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Click F5Try to answer each question on your own before revealing the
answer.
What is an allele?
What is an allele?
An allele is a version of a gene
How many alleles does an individual (from sexually-reproducing parents) inherit for each trait?
How many alleles does an individual (from sexually-reproducing parents) inherit for each trait?
2 One from each parent
What is a gamete?
What is a gamete?
A gamete is a sex cell Examples: egg (female) and sperm
(male)
How many alleles for each trait are present in gamete cells?
How many alleles for each trait are present in gamete cells?
Gametes have 1 allele for each trait This is because gametes are
produced by segregation, where the alleles separate so that each gamete is haploid
What is fertilization?
What is fertilization?
Fertilization is the joining of a male and a female gamete
Fertilization results in a zygote (fertilized egg)
Because zygotes are a combination of an egg and sperm, they have two alleles for each trait
What is a genotype?
What is a genotype?
The genotype is an organism’s actual combination of alleles
Example: BB or Gg or tt
What is a phenotype?
What is a phenotype?
Phenotype is how the trait is expressed
Examples: Brown eyes, green pea color, or short height
If something has a homozygous genotype, what does that mean?
If something has a homozygous genotype, what does that mean?
It has two identical alleles for that trait
Homozygous dominant = two dominant alleles (BB, TT, etc)
Homozygous recessive = two recessive alleles (bb, tt, etc)
What does it mean if something has a heterozygous genotype?
What does it mean if something has a heterozygous genotype?
The alleles are different Example: Bb, Gb, Tt
In pea plants, green (G) is the dominant color and yellow(g) is the recessive color. What will be the phenotypes of the individuals with these genotypes?
GG Gg gg
In pea plants, green (G) is the dominant color and yellow(g) is the recessive color. What will be the phenotypes of the individuals with these genotypes?
GG: green Gg: green gg: yellow
What is the name for this type of diagram?
What is the name for this type of diagram?
Punnett Square
What do these diagrams predict?
What do these diagrams predict?
Probabilities of certain offspring
What do the letters on the outside represent?
What do the letters on the outside represent?
Alleles from the gametes of the parents
What do the letters on the inside represent?
What do the letters on the inside represent?
The possible genotypes for thezygotes
What process are we simulating when we are filling in the letters on the inside?
What process are we simulating when we are filling in the letters on the inside?
Fertilization
If an gene is controlled by an allele that is incompletely dominant, what does that mean?
If an gene is controlled by an allele that is incompletely dominant, what does that mean?
Neither is dominant, so a heterozygous individual is going to be somewhere in between both phenotypes
Example: a red flower and a white flower make a pink flower
If an gene is controlled by an allele that is codominant, what does that mean?
If an gene is controlled by an allele that is codominant, what does that mean?
Both alleles are dominant, and a heterozygous individual will display both phenotypes
Example: a red cow and a white cow make a baby that is red and white spots
What is an autosome?
What is an autosome?
Any chromosome except the sex chromosome
What is a sex-linked gene?
What is a sex-linked gene?
Gene found on one of the sex chromosomes
In pea plants, purple (P) is dominant over white (p). Two heterozygous individuals mate.
What are the genotypes and phenotypes of the parents?
What % of their offspring will be purple? What % of their offspring will have a
homozygous dominant genotype?
Hint: Draw a punnett square
In pea plants, purple (P) is dominant over white (p). Two heterozygous individuals mate.
What are the genotypes and phenotypes of the parents? Both are Pp and purple
What % of their offspring will be purple? 75% (3/4)
What % of their offspring will have a homozygous dominant genotype? 25% (1/4)
In snapdragons, red flowers and white flowers are incompletely dominant. A heterozygous flower is crossed with a white flower.
What are the genotypes and phenotypes of the parents?
What % of their offspring will be red? What % of their offspring will have a
heterozygous genotype? Hint: Draw a punnett square.
R W
W RW WW
W RW WW
In snapdragons, red flowers and white flowers are incompletely dominant. A heterozygous flower is crossed with a white flower.
What are the genotypes and phenotypes of the parents? The heterozygous parents is RW and is pink, the white parent is WW
What % of their offspring will be red? 0% What % of their offspring will have a
heterozygous genotype? 50%
In humans, blood types show co-dominance. A and B are both dominant, O is recessive. A parent with AB blood is crossed with a parent with type O blood.
What are the genotypes and phenotypes of the parents?
What types of blood are possible for the offspring?
Hint: Draw a punnett square
A B
O AO BO
O AO BO
In humans, blood types show co-dominance. A and B are both dominant, O is recessive. A parent with AB blood is crossed with a parent with type O blood.
What are the genotypes and phenotypes of the parents? The AB parent has type AB blood (because they are codominant) and the type O blood parent has a genotype of OO
What types of blood are possible for the offspring? The offspring will have the genotypes of AO and BO, meaning they will all either have type A blood or type B blood (because O is recessive)
In humans, color-blindness is a sex-linked trait. A woman that is homozygous for regular vision mates with a color-blind male.
What are the genotypes and phenotypes of the parents?
What is the probability that they will have a colorblind child?
Hint: Draw a punnett square
Xc Y
X X Xc XY
X X Xc XY
In humans, color-blindness is a sex-linked trait. A woman that is homozygous for regular vision mates with a color-blind male.
What are the genotypes and phenotypes of the parents? The woman is XX and the male is XCY. She has normal vision and he is color blind.
What is the probability that they will have a colorblind child? 0%
What are the genotypes of human males and females?
What are the genotypes of human males and females?
Male: XY Female: XX
Why is it more likely for a male to have a disease that is present on the X chromosome?
Why is it more likely for a male to have a disease that is present on the X chromosome?
Males only have one X chromosome. So if there is a recessive allele on there, there’s no other X to cancel it out. Females have to inherit 2 copies of the recessive allele (one on each X chromosome)
In humans, blood type displays a special type of codominance. A and B are both dominant and O is recessive. What types of blood will the following genotypes have?
AA BB AB
AO BO OO
In humans, blood type displays a special type of codominance. A and B are both dominant and O is recessive. What types of blood will the following genotypes have?
AA type A BB type B AB type AB
AO type A BO type B OO type O
In this pedigree chart, how many males and females are there?
1
52 90
63 4 871
3 4
I I
In this pedigree chart, how many males and females are there?
Males are represented by squares, so there are 8 of them
Females are represented by circles, so there are 6 of them
1
52 90
63 4 871
3 4
I I
In this pedigree chart, how many children did the couple that is shaded have?
1
52 63 4 71
3 4
I 1
In this pedigree chart, how many children did the couple that is shaded have?
1- a male The circle represents the female that
married that male child
1
52 63 4 71
3 4
I 1
