Mutations, Genetics Disorders and Cancers
- Created by: Sophie
- Created on: 06-04-15 09:32
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- Mutations, Genetic Disorders and Cancer
- Mutations are changes in the base sequence of DNA
- Can be caused by errors in DNA replication
- Can be caused by mutagenic agents
- Types of errors:
- Substitution: One base is substituted for another
- Deletion: One base is deleted
- Different order of AAs, different protein formed.
- Not all mutations affect the order of AAs
- Degenerate nature of DNA means some AAs are coded for by more than 1 triplet
- Not all substitution mutations change the AA sequence
- Deletion always changes AA sequence
- Change in number of bases present, causing shift in base triplets after it
- Mutagenic Agents Increase the rate of mutation
- Mutations occur spontaneously
- Ultraviolet radiation, ionising radiation, some chemicals and some viruses are e.g.s
- Increase rate of mutation by...
- Acting as a base: chemicals called base analogs substitute for a base in replication.
- Altering bases: Some chemicals can delete or alter bases.
- E.g alkylating agents, add alkly group, changing structure so it pairs with something different.
- Changing the structure of DNA: Some radiation changes structure of DNA, causing problems in replication
- Genetic disorders and cancer are caused by mutation
- Hereditary mutations cause genetic disorders and some cancers
- Inherited disorders caused by abnormal genes or chromosomes
- If a gamete containing the mutation for a genetic disorder is fertilised, the fetus will have the disorder
- Some mutations increase the likelihood of developing cancers
- Acquired mutations can cause cancer
- Mutations that occur in individual cells after fertilisation
- If these mutations occur in the genes that control cell division, you may get a tumour
- A mass of abnormal cells
- Cancerous tumours invade and destroy surrounding cells
- 2 types of gene controlling cell division
- Tumour suppressor genes
- Tumour suppressor genes can be inactivated if a mutation occurs in the DNA sequence
- If a mutation occurs, the protein isn't produced. The cells divide uncontrollably.
- When functioning normally, tumour suppressor genes slow cell division by producing proteins that stop cells dividing or cause them to self destruct
- Tumour suppressor genes can be inactivated if a mutation occurs in the DNA sequence
- Proto-oncogenes
- If a mutation occurs in the DNA sequence, the effect of a proto-oncogene can be increased
- Oncogene produced
- When functioning normally, proto-oncogenes stimulate cell division by producing proteins that make cells divide
- If a mutation occurs, the gene cam become overactive, stimulating cells to divide uncontrollably resulting in a tumour
- If a mutation occurs in the DNA sequence, the effect of a proto-oncogene can be increased
- Tumour suppressor genes
- Mutations are changes in the base sequence of DNA
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