bio pre final

• Nucleotide


  Building block of any nucleic acid, composed of a phosphate group, a sugar portion, and an N-base
• DNA


  Double-stranded molecule, repository of genetic information, sequences of bases encode the blueprint of life processes

  
• RNA


  Single-stranded molecule, information in the form of base sequence is transformed (transcribed) into mRNA, tRNA and rRNA

  
• Purines


  Nitrogenous bases: adenine (A) and guanine (G)
• Pyrimidines


  Nitrogenous bases: cytosine (C), thymine (T in DNA only) and uracil (U, found only in RNA)
• DNA


  • Double-stranded, repository of genetic information, sequences of bases encode the blueprint of life processes

  
• RNA


  • Single-stranded, information in the form of base sequence is transformed (transcribed) into mRNA, tRNA and rRNA

  
• Structural levels of protein

  • Primary - Sequence of amino acids in the linear polypeptide chain
  • Secondary - Polypeptide chains form a helix or a pleated sheet structure
  • Tertiary - Coiling of the polypeptide
  • Quaternary - Association of two or more polypeptide

  
• Interphase


  1. Cell grows and makes a copy of DNA

  2. G1 (Gap/Growth 1) - Cell grows in size, copies organelles

  3. S (synthesis) - Copies DNA, Copies Centrosome

  4. G2 (Gap/Growth 2) - Cell grows more, reorganizes to prepare for Mitosis
• Deoxyribonucleic acid (DNA) is the molecule that carries the genetic information of an organism
• DNA


  • Replication, storage of information, expression of information, and genetic variation

  
• Nucleotide


  Composed of pentose sugar, phosphate group, and nitrogenous base, linked together by phosphodiester bonds
• Deoxyribose


  The sugar in DNA, has a missing oxygen atom on Carbon 2'
• Ribose


  The sugar in RNA
• Nucleoside


  Molecule composed of pentose sugar and nitrogenous base
• Nucleotide


  Nucleoside with a phosphate group added
• Base-pairing rules


  In DNA, A pairs with T, C pairs with G

  In RNA, A pairs with U, C pairs with G
• Messenger RNA (mRNA)


  Carries the genetic information from the DNA to the ribosome

  
• Transfer RNA (tRNA)


  Carries the amino acids to the ribosome during translation, has a specific anticodon

  
• Ribosomal RNA (rRNA)


  Important structural components of ribosomes, where the synthesis of proteins occurs
• DNA Replication


  DNA Helicase - Unwinds the double stranded DNA

  DNA Gyrase - Relaxes the DNA during supercoiling

  RNA Primer - Initiates the start of DNA replication

  DNA Polymerase - Assembles the DNA nucleotides forming the new daughter strand

  DNA Ligase - Joins the DNA fragments together

  
• Leading strand


  Continuous DNA synthesis, runs from 3' to 5' direction

  
• Lagging strand


  Discontinuous DNA synthesis, runs from 5' to 3' direction, produces Okazaki fragments
• Types of DNA Replication

  • Conservative Replication - New complete sets of strands synthesized

  Semiconservative Replication - Each replicated DNA molecule consists of one "old" parent strand and one "new" daughter strand

  Dispersive Replication - Parental strands disperse into both strands of the two new double daughter strands

  
• Transcription


  Initiation - RNA polymerase attaches to the promoter region on the DNA

  Elongation - RNA strand grows longer due to the addition of RNA nucleotides

  Termination - RNA polymerase reaches a terminal signal sequence that signals the stop of transcription
• Promoter


  Specific nucleotide sequence at the start of a gene where RNA polymerase attaches and begins transcription
• Translation


  Process where the amino acid sequence is produced from the mRNA molecule

  
• Ribosome


  Composed of small and large subunits that hold the mRNA and tRNA together and synthesize the proteins or polypeptides

  
• P (peptide) site


  Holds the growing chain of amino acids
• A (acceptor) site


  Holds the tRNA bringing the next amino acid to be added to the chain
• E (exit) site


  Releases the tRNA molecules back into the cytoplasm

  
• Translation


  Initiation - mRNA binds to a ribosome, tRNA corresponding to the START codon (AUG) binds

  Elongation - Ribosome moves down the mRNA, adding new amino acids to the growing polypeptide chain

  Termination - Elongation continues until a STOP codon is reached (UAG, UAA, UGA)
• Chromosomes are thread-like structures made up of DNA and proteins found inside the nucleus.
• Nucleotide


  The building block of any nucleic acid, composed of a phosphate group, a sugar portion, and an N-base
• DNA


  • Double stranded
  • Deoxyribose sugar
• RNA


  • Single stranded
  • Ribose sugar
  • Uracil instead of thymine
• Purines


  Adenine (A) and guanine (G)
• Pyrimidines


  Cytosine (C), thymine (T in DNA only) and uracil (U, found only in RNA)
• Base pairing in DNA

  A pairs with T, G pairs with C
• Main function of DNA


  Repository of genetic information; sequences of bases encode the blueprint of life processes