BB lecture 11-16-09 mutations, operons

BB lecture 11-16-09 mutations, operons - Chapter 17(pp...

Info icon This preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 17 (pp. 344-346 in conclusion) Learning objectives: Define mutagen ; mutation; point mutation Explain why point mutations are sometimes harmful, and sometimes harmless Be able to illustrate a frameshift mutation Chapter 18 (pp.351-356): Gene regulation Learning objectives: Define operon Explain the difference between repressible and inducible operons Be able to describe how the trp operon and the lac operon respond to different nutrient conditions
Image of page 1

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

View Full Document Right Arrow Icon
Mutagen: a natural or man-made agent (chemical or physical) which can alter the structure or sequence of DNA. Chemical mutagens 1. Base analogs – molecules structurally similar to purines and pyrimidines 2. Chemicals - which alter structure and pairing properties of bases 3. Intercalating agents – molecules which may “insert” between bases Physical mutagens Radiation Ionizing radiation (UV, x-rays, gamma rays, etc.) produce free radicals -Free radicals damage DNA, proteins, lipids in cell membranes, etc.
Image of page 2
Mutation : a change in a gene’s DNA . Mutations that cause cancer are typically called “carcinogens A spontaneous mutation occurs as a result of natural processes (example: during DNA replication, recombination, or repair). Point mutations: changes in a single base pair of a gene may change an amino acid codon to a termination codon or vice versa..can result in a prematurely shortened protein may be silent , NOT changing the sequence of amino acids in the protein often true in the third position of a codon, because of "wobble" base pairing
Image of page 3

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

View Full Document Right Arrow Icon
Types of Point Mutations Point mutations - two general categories 1. Base-pair substitutions 2. Base-pair insertions or deletions
Image of page 4
Substitutions A base-pair substitution replaces one nucleotide and its partner with another pair of nucleotides Base-pair substitution can cause nonsense or missense mutations Nonsense mutations change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein Missense mutations still code for an amino acid , but not necessarily the right amino acid - Missense mutations are more common
Image of page 5

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

View Full Document Right Arrow Icon
Base-pair substitution
Image of page 6
Image of page 7
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