Protein Synthesis

What are genes?

• Gene: coded DNA instructions that control the production of protein in the cell

We can’t do anything without proteins.

Instructions for telling our bodies what to do!

Genes = Instructions

What are genes?

DNA

• ONLY found in the nucleus

PROTEIN

•Synthesized OUTSIDE the nucleus

•BUT……•Need to get instructions out of nucleus

•Instructions found in nucleotide sequence of DNA

•HOW?!?!?!

DNA vs RNA

RNA CAN move out of the nucleus to other parts of the cell

Decode DNA into RNA

DNA vs RNA3 Differences

DNA RNADouble-Stranded Single-Stranded

Deoxyribose RiboseThymine Uracil

RNA

3 Types of RNA involved in synthesizing proteins

1. mRNA (messenger RNA)

• Carries copies of instructions from DNA to other parts of cell

From nucleus to cytoplasm

RNA2. rRNA (ribosomal RNA)

Sits in ribosome and decodes mRNA into amino acids (proteins)

RNA3. tRNA (transfer RNA)•Transfers amino acids (AA)

to ribosomes

Ribosomes•Protein factory

Proteins = AA+AA+AA+AA+AA……….

Transcription (RNA Synthesis)

• Process of copying DNA nucleotide sequence into COMPLEMENTARY RNA nucleotides.

STEPS:

1. RNA polymerase attachesto area of DNA molecule.

3. RNA poly synthesizes complementary RNA nucleotides (mRNA).

2. RNA poly “opens” DNA molecule.

Transcription (RNA Synthesis)

Base Pairing Rules

Nucleotides in DNA:A T C

G

Nucleotides in RNA:A U C

G

Video

Translation (Protein Synthesis)

• Decoding mRNA molecules to make proteins (AA/polypeptides)

TRANSLATING RNA sequence into protein sequence

Occurs on the ribosome

Uses all 3 RNAs

Translation (Protein Synthesis)

Translation (Protein Synthesis)STEPS:

1. mRNA in cytoplasm attaches to ribosome.

Translation (Protein Synthesis)2. mRNA codon moves through ribosome.

Translation (Protein Synthesis)3. tRNA (anticodon) brings matching AA.

CODON

ANTIcodon

Translation (Protein Synthesis)• Stopping and Starting

START CODON = AUGSTOP CODON = UGA, UAG, UAA