{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture 9 - Lecture 9 Mechanisms of spontaneous mutation...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 9 Mechanisms of spontaneous mutation and repair
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Mechanisms of spontaneous mutation errors in dna replication transition transversion indels spontaneous lesions/apurinic sites Repair Mismatch repair Base excision repair Nucleotide excision repair Double strand break repair
Image of page 2
Point mutation : the alteration of a single base pair or a small number of adjacent base pairs. Transition: replacement of a base by the other base of the same chemical category. purine replaces purine (A to G or vice versa) pyrimidine replaces pyrimidine (C to T or vise versa) Indel mutations: insertion or deletion of one or more base pairs. Transversion: replacement of a base of one chemical category by a base of the other. Pyrimidine replaces a purine (C to A or G; T to A or G) Purine replaces a pyrimidine (A to C or T; G to C or T)
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Consequences of point mutations within genes Figure 15-2
Image of page 4
Synonymous: the mutation changes one codon for an amino acid into another codon for the SAME amino acid. Synonymous substitutions never alter the amino acid sequence of a polypeptide chain. Missense or nonsynonomous : the codon for one amino acid is changed into a codon for a DIFFERENT amino acid. The severity of this kind of substitution depends the chemical similarity of the two amino acids in question: highly similar is called conservative versus non-conservative where difference is great affecting characteristics of the protein. Nonsense: the codon for one amino acid is changed into a translation termination codon (STOP)
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Transition: replacement of a base by the other base of the same chemical category. Transversion: replacement of a base of one chemical category by a base of the other.
Image of page 6
Point mutations can alter mRNA splicing Figure 15-3 transition transversion
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Consequences of point mutations on gene products TAA=stop ie: promoter Functional protein? Functional protein?
Image of page 8
Mechanisms of spontaneous mutations Errors in DNA replication can result from incorrect base insertion during synthesis. Base substitutions may result in transition or transversion. Transitions can result when tautomers (imino and enol) of the normal (keto) form of a given base occur in DNA leading to mismatched pairing of bases…hydrogen bonding characteristics are modified such that C and A will pair or G and T will pair Tautomers : isomers of a molecule such as DNA bases that
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern