Flashcards
Genetics and Evolution VI
Cards in this deck (35)
- 1Name 4 types of mutations.(i) Single base pair changes
(ii) Transition mutations
(iii) Transversion mutations
(iv) Spontaneous mutations - 2What are transition mutations?Purine for purine (AG)
Pyrimidine for pyrimidine (TCU) - 3What are transition mutations?Pyrimidine for purine and vice versa
- 4Name 5 causes for spontaneous substitutions1. Mis-pairing DNA during replication.
2. Tauntomerisation.
3. Anomalous base-pairing (non Watson-Crick).
4. Quantum tunneling.
5. Depurination. - 5What is depurination?Loss of a purine base from a nucleotide leading to an abasic site - a gap.
No info to say what base should be paired to it, can lead to faulty base pairing. - 6What are the stages of depurination leading to a spontaneous mutation? (4).1. During replication the apurinic site can't provide template.
2. Incorrect nucleotide incorporated. (usually A).
3. Next round of rep, wrong nucleotide incorporated opposite the apurinic site.
4. Leads to a permanent mutation. - 7What does deamination of cytosine generate?Uracil
- 8What does deamination of 5-methylcytosine generate?Thymine
- 9What do these deamination events generate?Mismatch pair e.g. A-G.
- 10What sort of mutations are common in species with heavily methylated cytosine?CG --> AT transversions.
- 11Name 2 examples of chemical mutagensAlkylating agents
Nitrous acid (HNO2) - 12Name an example of an alkylating agent and its effect.Ethyl Methyl Sulphonate (EMS)
Ethylates T / G, leads to transition mutations. - 13What are base analogues? Name an example.Compounds that look like bases and may be incorporated.
5-Bromouracil
Keto form resembles Thymine
Enol form resembles T' - 14What is tauntomeric shift?A spontaneous transient rearrangement to an alternative form,denoted by a '.
- 15What does this cause?Transition mutations in the complementary strand.
- 16What do the 4 bases shift to?G+T Keto <-> Enol
A+C Amino <-> imino - 17What do the tauntomers pair with?T' pairs with G (So enol form of T resembles C).
G' pairs with T
A' pairs with C
C' pairs with A - 18Draw some diagrams of 5-bromo/ bases binding boiiihehehe
- 19What causes this shift in forms?Shift in egdm-3 between keto and enol form, changing what's acting as a H bond acceptor and a H bond donor.
- 20Name 3 different types of mutations that affect protein functionSilent
Missense
Nonsense - 21What's the effect of a silent mutation?Changes codon to another codon, yet still encodes the same amino acid.
- 22What's the effect of a missense mutation?Changes codon, encodes a different amino acid, altering protein sequence.
- 23What's the effect of a Nonsense mutation?Changes codon to a stop codon, causes protein truncation.
- 24What are the potential consequence of single base pair changes?LOF of gene
GOF of gene
No effect on gene activity - 25Why is it unlikely for a SBP change to be serious?Only ~1% of the human genome is protein coding
Point mutations outside coding regions are generally silent, however can affect gene function - 26Why isn't this true for E.Coli?As only ~12% of the genome is non-protein coding.
- 27What can cause INDELs?Replication slippage in replicating DNA
- 28What can cause insertion?DNA intercalating agents
- 29What are DNA intercalating agents?Base-analogues that wedge into the DNA heilx, recognised as an extra base during DNA replications.
- 30Name an example of a DNA intercalating agent? How does it function?Ethidium Bromide, an intercalated dye
Causes DNA pol' to stutter, resulting in a frame shift mutation. - 31What is replication slippage?Loss/gain of base(s), occurs commonly in long stretches of the same base.
- 32Draw a diagram showing this process, describe what's going on.Brief moment of weakness, loss of base pairing causes strand slippage.
The base "bulges" out, and is repaired by DNA reparation.
When strands re-anneal after that moment of weakness it can re-anneal backwards/forwards instead of at its correct position.
The base is "shuffled into place" when strands separate for replication, then it is used as a template, leading to a base pair insertion.
Can also not be shuffled back in, leading to the omission of this base. - 33What is Huntington's caused by?CAG (Glutamate) repeats
If >40 repeats occur by FW/BW slippage
If the looped out repeat is annealed then the repeat expands during replciation. - 34What are the effects of small INDELs within the coding strand? (3)Leads to frameshift
Multiples of 3 don't cause frameshift, do alter protein.
Can cause triplet expansion diseases like Huntington's. - 35What are the effects of small INDELs outside of a coding strand?Effect often silent, although can alter gene regulator function.
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- User has deleted their subject information Flashcards on Genetics and Evolution VI, created by Deleted user on 05/03/2018.
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