3t Chapter 5 par. 1 en 2

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Inheritance(genetics)

genotype en phenotype

learning goals: 

you can describe the meaning of  genotype and phenotype.

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.
  

Chromosomes

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

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

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 en phenotype

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

1. true
2. false

chromosomes

A human cell contains 46 chromosomen

23 from mom and 23 from dad.

All nuclei of the cells in your body contain a combination of these chromosomes from both parents. 

Fertilisation

23 chromosomes mother

23 chromosomes father

46 chromosomes in the fertilised egg cell

(= 23 pairs of chromosomes)

body cells   ovary cells      testes cells   body cells            

egg cell

sperm cell

fertilisation

zygote

Cell division

= 46

= 46

= 46

= 46

= 23

= 23

= 46

All body cells, except sex cells, are diploid

Single chromosomes

Pairs of chromosomes

cell

cell

Each living organism has a different amount of chromosomes.

The amount of chromosomes in body cells of a:

• tomato plant = 12 
  
• cow = 60
• bee = 16 
• chicken = 78
  

A dog has 78 chromosomes.
How many are there in a liver cell?

A dog has 78 chromosomes.
How many are there in a sperm cell?

A dog has 78 chromosomes.
2n is?

1. 46
2. 78
3. 156
4. 39

A dog has 78 chromosomes.
n is?

1. 46
2. 78
3. 156
4. 39

A frog has 26 chromosomes.
n is?

1. 26
2. 13
3. 52
4. 23

A frog has 26 chromosomes.
an egg cell has?

1. 26
2. 13
3. 52
4. 23

A frog has 26 chromosomes.
an egg cell has?

1. 26
2. 13
3. 52
4. 23

Karyotype

   Male karyotype            Female karyotype

Karyotype

   Male karyotype            Female karyotype

sex chromosomes

Female:

Male:

-> 44 chromosomes are regular chromosomes:

     autosomes (chromosome pairs 1 - 22)

-> 2 chromosomes are sex chromosomes (X and Y)

What is the chance to get a boy?

What is the chance to get a boy?

• mother has: 22 pairs (44) of autosomes + XX     -> 46 = 2n

• father has: 22 pairs (44) of autosomes + XY        -> 46 = 2n

sex cells have a single set of chromosomes              -> 23 = n

• egg cell has: 22 + X
  
• sperm cell has: 22 + X  or  22 + Y
  

The chance is

50%

Mother gives always an X chromosome

Father gives an X or an Y chromosome

So the chance for  XY = 50%

Genes and alleles

In the chromosomes  all your genes 

for hear colour, eye colour, musicaloty and your character are located.

key words

homozygous

heterozygous

dominant

recessive

genotype

phenotype

genes

alleles