1. Chapter 13.1 and 13.2 RNA, Ribosomes, and Protein Synthesis
Remember ribosomes???
Our goal is to learn how proteins are made.
Keep in mind – amino acids are the building blocks of proteins.
A chain of amino acids are “polypeptides” .

2. Role of RNA
Ribonucleic acid (RNA) like DNA, but the bases direct protein production.
Proteins result in phenotypic traits.
Differences b/t DNA & RNA
RNA sugar ribose not deoxyribose
RNA single strand not 2.
RNA has uracil not thymine

3. RNA molecules make proteins 3 types of RNA
1. Messenger RNA(mRNA)- carries instructions for polypeptide from nucleus to ribosomes in cytoplasm.
mRNA

4. RNA molecules make proteins - 3 types of RNA continued….
2. Ribosomal RNA (rRNA) – cell structures where proteins are assembled
3. Transfer RNA (tRNA) – carries amino acids to ribosome and matches them to the mRNA message.
tRNA mRNA rRNA

5. RNA Synthesis Making RNA happens in “Transcription”
Segments of DNA are templates to produce RNA. The bases complement each other.
Eukaryotes – happens in nucleus and moves to cytoplasm to produce protein.

6. Steps to Make RNA
1. The enzyme RNA polymerase binds to DNA during transcription and separates DNA. 1 strand is the template.
2. RNA polymerase binds to promoter regions of DNA. (START)
RNA is edited. Introns cut out, Exons are left and spliced back together to form mRNA.

7. The Genetic Code
DNA has directions for making polypeptides (aka chain of amino acids).
The order and type of amino acids in the polypeptide determine the protein.
4 bases – A,C,G,U for uracil
Code is read 3 letters at a time the word is a codon.

8. mRNA bases Amino acids Codons (3 letters read in to out) AUG =
Methionine

9. Translation
Ribosomes use the codons in mRNA to assemble amino acids to a polypeptide chain or protein.
Process of decoding mRNA to protein is “Translation”.
mRNA transcribed (transcription) in nucleus goes to cytoplasm.
On ribosome, translation begins at START codon.
Each codon attracts an anticodon aka tRNA
tRNA carries an amino acid.
Amino acids bond and move along the mRNA
Continues until reaches STOP codon and forms polypeptide and mRNA is released.

10. Translation &tRNA - anticodons

11. Molecular Basis of Heredity
Molecular biology tries to explain living organisms using molecules like DNA/RNA
Central dogma of molecular biology is info is transferred from DNA to RNA to proteins.
Instructions for making proteins are in the genes.
Gene expression is the way in which DNA, RNA, proteins are involved in putting genetic info into action in living cells.
The genetic code is generally the same in all organisms.