In some cases, it is possible to change the sequence of bases in a codon and it will still code for the same amino acid. 6. All codons code for amino acids.
c. The genetic code is degenerate, so a single codon may code for several different amino acids d. By transcribing different segments of a single gene, RNA polymerase II can produce different mRNA molecules e. By translating different segments of a single mRNA molecule, ribosomes can produce different proteins a.
Look, for example, at leucine in the first column. There are six different codons all of which will eventually produce a leucine (Leu) in the protein chain. There are also six for serine (Ser). In fact there are only two amino acids which have only one sequence of bases to code for them - methionine (Met) and tryptophan (Trp).
The genetic code is read in groups of 4 bases. 2. The genetic code includes specific start and stop codons. 3. The genetic code is the same in almost all living organisms. 4. Deleting a single base from an mRNA molecule usually alters one codon only.
6.19 One feature of the genetic code is that it is degenerate.
a) The primary structure would be unchanged because the disease is caused not by a mutation, but rather by misfolding of the prion protein. Secondary structure is affected and is likely to lead to an altered tertiary structure b) If a genetic mutation led to an amino acid substitution, it would affect the primary structure. A particular amino acid substitution could make it more susceptible to being misfolded and lead to changes in secondary and tertiary structures
a) 70S prokaryotic ribosome has a 30S small subunit containing 16S rRNA and 20 different proteins, and a 50S large subunit and 34 proteins. The larger 80S eukaryotic ribosome has a 40S small subunit containing about 35 proteins and a 0S large subunit and about 50 ribosomal proteins b) Ribosomes function in translation. Initiation: small subunit and large subunit form initiation complex. Elongation: ribosome translocates one codon down the mRNA. Termination: dissociation of the two ribosomal subunits
6.22 A protein found in E. coli normally has the N-terminal amino acid sequence Met-Val-Ser-Ser-Pro-Met-Gly-Ala-Ala-Met-Ser... A mutation alters the anticodon of a tRNA from 5'-GAU-3' to 5'-CAU-3'. What would be the N-terminal amino acid sequence of this protein in the mutant cell? Explain your reasoning.
6.9 Random copolymers were used in some of the experiments that revealed the characteristics of the genetic code. For each of the following ribonucleotide mixtures, give the expected codons and their frequencies, and give the expected proportions of the amino acids that would be found in a polypeptide directed by the copolymer in a cell-free protein-synthesizing system:
6.17 A segment of polypeptide chain is Arg-Gly-Ser-Phe-Val-Asp-Arg. It is encoded by the following segment of DNA. Which strand is the template strand? Label each strand with its correct polarity (5' and 3').
6.10 Two populations of RNAs are made by the random combination of nucleotides. In population 1 the RNAs contain only A and G nucleotides (3A : 1G), whereas in population 2 the RNAs contain only A and U nucleotides (3A : 1U). In what ways other than amino acid content will the proteins produced by translating the population 1 RNAs differ from those produced by translating the population 2 RNAs?
a. increase the number of chromosomes per cell from 14 to 28
3 cells with 24 chromosomes and 1 cell with 22. b. 2 cells with 23 chr omosomes, 1 cell with 22, and 1 cell with 24.
A cell biologist examines a diploid cell from a barley plant during prometaphase of mitosis and determines that 28 chromatids are present. The role of meiosis in this plant is to (Check all that apply): a. increase the number of chromosomes per cell from 14 to 28.
c. germ-line cells. A geneticist examines the karyotype of a diploid cell from a particular species of frog and determines that 12 chromosomes are present. If a germ-line cell from this species divides by meiosis, then at the end of meiosis I each cell will have (Check all that apply.): a. 12 centromeres.
In the first generation, there would be two bands, one of light density and one of heavy density. In the second generation there would still be two bands, one of light density and one of medium density. c. In the first generation, there would be two bands, one of light density and one of heavy density.