Ch. 5 Genetics Flashcards
What is an allele?
Different expressions of a gene which leads to changes in phenotype such as different eye color.
What is Phenotype?
Someone’s observable characteristics.
What is a genotype?
Genetic makeup of an organisms genes coding for things such as Pp or Ww.
What does homozygous mean?
An organism with two do the same alleles such as PP or pp.
What does herteozygous mean?
An organism with two different alleles for a gene.
What is a punnett square?
A diagram which shows all the possible combinations for offsprings genotype.
What is a dominant allele
An allele that only needs to be in the genotype once to be expressed in the phenotype.
Capital is dominant (eg. A) and lowercase is recessive (eg. a). Aa would express A.
What is a recessive allele
And allele that can be masked completely if a more dominant allele is present.
What would be an example of a heterozygous individual using the letter T.
Tt
What would be an example of a homozygous recessive individual using the letter T
tt
What would be an example of a homozygous dominant individual using the letter T?
TT
What would be a carrier of a recessive gene’s genotype using the letter T?
Tt
What are the three types of gene dominance?
Complete dominance, co-dominance, and incomplete dominance.
What is co-dominance?
When a gene has alleles that can both be expressed at the same time in the phenotype. This could be something such as spots on a cow. It expresses both the black and white alleles at the same time.
What is incomplete dominance?
When neither allele fully covers the other. This means both mix together to make a new phenotype. This could be a red and a white flower producing pink offspring.
Which blood type alleles are more dominant over another? Use I(a) I(b) and i to represent the three possible alleles for blood.
I(a) and I(b) are dominant over type i.
What do the different blood type alleles actually mean?
The difference is the type of antigen (an antibody generator) that is carried on the surface of the red blood cells (erythrocytes).
AB type blood is an example of ___dominance. Which two alleles does it carry?
Co-dominance
I^a and I^b
What is sex linked inheritance?
A trait who gene is located on the x or y chromosome
What does wild type mean?
An individual who carries the most common trait in the population. For example, a tiger with orange fur with white stripes is a wild type because most tigers have that phenotype.
What is discontinuous variation?
When there are limited number of phenotypes a population can have. Not a range.
Eg. Blood type- A, B, AB, or O
Ability to roll tongue- yes or no
What is continuous variation?
When there are not set groups/phenotypes of variation. Phenotype is a spectrum-usually controlled by multiple genes.
Eg. Human skin colour
Height
Weight
What is gene linkage?
When two genes are very close together on a chromosome, they are unlikely to be separated during chromosome crossover in prophase I.
What is a barr body
Each cell only has one active x chromosome. A barr body is the inactive x chromosome in healthy females or males with Klinefelter’s syndrome (XXY). Genes on the x chromosome can be expressed differently throughout the body (Eg. Cat fur colour)
What is epistasis?
When the expression of one gene can have an impact on the expression of another.
Eg. One gene could code for red or brown hair
Another could code for being bald, masking the colour gene
What is Mendel’s law of independent assortment?
Any two genes which are located on different chromosomes will be inherited independently of each other. ie the allele passed down have no correlation to another allele
