DNA, RNA, and Protein Synthesis

Ch 12 section 3

A. Learning Goals

1. Tell how DNA differs from RNA

2. Describe the role of the ribosome during protein synthesis.

3. Compare and contrast Transcription and translation

4. Break down the Genetic Code…from

DNA TACCGATCATGGATT

A. DNA: Deoxyribonucleic Acid Double strand of nucleotides, called

double helix. Each nucleotide consist of 1.

deoxiribose sugar 2. phosphate and 3. base

Basis are adenine, guanine, thymine, cytosine.

DNA is a genetic library, the original blueprints!!

Discovered by Watson and Crick DNA From The Beginning

B. RNA- Ribonucleic acid

Single strand of nucleotides Each nucleotide consist of

1. Ribose sugar2. A phosphate group 3.

Nitrogen base Uracil instead of thymine !!!!! U and A, C and G

*RNA is a working copy of DNA

C. Base Pairing: Chargoff’s Rules In DNA… Adenine always pairs with Thymine Cytosine always pairs with Guanine Question: If you have 5673 cytosines in a strand of

DNA, how many guanines will you have? Answer: 5673 In RNA… Thymine is replaced by Uracil DNA TACATTGACCGATT RNA AUGUAACUGGCUAA

D. Central Dogma for Protein Synthesis…The Big Idea!!! Protein synthesis… the making of proteins

by putting Amino Acids together!

transcription translation

Dna Rna protein

Nucleus cytoplasm ribosome

E. Three types of RNA

1. Messenger RNA, mRNA: carry message with instructions for making proteins.Every three bases makes a codon. Ex. AAG

2. Ribosomal RNA, rRNA: part of the ribosome, proteins are assembled here.

3. Transfer RNA, tRNA; transfers amino acid to the ribosome as it is read by mRNA. Every three bases make one anticodon

Ex. UUC

F. Transcription: making a copy of the original message (like taking notes) Start ( ) and stop signals ( ) direct

beginning and end of note taking. mRNA make a summary: it takes out the info

that does not code for proteins . Introns are junk DNA!

It keeps the exons which will code for proteins. Exons yes, introns no!

animations

G. TRANSLATION: making sense of the genetic language mRNA codons are transcribed in nucleus, exits to

cytoplasm to attach to ribosome. tRNA brings the anticodon with the right amino acid

to the ribosome. The Amino acid is added to the polypeptide chain.

Ex. DNA AGCTTA mRNA UCG-AAU ( each 3 are a codon) tRNA AGC-UUA (each 3 are an anticodon) amino acid serine aspargine protein ser-aspanimations

H. Proteins

Can be from 2 to ____ amino acids long. There are 20 types of amino acids Your DNA codes for proteins. These

proteins contribute to how you look and how you function.

Can very in the sequence (order) and in the number of amino acids!!

Race the Cell