chapter 17: from gene to protein

mRNA synthesis led by DNA

polypeptide synthesis led by mRNA

used to copy DNA code

DNA sequence that duplicated itself during mRNA synthesis

DNA strand with a base sequence similar to that of RNA transcript

proteins that assist with binding between RNA polymerase and transcription initiation

cap on the 5’ end of an mRNA strand after transcription

sequence of A nucleotides on the 3’ end of the mRNA strand after transcription

structure of a singular mRNA strand being fed through multiple ribosome at once. this allows for multiple copies of the same polypeptide to be made at once

something that can cause mutations in DNA/RNA strand

• a metabolic pathway is the step-wise synthesis or break-down of molecules

• this relates to genes and proteins because genes are copied and step-wise created into proteins.

• exposed different bread mold to x-rays to destroy different genes in the bread mold used to synthesize a protein

• resulted in the bread molds each producing different variants of a protein, each being dysfunctional

• idea of “one gene-one enzyme” emerged

now become “one gene-one polypeptide”

dna > rna > protein

• RNA has U instead of T

• RNA can code for proteins

genetic code is a span of DNA which consists of 3 nucleotides coding for 1 amino acid.

set of 3 nucleotides which code for amino acids

• in prokaryotes, once the mRNA is made, translation immediately begins without any further modification

• prokaryotes have a terminator. eukaroytes have polyadenylation signal

• prokaryotes have no nuclear envelope so transcription and translation occur in same place

tells polymerase when to begin coding and when to stop coding

• consists of RNA polymerase 2 and transcription factors bound to promoter

• only in eukaryotes

• occurs at ends of primary transcription

• 5’ end gets cap and 3’ gets poly-A tail

• some interior parts are cut out or spliced together

intron: non-expressed region of a code

exon: coding-region which can be eventually expressed

introns being removed and exons being spliced together

catalytic RNA molecule used in RNA splicing

• consists of snRNPs, snRNA, and proteins

• removes introns and splices exons together

some genes code for different versions of polypeptides depending on what is classified as intron or exon during splicing

• exons brought over from different sequence or exons are duplicated

• results in new genes

• sequence of amino acids on one end of a tRNA molecule that base pairs with a mRNA codon

• located at bottom of tRNA

• aminoacyl-RNA. it corrects tRNA and amino acid match

• ATP

3’ end

• consists of large and small subunit, composed of rRNA.

• facilitates copying of tRNA and mRNA

• proteins, small and large subunit

• GTP used

• E: exit site for tRNA

• A: holds tRNA that has the next amino acid for protein

• P: holds the growing chain and tRNA

amino end

• folding

• attaching sugars, lipids, phosphate groups, etc.

has a protein “address label”

• signal peptide: bonds to peptides destined for ER or excretion

• particle: binds to signal peptide and brings it to ER

chemical changes in one base pair

a change in the code that still results in a protein, but not the right one

change in code that doesn’t make a functional protein

change in code which doesn’t affect the protein

base-pair

change in code where the entire code is read in a different way, causing the entire protein to be changed rather than just one amino acid