Genetics Flashcards
Locus def
The chromosomal location of a gene
Gene def
Genetic material coding for a single gene product (peptide, rRNA or tRNA)
Allele def
One variant of a gene
Homologous chromosomes def
Chromosomes that code for the same set of genes
- may have different alleles
- one recieved from each parent
Ex) both chromosomes have hair color on their gene
One may have blonde one may have brown
Genotype vs phenotype
B=brown
B=blue
Genotype: BB
Phenotype: brown
Law of segregation
Separation of alleles in the haploid gametes
-the two alleles for a gene separate into our gametes
Law of independent assortment
Genes assort independently into the progeny
Complete dominance
When a heterozygote has the phenotype of only one of the alleles (the dominant one)
Incomplete dominance
Phenotypes of the dominance are blends of the parental phenotypes
Codominance
Both inherited alleles are completely expressed
YyRr x YyRr
Y_R_ 9
Y_rr 3
yyR_ 3
Yyrr 1
Test cross
Determines a genotype
-cross with a homozygous recessive
Pleiotropism
When a gene has multiple phenotypes associated with its expression
Polygenism
Multiple genes affect a single trait
Penetrance
Probability an organism with a specific genotype will express a particular phenotype
Expressivity
Term describing the variation of phenotype for a specific genotype
Epistasis
Occurs when the expression of a gene is dependent upon another gene
-expression of red hair is dependent on whether you have hair
Out of the 46 chromosomes, which are linked to our gender
2 x and y chromosomes
All orher 44 chromosomes are called the autosomes
If you are a female what are your chromosomes
Male?
Female: xx
Male: xy
Who determines the sex of the offspring?
The male
- the female always provides an x
- it is up to the male whether he provides an x or y
X or y chromosome larger
X-has many genes
Y-is very small, not many genes
Turner syndrome
Child only has an x chromosome
- ends up a female
- from nondisjunction
Kleinfelter syndrome
Child has three sex chromosome
- xxy
- develop as a male
- from nomdisjunction
Point mutation
Substitution, insertion, deletion
-change of a single nucleotide
Missense mutation
Point mutation leading to a codon coding for a different amino acid
-may or may not have a big affect on the protein
Point mutation that has no consequence
Point mutation in the third position of the codon
Nonsense mutation
Point mutation that leads to a premature stop codon
Frame-shift mutations
Insertion or deletion lesding to a change in the reading frame of a gene
