Punnet Square
What is a Punnet square used for in genetics?
A Punnet square is used to predict the possible genotypes of offspring from a set of parental genotypes.
What are genotypes?
Genotypes are the genetic makeup of an organism, represented by the alleles it possesses.
What is inherited from parents to offspring?
DNA sequences in genes are inherited from parents to offspring.
What are chromosomes?
Chromosomes are thread-like structures within the nucleus that carry genetic information.
In a cross between two heterozygous pea plants (Tt), what are the expected genotypic ratios of the offspring?
The expected genotypic ratios are 1 TT : 2 Tt : 1 tt.
What is the difference between homozygous and heterozygous genotypes?
Homozygous means having two identical alleles for a trait, while heterozygous means having two different alleles.
How do genes influence inherited traits?
Genes contain instructions for making proteins that affect traits.
What are alleles?
Alleles are different forms of a gene that can exist at a specific location on a chromosome
If a homozygous dominant plant (AA) is crossed with a homozygous recessive plant (aa), what will be the phenotype of the offspring?
All offspring will display the dominant phenotype.
If the genotype of a flower is Bb, what are the possible alleles it can pass to its offspring?
The flower can pass either allele B or allele b to its offspring.
What is a trait?
A trait is a characteristic or feature of an organism that can be passed from parents to offspring.
How many pairs of chromosomes do humans have?
Humans have 23 pairs of chromosomes.
What do the letters in a Punnet square represent?
The alleles of the parents.
What does a phenotype represent in contrast to a genotype?
A phenotype represents the observable traits of an organism, while a genotype represents the genetic information that determines those traits.
What is the role of dominant and recessive alleles in inheritance?
Dominant alleles can mask the effects of recessive alleles in determining traits.
What is the relationship between genes and chromosomes?
Genes are located within chromosomes. Genes are the specific segments of DNA on chromosomes that determine specific traits.
How would you set up a Punnet square for a cross between a homozygous dominant (TT) and a homozygous recessive (tt) parent?
T T on one side and t t on the other; all offspring will be heterozygous (Tt).
In a trait controlled by a single gene with two alleles, if 60% of the population expresses the dominant trait, what can be inferred about the genotypic frequencies?
The population likely has a higher frequency of the dominant allele, but exact frequencies require more specific calculations.
How could a genetic mutation impact the inheritance of a trait?
if the DNA sequence is changed, then it MAY affect the trait (either altering, or changing it entirely)
Give an example of a mutation that could be beneficial in an owl population.
anything that changes an observable trait and becomes advantageous to the owl (sharper talons for prey, even larger eyes, better hearing, beak mutation that can eat more types of food, etc)