Genetics Flashcards
What is a gene?
A sequence of bases on a DNA molecule that codes for a protein/polypeptide which results in a characteristic
What is an allele?
Different versions of a gene
What is a diploid organism?
Have 2 copies os each chromosome- one from each parent
What is a locus?
Fixed position of a gene on a chromosome
What is a genotype?
All the different alleles an organism has
What is a phenotype?
The characteristics an organism has as a result of both its genes and the effects of the environment on its genes
What is a dominant allele?
One that is always expressed even if there is only one copy of it
How is a dominant allele represented?
Capital letter
What is a recessive allele?
Only appear in the phenotype if two copies are present
How is a recessive allele represented?
Lower case letter
If brown eyes are dominant, what could be the genotype for brown eyes?
BB or Bb
If blue eyes are recessive, what could be the genotype for blue eyes?
Bb
What is a co-dominant allele?
When both alleles are expressed - neither one is recessive
What does homozygous mean?
In a diploid organism, both copies of the same allele are the same
What does heterozygous mean?
In a diploid organism, both copies of the allele are different
What cells are haploid?
Gametes
What is monohybrid inheritance?
Inheritance of a characteristic controlled by one gene
What is the F1 generation?
First set of offspring
What is always produced when there in a monohybrid cross with homozygous parents?
All heterozygous offspring in F1 generation
What is a phenotype ratio?
Ratio of the different phenotypes in the offspring
What do genetic diagrams predict?
Phenotype ratio in F1 and F2 generation
What ratio is expected with two heterozygous parents?
3: 1
dominant: recessive
When is there not a 3:1 ratio with two heterozygous parents?
If codominant alleles or sex linkage
What is codominance?
When both alleles are expressed in the phenotype and neither one is recessive
How is codominance represented?
Main letter as normal capital and the alleles as superscript
