the heterogametic sex the notation…
ZZ (male) and ZW (female) is used
The diploid number of chromosomes in human cells is…
46!
In Klinefelter and Turner syndromes the non-disjunction of sex chromosomes results in…
Aneuploidy
Klinefelter syndrome is commonly designated
47, XXY
Turner syndrome involves a missing ? and is designated…
Sex chromosome, 45 XO
The human Y chromosome contains ( the same / far fewer / far more ) genes than the X
Far fewer
Key features of the human Y chromosome are (3):
• PAR Pseudo-autosomal region (homologous with the X chromosome)
• MSY Male-specific region (doesn’t synapse with X)
- SRY Sex-determining region Y produces Testis Determining Factor (TDF)
Sex determination in some organisms is governed by temperature during incubation. Temperature affects…
Enzymes and enzyme inhibitors relating to steroid hormones (e.g. oestrogen)
