BS 3 - genes and alleles

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Planning 

Recapitulation 5.2 (3, 5, 7 , 9) 

Homework check

5.3 genes and alleles

5.3.6 You can describe what genes and alleles are.

5.3.7 You can describe what a mutation is.

5.3.8 You can describe what cancer is.

Meiosis = a special form of cell division to create sex cells = gametes (page 110,  highlight this text) 

DNA, how it's built

Basepair

Combination of A-T or C-G. Other combinations are impossible in the DNA

Gene

Many (often thousands) of basepairs together contain the information of a gene. The order of the basepairs decides the code and its contents.

Base

Buildingblock of the DNA, there's 4 types:

• A (adenine)
• C (cytosine)
• T (thymine)
• G (guanine)

Time to try for yourself

Make question 1 page 122

Genes and characteristics

• 1 characteristic often is made up of different genes
• Genes contain information to make proteins

Proteins

Muscle cell - gene active  that contains info for producing muscle protein

Pancreas - producing insulin (hormones are proteins)

Melanin - pigment in your eye 

Alleles

Genes have different gene variants: alleles

Alleles (variants) of eyecolor: blue, brown, green, etc.

Some alleles are stronger than others

Allele pairs

Alleles of 1 gene form pairs:

• 2 same alleles = 2 alleles for straight hair
• 2 different alleles = 1 allele for straight and one for curly

Time to try for yourself

Make question 5 page 124

Which cells contain alleles for hair colour?
Pick the answer showing the most correct cells

1. Hair cells
2. Hair and head cells
3. Hair, head and brain cells
4. Hair, head, brain and eye cells

Which alleles could you both find in the same sperm cell?

1. Brown hair Blond hair
2. Blue eyes Green eyes
3. Brown hair Blue eyes
4. Red hair Blond hair

Mutations

• The genotyp of a person can not change
• Mutation = part of the DNA (in a cell) changes
• Usually little to no influence
• Organism where mutation shows in phenotype = mutant
• The moment and place of mutation are important

How does DNA mutate?

Mutations can be caused by mutagenic influences:

• Sunlight (UV-radiation)
• Radioactive radiation (Röntgen)
• Asbestos, smoke

Mutations also happen by mistake during cell division

Cancer, how and why?

• Happens due to mutations, Not bacteria/virus
• Mutation makes cells divide continously      
• this creates a tumour:

       - Benign: Divides slowly, stays at its spot

       - Malignant: divides quickly, disrupts tissues

• Metastasis > cancer cells are carried by blood/lymph. End up in different body parts and create more/new tumours

Time to try for yourself

Make question 2, 7, 8

Time to try for yourself

Make question 3

Homework

5.3 Questions 1 to 9 (skip summary)