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Honors Biology 2006-2007

The Structure of RNA

Honors Biology 2006-2007

Quick Review §  What do we know about DNA structure? §  What do we know about DNA function? §  What do we know about DNA replication?

Honors Biology 2006-2007

What do we know? §  DNA contains genetic information

  “transforming” factor

§  Metabolic pathways are controlled by enzymes   enzymes are proteins

§  How do we move information from �DNA to proteins?

Honors Biology 2006-2007

The “Central Dogma” §  Flow of genetic information in a cell

  How do we move information from DNA to proteins?

transcription translation

replication

protein RNA DNA trait

DNA gets all the glory,

but proteins do all the work!

Honors Biology 2006-2007

The Big Picture

Honors Biology 2006-2007

RNA is the Key! §  Traits, like eye color, are

determined by proteins that are coded in DNA.

  Our cells, however, need a “secret decoder ring” to express the code……….

  AND, we need to get the instructions on how to make the protein from the nucleus and to the ribosomes.

  ENTER: Ribonucleic Acid

(RNA)

Honors Biology 2006-2007

Protein Production §  DNA molecules provide the

instructions for making proteins

§  BUT, RNA molecules are what build the proteins based on those instructions.

  The workers for Protein Synthesis are RNA molecules.

Honors Biology 2006-2007

Honors Biology 2006-2007

RNA Structure §  RNA structure differs from DNA

structure in 3 ways:

  1. RNA is single stranded   2. RNA is composed of the sugar

Ribose   3. In RNA, a new base Uracil

replaces Thymine

Honors Biology 2006-2007

RNA Nitrogen Bases §  Both RNA and DNA contain four nitrogen bases,

but instead of Thymine, RNA contains Uracil (U)

  Uracil forms a base pair with Adenine, just as Thymine does in DNA.

§  RNA: U - A §  DNA: T - A

Honors Biology 2006-2007

DNA vs. RNA Venn DNA RNA

Honors Biology 2006-2007

Types of RNA Molecules §  3 types of RNA molecules help to build proteins:

1. Messenger RNA (mRNA): “the messenger”

–  Runs information from DNA in the nucleus to cytoplasm.

2. Ribosomal RNA (rRNA): “the builder”

–  Clamps onto the mRNA and use its information to assemble the amino acids in the correct order.

3. Transfer RNA (tRNA): “the transporter”

–  Transports amino acids to the ribosome to be assembled into protein.

Honors Biology 2006-2007

Where’s RNA?

Honors Biology 2006-2007