Sex Determination

What is the two-fold cost of sexual reproduction compared to asexual reproduction?

50% of offspring are unable to produce offspring (males).

What is isogamy?

The likely ancestral condition of sexual reproduction where gametes are of equal size.

Define aneuploidy.

The loss or gain of a single chromosome, leading to atypical gamete genotypes.

What phenotype typically results from the presence of the SRY gene?

A male-gamete-producing phenotype. SYR instructs the body to produce a protein that controls male sex determinations.

Describe the primary sexual characteristics in sexual reproduction.

Diploid phenotypes associated with producing gametes of a particular sex.

What is the significance of temperature-dependent sex determination?

Organisms like Chelonia mydas (Green Sea Turtle) have their sex determined by environmental temperature.

What type of sex determination system is prevalent in Aves (Birds)?

ZW/ZZ system.

How does non-disjunction relate to Down Syndrome in humans?

It causes trisomy 21, leading to overexpression of genes on chromosome 21.

Define autopolyploidy.

A type of polyploidy resulting from chromosomal duplication within a species.

What determines the mating type in organisms like Schizophyllum commune?

Mating-type genes that can exhibit multiple alleles.

What does dosage compensation refer to in Drosophila melanogaster?

Reduced transcription of the X chromosome in XX individuals compared to XY individuals.

What are the differences between autopolyploidy and allopolyploidy?

Autopolyploidy results from chromosomal duplication, while allopolyploidy results from hybridization.

How can environmental interactions affect diploid phenotypes in haplodiploidy?

Some diploid phenotypes only develop through specific environmental influences, such as ingestion of royal jelly.

What is the expected result of fusion in haplodiploidy?

Diploid offspring develop into female-gamete-producing phenotypes.

What genetic factors contribute to polygenic sex in Danio rerio?

The dmrt1 gene on chromosome 5 and the cyp21a2 gene on chromosome 16.