Punnett Square
Traits
Ratios
Vocabulary
Patterns in Data
100
What is a Punnett Square used for in genetics?
To predict the genotypes of offspring from two parents
100
What are dominant traits?
Traits that are expressed when at least one dominant allele is present. (AA, Aa)
100
What are the three ways we can write a ratio.
3:1, 3 to 1, 3/1
100
Define "gene"
A section of a chromosome that contains information for 1 trait.
100
What can patterns in genetic data help us determine?
They help us determine which traits are dominant or recessive.
200
In a Punnett square, what does each box represent?
Each box represents a possible genotype of the offspring
200
What are recessive traits?
Traits that are expressed when only two recessive alleles are present (aa)
200
If a cross results in a 3:1 ratio, what does that indicate about the dominant trait?
The dominant trait appears more frequently than the recessive trait.
200
What is an allele?
A form of a gene (type of trait expressed by one parent)
200
How can you determine if a trait is dominant or recessive?
By analyzing the number of individuals with a certain trait and comparing.
300
What must be known to predict possible genotypes and phenotypes of offspring?
The parents' genotypes
300
Give an example of a trait that was considered dominant in Mendel's first investigations with pea plant hybrid crosses.
purple flower, yellow seed color, round seed shape, smooth pod shape
300
Look at the following Punnett Square. What is the phenotype ratio of this cross?
2:2 (Brown: blonde)
300
What is the difference between genotype and phenotype?
Genotype is the allele combination (dominant or recessive traits), while the phenotype is the observable trait. A-red, a-blue (Aa creates red phenotype)
300
A pet store has 16 white rats and 9 grey rats. What is the ratio of white to grey rats? (simplified)
2:1
400
What are the possible phenotypes of the offspring if given this cross?
D-dimples, d-no dimples
All will have dimples
400
How do traits vary between parents and offspring?
Offspring inherit different combinations of alleles from each parent.
400
If you were given a ratio of 2:2 (recessive: dominant) that resulted from a cross, what were the genotypes of the parents?
Aa, aa
400
Define chromosome.
Structures of genetic information. (1 from each parent)
400
The following data was found among individual lady bugs with certain traits:
Wing color: 12 red, 6 yellow
#of spots: 4 with 6 or less spots, 10 with 7 or more spots
Leg length: 5 short legs, 8 long legs
Determine the dominant and recessive traits based on this data.
(dominant wing)-red / (recessive wing)-yellow
(dominant spot)-7 or more spots / (recessive spot)- 6 or less spots
(dominant leg) -long / (recessive leg)- short
500
If one parent is homozygous dominant (AA) and the other is homozygous recessive (aa), what will be the genotypes of the offspring?
All offspring will be heterozygous (Aa)
500
What are hybrid organisms?
Organisms that have two different alleles for a specific trait. (Aa) that came from parents with AA and aa.
500
How would you express the genotype ratio of offspring who came from heterozygous parents (Aa).
1:2:1- (AA: Aa: aa)
500
How many chromosomes do humans have?
46 (23 pairs)
500
The following data was found among individual lady bugs with certain traits:
Wing color: 12 red, 6 yellow
#of spots: 4 with 6 or less spots, 10 with 7 or more spots
Leg length: 5 short legs, 8 long legs
Determine the possible genotypes and phenotypes for each dominant and recessive trait. Use W for wing, S for spots, L for leg
WW, Ww (dom wing)-red / ww (rec wing)-yellow
SS, Ss (dom spot)-7 or more spots / ss (rec spot)- 6 or less spots
LL, Ll (dom leg) -long / ll (rec leg)- short