This lesson contains 14 slides, with interactive quizzes and text slides.
Lesson duration is: 45 min
Items in this lesson
Slide 1 - Slide
allele: variety of one gene
Plural = alleles
on each chromosome you
have an allele of a gene.
For example eye colour:
blue allele or brown allele
Slide 2 - Slide
Slide 3 - Slide
Is it a gene or an allele?
type A blood
short wings in a fruit fly
Slide 4 - Drag question
Evie says: 'all humans have the same genes, but not the same alleles'. Mila says: 'all humans have the same alleles, but not the same genes'. Who is right?
They both are
They are both wrong
Slide 5 - Quiz
dominant and recessive
genotype is written down in letters.
brown eye color A
blue eye color a
genotype Aa fenotype = brown eyes
Slide 6 - Slide
Slide 7 - Slide
dominant, recessive alleles
dominant A is always visible in the genotype
recessive a is only visible when there is no dominant allel
Dominant wins over recessive
Slide 8 - Slide
Two equal alleles: homozygous (AA or aa)
Two different alleles: heterozygous (Aa)
AA => homozygous dominant => brown eyes (fenotype)
Aa => heterozygous => brown eyes (fenotype)
aa => homozygous recessive => blue eyes (fenotype)
Slide 9 - Slide
we can calculate probable percentages of offspring with different genotypes/fenotypes
we use a Punnet square
Slide 10 - Slide
Slide 11 - Slide
Some fruit flies have curly wings instead of normal wings (see the pictures below). Answer the questions using the letter R for normal wings and r for curly wings:
normal wings curly wings
a. Which is the dominant allele? Give the letter and the characteristic.
b. Which is the recessive allele? Give the letter and the characteristic.
c. What is the genotype of a fruit fly that is homozygous for curly wings?
d. Which two genotypes will result in the ‘normal wings’ phenotype?
e. Can a fruit fly with curly wings have a heterozygous genotype? Explain your thinking.
Slide 12 - Slide
CALCULATE THE CHANCE.
Check out the steps on page 136.
Let's practice! A guinea pig is homozygous for blue fur. This guinea pig mates with a guinea pig with yellow fur. Use a punnet square to determine the probability of one of their offspring having blue fur.