Biochemistry 2280A Lecture Notes - Lecture 20: Pseudouridine, Chloramphenicol, Phenylalanine

20 views9 pages

browncod446

16 Jan 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

12:42 am mrna is used to synthesize protein. spells out the amino acid sequence in letter words called codons. Cells need at least 20 different codons to code for 20 amino acids. Given that there are 4 nucleotides (a,g,c,u), 64 3 base codons are possible (43) 2 base codon results in 16 codons which isn"t enough for 20 amino acids. 4 base codon results in 256 codons, too excessive. There are 61 codons for 20 amino acids, it"s redundant. Amino acids can be coded by more than 1 codon. The genetic code is universal, found in all organisms. Overlapping would place significant restrictions on what amino acid can come before and after it as they would rely on each other. There are no gaps between codons, gaps were removed by splicing introns. Redundancy: some codons code for the same amino acids. Redundancy often occurs at the third position of the codon(wobble)

Related Questions

Fill in the blank. Elongation during translation does NOT involve ____________.

Question 16 options:

	the translation of codons according to the genetic code
	the formation of bonds catalyzed by the ribosome
	complementary base pairing between RNA molecules
	amino acids being linked together in a polypeptide
	reading the DNA template 3' to 5'

For a given gene, what establishes the reading frame for translation?

Question 17 options:

	the location of the enhancer relative to the gene
	the first three nucleotides at the 5' end of the mRNA
	the first three nucleotides at the 3' end of the mRNA
	the start codon in the mRNA
	the location of the promoter relative to the gene

Which of the following is the LEAST likely direct consequence of a substitution mutation?

Question 18 options:

	changing the length of a protein coded for by a gene
	changing one amino acid in a protein
	creating a stop codon
	eliminating a start codon
	changing the length of the DNA molecule containing a gene

Suppose that the pre-mRNA transcript from a eukaryotic gene is 30,000 nucleotides long, and the gene codes for a sequence of 300 amino acids. What is the best explanation for the relationship between these numbers?

Question 19 options:

	only the first 900 nucleotides of the pre-mRNA transcript are translated
	it takes 100 nucleotides to specify a single amino acid
	300 of the nucleotides in the transcript are important, and the rest are "junk"
	only the last 900 nucleotides of the pre-mRNA transcript are translated
	large portions of pre-mRNA transcripts are cut out during RNA processing

Suppose an individual is born into a population with a novel mutation. Is the new mutation an evolutionary change, and why?

Question 20 options:

	no, because it is not a big enough change to count
	yes, because new mutations are always adaptive
	yes, because the appearance of a new genetic variant is a genetic change in a population
	no, because not enough individuals have the mutation for it to matter
	no, because most mutations are not adaptive

Biochemistry 2280A Lecture Notes - Lecture 20: Pseudouridine, Chloramphenicol, Phenylalanine

Document Summary

Get access

Related Questions