chapter 14 notes

Multicellular Organisms: For a mutation to be heritable to the next generation of organsisms, that mutation must be to the DNA in gametes,

Conditional Mutations: Effects are felt only under a set of environmental conditions and not under others. The mutation only effects the phenotype of an organsism under particular environmental factors.
Ex: Temperature Sensitive mutants: There is a change to the DNA sequence, which causes a change in the amino acid sequence of a protein, making the protein not fold properly. The protein therefore does not fold well at higher temps, but folds just fine at lower temps.
Ex: Siamese Cats: They have a color depth pattern, because their regulatory protein that controls Melanin expression is temperature sensitive conditional mutant. That is why on the cooler parts of the body (paws, ears, and tail) is where the Melanin is expressed. The warmer parts of the body, lack the Melanin expression.

Classification by Function:
1.) loss-of-function/knockout: A gene product that is eliminated entirely;not being produced at all. (ex: Mutation to HSF-1 would knockout hsp70 expression. HSF-1 would replaced K80 with Arginine) In diploid organsisms these are usually recessive.
2.) Hypomorphic: Reduction in expression or activity of a gene product. (ex: temp. sensitive)
3.) Hypermorphic: Leads to an increase in gene procuct activity or expression. (ex: better promoter sequence because it has better transcriptional activators.)
4.) Gain-of-function/ectopic expression: Gene expression changes, so the gene product is pressent in more cell types than in the wild-type.

Classification by kind of molecular change:
1.) Nucleotide substitution: 1:10 to the 5th bases are added to replicating strand of DNA is not complementary to other strand. Even though most DNA polymerases have proofreading function, some of the wrong bases are still copied.
2.) Insertion: Everything is going normally and then an extra base is added.
3.) Deletion: Base in the original strand is not copied. So, in the replicating strand, the original base is deleted.
4.) Duplication: A long swatch of DNA is copied more than once per round of replication.
5.) Inversion: Copied swatch of DNA is flipped into the opposite orientation.-


silent/ synonymous - change to DNA sequence, but no change to amino acid sequence. often can change 3rd base in a given mRNA codon with no change to amino acid it codes for.

wobble hypothesis - only 1st 2 bases in anticodon bind with codon.

Missense/ non-synonymous - change in DNA lead to change in amino acid sequence. can have major effect. ex: HSF1 and K80R

nonsense/ termination - early stop codon, short protein.

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