5.4 Inheritance

5.4 inheritance
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This lesson contains 14 slides, with interactive quizzes and text slides.

time-iconLesson duration is: 45 min

Items in this lesson

5.4 inheritance

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?
skin colour
curly hair
flower colour
blue eyes
blood type
type A blood
hair type
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.
for example
brown eye color A
blue eye color  a
genotype Aa    fenotype = brown eyes

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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

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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)

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mendelian inheritence
we can calculate probable percentages of offspring with different genotypes/fenotypes
we use a Punnet square

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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

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.

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Exercises 23, 24, 25, 27, 28, 29

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