Translation
Define mutation
a change in a sequence of bases in DNA sequence compared to the original template, caused by environment, mistakes in cell division or random location and timing
What are the nucleotide bases in DNA and RNA
DNA: adenine (A) guanine (G) Cytosine (C) and thymine (T)
RNA:adenine (A) guanine (G) Cytosine (C) and uracil (U)
Chromosomal mutation
extensive changes:Deletions, inversions and translocations
Small scale mutation v large scale
Small: Point mutations - single nucleotide (substitution, insertion/deletion)
Large:Chromosomal mutations –extensive changes
(Deletions, inversions and translocations, duplications)
Give an example of 3 enzymes from this chapter and what they do
Helicase: unwinds DNA
DNA polymerase: links new nucleotides
RNA polymerase: Unwinds DNA and adds nucleotides to RNA strand
Frameshift
frameshift mutations
- example of insertion/deletion
– alter reading frame of codons
– depends on number of nucleotides involved
Translation stage 1
Initiation: ribosome attaches at start codon on mRNA. Ribosomes + start codon and RNA establishes reading frame.
Transcription first stage
Initiation: RNA polymerase binds to sequence at promotor and signals DNA to unwind (with Helicase) so enzyme (DNA polymerase) can read DNA bases.
Why do mutations matter?
Mutation produces variance!
define Transcription
Transcription is the first step of DNA based gene expression, in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase.
1: Codon
2: reading frame
1: triplet of mRNA bases that specifies one amino acid
2: nonoverlapping three-letter words
Translation stage 2
Elongation: tRNA anticodon match with mRNA codons. Peptide bonds and amino acids are joined together.
transcription stage 2
Elongation: Rna polymerase reads DNA strand and adds complimentary RNA nucleotides to mRNA strand (As match with Us and Gs with Cs)
Explain Substitution mutations
Substitutions
Silent mutation:same amino acid
Missense mutation: amino acid replaced
Nonsense mutation: forms stop codon
define translations
translation is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called gene expression.
1) tRNA
2) mRNA
1) links information in mRNA codons with the corresponding amino acids
2) moves out of nucleus
translation stage 3
Termination: Process ends with the stop codon. Ribosomes disassembles and polypeptide is released.
Transcription stage 3
Termination: RNA polymerase crosses a stop sequence gene. mRNA strand is complete and detaches from DNA
Follow a disease through DNA process
Disease has a missence substitution mutation in DNA (Ex sickle cell a to t)
Transcription: the RNA made will create one different amino acid where there was a substitution
Translation: that nucleotide change in the RNA results in a different codon which will produce a different amino acid than what should be produced (EX sickle cell is glutamic acid codon to a valine codon)
Exon v intron
An exon is a sequence of nucleic acids that are represented in the mRNA molecule. An intron, on the other hand, is a sequence of nucleotides within the gene but are removed from the sequence before a final mRNA molecule is made.
The genetic code
Redundant and universal. Specific 3 base pair nucleotides (codons) are representing specific amino acids. It is redundant because a single amino acid may be coded for by more than one codon. Furthermore, the genetic code is nearly universal, with only rare variations reported. It is universal because the assembly of exactly the same amino acids are in nearly every organism on Earth: Bacteria, plants and you all use exactly the same genetic code.