Nucleic Acid

Nucelic Acids revsion:

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  • Created by: harry
  • Created on: 25-11-11 14:04

Nucleic Acids

2 types:

DNA (deoxyribonuceic acid) (polynucleotide)The sequence of the bases in DNA codes for the sequence of the amino acids in a protein. Proteins determines the characteristics of a organism. Contains the pentose sugar (deoxyribose) NO O2)

RNA (Ribonucleic acid)  RNA are used in Protein Synthesis. Contains the pentose sugar (RIBOSE)

Nucleic Acids, are made from monomers called nucelotides. Nucleotides are made from 3 components.

Phosphate (the sun), Five carbon sugar (pentose) "(your house), Organic nitrogenous bases (contants n2)The five bases:

(A) Adenine, (T) Thymine, (C) Cytosine. (G) Guanine, (U) Uracil 

DNA: A=T C---G (A&T) (purines) (T&C) Pryimide

Completementary base pairing: Adenines pairs with Thymine (DNA) Uracil pairs with adenine (RNA)both have 2 hydrogen bonds. Guanine pairs with Cytosine (ALL THE TIME!!) 3 hydrogen bonds.

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Structure of DNA, and Semi Conseravtive replicatio

Formation of nucleic acids: Nuclotides join together through a condensation reaction. Covalet bond: Phosphodiester bond is formed between the nucleotide. The sugars and phosphates form the sugar- phosphate-backbone the nitrogenous bases are free to pair wth complementary base on another nucelotide.

DNA: structure: Double helix, two anti parallel polynucelotide chains join together through H2 bonds. Through complementary base pairing (at,cg) This makes DNA a stable molecule!! the 2 chains then twist around each other to form a DOUBLE HELIX!!

Semi- Conserative Replication:

Cell divides: (interphase) (to make identical copies of DNA to form sster Chromatids)

Double helix untwists. H2 bonds brea, between the complementary bases, this then allows the two strands to 'unzip' and expose nucleotides. Each strand acts as a template. Free complementary nucleotide bases hydrogen bond, to the exposed bases according to the base (AT,CG) Phospodiester bonds form between the nucelotides to join sugar phospate back bone using DNA POLYMERASE. Each DNA molecule consists of  old and new strand.

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Meselsohn and Stahl:

15NH4: heavy nitrogen. 14NH4: light nitrogen.

1Heavy Nitrogen--> 2Heavy and light mixed--> 2 light, 2 mixed

Sequence of organic bases: determines sequence of amino acids and primary structure.

Long molecule: Large ammounts of info can be stored.

Base pring rule (AT)(CG): complementray strands of info replicated.

Double helix structure: stability!

H bonds between base pairings: allows easy unzipping to copy/ reading info.


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Transcription continued:

Protein synthesis:

Sequence of bases coding for one protein (1 gene) is exposed when h2 bonds are broken. Complemetary RNA nucleotides come into poistion to form complementary copy of the gene. This known as messengerRNA (TRANSCRIPTION.

mRNA leaves through the nucleaus through the nuclear pore. mRNA attaches to the ribosomes, in the cytolasm. Codons set of 3 bases) on the mRNA determines whihc specific transfer tRNA comes to poistion. tRNA bings specific amino acids to the rbosome in the correct order. The amino acids then joined together via peptider bonds to form the primary structure of a protein. This process is called translation.

DNA--> mRNA--> tRNA-->protein.

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