NUCLEIC ACIDS

Topic Outline:

Structure and Function Types of Nucleic Acids

1. DNA2. RNA

Central Dogma of Life

Nucleic acids- comprise the fourth major group of biomolecules in living cells.

- play extremely important roles in the cell.

- also called as biopolymersCommon nucleic acids:

1. DNA- deoxyribonucleic acid- the hereditary molecule

2. RNA- Ribonucleic acid- participate in the conversion

of the genetic code into proteins and other gene products.

Nucleotides- are building blocks of the nucleic acid polymers.

- are complex monomers than amino acids.

Structural Components of the Nucleotides:a. Nitrogen-containing base

- nitrogenous baseb. A five-carbon sugar- pentosec. A phosphate group

Types of Nucleic acids:1. DNA- deoxyribonucleic acid

- DNA nucleotides- found in the nucleus with

small amount of mitochondria and chloroplast

Component:a. Nitrogenous baseb. Deoxyribosec. Phosphate group-genetic instructions used in

the development and functioning of all known living organisms.

- The DNA segments that carry this genetic information are called genes,

2. RNA- Ribonucleic acid- RNA Nucleotides- found throughout the cell

Component:a. Nitrogenous base b. Ribosec. Phosphate group

- plays several important roles in the processes of transcribing genetic information from deoxyribonucleic acid (DNA) into proteins.

PHOSPATE SUGAR

Ribose or Deoxyribose

NUCLEOTIDE

BASEPURINES PYRIMIDINES

Adenine (A)Guanine(G)

Cytocine (C)Thymine (T)Uracil (U)

Difference between the pentose sugar of DNA and RNA

RIBOSE DEOXYRIBOSE

CH2OH

H

OH

C

C

OH OH

C

O

H HH

C

CH2OH

H

OH

C

C

OH H

C

O

H HH

C

THE SUGAR-PHOSPHATE BACKBONE

The nucleotides are all orientated in the same direction

P

P

P

P

P

P

ADDING IN THE BASES

The bases are attached to the 1st Carbon

Their order is important It determines the genetic information of the molecule

P

P

P

P

P

P

G

C

C

A

T

T

DNA IS MADE OF TWO STRANDS OF POLYNUCLEOTIDE

P

P

P

P

P

P

C

G

G

T

A

A

P

P

P

P

P

P

G

C

C

A

T

T

Hydrogen bonds

DNA IS MADE OF TWO STRANDS OF POLYNUCLEOTIDE

The sister strands of the DNA molecule run in opposite directions (antiparallel)

They are joined by the bases Each base is paired with a specific partner:

A is always paired with T G is always paired with C“Purine with Pyrimidine”

The sister strands are complementary but not identical

The bases are joined by hydrogen bonds, individually weak but collectively strong

There are 10 base pairs per turn

Difference between Pyrimidine and Purine Bases

Major difference between DNA and RNA

*DNA is double stranded, whereas RNA is single stranded

*DNA contains deoxyribose, whereas RNA contains ribose

* DNA contains thymine, whereas RNA contains uracil.

CENTRAL DOGMA

It was Francis Crick who in 1957, proposed what referred to as the central dogma.

DNA mRNA PROTEIN

Cellular Processes

DNA

RNA (mRNA)

Proteins

replication

transcription

translation

Replication

- 0ccurs by the separation of the DNA strands and the building of complementary strands by the addition of the correct DNA nucleotides.

Replication-formation of two new double-DNA strands

from a parent strand

Transcription-the information in one gene of a DNA molecule is used to produce mRNA molecule.

Events:1. one strand of DNA unwinds

temporarily exposing the bases.2. Attraction of the bases of RNA

nucleotides and a MRNA molecule begins to built alongside of one of the strand.

Initiating codon:AUG

Stop codon:UAAUAGUGA

Translation- information of one mRNA molecule is used to produce protein

- The base sequence of the mRNA molecule to interpreted in the group of three bases are called codons.- this will be used for the determination of amino acid .

GENETIC CODE in mRNA

Alanine- Ala Glycine- Gly Methionine- Met Tyrosine-Tyr

Arginine- Arg Histidine-His Phenylalanine- Phe Valine- Val

Asparagine- Asn Isoleucine- Ile Proline- Pro

Aspartic Acid-Asp Leucine- Leu Serine- Ser

Cysteine- Cys Lysine- Lys Threonine- Thr

Glutamic Acid- Glu Glutamine-Gln Tryptophan- Trp

GENERAL ILLUSTRATION ON THE FLOW OF GENETIC

INFORMATION

Solve:

Using the genetic code, identify the amino acid sequence:

5’- C G C G A A T T C G C G –3’ 3’- G C G C T T A A G C G C –5’