17.Inherited Change Flashcards
What is a genotype
Describes the alleles the organism has, what its inherited
What’s a phenotype
The observable characteristic of organism, it’s the result of interaction between genotype and environment
What’s a gene
Length of dna that’s a sequence of nucleotide bases that code for a particular protein/polypeptide
What’s an allele
Variation or different form of a gene
What’s a locus
Postiiton of a gene on a particular DNA molecule
What’s homozygous and heterozygous
When each allele of gene is same
When each allele of gene is different
What is dominant alleles
Dominant means the allele that expresses itself in the phenotype
What’s codominant
When two alleles contribute to the phenotype
What is monohybrid inheritance
Inheritance of single gene
What does a monohybrid cross look at
Gametes of female and gametes of male
Eg G G and g g
What is the common ratio when breeding a homozygous dominant and a homozygous recessive
Gg, Gg, Gg, Gg
4:0
What’s common ratio when breeding two heterozygous
GG, Gg, Gg, gg
3:1
What is the basic law of genetics
In diploid organisms, characteristics are determined by alleles that occur in pairs, only one of each pair of alleles can be present in single gamete
What is a dihybrid
Inheritance of two characteristics at once
What is the theoretical ratio of a dihybrid between two heterozygous cells
9:3:3:1
What is sex linkage
A gene carried on the X or Y chromosome
Where does the gene for haemophilia lie
On X chromosome
Males only get X chromosome from mum
What’s autosomal linkage
Two or more genes carried on same autosome
When do you use chi squared
Used to test null hypothesis, suggesting that no significant difference, any difference is due to chance
Sample size larger than 20
Data must be discrete
Only raw counts not percentages
Compare experimental rates with theoretical rates
What are multiple alleles and what’s their nature
When gene has two or more allelic forms
As only two chromosomes in homologous pair, only 2 out of 3 or more will be present in single organism
Explain how to make genetic diagram
Example - Green or yellow pea
- if letters not given, choose single letter for each characteristic (G)
- higher case is dominant and lower case is recessive G-green g-yellow
- label parents and state their phenotypes (GG and gg)
- state gametes produced by each parent (G) (G) (g) (g)
- use punnet square to show results of random crossing of gametes
- state phenotype of each genotype (Gg is green)
- indicate numbers of each genotype
Explain how single gene is inherited
Mendel peas
- Green pods repeatedly bred with each other they are pure breeding for green
- said to be homozygous (two green alleles)
- if pure breeding green pod crossed with pure breeding yellow pod, first filial will be green pods
- green is dominant
- is heterozygous pods crossed together, f2 generation is 3:1 green:yellow
What is the law of segregation
In diploid organisms characteristics are determined by alleles that occur in pairs, only one of each pair of alleles can be present in single gamete
Why are actual results of genetic crosses rarely same as predicted
- Chance determines which gametes fuse with which gamete
- larger samples more likely to show results near theoretical ones
