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M15) Mutation
| Question | Answer |
|---|---|
| What are mutations? | Permanent changes in the sequence of DNA and ultimately the source of any new form of gene. |
| Define base substitution. | A mutation where one nucleotide is substituted for another - a wrong base is placed into position on the DNA. |
| Define base insertion or deletion. | A mutation where nucleotides are added or deleted, They can have disastrous consequences as mRNA is read in codons, adding or deleting nucleotides may alter the frame of the reading of the nucleotide message. |
| What are mutations involving changes to chromosomes? | Translocations, inversions and duplications. |
| Define translocations. | Mutations that occur when a part of one chromosome is moved to another. |
| Define inversions. | Mutations that occur where a segment in a chromosome may be flipped upside down from its normal position. |
| Define duplications. | Mutations where parts of a chromosome appear twice. |
| Can mutations occur spontaneously in organisms? | They can but the natural rate is quite low. |
| How are mutations passed onto the next generation? | When the mutation occurs in the germ line cells, i.e. those producing gametes. |
| Define spontaneous mutations. | Ones that occur during DNA replication or recombination. |
| How may rates of mutation be increased? | Physical factors or chemical factors called mutagens. |
| Examples of physical mutagens? | Atomic radiation, UV radiation, excess heat. |
| Examples of chemical mutagens? | Chemicals that are similar to normal DNA bases like acridine dyes, nitrous acid, and hydroxylamine. |
| What is the danger of mutations induced by mutagens? | They may lead to changes in genes that control cell division and ultimately lead to the development of cancerous cells. |
| What may changes in DNA lead to if inherited through the gametes? | Absent or altered proteins in the offspring. |
| Complete this sentence. Most mutations are harmful but can... | provide a source of variation for natural selection to act. |
| Examples of human diseases caused by single mutations at one nucleotide? | Cystic fibrosis and sickle cell anaemia. |
| What is sickle-cell anaemia? | A blood condition that is often fatal and involves an altered base on a gene located on chromosome 11, which gives rise to a single amino acid alteration. Haemoglobin formed is abnormal and gives rise to inefficient sickle red blood cells. |
| What often happens to the blood vessels of sickle-cell anaemia sufferers? | They are blocked by the distorted red blood cells. |
| How does sickle-cell anaemia occur? | A molecule of haemoglobin is made of 2 pairs of polypeptide chains, one with 141 amino acids and another 146. In S.C.A, in one of the chains, glutamic acid is replaced by valine. |
| What is haemophilia? | A genetic disorder. Those afflicted bleed excessively and have inherited an abnormal gene involved in the process of blood clotting. |
Created by:
MahaliaMcD
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