Sequence Of Nucleic Acid And Structure Of Gene by Hussan Ahmad Ks (books for new readers .txt) π
Nucleic acid
β’ Nucleic acids are molecules that store information for cellular growth and reproduction.
β’ Nucleic acids are polymers of nucleotides.
β’ Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar and a phosphate group.
History
β’ Firstly it is called nuclein because it is isolated from the nuclei of pus cells
β’ Nuclein was shown to have acidic properties, hence it became called nucleic acid.
Nucleic acid structure
β’ Nucleic acid are polynucleotides.
β’ Their building blocks are nucleotides.
β’ All nucleotides contain three components β’ A nitrogen base
β’ A pentose sugar
β’ A phosphate group
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- Author: Hussan Ahmad Ks
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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
β’ Nucleic acids are molecules that store information for cellular growth and reproduction.
β’ Nucleic acids are polymers of nucleotides.
β’ Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar and a phosphate group.
History
β’ Firstly it is called nuclein because it is isolated from the nuclei of pus cells.
β’ Nuclein was shown to have acidic properties, hence it became called nucleic acid.
Types of nucleic acid
β’ There are two types of nucleic acid
β’ Deoxyribonucleic acid (DNA)
β’ Ribonucleic acid (RNA)
The distribution of nucleic acids in the eukaryotic cell
β’ DNA is found in the nucleus
β’ with small amounts in mitochondria and chloroplasts
β’ RNA is found throughout the cell
Nucleic acid structure
β’ Nucleic acid are polynucleotides.
β’ Their building blocks are nucleotides.
β’ All nucleotides contain three components β’ A nitrogen base
β’ A pentose sugar
β’ A phosphate group
Ribose is a pentose
Difference
Nucleotide structure
The sugar phosphate backbone
β’ The nucleotides are all orientated in the same direction
β’ The phosphate group joins the 3rd Carbon of one sugar to the 5th Carbon of the next in line.
Bases in nucleotides
β’ The bases are attached to the 1st carbon
β’ Their order is important because it determines the genetic information of the molecule.
DNA is made of two strands of polynucleotide
Nucleotides and Nucleosides
β’ Nucleotide = Nitrogenous base + Pentose + Phosphate
β’ Nucleoside = Nitrogenous base + Pentose
Nucleic Acid Functions:
β’ Storage of genetic information (DNA)
β’ Transmission of genetic information (mRNA)
β’ Processing of genetic information (ribozymes)
β’ Protein synthesis (tRNA and rRNA)
How DNA Works
β’ 1- DNA stores genetic information in segments called genes
β’ 2- The DNA code is in Triplet Codons (short sequences of 3 nucleotides each)
β’ 3- Certain codons are translated by the cell into certain Amino
β’ acids.
β’ 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
β’ 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
β’ Each triplet codes for a specific amino acid
β’ CGA - CAA - CCA - CCA - GCT - GGG - GAG -CCA
β’ Ala Val Gly Gly Arg Pro Leu Gly
β’ The amino acids are joined together in the correct sequence to make part of a protein
Structure of gene in prokaryotes and eukaryotes
Introduction
β’ A gene is specific sequence of DNA containing genetic information required to make a specific protein
β’ Prokaryotic gene is uninterrupted.
β’ In eukaryotic gene the coding sequences (exon) are separated by non coding sequences called introns.
History
β’ 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
β’ But firstly this term gene is coined by wilhelm in 1909.
What is gene?
β’ The gene is the functional unit of heredity.
β’ Each game is a segment of DNA that give rise to protein
β’ A gene may exist in alternative forms called alleles. β’ Chromosome in fact carry gene.
Prokaryotic gene structure
Prokaryotic genes are collinear with their proteins
Coding regions
Promoter element
Terminal region
Coding region
β’ Starts with an initiator codon and ends with termination codon
β’ No introns
β’ Collinear to its k RNA
Promotes elements
β’ The upstream elements from the start of the coding region include promoter sequences.
β’ At -10 there is a sequence TATAAT
β’ At-35 another consensus sequence is TTGACA
Terminal region of the gene
β’ Sequences for the termination of transcription
β’ It take place by Rho dependent more or Rho independent mode
Eukaryotic gene structure
β’ Exons β’ Introns
β’ Promoter sequences
β’ Terminator sequences β’ Enhancer
β’ Silencer
Exons
β’ Coding sequence, transcribed and translated. Coding for amino acids in the polypeptide chain.
β’ Vary in number, sequence and length. A gene start and ends with exon
Introns
β’ Coding sequences are separated by non coding sequences called introns .
β’ Any nucleotide sequence that are removed when the primary transcript is processed to give the nature RNA are called introns.
β’ All introns share the base sequence GT in the 5' end and AG in the 3' end.
Promoters
β’ A promotor is a regulatory region. β’ Core promotor
β’ Transcription start site
β’ Finding site for RNA polymerase
β’ General transcription factor binding sites. β’ Proximal promotor
β’ Specific transcription factor binding site
Terminator
β’ Recognized by RNA polymerase as a signal to stop transcription.
β’ Enhancer
β’ Enhance the transcription of a game β’ silences
β’ reduce or shut off the expression of a near by gene
Significance of introns
β’ Introns don't specify the synthesis of proteins but have other important cellular activities.
β’ Introns allow exons to he joined in different combinations, resulting in the synthesis of different proteins from the same gene.
β’ Important role in evolution by facilitating recombination between exons of different genes (exon shuffling)
Publication Date: 12-29-2020
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Dedication:
Book By Hussan Ahmad Ks Nucleic acid β’ Nucleic acids are molecules that store information for cellular growth and reproduction. β’ Nucleic acids are polymers of nucleotides. β’ Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar and a phosphate group. History β’ Firstly it is called nuclein because it is isolated from the nuclei of pus cells β’ Nuclein was shown to have acidic properties, hence it became called nucleic acid. Nucleic acid structure β’ Nucleic acid are polynucleotides. β’ Their building blocks are nucleotides. β’ All nucleotides contain three components β’ A nitrogen base β’ A pentose sugar β’ A phosphate group
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