Bio Unit 6 Test Flashcards
Where do alleles come from?
one from mom, one from dad
What is a recessive allele?
gene that is overpowered and doesn’t show up
an allele that when present alone can’t effect the individual
If an DD individual is crossed with a dd individual, then _____% of the offspring will be dominant and _____% of the offspring will be recessive.
100%, 0%
All squares are Dd. “D” is dominant, therefore all of the offspring are dominant.
What percentage is filled in the square?
75%
What is incomplete dominance?
a lack of dominance in either of two different alleles in heterozygotes resulting in a phenotype that is intermediate
Example: red rose (RR) with a white rose (rr) equals a pink rose (Rr)
What is genotype?
the letters that represent the different forms of a trait
Example: dd / DD
What does homozygous mean?
having 2 identical alleles
BB / bb
What does heterozygous mean?
having 2 different alleles
Bb
The following is an example of what type dominance?
a) incomplete
b) complete
c) codominant
a) incomplete
How many alleles do we have for each trait?
two
What is a carrier?
the dominant gene shows up, but carriers the recessive gene
an individual who “carries” and can pass on an allele associated with a disease (or trait) that is inherited and who does not show symptoms of that disease (or features of that trait)
Why are more men colorblind than women?
only need a mutation to be present in the singular X chromosome
colorblindness is a recessive gene, so males only need to inherit one gene for color blindness because they only have one X chromosome.
If 2 parents have a 1 in 4 chance of having a child with hemophilia, what percentage chance do they have EACH TIME they have a child of having one with hemophilia?
25%
What is complete dominance?
heterozygous condition where the allele that is dominant completely masks the effect of the allele that is recessive.
if the individual carries two alleles in a manner that one is dominant and the other one is recessive, (e.g. Aa), the dominant allele will be expressed while the recessive allele will be suppressed.
What is a dominant allele?
a gene that overpowers and shows up in the living thing
What is codominance?
When two alleles for a trait are equally expressed with neither being recessive or dominant, it creates codominance.
“fighting for control”
What is phenotype?
the physical trait expressed from the genes & what we see
What is a sex-linked trait?
traits that are influenced by genes carried on the sex chromosome (X or Y)
What 2 sex chromosomes does a female have?
XX
What 2 sex chromosomes does a male have?
XY
What is the difference between the X and the Y chromosome?
Men inherit one X from their mother and one Y from their father. Females inherit one X from each parent.
What is (are) the genotype(s) for type O blood
OO
What percentage is filled in the square?
50%
What are the genotypes for type A blood?
AA, Aa, AO
What are the genotypes for type B blood?
BB, Bb, BO
What are the genotypes for type AB blood?
AB
Who is Gregor Mendel and what did he study and discover?
Austrian scientist known for cross breeding pea plants, inheritance.
Known as the “father of modern genetics.”
What is a polygenic trait?
A polygenic trait is a characteristic, such as height or skin color, that is influenced by two or more genes. Because multiple genes are involved, polygenic traits do not follow the patterns of Mendelian inheritance.
What is an example of a polygenic trait?
height; skin color
How does epistasis inheritance work?
An allele of one gene
a gene that determines whether or not a trait will be expressed
a circumstance where the expression of one gene is modified (masked, inhibited or suppressed) by the expression of one or more other genes
What percentage is filled in the square?
25%
What is the correct definition of an allele?
a) The physical trait expressed from the genes & what we see
b) The options for a trait
c) Gene that is overpowered and doesn’t show up
B) The options for a trait
What is the correct definition of a phenotype?
a) The physical trait expressed from the genes & what we see
b) The letters that represent the different forms of a trait
c) The options for a trait
A) the physical trait expressed from the genes & what we see
Black (B) is dominant
White (b) is recessive
What percentage of the offspring are homozygous black?
0%
Black (B) is dominant
White (b) is recessive
What percentage of the offspring will homozygous white?
50%
What is the correct definition of recessive?
a) Gene that overpowers and shows up in the living thing
b) Gene that is overpowered and doesn’t show up
c) The options for a trait
B) gene that is overpowered and doesn’t show up
If an Bb individual is crossed with an bb individual, then ____% of the offspring will be heterozygous and _____% of the offspring will be homozygous.
50%, 50%
