BS1 - Genotype and Phenotype

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Today's lesson

1. Introduce new topic: Heredity and evolution

2. Review DNA

3. Discuss Genotype and Phenotype

Basics of heredity

• Gene: part of your DNA with info on one trait 
• You get one set of genes from your mom and one set of genes from your dad
• For every trait you have two genes (pieces of info)
• These pieces of info can be different variations of the gene
• The combination of the two pieces decides what that trait will be for you

Example:

• Trait : Hair color - brown
• Gene : part of the DNA carrying the info for this trait
• Variations in this gene: blond, brown, red, black
• Mother's hair : blond   x    Father's hair : brown
• You : one gene (blond) x one gene (brown) = Brown hair

00:44

How does DNA act as a blueprint for life?

1. By making proteins
2. By making carbohydrates
3. By making new cells
4. By making amino acids

01:02

Amino acids attach to eachother to create...

01:24

What is a name of a group of organs function together as one?

01:43

Give 2 examples of proteins in your body.

02:39

Give the code to the 2nd strand of this piece of DNA:
A T T C C G T A C

03:15

What is the RNA code from this piece of DNA:
A T G C A G

03:42

In which organelle is the protein folded?

1. Rough ER
2. Smooth ER
3. Golgi Apparatus

Genetic material

• Genetic material is located in the nucleus of every cell.
  
• Each nucleus has chromosomes  that contain DNA.
  
• The genetic material is located in DNA molecules.
  
• Nuclei of human cells have 46 chromosomes.
  

Each human being has 46 chromosomes. How many did you get from your mother?

1. 46
2. 23
3. 22
4. 45

12.1 genotype phenotype

Genotype

• complete set of your inherited characteristics
• information from DNA
• you are born with it

Phenotype

• your appearance 
• seen from the 'outside' 
• combination of genotype + environmental factors

genotype

phenotype

XY chromosomes

cannot change!

you inherit this

can sometimes change during your life

you do not inherit this

a scar

Is not always visible

genotype and phenotype

Identical twins do have the same genotype but not necessarily the same phenotype

1. true
2. false

12.1 

dominant 

ressecive 

Dominant alleles

A dominant allele is always expressed, even if only one copy is present. Dominant alleles are represented by a capital letter, for example, A. The allele for wet earwax is dominant. You only need one copy of this allele to have wet earwax. Two copies will also give you wet earwax.

Recessive alleles

A recessive allele is only expressed if the individual has two copies and does not have the dominant allele of that gene. Recessive alleles are represented by a lower case letter, for example, a. The allele for dry earwax is recessive. You need two copies of this allele to have dry earwax.

12.1 homozygous / heterozygous 

homo and heterozygous

Homozygous alleles are both identical for the same characteristic, for example AA or aa. A homozygote is an individual who has identical alleles for a particular gene.

Heterozygous alleles are both different for the same characteristic, for example Aa. A heterozygote is an individual who has different alleles for a particular gene.

Do Now:

Read 12.1

Finish quetsions 11.1 till 11.4 and 12.1 

12.2 

It runs in the family 

content

Introduction video 

genetic variation and diseases

punnett square 

pedigree chart 

Introduction 

Mono genetic 

 When a disorder is determined by one gene, it is called monogenic. 

Example = albinism 

Recessive inheritance 

Lisa (figure 3) suffers from phenylketonuria (PKU). Her parents, brothers, and sister are healthy. Children with PKU are born healthy. After about six months, however, the intellectual development lags behind due to damage to the brain. If PKU is discovered early, brain damage can be prevented with a special diet. That is why every baby’s blood is tested for PKU in the first week after birth: the so-called heel prick test.

Gender-linked recessive inheritance

Some disorders, such as colour-blindness, mainly occur in boys and men. This is because the gene for having or not having disorders such as colourblindness lies on the X chromosome. A male has only one X chromosome. If that X chromosome has the allele for colour-blindness, he will be colour-blind.  

Punnet square 

1. Determine the parental genotypes. You can use any letter you like but select one that has a clearly different lower case, for example: Aa, Bb, Dd.

2. Split the alleles for each parent and add them into your Punnett square around the edges.

3. Work out the new possible genetic combinations inside the Punnett square.

Pedigree chart