Download Nucleic Acids (DNA & RNA

What is
DNA?
Where do we find DNA? In the nucleus
What the heck is it?
Why is it soooooooooo important?
Cell
DNA
Nucleus
Chromosome
Nucleotide
Nucleic Acid
Hint… It’s SUPER IMPORTANT and Mz. C. will be mentioning it
over and over and over and… you get the picture!
What do ALL of these organisms
have in common?
WE all share a universal
genetic code: DNA
How do we know what DNA
looks like????
•Rosalind Franklin
•Chemist…
•Used X-Rays and was able
to get two photos of
crystallized DNA
•Watson and Crick used
the X-ray data Franklin
obtained to figure out the
3-D structure of DNA
•Died before she was 38...
(due to Cancer caused by
Radiation Poisoning)
Watson & Crick
•1953
•Watson & Crick
used Rosalind's
X-Rays to figure
out the structure
of DNA…
•(Did they give
her any credit???
NAH… not until
later!)
What they “Announced”
•Using Rosalind X-Rays, Watson & Crick
determined that phosphates and sugars
were on the “outside” of the DNA molecule
and nitrogen bases were on the “inside”
•They also figured out that DNA is a double
helix…
•Rosalind figured out that DNA was in a
helical shape… but… didn’t get any further
details
• What’s a helical shape? Let’s talk
helicopters… and screws…!
Helix = Spiral
Helical screw…
Helical spring…
Helical staircase…
Helic-opter…
Helical drill…
DNA
Purpose of DNA
DNA is one of “THE BIG
FOUR” Organic Macromolecules (a Nucleic Acid)
Deoxyribonucleic Acid
Why do we have DNA?
It is our genetic information
• The “code” for all of our
traits/characteristics!
It gives each cell it’s
“instructions”
Nucleic Acids…
sugar
2 Types:
 DNA & RNA
Nucleic Acid is a
Polymer
 Nucleotides are the
monomers
Stores genetic
information (genes)
Gives instructions to
make proteins
 One gene=One protein
phosphate
nitrogen
base
What is a Nucleotide?
3.
1.
1. Phosphate Group
2. 5-Carbon Ribose Sugar
2.
O
O
P
O
3. Nitrogen Base
3.
1.
2.
O
C H2
C H3
C
O
CH
HC
C H CH
HO H O
O
C
CH
N
N
C
O
H
Three “Similar” Parts
One phosphate group
Bonded to
One sugar (ribose)
To make the “side” of the ladder
One nitrogen base
Makes the “rungs” (steps) of the
ladder
•There are different Nitrogen bases
• DNA & Genes
Different Nitrogen Bases
There are four nitrogen bases in DNA
(making up four different nucleotides)
Adenine
A
Guanine
G
Thymine T
Cytosine C
Nucleotide Bonding
Nucleotides are bonded
together in alternating
sugar and phosphate
groups
•The “Backbone”
This creates a long chain
with nitrogen bases
sticking off of the side
Making the DNA
Ladder
• Two chains line up next to each
other...
• The Nitrogen bases bond
together in the center to hold the
two chains together like a
“zipper”
• The bases are held by Hydrogen
bonds
 The Nitrogen bases only bond in
“Complementary Pairs”!
DNA: Double
Stranded (Helix)
• The Nitrogen bases bond
in the center of the
“Ladder”
• The ladder then “twists”
into a helix
• The tighter it “twists”,
the more “condensed” it
becomes
Which means it is more
dense and compact
DNA DOUBLE HELIX
ladder
shaped
molecule
Erwin Chargaff
Chargaff discovered that DNA contains
the same amount of adenosine as
thymine (A-T) and the same amount of
cytosine as guanine (C-G).
A
AA
A
A AA
T
TTTT
TT
C
CC
ALL THUGS CARRY GUNS!
G
G G
Chargaff’s Base Pair Rules
Adenine always bonds with Thymine. A = T
A
T
DNA: All Thugs Carry Guns
G
C
Cytosine always bonds with Guanine. C = G
Pairing DNA Nucleotides
a the
nucleotide?
What What
wouldisbe
the
base
complementary
pairing rule?
nucleotide pairing for these strands?
Nucleotide
Rule:
A with T
C with G
P
S
N-b
DNA
•DNA is the “instruction manual” (the “recipe
book”) which tells the cell what proteins to
make
•But, DNA is “stuck” in the nucleus
•It is too large to pass through the nuclear
membrane
•Which organelle makes proteins?
•__________________
•How do the instructions get from the
nucleus to the Ribosome???????
RNA – Ribonucleic Acid
Small, Single Stranded COPY of the DNA
message
Copy of ONE GENE
RNA is small enough to pass through the
nuclear membrane and bring the message
to the Ribosome in the cytoplasm
3 differences from DNA
This allows the organism to recognize that
the RNA is NOT the original!
DNA vs. RNA
RNA is Ribonucleic Acid – DNA is
Deoxyribonucleic Acid
An Oxygen molecule is missing… making
it “Deoxy”…
RNA is a short, single stranded copy
DNA is large, double stranded orginal
RNA contains a different Nucleotide!
Uracil (Not Thymine)
Remember: ALL UNDERACHIEVERS CAN'T GRADUATE
Rules for RNA Base Pairing
C=G
DNA
C
G
A
U
G
C
T
A
RNA copies the DNA
message by pairing
with the DNA
nucleotides… An “A”
is paired with a “U”.
“C” and “G” are
always paired
together…
A=U
ALL
UNDERACHIEVERS
CAN’T GRADUATE!
RNA
What is the function of RNA?
Carries the DNA coded message
out of the nucleus
RNA copies the information for one
gene
One gene = One protein
Brings message to the Ribosome
Ribosome reads the code and
makes the correct protein
Types of RNA
There is only ONE Type of DNA
There are THREE Types of RNA
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
You only need to know two!
RNA
Nitrogen Base
Phosphate
Group
Sugar
(Ribose)
RNA Codes for
Amino Acids
The nitrogen bases in
RNA code for amino acids
Monomers of Protein
A triplet of nitrogen bases
codes for one amino acid
The triplet is called a
“codon”
(You NEED to know that!)
DNA vs RNA
DNA
RNA
Nucleic Acids
RNA to Polypeptide
•The Scientific Name for Protein is:
Polypeptide
- Because peptide bonds hold
Amino Acids together
•The Ribosome reads each “codon”
(triplet code) and calls for different
Amino Acids to be bonded in the chain
•Think “CAN of PEPSI”
Peptide Bond
C
N
Overall process of protein
synthesis
translation
transcription
DNA
RNA
Protein
What does a chain of amino acids
represent?
- a protein!
Threonine
Asparagine
Arginine
Glycine
Proline
Proline
Glycine
Polypeptide Chain – A Protein
Alanine
Codons
One codon codes for one amino acid.
EX: ACG = amino acid (threonine)
CGC = amino acid (arginine)
GGA = amino acid (glycine)
Threonine
ACG
Amino Acid
Asparagine
AAC
CGC
Arginine
Glycine
GGA
Proline
CCG
Alanine
GCC
Proline
CCA
Glycine
GGC
protein
A sequence of amino acids is a protein... A
different sequence makes a different protein!
Let’s Try It…
• DNA “Complementary
Pairs”
• Remember:
• All Thugs
• Carry Guns
Let’s Try It…
• RNA “Complementary
Pairs”
• Remember:
• All Underachievers
• Can’t Graduate