Download Messenger RNA

DNA
What is DNA?
DNA stands for deoxyribonucleic acid
It stores all of our genetic
information
It’s function is to tell the cell what
proteins to make and when to make
them.
Remember: it is the brain of the cell.
Who Discovered It?
First identified in 1868 by
Friedrich Miescher but he
didn’t know what it’s job
was.
Then in 1953, James
Watson and Francis Crick
figured out the molecular
structure of DNA.
The shape was called a
double-helix
They won the
Nobel Prize in 1962
Structure of DNA
It has 3 parts making a
nucleotide. (sugar, P’s, and N
groups)
It looks kind of like a ladder.
The sides are made of alternating
sugar and phosphate groups (P)
The steps are made of nitrogen
groups that pair together
The ladder isn’t straight, it has
a twisted shape called a double
helix.
Structure of DNA
Nitrogen-containing bases
There are only 4 found in DNA
1 ______
2 _____
3 ______
Complementary base pairing
4 ______
A-T will pair up and C-G will pair up using hydrogen
bonding
Characteristics of DNA
There are very strong bonds between
the sugar (deoxyrobse) and the
phosphates
Weak hydrogen bonds are holding the
nitrogen groups (A to T and C to G)
So, the rails of the ladder are fairly
strong but the steps can be easily
separated.
DNA Replication
1. The 2 chains unwind and separate.
2. An enzyme call helicase unzips the chain
and move up the chain to help it separate
by breaking Hydrogen bonds between the
A,T,C and G’s
3. Meredith Heth is awesome
4. Another enzyme call DNA polymerase
binds to the chain and identifies and
locates the unpaired A,T,C and G’s to help
assemble the new chain. (The Copy)
D = the sugar
P = phosphate group
So you end up
with 2 copies of
the DNA.
Then polymerase
proofreads the
nucleotides for
mistakes and cuts
any part that is
incorrectly
matched.
Practice
What is the compliment?
ATCATGGC
TAGTACCG
How to Make a Protein?
Pathway to Making a
Protein
DNA
mRNA
tRNA (ribosomes)
Protein
DNA  RNA  Protein
Nuclear
membrane
DNA
Transcription
Eukaryotic
Cell
Pre-mRNA
RNA Processing
mRNA
Ribosome
Translation
Protein
Transcription
DNA  RNA
What is RNA?
Ribonucleic acid
Its job is to take information from
the DNA and bring it to the
ribosomes in the cytoplasm.
DNA is the MASTER PLAN
RNA is the BLUEPRINT of
the Master Plan
DNA vs. RNA
DNA
RNA
Deoxyribose sugar Ribose Sugar
Nucleotide
Nucleotide
Thymine
Uracil
Double Helix
Single Strand
.
Three Types of RNA
Messenger RNA (mRNA) copies
DNA’s code & carries the genetic
information to the ribosomes
Ribosomal RNA (rRNA), along with
protein, makes up the ribosomes
Transfer RNA (tRNA) transfers
amino acids to the ribosomes where
proteins are synthesized
Messenger RNA
Long Straight chain
of Nucleotides
Made in the Nucleus
Copies DNA & leaves
through nuclear
pores
Contains the
Nitrogen Bases A, G,
C, U ( no T )
Transcription
The DNA uncoils and copied.
mRNA copies the template strand of DNA
with the enzyme RNA Polymerase
RNA Polymerase bind to one side of the
DNA template at the promoter site.
When the enzyme gets to the terminal signal,
it comes off of the DNA and transcription
has stopped
Template Strand
http://wwwclass.unl.edu/biochem/gp2/m_biology/animation/
gene/gene_a2.html
Practice Question
Transcribe the following sequence to
show the resulting mRNA.
ATGATTCGT
UACUAAGCA
Translation
RNA  Proteins
Protein Synthesis
Translation is the process of decoding
mRNA into Protein (or polypeptide
chains)
Proteins are the physical display of your
genetic information or DNA.
Ribosomes read mRNA three bases or 1
codon at a time to construct the proteins
Start codons= translation to
starts(AUG)
Stop codons = translation to stop
(UAA, UAG, UGA)
Translation
Once mRNA is made, it leaves the nucleus
and moves to the ribosome.
The mRNA is attached to the ribosome
Finds a start codon. AUG
The tRNA brings a specific amino acid at
one end and has an anticodon
(complementary to the mRNA) on the
other.
Each tRNA brings an amino acid that
binds together to form a protein.
Translation
Translation occurs in 3 parts:
Initiation-mRNA attaches to ribosome
Elongation-tRNA bring specific amino
acids that match with mRNA building the
polypeptide chain
Termination-mRNA detaches from
ribosome and protein is finishes
assembling.
http://wwwclass.unl.edu/biochem/gp2/m_biology
/animation/gene/gene_a3.html