Download Nucleic Acids

Nucleic Acids
What are they ?
The 4th type of
macromolecules
The chemical link between
generations
The source of genetic
information in chromosomes
What do they do ?
Dictate amino-acid
sequence in proteins
Give information to
chromosomes, which is then
passed from parent to
offspring
What are they made of ?
• Simple units called nucleotides,
connected in long chains
• Nucleotides have 3 parts:
1- 5-Carbon sugar (pentose)
2- Nitrogen containing base
(made of C, H and N)
3- A phosphate group ( P )
• The P groups make the links that
unite the sugars (hence a “sugarphosphate backbone”
Nucleic Acids
1. Are the genetic material
2. DNA = Deoxyribonucleic acid
3. RNA = Ribonucleic acid
4. Are polymers of nucleotides
5. A nucleotide consists of three
parts :
- a pentose(5C-sugar)
- a phosphate
- a nitrogenous base
Types of N.A.
(depending on the sugar they
contain)
1- Ribonucleic acids (RNA)
The pentose sugar is Ribose
(has a hydroxyl group in the
2nd carbon---OH)
2- Deoxyribonucleic acids (DNA)
The pentose sugar is
Deoxyribose (has just an
hydrogen in the same place-H)
Deoxy = “minus oxygen”
MICROMOLECULE:
(monomer)
Nucleotide
MACROMOLECULE:
(polymer)
Nucleic acid
1. RNA
2. DNA
Anatomy of Nucleotide
I. Phosphate group (always the same):
O
OH
P
O~
OH
OR
P
II. SUGAR=5 CARBON
(PENTOSE)
A. RIBOSE (USED IN RNA)
B. DEOXYRIBOSE (USED IN DNA)
-OH REMOVED AT CARBON 2’
O
O
1’
1’
2’
OH
OH
RIBOSE
2’
OH
DEOXYRIBOSE
III. BASES
1.
2.
3.
4.
5.
ADENINE
GUANINE
THYMINE
CYTOSINE
URACIL
PURINES (Double Ring)
PYRIMIDINES (Single Ring)
Nitrogenous Bases
1. Compounds that contain nitrogen
2. Two types:
- pyrimidines (single ring bases)
- purines (double ring bases)
PYRIMIDINES
PURINES
COMBINATIONS OF FIVE
DIFFERENT BASES
• DNA USES
THYMINE*
GUANINE
CYTOSINE
ADENINE
BASE PAIRS
T+A=2 H-BONDS
G+C=3 H-BONDS
• RNA USES
URACIL*
GUANINE
CYTOSINE
ADENINE
BASE PAIRS
U+A=2 H-BONDS
G+C=3 H-BONDS
Single-strand of a Nucleic Acid
1. Consist of a polymer of nucleotides.
2. Joined by phosphodiester linkages.
P
A
T
G
S
P S
P S
C
P S P
Double-stranded DNA
1. Will be discussed in detail later in the course
GENETICS. (TWISTED LADDER=DOUBLE HELIX)
2. DNA=2 CHAINS OF NUCLEOTIDES SIDE
BY SIDE H-BONDED TOGETHER AT
BASES
The Double Helix (DNA)
Structural model:
• Model proposed by Watson & Crick, 1953
• Two sugar-phosphate strands, next to each
other, but running in opposite directions.
• Specific Hydrogen bonds occur among bases
from one chain to the other:
A---T
,
C---G
Due to this specificity, a certain base on
one strand indicates a certain base in the
other.
• The 2 strands intertwine, forming a doublehelix that winds around a central axis
Chargraff’s Rule:
• Adenine and Thymine
always join together
A
T
• Cytosine and Guanine
always join together
C
G
16
DNA Nucleotides
Composition (3 parts):
1- Deoxyribose sugar (no O in 2Nd
carbon)
2- Phosphate group
3- One of 4 types of bases (all
containing nitrogen):
- Adenine
- Thymine (Only in DNA)
- Cytosine
- Guanine
How DNA Works
1- DNA stores genetic information in
segments called genes
2- The DNA code is in Triplet Codons
(short sequences of 3 nucleotides
each)
3- Certain codons are translated by
the cell into certain Amino acids.
4. Thus, the sequence of nucleotides in
DNA indicate a sequence of Amino
acids (Primary Structure) in a
protein.
RNA Nucleotides
Composition ( 3 parts):
1- Ribose sugar (with O in 2’carbon)
2- Phosphate group
3- One of 4 types of bases (all
containing nitrogen):
- Adenine
- Uracil (only in RNA)
- Cytosine
- Guanine
DNA vs RNA
• DNA
1- Deoxyribose sugar
2- Bases: Adenine, Thymine, Cytosine,
Guanine
3- Double-stranded helix arrangement
• RNA
1- Ribose sugar
2- Bases: Adenine, Uracil, Cytosine,
Guanine
3- Single stranded
How does DNA make a
Protein?
• Transcription - RNA is made from DNA
• Translation - Proteins are made from the
message on the RNA
DNA->transcription->RNA->translation->protein
•
Messenger RNA (mRNA) is the blueprint for construction of a protein.
•
Ribosomal RNA (rRNA) is the construction site where the protein is made.
•
Transfer RNA (tRNA) is the truck delivering the proper amino acid to the site
at the right time.
ATP
1. Adenosine triphosphate
2. Is a nucleotide.
3. Involved with energy currency of the cell.
4. MOST IMPORTANT NUCLEOTIDE
THE ENERGY TRANSFER MOLECULE
MONEY OF ALL LIVING THINGS
5. 3 PHOSPHATES-RIBOSE SUGAR-ADENINE BASE
ATP/ADP/AMP—LIKE
NICAD(battery) THEY CAN BE
RECHARGED
ENERGY + P + P
ATP
FULLY CHARGED
AMP
RUN DOWN
P
ADP
PARTIAL CHARGE
P
MITOCHONHDRIA IS THE RECHARGER-THEY ADD PHOSPHATES BACK ON
OTHER INFO:
•
•
•
NAD &FAD ARE ALSO NUCLEOTIDES
(COENZYMES)
Review of NUCLEIC ACIDS
MACROMOLECULES
•
•
•
•
•
RNA=RIBONUCLEIC ACID
DNA=DEOXYRIBONUCLEIC ACID
LONG CHAINS OF NUCLEOTIDES HOOKED
TOGETHER BY CONDENSATION REACTIONS.
DNA=MILLIONS OF NUCLEOTIDES
RNA=millions but shorter than DNA(piece of dna)