dna

• DNA


  Deoxyribonucleic Acid
• DNA turns into our blonde hair, blue eyes, attached earlobes, rolling tongues, widow's peaks, etc.
• DNA as "master" program


  • Our traits depend on the order of the nitrogen bases of DNA
  • Every 3 nitrogen bases codes for an amino acid
  • DNA doesn't control protein synthesis directly...instead DNA → RNA → Amino Acids→ Protein

  
• DNA as "master" program


  DNA codes for the primary structure (sequence of amino acids) of a protein which impacts the tertiary structure, (which determines the function of the protein)

  
• RNA


  Also a nucleic acid, made up of nucleotides, but is made up of ribose (sugar) instead of deoxyribose & it has Uracil instead of Thymine

  
• Bases in RNA


  • Adenine
  • Guanine
  • Cytosine
  • Uracil (pyrimidine)

  
• U Bonds with A in RNA
• RNA is only single-stranded
• Genetic material


  • DNA & RNA (nucleic acids)
  • Both made up of nucleotides: nitrogen bases, sugar, & phosphate
  • Repeating subunits that act like letters in a code
  • Bases of one strand pair with another (needed for genetic messages); one acts as a template – just like you saw in DNA replication

  
• Messenger RNA (mRNA)


  RNA nucleotides in an uncoiled chain that carries genetic information from DNA in the nucleus to the cytosol

  
• Messenger RNA (mRNA)


  1. Transcription – the process of making RNA from DNA

  2. Translation – the process in which amino acids (coded for in the mRNA) are added to a protein being made = Protein Synthesis

  
• Ribosomal RNA (rRNA)


  • Most abundant
  • In a globular form & makes up ribosomes, where protein synthesis occurs

  
• Transfer RNA (tRNA)


  Single chain folded into a hairpin shape that binds to a specific amino acid

  
• Genetic code


  How the sequence of bases in DNA or RNA translates into the sequence of amino acids in a protein

  
• So how many DNA nucleotides are needed to code for the 20 possible amino acids?
• Triplet


  3 base sequence of DNA
• Codon


  Triplet in mRNA - 3 nucleotide sequence in mRNA
• Anticodon


  Triplet in tRNA - 3 nucleotide sequence in tRNA

  
• Start codon


  AUG is always the "start" codon, and from this point mRNA is read 3 bases at a time
• Stop codons


  UAA, UAG, UGA - Translation will stop once one of these codons is reached
• Each nucleotide triplet in DNA directs a particular codon of mRNA to be made during transcription
• The mRNA codon matches with a tRNA anticodon which is carrying a particular amino acid during translation

  
• DNA Strand


  • T A C C G C A G T C G A C T C A C T
• Proteins


  • Organic molecules made up of amino acids that are a necessary part of every living thing (muscles, enzymes, hormones, immune responses, etc.)
  • There are only 20 amino acids that are coded for by DNA, but each protein molecule could be made up of 100s – 1000s of amino acids
  • Each amino acid has an amino group (-NH2), a carboxylic acid (-COOH), & an "R group" that varies in structure
• Importance of Proteins


  • Keratin – found in skin
  • Collagen – major component of connective tissue
  • Myosin – helps muscles contract
  • Muscles
  • Enzymes make chemical reactions of living systems happen quickly
  • Proteins bond to other molecules (ex. hemoglobin binds to O2 in blood)
  • Key role in communication; hormones – chemical signals given off by cells that regulate behavior of cells in different area
  • Immune responses
• Protein's structure determines its function!

  
• Information coded for by DNA determines the structure of a protein

  
• Without the correct structure, the proteins discussed before would not have the proper function