Inheritance Flashcards
Who is the father of genetics?
Gregor Mendel
What are Gregor Mendel laws?
- law of segregation: for any particular trait the alleles sepinheritedarate during gamete formation and are passed from each parent into the offspring.
-Law of independent assortment: The alleles are passed on to the offspring independently from the alleles for other genes.this results in new allele combinations of genes from the parents.
The structure of DNA
DNA was not discovered until the 1950’s and it’s structure was unknown until James Watson and Francis crick (with help from Rosalind Franklin) identified it.
Homologous pairs
The chromosomes in a homologous pair each have the same genes in the same order, but there may be variation between them, resulting in different alleles.
Probability
The chance that an event will happen and is expressed as a fraction or percentage.
What are the patterns of inheritance?
Dominant and recessive alleles, incomplete dominance, multiple alleles and codominance, sex-linked inheritance: X- linked genes, polygenic inheritance.
Dominant and recessive alleles
Included in simple inheritance. One gene determines the phenotype.
Incomplete dominance
A form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype.
Polygenic inheritance
Two or more genes interact to determine a phenotype.
Sex-linked inheritance
Genes located on the sex chromosomes.
Multiple alleles
Three or more different alleles that a particular trait has
Co-dominance
Offspring receives a mixture of characteristics of both parental genes, irrespective of dominant or recessive genes.
Cystic fibrosis
An autosomal recessive disease. The gene affected is located on an autosomal chromosome; the individual must have two copies of the recessive allele to have cystic fibrosis.
Huntington’s disease
Caused by a defective gene on chromosome #4. It is an autosomal dominant disease. There is a CAG repeat and it tends to increase as it is passed down in families. The more CAG repeats the worse the disease.
Incomplete dominance
The inheritance pattern in which heterozygous alleles produce a phenotype that is different from the homozygous dominant and homozygous recessive phenotypes.
RR x rr = Rr
