Unit 3 Aos 1

• DNA


  contains the instructions to code for a protein and found in the nucleus
• Nucleic acid


  information molecules of living things
• mRNA


  Carries a complimentary copy of the DNA from the nucleus to the ribosome
• tRNA


  carries a specific amino acid to the ribosome to create a polypeptide strand
• ribosome


  made of rRNA and proteins and is the site of protein synthesis
• Introns


  sequence of a gene that does not code for a protein. Removed during RNA processing
• Exons


  sequence of a gene that code for a protein. Added together during RNA processing
• monomer


  A simple compound whose molecules can join together to form polymers
• polymer


  large compound formed from combinations of many monomers
• Anti-parallel


  Separate strands that run in a different direction. In a DNA molecule, one strand is in the 3' to 5' orientation, and the other is in the 5' to 3' orientation.
• Gene


  A segment of DNA on a chromosome that codes for a specific protein
• allele


  An alternative form of a gene.
• Adenine


  the nitrogenous base that hydrogen bonds with the nucleotide thymine in DNA and Uracil in RNA.
• Cytosine

  the nitrogenous base that hydrogen bonds with the nucleotide guanine in DNA and RNA.
• Guanine


  the nitrogenous base that hydrogen bonds with the nucleotide cytosine in DNA and RNA.
• Thymine


  the nitrogenous base that hydrogen bonds with the nucleotide adenine in DNA.
• Uracil


  the nitrogenous base that hydrogen bonds with the nucleotide adenine in RNA.
• degenerate code


  more than one codon can code for the same amino acid
• gene expression


  The process by which information encoded in DNA directs the synthesis of proteins
• Transcription


  The process of synthesising a complimentary mRNA molecule from DNA. Includes RNA processing
• RNA processing


  The modification of mRNA before it leaves the nucleus that is unique to eukaryotes. Removal of introns, joining of exons and addition of methyl cap and poly A tail
• Translation


  Process by which mRNA is decoded by the ribosome and a polypeptide is produced
• Promoter


  The specific region of a gene where RNA polymerase can bind and begin transcription
• redundancy


  a given biochemical function is encoded by two or more genes.
• Nucleic acids are biomolecules vital for life, in all organisms, and provide the genetic blueprint that provides the information for protein synthesis
• Nucleotides


  The sub-units that make up nucleic acids
• Components of nucleic acids

  • Sugar
  • Nitrogen-containing bases
  • Number of strands
• DNA


  • Double stranded
  • Two complementary chains of nucleotides running anti-parallel (3' to 5' and 5' to 3')
  • Adenine pairs with Thymine (2 hydrogen bonds)
  • Cytosine pairs with Guanine (3 hydrogen bonds)
  • Adenine and Guanine are purines
  • Cytosine and Thymine/Uracil are pyrimidines
• RNA


  • Single stranded
  • Nitrogenous bases (A, U, G, C)
  • 5-carbon pentose sugar
  • Runs 5' to 3'
  • Contains Uracil instead of Thymine
• Forms of RNA


  • mRNA (Messenger RNA)
  • rRNA (Ribosomal RNA)
  • tRNA (Transfer RNA)
• mRNA


  Carries the genetic message from the DNA within the nucleus to the ribosomes, where the message is translated into a particular protein
• rRNA


  Stable form of RNA found in ribosomes, where protein synthesis occurs
• tRNA


  Carries amino acids to ribosomes that are free in the cytoplasm, where they are used to construct proteins
• The genetic instructions for all organisms are written in a code = A, T, C and G
• Genetic code


  A non-overlapping series of groups of three bases (triplets) in a DNA template chain
• Features of the genetic code

  • It is a triplet code
  • It is universal (same in bacteria, plants and animals)
  • The same sequence of nucleotides codes for the same amino acid
  • It is degenerate or redundant (more than one triplet can code for one amino acid)
• Gene expression


  1. Transcription (DNA to mRNA)

  2. RNA processing (pre-mRNA to mature mRNA)

  3. Translation (mRNA to protein)
• Transcription


  DNA to mRNA
• Translation


  mRNA to protein
• Transcription


  • Occurs in the nucleus
  • RNA polymerase attaches to the promoter sequence and moves along the DNA template, adding complementary nucleotides to form an RNA chain