Chapter 3- Genetics- Theoretical Genetics Flashcards
Define phenotype
Characteristics of traits of an organisms
Eg: five fingers, colour blindness and type O blood
Define genotype
Symbolic representation of a pair of alleles possessed by an organism
eg: Bb GG tt
Define dominant allele
Always expressed when its present it cannot be masked by a normal allele
Define recessive allele
Can be masked by another allele- only expressed when 2 copies are present
Define co dominant allele
Pairs of alleles that both have affect on the phenotype when present on a heterozygous
Define locus
Particular position on homologous chromosomes of a gene. Each gene is found on a specific pair of chromosomes
Define homozygous
Having 2 identical alleles of a gene
Eg: AA
Define heterozygous
Having 2 different alleles of a gene
Eg: Aa
Define carrier
An individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this alleles
Define test cross
Testing a suspected heterozygous by crosses it with a homozygous recessive
Do a diagram of a punnet grid
Martha.
What is an example of genes that have more that 2 alleles?
ABO blood group system in humans
How does the ABO work as 3 alleles?
Share co-dominance (can be expressed equally in phenotype) and share incomplete dominance (neither fully expressed phenotype=blending)
What do ABO blood types demonstrate ?
A dominance order (allele A > allele B > allele C)
What are the four possible phenotype types for ABO blood groups?
A, B, AB and O
How to ABO create these 4 blood types?
There are 3 alleles of the gene and these alleles can produce 6 different genotypes
What is the gene for ABO blood type represented as?
Letter I
What is the allele for type A blood group?
I^A
What is the allele for type B blood group?
I ^ B
What is the allele for type O
ii
Crossing over of the ABO gives how many possibilities?
6
What does I^A I^A or I^A i give?
Gives phenotype blood group A
What does I^B I^B or I^B i give?
Blood group B
What does I^A I^B give?
Type AB