TODAY YOU WILL NEED Your science notebook Scissors

TODAY YOU WILL NEED: Your science notebook Scissors Glue Something to write with Please turn in your homework

PROTEIN SYNTHESIS Consists of 2 main steps Step 1: Transcription Step 2: Translation

CENTRAL DOGMA DNA Transcriptio n Translation Step 1 Step 2 RNA Occurs in the Nucleus Protein s Occurs at the Ribosome

Transcription DNA Step 1 Occurs in the Nucleus RNA

WHAT IS RNA? RNA is different from DNA in 3 ways

The sugar is Ribose instead of deoxyribose

RNA is Single stranded instead of double stranded

Thymine is replaced by Uracil How to code DNA into m. RNA In RNA • There is no Uracil Adenine Let’s make an RNA strand DNA A T G C A C m. RNA U A C G U G G C Thymine • Adanine bonds to G C Uracil T A – UA A U

Types of RNA There are 3 types of RNA: 1. Messenger RNA (m. RNA) – Carry copies of instructions for the assembly of amino acids into proteins – Serve as “messengers” from DNA to the rest of the cell 2. Ribosomal RNA (r. RNA) – Helps build ribosomes 3. Transfer RNA (t. RNA) – Transfers the amino. C 10 L 10 C 12 acid to the ribosome

STEP 2 OF PROTEIN SYNTHESIS TRANSLATION

During translation, the nitrogen bases of m. RNA tell the cell which amino acids (building blocks of proteins) are needed to build a protein (polypeptide).

m. RNA bases are read in groups of 3 called codons. Each codon codes for an amino acid. Example: RNA Strand: U C G C A C G G U Reads as: UCG – CAC – GGU (3 codons) Represents the amino acids: Serine – Histidine – Glycine

AMINO ACIDS There are only 20 different amino acids, but 64 different codon possibilities, so several codons might represent 1 amino acid. example: UCU, UCC, UCA, and UCG all code for the amino SERINE acid • There is also one codon AUG that is called the START codon because it starts protein synthesis. • There are 3 stop codons that stop protein synthesis.

LETS PRACTICE m. RNA AUG Amino Acid m. RNA GCG Amino Acid UGA GAU CCU UGC

Second Base of Codon U UUC U C Pheny lalanin e phe UUA UUG C CUA Leucin e leu CUG AUU AUC A AUG G UAU UCC UAC Isoleu cine ile Methi onine Met (start) Serine ser UAG CCU CAU CCA Prolin e pro CAC CAA CCG CAG ACU AAU ACC AAC ACA Threo nine thr AAG GUU GCU GAU GUC GCC GUA GUG Valine val GCA GCG C 10 L 10 C 12 STOP Histad ine his Gluta mine gln Aspar agine asn AAA ACG Alanin e ala Tyrosi ne tyr UAA UCG CCC G GAC GAA GAG UGU UGC Cystei ne cys Aspar tic Acid asp Gluta mic Acid glu C UGA STOP A UGG Trypt ophan trp G CGU CGC CGA U Argini ne arg CGG AGU AGC AGG Serine ser GGA GGG A U C A Argini ne arg GGU GGC C G AGA Lysine lys U Glycin e gly C A G Third Base of Codon First Base of Codon CUU CUC UCU UCA Leucin e leu A AUG START Methionine

LETS PRACTICE m. RNA AUG Amino Acid Met (Start) UGA Stop m. RNA GCG GAU Amino Acid Asp Ala C 10 L 10 C 12 CCU Pro UGC Cys

TRANSLATION During translation the m. RNA strand synthesized during transcription will be used to make a protein.

HOW IS A PROTEIN (POLYPEPTIDE) MADE? 1. The m. RNA leaves the nucleus and attaches to a ribosome C 10 L 10 C 12

HOW IS A PROTEIN (POLYPEPTIDE) MADE? 2. Translation begins at the START codon (AUG) on the m. RNA. 3. The codons in m. RNA match anticodons in t. RNA. 4. TRNA transfers amino acids to the ribosome when they are called for by the codons in m. RNA. C 10 L 10 C 12

HOW IS A PROTEIN (POLYPEPTIDE) MADE? 5. The ribosome moves down the m. RNA strand, codon by codon, and each t. RNA brings an amino acid that is added to the growing protein (polypeptide). C 10 L 10 C 12

C 10 L 10 C 12