Genotype and Phenotype Flashcards
What are chromosomes?
Thread-like structures bearing genes found in the nucleus of a cell.
Define genes.
A length of DNA carrying a code for one feature.
What are alleles?
One of a number of possible forms of a gene. Each characteristic has two alleles.
What is a genotype?
The combination of two alleles that an organism has for a particular gene.
How is the genotype represented?
By an upper case and lower case letter.
What does homozygous mean?
The alleles are the same case.
What does heterozygous mean?
The alleles are different.
Define phenotype.
Physical trait we can see because of the combination of alleles (genotype).
What influences phenotype?
An interaction with the environment.
What is a dominant allele?
An allele that controls the phenotype regardless of what the other allele is.
What is a recessive allele?
An allele which is only expressed in the offspring if the dominant allele is absent.
Fill in the blank: A trait in squash is the colour of the fruit. White fruit is due to a dominant allele, ___.
F
Fill in the blank: Yellow fruit is due to a recessive allele, ___.
f
What is a Punnett Square?
A diagram used to predict the phenotype and genotype ratios of offspring by showing how alleles combine together during fertilisation.
What are the alleles for a homozygous red apple tree?
RR
What are the alleles for a heterozygous red apple tree?
Rr
What are the alleles for a homozygous recessive green apple tree?
rr
True or False: A Punnett Square can show the possible results of a cross between two homozygous dominant red apple trees.
True
