Slide 16 Flashcards
Mendel’s Heredity Factors
Genes
Location of Genes
Genes are located on chromosomes
The Chromosome Theory of Inheritance
1) Mendelanian Genes have specific loci on chromosomes
2) Chromosomes go thru LAW OF SEGREGATION & INDEPENDENT ASSORTMENT. (Both account for Chromosome behavior in Meiosis)
Thomas Morgan Fruit Fly Experiment
Got Solid evidence of specific gene on specific Chromosome
Sex Chromosome
XX female
1 X Chromo is inactivated (Barr body)
XY male
Large X and small Y for males
Y chromosomes
- less Y than X chromosomes
- heavily responsible for sex determination
- SRY gene: develop male organs and prevent female organs
- MUTANT SRY: develop female organs instead
Sex linked gene
A gene located on either sex chromosome
X linked genes= X chromosome
Y linked genes= Y chromosome
Expression of Recessive X-linked genes
For a recessive X-linked trait to be expressed, female needs 2 copies of the allele (X^h X^h)
While men need 1 (X^h Y)
Linked Genes
Inherited together once they are located near the same Chromosome
Sturtevant’s Genetic Map
The farther apart genes are crossover will likely occur (higher recombination frequency)
Nondisjunction (abnormality)
Pair of homologous chromosomes don’t separate normally in meiosis
Aneuploidy (post m-nondisjunction)
Abnormal # of a particular chromosome
Alterations of Chromosome Structure
- Insertion
- Deletion
- Inversion
Genomic imprinting
Only 1 allele is expressed for autosomal gene while the other 1 is inactive
Mitochondria (mom)
From mom. Small circ Chromosome.
