Transcript Understanding DNA

Understanding RNA
Ribonucleic Acid
1
. Made of Nucleotides:
Sugar (ribose),
Phosphate Group,
Nitrogen Bases
A
C
Differences Between DNA & RNA
1) Sugar –
Deoxyribose
2) Pyrimidines – Cytosine &
vs.
Ribose
vs.
Cytosine &
Thymine
Uracil
3) Shape – Double Helix
vs.
Single Strand
4) Location – Nucleus Only
vs.
Everywhere in
Cell
5) Purpose – Stores genetic Info vs. Makes Proteins
2. Rules for Base Pairing:
A.
Cytosine
(C
G)
Guanine
B.
Adenine
(A
U)
Uracil
Notice that RNA has Uracil
(not thymine)
3. What is the function of RNA?
Helps to make proteins
Types of RNA
A. Messenger (mRNA)
Reads DNA and carries message to
ribosome
B. Ribosomal (rRNA)
Component of ribosome and organizes
formation of protein
C. Transfer (tRNA)
Transfers amino acids (AA) from storage
sites in cytoplasm to ribosome for
protein production
Nitrogen Base
Sugar
(ribose)
Phosphate Group
Protein Synthesis:
How Proteins are Made
Making Proteins
is a Two Step
Process:
Click here to go to
Transcription Animation
Step 1:
Transcription –occurs in the
nucleus; rewriting DNA into mRNA
Why Transcription?
Don’t Write This Slide, Just Read!!!
 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.
 DNA is too important to cellular
function to risk damage in the
cytoplasm
Summary of Transcription
A. The DNA molecule unzips
at the nitrogen bases
B. mRNA nucleotides pair up
with DNA nucleotides; (one
side) RNA Polymerase
action
C. DNA “rezips” and
mRNA releases at
terminator sequence;
undergoes further
processing
Step 2:
Translation – amino acids
are being assembled into
proteins; occurs in the
ribosomes
Click here to go to
Translation Animation
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
* Codon – three mRNA bases
* Anticodon – three tRNA bases
* 1 codon makes 1 amino acid;
3 nitrogen bases makes
1 amino acid
Example:
DNA: GCA – AAT- TTA
mRNA: CGU – UUA - AAU
tRNA:
Amino
Acid:
Example:
DNA: GCA – AAT- TTA
mRNA: CGU – UUA - AAU
tRNA: GCA – AAU - UUA
Amino
Acid:
Write this on the bottom of
your “Chart of Amino Acids”:
Use mRNA to find
the Amino Acid
on the Chart
Second mRNA Base
U
A
G
Phenylalanine
Phenylalanine
Leucine
Leucine
Serine
Serine
Serine
Serine
Tyrosine
Tyrosine
Stop
Stop
Cysteine
Cysteine
Stop
Tryptophan
U
C
A
G
C
Leucine
Leucine
Leucine
Leucine
Proline
Proline
Proline
Proline
Histidine
Histidine
Glutamine
Glutamine
Arginine
Arginine
Arginine
Arginine
U
C
A
G
A
Isoleucine
Isoleucine
Isoleucine
Methionine
Threonine
Threonine
Threonine
Threonine
Asparagine
Asparagine
Lysine
Lysine
Serine
Serine
Arginine
Arginine
U
C
A
G
Valine
Valine
Valine
Valine
Alanine
Alanine
Alanine
Alanine
Aspartic Acid
Aspartic Acid
Glutamic Acid
Glutamic Acid
Glycine
Glycine
Glycine
Glycine
U
C
A
G
U
First
mRNA
Base
C
G
Third
mRNA
Base
Example:
DNA: TAC – AGG – GGT - ACG – CCG – AAT – GGG – ATT –
mRNA: AUG – UCC – CCA – UGC – GGC – UUA – CCC – UAA -
tRNA:
Amino
Acid:
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:
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 Methioine – Serine – Proline – Cysteine – Glycine
Acid:
– Leucine – Proline - STOP
Anticodon
Codon