Variation and Inheritance
Variation is differences within a population. For example, some people have blue eyes, some have brown.
Variation occurs due to inheritance. You inherit genes from both your paternal and maternal parents. This creates a unique mixture of genes, that makes individuals vary within populations.
In this section we will discuss how these variations come around and how we can predict variations.
Discrete vs Continuous Variation
Discrete variation is variation of characteristics that can be separated into groups or categories, such as eye colour. This is also called single gene inheritance.
Continuous variation is variation of characteristics that can be measured with a continuous range of phenotypes, such as height. This is also called polygenic inheritance.
A phenotype is an organism’s observable characteristics.
A genotype is an organism’s set of genetic material.
Inheritance Patterns
Alleles are variations of the same gene.
A dominant allele produces its associated phenotype whether it’s paired allele is the same or different.
A recessive allele produces its associated phenotype only when its paired with the same recessive allele.
A homozygous cell is one that has inherited two identical alleles of the same gene.
A heterozygous cell is one that has inherited two different alleles of the same gene.
Punnet Squares and Pedigree Charts
Punnet squares allow us to calculate the likelihood of offspring inheriting a particular phenotype.
Pedigree chards are diagrams that present the rates and likelihoods of phenotypes of a particular gene within an organism and the organism’s relatives.
By giving recessive alleles a small letter and dominant alleles a large letter, we can create punnet squares to determine the likelihood of inheriting certain phenotypes.
Key Points!
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Variation
Discrete variation is variation of characteristics that can be separated into groups or categories, such as eye colour. This is also called single gene inheritance.
Continuous variation is variation of characteristics that can be measured with a continuous range of phenotypes, such as height. This is also called polygenic inheritance.
A phenotype is an organism’s observable characteristics.
A genotype is an organism’s set of genetic material.
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Inheritance Patterns
Alleles are variations of the same gene.
A dominant allele produces its associated phenotype whether it’s paired walleye is the same or different.
A recessive allele produces its associated phenotype only when its paired with the same recessive allele.
A homozygous cell is one that has inherited two identical alleles of the same gene.
A heterozygous cell is one that has inherited two different alleles of the same gene.
-
Punnet Squares and Pedigree Charts
Punnet squares allow us to calculate the likelihood of offspring inheriting a particular phenotype.
Pedigree chards are diagrams that present the rates and likelihoods of phenotypes of a particular gene within an organism and the organism’s relatives.
By giving recessive alleles a small letter and dominant alleles a large letter, we can create punnet squares to determine the likelihood of inheriting certain phenotypes.