How your cell makes proteins

2 phases:

1. Transcription

2. Translation

DNA RNA Protein

Before making proteins, Your cell must first make RNA

How does RNA (ribonucleic acid) differ from DNA (deoxyribonucleic acid)?

RNA differs from DNA

1. RNA has a sugar riboseDNA has a sugar deoxyribose

2. RNA contains uracil (U)DNA has thymine (T)

3. RNA molecule is single-strandedDNA is double-stranded

DNA Transcription DNA can “unzip”

itself and RNA nucleotides match up to the DNA strand

This process is started and controlled by an enzyme called RNA polymerase.

Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.

Question:

What would be the complementary RNA strand for the following DNA sequence?

DNA 5’-GCGTATG-3’

Types of RNA

Three types of RNA:

A. messenger RNA (mRNA)

B. transfer RNA (tRNA)

C. ribosome RNA (rRNA)

Remember: all produced in the nucleus

mRNA

Carries instructions from DNA to the ribosome.

Tells the ribosome what kind of protein to make

(1961) Watson & Crick proposed…

…DNA controlled cell function by serving as a template for PROTEIN structure.

3 Nucleotides = a triplet or CODON(which code for a specific AMINO ACID)

AMINO ACIDS are the building blocks of proteins.

DNA Translation

The cell uses information from “messenger” RNA to produce proteins

A. Messenger RNA (mRNA)

methionine glycine serine isoleucine glycine alanine stopcodon

protein

A U G G G C U C C A U C G G C G C A U A AmRNA

startcodon

Primary structure of a protein

aa1 aa2 aa3 aa4 aa5 aa6

peptide bonds

codon 2 codon 3 codon 4 codon 5 codon 6 codon 7codon 1

rRNA

Part of the structure of a ribosome Helps in protein production

tRNA

A go-getter Gets the right parts to make the right protein according to mRNA instructions

B. Transfer RNA (tRNA)

amino acidattachment site

U A C

anticodon

methionineamino acid

End Product

The end products of protein synthesis is a primary structure of a protein.

A sequence of amino acid bonded together by peptide bonds.

aa1

aa2aa3

aa4aa5

aa200

aa199

Transcription/Translation Quiz1. Why is transcription necessary?2. Describe transcription.3. Why is translation necessary?4. Describe translation.5. What are the main differences

between DNA and RNA.6. Using the chart identify the

amino acids coded for by these codons:UGGCAGUGC

1. Why is transcription necessary?Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm.

2. Describe transcription.RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA.

3. Why is translation necessary?Translation assures that the right amino acids are joined together by peptides to form the correct protein.

4. Describe translation.The cell uses information from MRNA to produce proteins.

5. What are the main differences between DNA and RNA.DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil.

6. Using the codon chart, identify the amino acids coded for by these codons: UGGCAGUGCtryptophan-glutamine-cysteine