U5 B8 2HVTTO

• Biologie
• Middelbare school
• havo, vwo
• Leerjaar 2

B8 Dominant and recessive

• Take off your jacket
• Put your things on your desk

       Book, notebook, pencil case

• Bag on the floor
  
• Read pages 162-163

Lessongoals

• You can understand and write out the difference between a heterozygous and homozygous genotype using gene symbols.
• You can explain the impact of combinations of dominant and recessive alleles on the phenotype.
• You can make predictions about possible genotypes that can arise in offspring when you know the genotypes of the parents.
• You can make predictions about possible phenotypes resulting from the resulting genotypes.

Wheel of homework

Go to Lessonup.app and use this code

Reward

Penalty

What is the best description of genes and alleles?

1. A gene is in the DNA An allele is on a chromosome
2. a gene is a characteristic an allele is a variant of this characteristic
3. allele and gene are synonymous
4. an allele is a characteristic a gene is a variant of this characteristic

Give an example of a gene

Healthy organisms always have 2 alleles of each gene.
Explain why these alleles aren't always the same.

Homo- & heterozygous

Homo = same            hetero = different

Homozygous > both alleles for the characteristic are the same 

Heterozygous > alleles of the characteristic are different

Dominant and recessive

• Alleles are either dominant or recessive
• Dominant is 'stronger' than recessive
• A dominant trait means dominant for all members of the species
• Heterozygous genotype > Dominant allele visible in phenotype

Flowers of the bean plant can be pink or white.
Plant 1 has white flowers and is heterozygous.
Plant 2 has pink flowers and is homozygous.
Which colour is recessive?

1. White
2. Pink
3. Impossible to know

Cats can have black or red fur colour.
Black is dominant.
What are possible genotypes for a black cat?

1. Always homozygous
2. Always heterozygous
3. Homozygous or heterozygous

Cats can have black or red fur colour.
Black is dominant.
What are possible genotypes for a red cat?

1. Always homozygous
2. Always heterozygous
3. Homozygous or heterozygous

Gene symbols

Alleles are usually shown using a letter.

• Alleles of the same gene use the same letter
• Dominant = capital letter,  Recessive = normal letter
• AA = homozygous dominant
• aa = homozygous recessive
• Aa = heterozygous

For humans, red hair is dominant over blond hair.
A man is heterozygous for hair colour.
What is his geno- and phenotype?

1. AA and red hair
2. aa and blond hair
3. Aa and red hair
4. Aa and blond hair

A father has genotype AA, the mother Aa.
Which genotypes are possible for their kids?

1. AA, aa en Aa
2. Aa en aa
3. Aa en AA
4. aa en AA

What you should do:

• Read pages 162-163
• Do asgmt  1-3 pgs. 163-165
• Challenge: how it fits together pgs. 156-157,  pgs 145-146 can help

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zs = Working in Silence

• No asking questions
• Silent, don't disturb anyone
  
• Stay at your  desk

What you should do:

• Read pages 162-163
  
• Do asgmt 1-3 pgs. 163-165
  
• Challenge: how it fits together pgs. 156-157, pgs 145-146 can help

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zw = Working with whispering

• Teacher is available for questions
• Only whisper with the student next to you
• Stay at your  desk

docs.google.com

Tidy Duty

Today these people are on tidy duty

• Desks: empty and straight
• Chairs:  underneath the desks
• Floor: no rubbish