5.3 Inheritance Patterns for Linked Genes Flashcards
What is the chromosome theory of inheritance?
states that genes are located at specific positions on chromosomes, and the segregation and assortment of these chromosomes during meiosis is responsible for
inheritance patterns
Define the term “gene locus.”
gene locus (plural gene loci) is a site on a chromosome that a specific gene occupies
What are sex chromosomes?
XX and XY chromosomes
Define the term “genetic linkage.”
ability for several genes on the same chromosome to be inherited together
Where are the oldest individuals located on a pedigree?
left most side
Gene loci far apart =
regular meiosis
Gene loci close together =
linked genes
Recombination frequency
Scientists can look at the frequency with which certain genes turn up together
Genetic mapping
diagram used to show relative locations and distances of genes on a chromosome
Sex-linked trait
Any gene located on a sex chromosome
Give 2 examples of recessive x-linked disorders
Hemophilia and red-green colour blindness
What is SRY?
“sex determining region” on the Y chromosome
How are chromosomes related to the
inheritance of traits?
segregation and assortment of chromosomes during meiosis is responsible for inheritance patterns
How is distance between gene loci related to
genetic linkage?
gene loci close together = alleles stay together=linked genes
gene loci far apart = new combo of alleles=regular meiosis
Describe two differences between X and
Y chromosomes in humans
females have 2 X chromosomes, males have 1 X and 1 Y (hemizygous for x-linked traits)
What is the relationship between alleles and
gene loci?
The alleles of a gene reside at the same
location, or locus, on homologous chromosomes.
What inheritance pattern would you expect
to see for a Y-linked trait in humans?
-females wouldn’t get it (don’t have Y)
-also would be hemizygous in males (only 1 Y)
-no carriers
Which human chromosome carries most of the
genes for sex-linked traits?
X chromosome
Male birds have two Z chromosomes (ZZ),
while female birds have a Z chromosome and a
W chromosome (ZW). Suggest why birds would
make poor model organisms for understanding
the inheritance of human sex-linked traits
-birds use different chromosome letters for sex
chromosomes than humans do, which would make it
confusing
when you have only one x allele what is that called
hemizygous
in a pedigree, what do the circles symbolize
females
in a pedigree, what do the squares symbolize
males