5.3 DNA and Genes 2HVTTO

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

5.3 DNA and genes and part 1 of 5.4

• Take off your jacket

• Put your things on your desk

       Book, notebook, pencil case

• Bag on the floor

• Read pages 127-129, 132-133

5

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Lessongoals

• Understand: I can describe what genes and alleles are by explaining their role in storing genetic information and showing how they can vary.

• Understand: I can describe what a mutation is by explaining how changes in DNA can happen and what effects they may have.

• Understand: I can describe how cancer develops by explaining how mutations can lead to uncontrolled cell division.

• Apply: I can give examples of causes of mutations, such as radiation or harmful chemicals, and link them to possible health effects.

< Mostly influenced by >

Genotype

Lifestyle

Suroundings

Phenotype

What is the difference between genotype and phenotype?

A

genotype is the information fenotype is how you look/work

B

phenotype is the information genotype is how you look/work

C

They are nearly the same thing

D

What genes are found in the cells of your liver?

A

all genes used by the liver, once

B

all genes used by the liver, twice

C

all genes found in humans, once

D

all genes found in humans, twice

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)

Nucleotide

one base together with the substances that connect it to other bases on the same half of the DNA strand

Genes and characteristics

• Gene = (part of) the genetic code for 1 characteristic

• Genes contain information to make proteins

This might help you understand:

You complete DNA (your genotype) = a recipe book

1 gene = a recipe from the recipe book

These recipes are used to make lots of different proteins.

These proteins are part of your body and make it function.

!

Example:

The colour of your skin (1 characteristic) is decided by about 16 genes.

!

Alleles

Allele = a version/variant of a gene

Gene = characteristic

Examples:

If you compare genes > alleles to other things:

Tree > oak

Dog > labrador

Cat > siamese

Flower > rose

A pair of chromosomes is shown; Gene A is indicated on both chromosomes.

This gene contains information for the same characteristic.

The colors are different, indicating the alleles are different.

This means the information contained in the genes is different

A

A pair of chromosomes is shown; Gene B is indicated on both chromosomes.

This gene contains information for the same characteristic.

The colors are the same, indicating the alleles are the same.

This means the information contained in the genes is the same

B

Gene: Alleles

Eye colour: blue, green

Hair shape: straight, curly

Height: tall—short

Skin colour: black—white

Feet size: 40, 42

Earlobe: attached, loose

Allele pairs

Alleles of 1 gene form pairs

• 2 same alleles = homozygous

• 2 different alleles = heterozygous

You have 2 sets of each gene (1 from mother, 1 from father)

This means you have 2 alleles for each gene.

1 allele from your father, the other is given by your mother.

These alleles can be the same or different.

!

Sexual reproduction

• Sperm/egg cells are made during a special cell division: meiosis. 

• Meiosis randomly splits all chromosome pairs, giving each daughter cell only 1 of each pair.

• Lots of different chromosome combinations are possible

• During fertilization two sex cells combine, creating new chromosome pairs

During fertilization a spermcell and egg cell combine.

This combines the single genes into pairs of genes

Every body cell has 2 versions of each gene.

Meiosis creates cells that only have 1 version of each gene

What genes are found in a sperm cell?

A

All genes used by the sperm, once

B

All genes used by the sperm, twice

C

All genes found in humans, once

D

All genes found in humans, twice

1 part of a gene might be ATCCCGA What would the other part look like?

A human egg cell contains ... pairs of chromosomes. (number)

Zs = Working in Silence

• No asking questions

• Silent, don't disturb anyone

• Stay at your  desk

What you should do: 5.3

• TB: Pages  127-129

• WB: Asgmt  13-15

• Lt: Asgmt 5-7

Done with the above?

• Work on the next chapter(s)

• Learn for the test 

• Make other homework

• Read a book

6

minute

00

second

add30s

What you should do: U5 B3

• TB: Pages  127-129

• WB: Asgmt  13-15

• Lt: Asgmt 5-7

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

Tidy Duty

3 people each lesson

• Desks: empty and straight

• Chairs:  underneath the desks OR end of day: on the desks

• Floor: no rubbish