Lecture 2 - Human Inheritance Flashcards
Definition
Crossover
homologous chromosomes cross over during meiosis
Definition
Law of Segregation
One chromosome per gamete, seperation of maternal and paternal alleles is independent of each other
Definition
Law of independent assortment
Chromosomes segregate independently from each other into gametes
Definition
Linkage
Genes located close to each other often segregate together
What is the overall big picture of crossing over during meiosis?
Each zygote is a new roll of the dice for what genes will come together
Definition
Co-Dominant
The heterozygous genotype (Bb) expresses a unique phenotype; intermediate to the homozygotes
What disease is an example of codominance?
Sickle Cell Anemia
Caused by a single nucleotide polymorphism
developed in areas associated with high malaria, but can cause blood clots and low O2 levels
Definition
Autosome
All chromosomes that are not sex chromosomes
Humans = 22 pairs
Definition
Allosomes
Chromosomes that determine the sex of individual
humans = 1 pair
Definition
Sex-Linked
Gene is carried on sex chromosome
Men = XY, women = XX
What is color blindness an example of?
Sex-linked hereditary disorder
Definition
Penetrance
The probability that a phentype will appear when its genotype is present
Ex: Are there extra digits or not?
Definition
Expressivity
Range of phenotypic variation present
Ex: How many extra digits are there?
Definition
Gene Frequency
How often the allele for a particular trait occurs in a population
Ex: polydactyl is a dominant trait, but gene is rare so frequency is low
