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Index
»
Genetics
»
Chapter 1
»
Level 1
level: Level 1
Questions and Answers List
level questions: Level 1
Question
Answer
the gene variation an individual possesses for a particular trait
Genotype
different variations of the same gene trait represented as uppercase and lowercase letters; genotypes consist of two allele letters, one comes from and one from dad
Alleles
hides the expression of the other allele’s trait
Dominant Allele (uppercase letter) -
how the genotype is physically expressed; the physical appearance
Phenotype
Father of Genetics
Gregor Mendel
-an organism’s offspring will look like the parent due to its homozygous purebred genotype
True breeding
alleles separate during the formation of sex cell gametes
Law of Segregation
Dominant alleles are not always the most common and not always the most advantageous either…
True
Dominant alleles are not always the most common and not always the most advantageous either… ex
Ex: Huntington’s Disease is a rare, dominant disorder
hidden by the dominant allele’s trait
Recessive Allele (lowercase letter)
- predicts the outcome probability of genetic crosses
Punnett Square
two gene punnett square
Dihybrid Cross
genes can separate during the formation of sex cells gametes and do not have to be linked or inherited together
Law of Independent Assortment
genes can separate during the formation of gametes and do always have to be inherited or linked together
false, they do not
ow did Mendel figure out the possible gamete combinations written along the two axes of his dihybrid cross?
He “foiled” each parent’s genotype.
1 TT : 2 Tt : 1 tt
Genotypic Ratio:
3 Tall : 1 Short
Phenotypic Ratio:
In ratios, the more ----- version comes first
dominant
Axes are ------- genotypes
parent’s
boxes are ------- genotypes
offsprings
both alleles are equally as dominant so both are expressed side by side at the same time in a third phenotype
Codominance
when one allele is not completely dominant over another resulting in a third mixed phenotype
Incomplete Dominance
BLOOD) genes with more than two alleles resulting in more than just two phenotypes
Multiple Alleles
Type A heterozygus is also
Ao
what does oo stand for
resessive/type o
Positive (+) and negative (-) blood type is not determined by multiple alleles. They are just carried on the blood type alleles. Positive blood types are dominant over negative blood types.
true
EX: Skin, hair- traits controlled by two or more genes resulting in many phenotypes
Polygenic Traits
the sex of an individual depends on the presence or absence of a Y chromosome. A male’s sex genotype is XY while a female’s is XX.
Sex Chromosomes
only located on the “X” sex chromosome
X-Linked Traits
Since males do have a second back up X they are less susceptible to expressing X-linked traits making these traits more uncommen in men.
False, they are more susceptible
Pedigrees
Trace a family’s genotypes and phenotypes and therefore autosomal or X-linked traits
Circle
Female
Square
Male
Shaded
Expresses Trait
Half-shaded
Carrier
Crossed out
Deceased
What is the first step in solving a pedigree
Identify whether the trait is Dominant or Recessive.
If every “affected” child in the pedigree has a least one parent who is also affected, then the trait is
Dominant
If there are “affected” children where neither of their parents are also affected, then it’s
Recessive
Step two in solving a pedigree is
Identify whether the trait is Autosomal or X-linked.