ch20.1 - monogenic inheritance

what is a gene

a part of DNA (a sequence of bases) that codes for a protein - which results in a characteristic e.g. eye colour

what is a genome

the entire genetic material of an organism

what is an allele

different version of a gene

> codes for a variant/ variation of a same characteristic e.g. blue coloured eyes, green coloured eyes

how many copies of a gene (alleles: versions) do organisms usually have in their body cells

body cells are diploid so have 2 copies for every characteristic

one allele from mother

one allele from farther

is this number the same for gametes

no gametes only have 1 copy of each gene since they are haploid - have just 1 set of chromosomes

why do members of the same species show variation

because they can inherit different combination of alleles for the same gene

what is the genotype

the genetic makeup (combination of alleles) of an organism

what is the phenotype

observable characteristics of an organism

what is the phenotype usually determined by

genetics AND environment

what is a dominant allele

only requires one copy of an allele to be present to be expressed

> represented by upper case letter e.g. A

what is a recessive allele

both copies of an allele must be present to be expressed

> represented by lowercase letter e.g. a

what is locus

refers to the specific position of a gene on a chromosome

what is loci

the plural of locus

what is homozygous

an organism which carries 2 identical alleles for a particular gene

what is heterozygous

an organism which carries 2 different alleles for a particular gene

what are the 3 types of genotypes

AA - homozygous dominant

Aa - heterozygous

aa - homozygous recessive

what is a carrier

an organism which carries an allele

> it is not expressed in their phenotype however they can pass it onto their offspring

what does breeding mean

mating two organisms to produce an offspring

what does interbreeding mean

mating two organisms within the same species to produce an offspring

what is the difference between breeding and interbreeding

breeding is the general term for mating BUT interbreeding is mating specifically within the SAME species

what is the term for breeding/mating animals to study how traits are inherited

genetic cross

what is monogenic inheritance

inheritance of a characteristic controlled by one single gene

what is a monohybrid cross

genetic cross of the alleles for a single characteristic, controlled by one gene with two possible alleles

what is P/ F0

parent generation

what is F1

first generation - the offspring’s after breeding 2 parents

what is F2

second generation - the offspring´s after interbreeding 2x F1 organisms

what is the name for genetic diagrams and why are they useful

punnet squares

> they allow us to predict the genotype and phenotype ratios

what is pure breeding

breeding homozygous individuals together

what type of offspring does pure breeding produce

100% heterozygous offspring

what is another term for pure breeding

homozygous cross - crossing/breeding homozygous individuals together

5 steps for how to use punnet squares

1. state phenotype of both parents (purple X white)

2. state genotype of both parents (AA X aa)

3. state gametes of each parent (A and a)

4. draw punnet squares diagram

5. write conclusion: proportion of each genotype with ratio or percentage & phenotype