Chapter 14-Chromosomes & Human Genetics Flashcards
Linkage can be disrupted by what?
Crossing over
Linkage
Genes on the same chromosome transmitting together in inheritance
Crossing over
An exchange of parts of homologous chromosomes (prophase l)
Crossing over results in what?
Genetic Recombination
Linkage group
A large number of linked genes on a specific chromosome
Genetic recombination
Combination of alleles that were not present in the parental cell
Changes in chromosome structure can lead to what?
Genetic abnormalities or disorders
Wild-type
Most common form of alleles
Less common form of an allele?
Mutant Allele
How many autosomes do human somatic cells have?
Human somatic cells have 22 pairs
Sex chromosomes determine what?
An individuals sex
All humans have how many pairs of sex chromosomes?
1 pair
An absence of a Y chromosomes results in what?
The formation of ovaries
What governs the development of testes?
A gene on the Y chromosome
What did Thomas Hunt Morgan discover?
Each gene has a specific location on a chromosome
The probability that a crossover will disrupt a linkage between 2 genes at 2 different loci is directly proportional to what?
The distance that separates the 2 loci
What is a Pedigree?
Chart of genetic connections
Genetic abnormality
Traits that are not inherently life-threatening
Genetic Disorder
Causes medical problems that may be severe
Single genes on autosomes or sex chromosomes govern what?
More than 6,000 genetic abnormalities
Polygenic
Human traits influenced by multiple genes.
List the variations in single genes
- Autosomal dominant
- Autosomal recessive
- X linked recessive
- X linked dominant
List the variations in a whole chromosome
-Changes in chromosome number & structure
List the reasons mutations survive in populations.
- Reintroduction by new mutations
- Recessive alleles are masked in heterozygotes
- Heterozygotes have an advantage in their environment
Autosomal Dominant Inheritance
Draw Punnet Square of a heterozygous parent and homozygous parent
At least one parent has to have a dominant allele (A) in order to have a 50/50 chance of the child being affected
Autosomal Recessive Inheritance
Draw a Punnet Square of 2 heterozygous parents
Depending if the parents are a carrier of a recessive allele (a), they have a 25% chance their child will be affected (aa)
List the 4 categories of chromosome aberration
- Deletion
- Duplication
- Inversion
- Translocation
Nondisjunction
Causes changes in chromosomes number
Aneuploidy
One extra or one less chromosome
Polyploidy
Three or more of each chromosome
