Section7:Inherited change Flashcards
What is a gamete?
An egg or sperm cell formed by meiosis and contains 23 single chromosomes.
What is a somatic cell?
A general term for body cells containing 46 chromosomes.
What is the definition of genotype?
Genotype is the genetic constitution of an organism
Genotype refers to the specific alleles present in an organism’s DNA.
What is the definition of phenotype?
Phenotype is the physical/observable characteristics of an organism which is determined by a combination of environment and genotype
Phenotype includes traits such as height, eye color, and behavior.
What is the key difference between a dominant and recessive allele?
A dominant allele only requires one copy to express itself in the phenotype
In contrast, a recessive allele requires two copies to be expressed.
What does co-dominant mean?
Two alleles contribute equally to the phenotype
Co-dominance is a form of inheritance where both alleles in a heterozygote are fully expressed.
Define monohybrid inheritance.
The inheritance of a single gene that causes a single characteristic
Monohybrid crosses typically involve one trait and can be analyzed using a Punnett square.
What is dihybrid inheritance?
The simultaneous inheritance of two characteristics
Dihybrid crosses consider two traits and can reveal the independent assortment of genes.
What is sex linkage?
When a gene controlling a particular characteristic is found on a sex chromosome
Sex-linked traits often exhibit different patterns of inheritance in males and females.
What is pure breeding?
When the genotype of each of the parents is homozygous
Pure breeding is essential for creating organisms that consistently express specific traits.
What are the steps to showing a genetic cross for an offspring?
- Parents phenotype
- Parents genotypes
- Parents gametes
- Genetic cross (F1)
- Genotype
- Phenotype
- Ratio
Why are the observed ratios of monohybrid/dihybrid inheritance often not the same as the expected ratio?
- Random fertilisation/fusion of gametes
- Population is small
- Selection advantage (survival)
What is the expected ratio for dihybrid inheritence?
9:3:3:1
