Recap basic 1 - 3 genetics V3 2425

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Welcome!

• Finishing up LearnBeat
• Recap basic 1 - 3 unit 5
• 
  

After today you can...

- Explain what the planning of the next weeks are 

- Explain where you can find the checklist for the next test

- Tell what we have done so far for unit 5

Pedigree 

•  In this pedigree, daughter 2 has a phenotype we do not see in her parents. This means that she has the recessive phenotype. Daughter 2 will have phenotype ‘aa’.

● Because her parents do not show the recessive phenotype, but their daughter does, it means that bothparents are heterozygous (Aa). They both gave their recessive allele (a) to their daughter.

Planning upcoming week

Checklist endtest 

Basic 1 genotype and phenotype

• I can describe what the genotype and phenotype are.
  

Concepts: nucleus, chromosomes, DNA, inherited characteristics, gene, genotype, phenotype.

• I can explain that cells only use the hereditary information that they need.
  

Concepts: genes, activation.

1. What is the difference between your genotype and your phenotype.
2. Give an example of your genotype and phenotype

Genotype

Phenotype

Risk for a genetic disease

Phenotype = genotype + environmental influences

The phenotype changes…

…but the genotype doesn’t.

Put the following in order of size

Smallest                                                                         Biggest

gene

Chromosome

Nucleus

cell

What is what?

• DNA  = substance that contains information for hereditary characteristics
• Gene = the pieces of DNA that together contain the information for a hereditary characteristic
• Chromosome = a long, thin thread in the cell nucleus
• Cell = building block of an organism

In this question we will compare a liver cell and a muscle cell of 1 person
A. Is the genotype of the liver cell and muscle cell the same?
B. Can you find the same substances in the two cells?
C. Are all genes activated in the two different cells?

Gene activation

Basic 2 Chromosomes 

• I can explain how each of the parent supplies 50% of the chromosomes.
  

Concepts: body cells, sex cells, chromosome pair, gene variant (allele)

• I can say how the sex of humans is determined by sex chromosomes.
  

Concepts: female (XX), male (XY), intersex (XXY)

• I can explain how sexual reproduction causes variation in genotypes.
  

Concepts: sex cells, meiosis, daughter cells, sexual reproduction, variation in genotypes

Drag the number of chromosomes to the correct place

46 chromosomes

46 chromosomes

46 chromosomes

  23 chromosomes

23 chromosomes

A human cell has 23 chromosomes, so it must be a...

1. Body cell
2. Sex cell

A cell of a random organism has 7 chromosomes, this must be a...

1. Sex cell
2. Body cell

Sexual reproduction 50% DNA of each parent 

Karyogram picture set of chromosomes

• Chromosomes comes in pairs in body cells
• Sex chromosomes determine your sex
• XX = female
  XY = male

This is a karytype of.

1. sperm cell
2. egg cell
3. body cell
4. you can't tell

In the picture on the right are two cells of a plant drawn. Use the picture to answer the following questions:
1. How many chromosomes pairs does the plant have?
2. Which of the two cells is a sex cell, explain your answer.
3. How many chromosomes does the plant has in total?

What is genetic varation?

Genetic variation caused by sexual reproduction

Basic 3 genes and alleles 

• I can describe what genes and alleles are.
  

Concepts: DNA, base pairs, genes, alleles, allele pair, proteins

• I can describe what a mutation is.
  

Concepts: mutation, mutant, mutagenic influences

• I can describe what cancer is.
  

Concepts: cancer, metastasis, cell division

Gene versus Allele 

Name the gene that belongs to the following traits:
1. Blue eyes
2. Brown eyes
3. Curly hair
4. Straight hair
5. Dark skin

2. Give the alleles for the following traits (tip: look at your classmates):
1. Hair texture
2. Hair colour
3. Eye colour
4. Nose shape

Alleles

• Chromosomes come in pairs
• So for each genes you have two copies
• an alle is a variant of a gene
• You can have the same or two different alleles for a gene 

What happens if there is a change in the DNA sequence?

1. You die
2. You will be a superhero
3. Nothing happens
4. You get a new trait

Mutation: change in DNA sequence

Mutations are caused by mutagenic influences.
Can you give three examples of mutagenic influences?

Mutagenic influences

• All cause mutations, change in DNA sequences
• Are mutations bad, neutral or good?  

How cancer arises 

Homework

Go to Learnbeat --> Biology

Open from parent to offspring

Read the theory of part 1 - 3

Welcome

• Throwback basic 3 
• Start from parent to offspring

How cancer arises 

After the basic from parent too offspring you can

• explain if an allele is dominant or recessive and know that a dominant allele is indicated with a capital letter and a recessive alle is indicated with a small letter
  

Concepts: dominant, recessive

•  explain how the phenotype of an organism comes about using the terms Concepts: homozygous dominant, homozygous recessive and heterozygous
  
• make from a monohybrid crossing a punnet square and give the probability of the occurrence of genotypes and phenotypes of the offspring.
  

Concepts: P-generation, F-generation, punnet square

Chromosomes, genes and alleles

• Chromosomes comes in pairs
• On chromosomes you can find genes 
• Different variants of genes are called alleles
• The allele that is visible in the phenotype is called dominant allele, the other is recessive
• Dominant alleles are written with a capital letter, recessive alleles with a small letter

Dominant versus recessive 

• For the gene eye colour there are two alleles in the picture on the right
  
• B = brown, b = blue
• Brown is dominant, because if you are Bb brown is visible in the phenotype

How to name the different genotypes

Genotypes: 

BB = Homozygous dominant (2  of the dominant alleles)

Bb= heterozygous ( 1 dominant allele, 1 heterezygous allele)

bb = Homozygous recessive ( 2 recessive alleles)

Time to work

From parent to offspring on Learnbeat

Part 1 

Question A - E

Monohybrids crossings questions?

• Black hair is dominant for dogs and brown hair is recessive.   A homozygous black haired dog is crossed with a brown haired dog
• How many of the F2 generation have brown hair? 

• P generation = parents first generations
• F generations = is following generations, F1, F2 

Monohybrids crossings questions?

• Black hair is dominant for dogs and brown hair is recessive.  A homozygous black haired dog is crossed with a brown haired dog.
• How many of the F2 generation have brown hair? 

• First step write down genotypes of P generation=  BB x bb 
• 2 step make a punnet square.

Monohybrids crossings questions?

• Black hair is dominant for dogs and brown hair is recessive.  A homozygous black haired dog is crossed with a brown haired dog.
• How many of the F2 generation have brown hair? 

• F1 = 100% Bb
• Two dogs from F1 makes F2 so
• Bb x Bb

Monohybrids crossings questions?

• Black hair is dominant for dogs and brown hair is recessive.  A homozygous black haired dog is crossed with a brown haired dog.
• How many of the F2 generation have brown hair? 

• Read conclusion for the Punnet square = 1 out of 4 is brown = 25%

Time to work

From parent to offspring 

Part 2 

Question A - E

Done read part 3 and start making questions

Monohybrids crossings questions?

• How many of the F2 generation have brown hair? 

• Read conclusion for the Punnet square = 1 out of 4 is brown = 25%
• Phenotypic ratio: Black : brown = :3:1 
• Genotypic ratio: BB:Bb:bb = 1:2:1

Homework!

From parent to offspring 

Part 2 and 3 

Question A - E