Sexual Reproduction and Inheritance

Flashcards covering sex determination, meiosis, and inheritance.

Whole arm syndrome/heart hand syndrome

A condition where the thumb looks like a finger and there may be a massive atrial defect, often linked to the TBX5 gene.

TBX5 Gene

A gene involved in the formation of both the thumb and the heart; its expression can be influenced by its environment.

In Vitro Fertilization (IVF)

A procedure resulting from developmental biology advancements, now used by a significant percentage of couples.

Fertilization

The process that activates the egg to begin development, restoring the diploid number of chromosomes.

Zygote

The cell formed when the sperm nucleus migrates to the female pronucleus and creates a diploid nucleus.

Diplotic

refers to sexual reproduction where two haploid gametes meet to form a diploid individual.

SRY Region

The sex-determining region on the Y chromosome; without this gene, an individual cannot be male.

Default State of vertebrate embryos

Female, unless overridden by the SRY gene.

Wnt4

Activates DAX1 to make ovaries

SOX9

Allows activation/development of testes.

Thermosensitive Period

A period in some species (e.g., turtles) where temperature determines the sex of the offspring through the expression of SOX9.

Main benefit of sexual reproduction

Variability due to meiosis, allowing for crossover events and unique combinations of genes.

Meiosis

The process of cell division that separates homologous chromosomes and allows for genetic crossover, resulting in haploid cells.

Crossing Over

The exchange of genetic information during meiosis, leading to recombinant chromatids and increased genetic variation.

Recombination Frequency

The frequency at which crossover events occur, often used to create genetic maps; higher frequency means genes are further apart on the chromosome.

Alfred Sturtevant

The scientist who first proposed using recombination frequency to map genes on a chromosome.

Linked Genes

Genes located close together on a chromosome with a lower recombination frequency.

X-linked Recessive Condition

A condition that manifests when there is a genetic variation on both X chromosomes (females) or a single X chromosome (males).

X-linked Dominant Condition

A condition that manifests with a mutation on a single X chromosome.

Hemizygous

Having only one copy of a gene or set of genes. This is used to describe males for genes on the X chromosome.

Aneuploidy

An abnormal number of chromosomes, leading to conditions like trisomy 13 (Down syndrome) or missing chromosome structures.