Biology - Unit 10: Protein Synthesis

DNA vs. RNA Base pairing rules

DNA: A-T C-G

RNA: A-U C-G

DNA vs. RNA strand numbers

DNA = Double Stranded

RNA = Single Stranded

mRNA Structure

Single stranded and linear

rRNA Structure

Single Stranded and Globular

tRNA Structure

Single stranded and clover leaf

Why do we need to do Transcription?

DNA cannot leave the nucleus but the mRNA can, so an mRNA takes its place.

What is the product of Transcription?

RNA transcript

Where does transcription happen?

Euk-Nucleus

Prok-Cytoplasm

Helicase

unzips DNA

Transcription Factors

look for promoter region

Promoter Region

DNA Nucleotides sequence flag down RNA Polymerase so it can bind

TATA Box

Region where transcription begins; place where RNA Polymerase binds to DNA

RNA Polymerase

Transcribe genetic information from DNA to RNA sequence; 3’ to 5’

Complementary Base Pairing Rules

(A→U, T →A, C→G, G→C)

Termination Sequence

AAUAAA;

How quickly after the termination sequence does transcription end?

10-35 nucleotides after termination sequence

Where does translation happen?

Cytoplasm (More specifically the ribosomes)

What is the product of translation?

Proteins

How do we read and process mRNA?

Read in sets of triplets called codons

tRNA in translation

carries amino acids to ribosome based on mRNA

Anticodons

sequence at end of transfer RNA

Peptide Bonds

the bonds responsible for attaching amino acids to the polypeptide chain

Ribosomes

Big and small ribosomal subunit attach where tRNA attaches connect amino acids

5’GTP Cap

Attach to small ribosomal subunits

Small Ribosomal Subunit

Attaches to Large Ribosomal Subunit

Start anticodon

Part of tRNA that had complementary nucleotides for codon

Large Ribosomal Subunit

Attaches to Small Ribosomal Subunity

A Site

tRNA attaches here and takes amino acids from P site

P Site

tRNA from A Site moves here and P tRNA moves to next site

E Site

tRNA from P site moves here to exit

Methionine

AUG - Start codon amino acid

Stop Codon

Sequence that signals stop: UAA, UGA, UAG

Release Factor

protein that recognizes stop codon and ends translation

Point Mutations

Change only one base pair; most mutations fit under this category

Substitution definition

Swap out base pairs for a different base pair

Types of Substitution

Silent, Missense, Nonsense

Silent

Has no effect on the amino acid; inserted at wobble position

Wobble position

third base pair in codon

Missense

Change the amino acid being created (can change shape or function of entire polypeptide); 1st or 2nd base pair in codon

Nonsense

Creates a stop codon and ultimately creates a nonfunctional polypeptide

Frameshift definition

Changing the reading frame of the code

Frameshift types

Insertion and Deletion

Insertion

Nucleotide is added to the gene and changes all amino acids after that; shifts reading frame to the right

Deletion

Nucleotide is removed from the gene; all amino acids change after that; shifts reading frame to the left