RNA

Review of DNA

DNA is a double Helix that is a code for something What? Structure/Shape explains how it is replicated, but

not how genes work. Helicase and DNA Polymerase Chargaff’s Rule Nucleotide

5 Carbon Sugar (Deoxyribose), Phosphate and Nucleic Acid (Guanine, Cytosine, Adenine, Thymine)

First Step in Decoding Messages: Copy DNA (Deoxyribonucleic Acid) into

RNA (Ribonucleic Acid) Note: “Deoxyribo” in Deoxyribonucleic Acid

is in reference to the 5-Carbon Sugar in the backbone of the molecule Deoxyribose

So what do you think the 5-Carbon Sugar is in the backbone of Ribonucleic Acid? Ribose

Differences (Between DNA and RNA)

DNA RNADeoxyribose RiboseDouble Stranded Single

StrandedThymine Uracil

RNA is a disposable copy of DNA 3 Types of RNA

mRNA Messengers – they carry copies of the

instructions for proteins. (From Nucleus to Ribosome)

rRNA Ribosomal – where the proteins are assembled.

Reminder: Ribosomes are made up of protein and RNA

tRNA Transfers each amino acid to the ribosome

How is a copy made?

Transcription “Transcribe” or write a code Only 1 strand is made!

RNA Polymerase Separates DNA strands (at Hydrogen bonds) and acts as

“Police” in creating the mRNA

Where does it start? There are “start sites” called Promoters

Just like promoters for events let people know what is going on.

Introns “Extra” parts that are cut out of the final mRNA strand.

Exons “Good” parts that are spliced together to make the final mRNA strand

Codons 3 (consecutive) nucleotides long Each one specifies for one of 20 amino acids 64 different codons

Special Codons:

Start Codon: AUG Stop Codons: UAA, UAG, UGA

Translation

“Translates” from one language to another Creates a chain of amino acids

Known as a protein. It is the process of translating codons

(mRNA) by using anti-codons (tRNA) into the amino acids they code for (which makes proteins) Occurs at the Ribosomes

Anti-codons are complementary to codons

Translation

Can you identify the following:1. mRNA2. Codon3. Anti-Codon4. Amino Acid5. Protein

What is the big picture?

DNA is the Master Plan Remains safe in the nucleus

mRNA is the Blueprint Disposable copy

rRNA is the Building site tRNA are the builders

Workers that make the proteins (amino acid chains)

DNA makes proteins and proteins express genes!

Mutations

Changes in the letter sequence of the DNA Chromosomal

Whole chromosome has been changed Change in the number of chromosomes or

their structure. Gene

Single gene change (one or more letters) Two types

Point Frameshift

Point Mutation

One nucleotide changes – May change the Amino Acid it codes for (and it may not)

Frameshift Mutation

Typically makes the entire protein not useable.

Deletion Removal of one or more

Nucleotides Insertion

Addition of a Nucleotide

Frameshift Mutation (Continued)

http://www.youtube.com/watch?v=4PKjF7OumYo