Download Nucleic Acids

James Watson and Francis Crick
are credited with discovering the
structure of DNA in April 1953
Nucleic Acids
• Function:
– genetic material
• stores information
– genes
– blueprint for building proteins
» DNA  RNA  proteins
DNA
• transfers information
– blueprint for new cells
– blueprint for next generation
proteins
Nucleic Acids
• Examples:
– RNA (ribonucleic acid)
• single helix
– DNA (deoxyribonucleic acid)
• double helix
• Structure:
– monomers = nucleotides
DNA
RNA
Nucleic Acids
Function: carry hereditary info
DNA
•Double stranded helix
• N-bases: A, G, C,
Thymine
•Stores hereditary info
•Longer/larger
•Sugar: deoxyribose
RNA
•Single stranded
• N-bases: A, G, C, Uracil
•Carry info from DNA to
ribosomes
•tRNA, rRNA, mRNA
•Sugar: ribose
Nucleic Acids
• Two types
– Deoxyribonucleic Acid (DNA)
– Ribonucleic Acid (RNA)
• DNA is the genetic material inherited
from parent to offspring
• The DNA molecule usually consists of
hundreds or thousands of genes
• DNA carries the information to make
proteins
How Does DNA Direct The
Formation of Proteins?
DNA → RNA → Protein
1. From the DNA Template, mRNA is
made
2. mRNA then travels from the nucleus to
the ribosome
3. At the ribosome, tRNA “reads” the
code on the mRNA and assembles the
amino acids
4. The long sequences of amino acids
form polypeptides which form proteins
Nucleotides
• Nucleic Acids = polymers
• Nucleotides = monomers
• Nucleotides consist of a nitrogenous
base, a pentose (5-carbon sugar), and
a phosphate group
• Two types of nitrogenous bases
–Pyrimidines
–Purines
Pyrimidines
• Six-membered ring of nitrogen and
carbon atoms
• Includes Cytosine (C), Thymine (T) – only
in DNA, and Uracil (U) – only in RNA
Purines
• Six-membered ring fused to a Fivemembered ring.
• Includes Adenine (A) and Guanine (G)
Nucleotide
• DNA’s sugar is
deoxyribose
• RNA’s sugar is
ribose
DNA Replication
• DNA is two-stranded forming a double helix
Nucleotide
Phosphodiester
bonds
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
DNA Base Pairing Rules
• Each "Rung" of the DNA "staircase" is formed by the linking of
2 Nucleotides through Hydrogen Bonds.
• These Hydrogen bonds form only between specific Nucleotides.
This is known as Base Pairing. The rules are as follows:
– Adenine (A) will ONLY bond to Thymine (T)
– Cytosine (C) will ONLY bond to Guanine (G)
ATCGAGGTGCATGCTGATGCTGAT
TAGCTCCACGTACGACTACGACTA
DNA
Replication
Summary of DNA Structure
Phophodiester bonds-linkage of OH group from 3’
Carbon to a phosphate of next group
Hydrogen
Bonds
Is DNA a Measure of Evolution?
Summary of DNA Structure
Phophodiester bonds-linkage of OH group from 3’
Carbon to a phosphate of next group
Hydrogen
Bonds
Review Questions
1. What substance varies within a nucleotide of
DNA?
A.
B.
C.
D.
E.
Deoxyribose
Nitrogenous Base
Phosphate Group
Ribose
Sugar
2. All of the following bonds are correct
EXCEPT:
I. A Ξ T
II. C Ξ G
III. A Ξ U
A.
B.
C.
D.
E.
I only
II only
III only
I and II only
I and III only
3. A sample of double-stranded DNA has equal
numbers of
A. Adenine nucleotides and guanine nucleotides.
B. Adenine nucleotides and cytosine nucleotides.
C. Cytosine nucleotides and Thymine
nucleotides.
D. Purines and pyrimidines.
E. Thymine and Uracil Molecules.
Macromolecule
Review
2006-2007
Carbohydrates
• Structure / monomer
– monosaccharide
• Function
– Short term energy
– energy storage
– structural compounds
glycosidic bond
• Examples
– glucose, starch, cellulose, glycogen
Lipids
• Structure / building block
– glycerol, fatty acid, cholesterol, H-C chains
• Function
– energy storage
– membranes
– hormones
• Examples
ester bond (in a fat)
– fat, phospholipids, steroids
Proteins
• Structure / monomer
– amino acids
– levels of structure
• Function
– enzymes
– transport
– signals
defense
u structure
u receptors
u
peptide bond
• Examples
– digestive enzymes, membrane channels,
insulin hormone, actin
Nucleic acids
• Structure / monomer
– nucleotide
• Function
– information storage
& transfer
• Examples
– DNA, RNA
phosphodiester bond
Fig. 5-UN9