Understanding RNA

Ribonucleic

Acid

1. Made of Nucleotides:

A

B

C

B. Phosphate Group

A. Sugar (ribose)

C. Nitrogen Bases

2. Rules for Base Pairing:

A.     Cytosine Guanine

(C G)

Notice that RNA has Uracil (not thymine)

B.     Adenine Uracil

(A U)

* helps to make protein

4. Types of RNA

A. Messenger (mRNA)

B. Transfer (tRNA)

C. Ribosomal (rRNA)

3. What is the functionof RNA?

Sugar

(ribose) Phosphate Group

Nitrogen Base

Comparing DNA & RNA

DNA RNA

Sugar is deoxyribose

Sugar is

ribose

Adenine base is present

Cytosine base is present

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DNA RNA

Guanine base is present

Thymine base is present

Uracil base is present

Shape is double helix

Comparing DNA & RNA

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Comparing DNA & RNA

DNA RNA

Shape is single stranded

Located in nucleus only

Composed of nucleotides

Stores genetic information

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Comparing DNA & RNA

DNA RNA

Helps to make proteins √

Protein Synthesis:

How Proteins are Made

Making Proteins is a Two Step

Process:

Transcription – making a mRNA copy of DNA; occurs in the nucleus

Step 1:

Why Transcription?

DNA contains volumes of information about making protein.

Unfortunately, DNA is too huge to leave the nucleus but the protein is made in the ribosomes.

Don’t Write This Slide, Just Read!!!

Summary of Transcription

A. The DNA molecule unzipsat the nitrogen bases

B. mRNA nucleotides pair upwith DNA nucleotides(one side)

Summary of Transcription

C. DNA “rezips” and mRNA

leaves the nucleus

Click Here for Transcription Animation

Translation – amino acids are being assembled into proteins; occurs in the ribosomes

Step 2:

Summary of Translation

A. mRNA enters the ribosome

B. 3 mRNA nucleotides(codons) pair up with 3 tRNA

nucleotides (anticodons)

C. amino acids are added until

the “stop” message is reached

Click Here for Translation Animation

* Codon – three mRNA bases

* Anticodon – three tRNA bases

* 1 codon makes 1 amino acid; 3 nitrogen bases makes

1 amino acid

Example:

DNA: TAC – AGG – GGT - ACG – CCG – AAT – GGG – ATT –

tRNA:

Amino

Acid:

DNA:

mRNA: – UCC – CCA – UGC – GGC – UUA – CCC – UAA - AUG

Example:

DNA: GCA – AAT- TTA

tRNA:

Amino

Acid:

mRNA: CGU – UUA - AAU

Example:

DNA: TAC – AGG – GGT - ACG – CCG – AAT – GGG – ATT –

mRNA: AUG – UCC – CCA – UGC – GGC – UUA – CCC – UAA -

Amino

Acid:

tRNA: UAC – AGG – GGU– ACG– CCG – AAU – GGG– AUU -

Example:

DNA: GCA – AAT- TTA

mRNA: CGU – UUA - AAU

GCA

Amino

Acid:

tRNA: – AAU - UUA

Use mRNA to find the Amino Acid on the Chart

Write this on the bottom of your “Chart of Amino Acids”:

  U C A G  

UPhenylalaninePhenylalanineLeucineLeucine

SerineSerineSerineSerine

TyrosineTyrosineStopStop

CysteineCysteineStopTryptophan

UCAG

C LeucineLeucineLeucineLeucine

ProlineProlineProlineProline

HistidineHistidineGlutamineGlutamine

ArginineArginineArginineArginine

UCAG

A IsoleucineIsoleucineIsoleucineMethionine

ThreonineThreonineThreonineThreonine

AsparagineAsparagineLysineLysine

SerineSerineArginineArginine

UCAG

GValineValineValineValine

AlanineAlanineAlanineAlanine

Aspartic AcidAspartic AcidGlutamic AcidGlutamic Acid

GlycineGlycineGlycineGlycine

UCAG

FirstmRNA Base

Second mRNA Base

ThirdmRNABase

Example:

DNA: TAC – AGG – GGT - ACG – CCG – AAT – GGG – ATT –

mRNA: AUG – UCC – CCA – UGC – GGC – UUA – CCC – UAA -

tRNA: UAC – AGG – GGU – ACG – CCG – AAU – GGG – AUU -

Amino

Acid:Met – Ser – Pro – Cys – Gly – Leu – Pro - STOP

Codon

Anticodon