Foundations of Biology Exam 4: Gene Expression III- Translation and Mutations

initiation of translation

the tRNA attaches to the AUG codon (methionine) and calls over for the large subunit of rRNA to bind to the mRNA strand

methionine

the first amino acid coded for in translation is ___________

elongation of translation

the second charged tRNA enters the A site; the large subunit of rRNA catalyzes peptides bod between the amino acids; when the first tRNA has released its methionine, it moves to the E site and dissociates from the ribosome

termination of translation

a stop codon enters the A site; release factor (protein) binds to stop codon and ribosome falls off mRNA transcript

release factor

a protein that binds to a stop codon at the A site; causes the ribosome to fall off the mRNA transcript

phosphorylation

a possible protein modification after synthesis; added phosphate groups alter the shape of the protein

glycosylation

a possible protein modification after synthesis; adding sugars is important for targeting and recognition

proteolysis

a possible protein modification after synthesis; cleaving the polypeptide allows the fragments to fold into different shapes

mutation

change in the structure or sequence of DNA

somatic mutations

occur in body cells; they have consequences for the phenotypes of an individual but are not passed to offspring

germ line mutations

occur in gametes; are passed to offspring and can have consequences for further generations

silent

a mutation that does not affect protein sequence; a change in the DNA bases, but the amino acid stays the same

missense

a mutation that swaps a DNA base for another; results in a different amino acid being coded for

conservative missense

a missense mutation where the chemical property of the new amino acid is the same as the original; can have similar chemical interactions as the original amino acid

non-conservative missense

a missense mutation where the chemical property of the new amino acid is different from the original; cannot have similar chemical interactions as the original amino acid

nonsense

a mutation where the amino acid coded for is changes to a stop codon; translation is ended early

frameshift

addition or deletion of a DNA base; changes how the mRNA is read; shifts the reading frame; can have more significant effects on the final protein depending on where the mutation occurs

impacts of mutations

- alternative splicing does not occur as it should

- TFs bind outside of the protein coding region