genetic change Flashcards
1
Q
how does UV radiation cause mutation?
A
- cause adjacent base pairs to form covalent bonds –> thymine dimer structure.
- DNA double helix structure –> distorted
- formation of dimer molecule prevents both of the adjacent bases bonding with complementary bases –> premature ending of DNA strand
- premature DNA transcribed into an incorrect mRNA strand –> incorrect anticodons.
- leads to different amino acids –> non-functional protein.
- pyrimidine dimer main cause of melanoma (skin cancer)
2
Q
how does X-ray and gamma radiation cause mutations?
A
- directly alters nitrogenous base sequence of DNA due to high ionising energy (short wavelength).
- damages DNA indirectly by ionising other molecules in cell produce free radicals –> highly reactive
- free radicals break any molecules they encounter incl. DNA –>
frameshift/translocation
3
Q
how do chemical mutagens work?
A
- chemicals cause mutations with high exposure/prolonged contact.
- similar to DNA bases, may be mistakenly incorporated during DNA replication.
- distorts double helix where inserted.
- results in incorrect nucleotide pairing –> non-functional protein.
4
Q
what do naturally occurring mutagens include?
A
- biological naturally occurring mutagens: viruses, bacteria, fungi+their products
- non-biological naturally occurring mutagens: metals such as mercury +cadmium
5
Q
whats the effects of point mutations?
A
