5.3 Genes and DNA

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

today''s program 

learning objectives : you are able to answer the questions ... 

• what is DNA made of?
• how can DNA store information?
• what is a gene? 
• what is the link between gene, protein and phenotype? 

DNA-chromosomes, genes and traits 

• While watching the video, listen carefully!
• Write down the meaning of things and how they are connected. Use the concept list!
• Stay focussed! (9 min.) 
• Write down all the questions that you have!
• Write down the things that you need extra explanation on!

Write down all the questions that you have!

today''s program 

learning objectives : you are able to answer the questions ... 

• what is DNA made of?
• how can DNA store information?
• what is a gene? 
• what is the link between gene, protein and phenotype? 

Mutations

Learning Objectives

You can explain what a mutation is.

You can explain how a disease can be inherited from one generation to the next.

Mutations

= change in a gene or chromosome (genotype).

Somatic mutations can cause cancer, for example UV-light can cause skin cancer.

Germline mutations may result in no/small/large change in phenotype.

Mutations

= change in a gene or chromosome (genotype)

This may result in no/small/large change in phenotype

the change can be negative/neutral/beneficial

Mutations 

Mutations 

External caused by known mutagens 

• Radiation: (eg. UV light, X-ray, radioactive decay)
• Chemicals (eg. benzene in cigarette smoke)
• Bacteria or viruses (eg. HPV)
  

Internal

• DNA replication
  

Mutations 

Gene mutations

    Defect of a gene

    eg. sickle cell disease

Chromosome mutations

    Change in a whole chromosome

     e.g. extra chromosome 21 leads to Down Syndrome

Why do you think that Huntington’s disease is still around (1 in 20.000 people) whereas other dominantly inherited diseases are not that common?

A man who gets Huntington’s disease at the age of 40 had two children with a woman who doesn’t have it. He had himself tested and he turns out to be a heterozygote. What is the chance both his children will get it? Explain by using Punnett squares.

A man who is a carrier of cystic fibrosis wants to have a child with a woman whose parents are carriers of cystic fibrosis. She doesn’t know if she is a carrier. What is the chance that the child will get cystic fibrosis? Is it advisable to get herself tested?

Learning Objectives

You can explain what a mutation is.

You can explain how a disease can be inherited from one generation to the next.

questions...

• How many sex chromosomes are there to be found in a gamete? 
• What are the chances of having a baby girl of baby boy?
• Who is ‘responsible’ for the gender of a baby: the mother, the father or both?