Biology

Unit 6 Notes:RNA &

Protein Synthesis

(1) What is Protein Synthesis?•The process of using the “code” in DNA to make proteins.

•Happens in 2 parts:•Transcription•Translation

(2) Molecules & Locations• In the Nucleus:•DNA•mRNA

•Outside the Nucleus:•mRNA• tRNA•rRNA•Amino Acids

(3) What is RNA?• A type of nucleic acid (like DNA).

• RNA Nucleotides are made of:• Phosphate• Ribose Sugar• Nitrogenous Base

• The 4 Types of RNA Bases are:• Adenine (A)• Uracil (U)• Guanine (G)• Cytosine (C)

• RNA is 1 single spiraling strand.

(4) What happens in Transcription?•The “code” from DNA is transcribed (or copied) onto a molecule of mRNA (messenger RNA).

•The cell matches up the bases from a strand of DNA, with RNA nucleotides to make the strand of messenger RNA.•No T’s (thymine)•Any place you would normally put a T, you put a U (for uracil)

in RNA.

(5) Transcription Example•A strand of DNA has the following base sequence:

T A C - G G C - A T C

•Write out the matching bases for the strand of mRNA:

(6) What happens in Translation?•The copied code on messenger RNA is used to sequence Amino Acids and make a protein.•mRNA leaves the nucleus.• Every 3 bases on mRNA matches up with a specific tRNA

(transfer RNA).• Each specific tRNA brings in (or transfers) in a specific Amino

Acid.•All parts move through the rRNA (ribosomal RNA) unit.•Amino Acids connected at the end to make a protein.

(7) Translation Example•A strand of mRNA has the following base sequence:

AUG - CCG - UAG

•Write out the matching amino acids:

(8) Codons & Anticodons•A codon is:3 bases on messenger RNA.

•An anticodon is:3 bases on transfer RNA.

•The codons on mRNA and the anticodons on tRNA must match up to bring in the correct amino acid sequence.

(9) Mutations•A mutation is when there’s a change to 1 or more bases in DNA.

•Can be caused by: Genetics, random error, chemicals, radiation.

•When the DNA bases change, the mRNA bases change.This brings in the wrong tRNA and Amino Acid.This makes the wrong protein.