Project Flashcards
Define Chromosome
A combination of DNA with its associated proteins.
Define Karyotype
An image of the chromosome in a cell.
Define Homologous Chromosomes
The chromosomes present in a set. They have the same genes, but possibly different alleles. The number per set is called ploidy. They are the same size and structure, have the same genes, and you get 1 from each parent.
Mature gametes (sperm and egg cells) are _____.
Haploid
Define Autosome
Not the sex chromosomes, but they do contain sex determining genes.
Define Sex Chromosomes
Chromosomes that are involved in sex determination and segregate differently between the sexes. Many mammals have an XY sex determination where the XX is the female and the XY IS THE MALE.
Define SRY Gene
The SRY gene is the gene on the Y chromosome that acts as a master switch when it comes to turning on male development and suppressing female development. The female with XX lacks an SRY gene and develops as a female.
How is the creeping vole an exception when it comes to the SRY gene?
The X chromosomes do not have genes required for female development (SRY not required); those genes are distributed across the autosomes.
Define Chromatin
The DNA plus histones and other proteins that make up the chromosome.
Define Heterochromatin
When the chromatin is tightly wound up and condensed, it is called a heterochromatin.
Define Euchromatin
When the chromosome is relaxed, it is called euchromatin.
Gene expression takes place in the _____ and is generally suppressed in ______.
Euchromatin-Heterochromatin
The Y chromosome is mostly _____.
Heterochromatin
Do complete dominant and recessive alleles exist? What actually happens instead?
No, this is rarely the case; rather, both alleles are typically expressed from each autosome in equal amounts.
How does the balance of gene expression get messed with?
When errors in meiosis result in more than one homologous chromosome in a gamete, the balance of gene expression is off due to the increases in dosage.
