Sequence Of Nucleic Acid And Structure Of Gene, Hussan Ahmad Ks [best books to read for students TXT] 📗

Sequence Of Nucleic Acid And Structure Of Gene

Sequence of nucleic acid and structure of gene in prokaryotes and eukaryotes

 

 

 

 

Presented to: Mam Syeda Amna Batool Presented by: Sadiqa Salamat Roll No 39 BS Botany 7th

Nucleic acid

 

 

• Nucleic acids are molecules that store information for cellular growth and reproduction.

 

 

 

• Nucleic acids are polymers of nucleotides.

 

 

 

• Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar and a phosphate group.

History

 

 

 

 

 

 

• Firstly it is called nuclein because it is isolated from the nuclei of pus cells.

 

 

 

• Nuclein was shown to have acidic properties, hence it became called nucleic acid.

Types of nucleic acid

 

 

• There are two types of nucleic acid

 

 

 

• Deoxyribonucleic acid (DNA)

 

 

 

 

 

 

• Ribonucleic acid (RNA)

The distribution of nucleic acids in the eukaryotic cell

 

 

 

 

 

 

 

• DNA is found in the nucleus

• with small amounts in mitochondria and chloroplasts

 

 

 

• RNA is found throughout the cell

Nucleic acid structure

 

 

• Nucleic acid are polynucleotides.

• Their building blocks are nucleotides.

 

 

 

• All nucleotides contain three components • A nitrogen base

• A pentose sugar

• A phosphate group

Ribose is a pentose

Difference

Nucleotide structure

The sugar phosphate backbone

 

 

 

 

• The nucleotides are all orientated in the same direction

• The phosphate group joins the 3rd Carbon of one sugar to the 5th Carbon of the next in line.

Bases in nucleotides

 

 

 

 

 

 

• The bases are attached to the 1st carbon

 

 

 

• Their order is important because it determines the genetic information of the molecule.

DNA is made of two strands of polynucleotide

Nucleotides and Nucleosides

 

 

 

 

 

 

 

 

• Nucleotide = Nitrogenous base + Pentose + Phosphate

 

 

 

 

 

 

• Nucleoside = Nitrogenous base + Pentose

Nucleic Acid Functions:

 

 

 

 

 

• Storage of genetic information (DNA)

 

 

 

• Transmission of genetic information (mRNA)

 

 

 

• Processing of genetic information (ribozymes)

 

 

 

• Protein synthesis (tRNA and rRNA)

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 in a protein.

The sequence of bases in DNA forms the genetic code

 

 

 

 

 

 

• A group of three bases (a triplet) controls the production of a particular amino acid in the cytoplasm of the cell.

This is known as the triplet code

 

• Each triplet codes for a specific amino acid

 

 

 

• CGA - CAA - CCA - CCA - GCT - GGG - GAG -CCA

• Ala Val Gly Gly Arg Pro Leu Gly

 

 

 

• The amino acids are joined together in the correct sequence to make part of a protein

 

 

 

 

 

 

 

Structure of gene in prokaryotes and eukaryotes

Introduction

 

 

 

• A gene is specific sequence of DNA containing genetic information required to make a specific protein

 

 

 

• Prokaryotic gene is uninterrupted.

• In eukaryotic gene the coding sequences (exon) are separated by non coding sequences called introns.

History

 

 

• Mendel in 1865 on the basis of breeding experiment with peas. He assumed that each trait determined by a pair of inherited factor which are now called gene

 

 

 

 

 

 

• But firstly this term gene is coined by wilhelm in 1909.

What is gene?

 

 

 

 

 

 

 

 

 

 

• The gene is the functional unit of heredity.

• Each game is a segment of DNA that give rise to protein

• A gene may exist in alternative forms called alleles. • Chromosome in fact carry gene.

Prokaryotic gene structure

 

 

Prokaryotic genes are collinear with their proteins

 

 

Coding regions

 

 

Promoter element

 

 

Terminal region

Coding region

 

 

• Starts with an initiator codon and ends with termination codon

 

 

 

• No introns

 

 

 

• Collinear to its k RNA

Promotes elements

 

 

• The upstream elements from the start of the coding region include promoter sequences.

• At -10 there is a sequence TATAAT

• At-35 another consensus sequence is TTGACA

Terminal region of the gene

 

 

• Sequences for the termination of transcription

• It take place by Rho dependent more or Rho independent mode

Eukaryotic gene structure

 

 

• Exons • Introns

• Promoter sequences

• Terminator sequences • Enhancer

• Silencer

Exons

• Coding sequence, transcribed and translated. Coding for amino acids in the polypeptide chain.

• Vary in number, sequence and length. A gene start and ends with exon

Introns

• Coding sequences are separated by non coding sequences called introns .

• Any nucleotide sequence that are removed when the primary transcript is processed to give the nature RNA are called introns.

• All introns share the base sequence GT in the 5' end and AG in the 3' end.

Promoters

 

• A promotor is a regulatory region. • Core promotor

• Transcription start site

• Finding site for RNA polymerase

• General transcription factor binding sites. • Proximal promotor

• Specific transcription factor binding site

Terminator

 

 

• Recognized by RNA polymerase as a signal to stop transcription.

• Enhancer

• Enhance the transcription of a game • silences

• reduce or shut off the expression of a near by gene

Significance of introns

 

 

• Introns don't specify the synthesis of proteins but have other important cellular activities.

• Introns allow exons to he joined in different combinations, resulting in the synthesis of different proteins from the same gene.

 

• Important role in evolution by facilitating recombination between exons of different genes (exon shuffling)

Imprint

Publication Date: 12-29-2020

All Rights Reserved

Dedication:
Book By Hussan Ahmad Ks Nucleic acid • Nucleic acids are molecules that store information for cellular growth and reproduction. • Nucleic acids are polymers of nucleotides. • Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar and a phosphate group. History • Firstly it is called nuclein because it is isolated from the nuclei of pus cells • Nuclein was shown to have acidic properties, hence it became called nucleic acid. Nucleic acid structure • Nucleic acid are polynucleotides. • Their building blocks are nucleotides. • All nucleotides contain three components • A nitrogen base • A pentose sugar • A phosphate group