3rd Term Exam

• Gene


  Segment of DNA that codes for a specific trait
• Genome


  Organism's complete set of genetic make-up
• DNA


  Molecule that carries genetic information
• Basic structure of DNA

  • Nucleotides (monomers/simplest form)
• Nucleotides


  Basic unit of nucleic acid (DNA and RNA), made up of Sugar deoxyribose (DNA) and ribose (RNA), phosphate group, Nitrogen-containing base
• Differences between DNA and RNA

  • 2 Strands (DNA)
  • 1 Strand (RNA)
  • Adenine = Thymine (DNA)
  • Uracil (Replacement for Thymine) = Adenine (RNA)
  • Guanine = Cytosine (DNA and RNA)
• Scientists in the study of DNA

  • Rosalind Franklin and Maurice Wilkins
  • James Watson and Francis Crick
  • Matt Meselson and Frank Stahl
• Rosalind Franklin and Maurice Wilkins


  • Produced the image of DNA using X-RAY
• James Watson and Francis Crick

  • Discovered the structure of DNA molecule as a Double Helix
  • DNA Strand run Anti-parallel (2 DNA strands run opposite to each other)
• Matt Meselson and Frank Stahl


  • Experimented with E. Coli (bacteria)
  • Proved the Semi-Conservative replication of DNA (1 old strand and 1 new strand to make 2 strands to make DNA)
• DNA Replication


  1. Initiation

  2. Elongation

  3. Termination
• Initiation


  Unwinding of complementary DNA Strands
• Helicase


  • Breaks hydrogen bonds between complementary base pairs
  • Bind to DNA to be single-stranded to have 2 separate and unwinded strands
  • Single-stranded binding proteins attach by itself
• Elongation


  • Each strand of unwound DNA gets new complementary strands
• Primase


  • Adds short RNA Primase to template strands to start process
  • RNA Primase: STARTING POINT of replication of complementary strand
• DNA Polymerase


  • Adds nucleotides to template strand, forming a new complementary strand
  • Can only add nucleotides in a 5' - 3' direction
  • Replication occurs in different directions on leading and lagging strands
  • Creates Okazaki fragments in lagging strand
• Okazaki fragments


  Segment of DNA produced due to incontinous duplication of template DNA Fragments
• Ligase


  • Removes RNA Primase
  • Links gaps between segments in the lagging strand
• Termination


  • Completed DNA Synthesis
  • Enzymes are removed and disassembled
  • Daughter DNA molecules are produced
• DNA Replication is a critical process that ensures accurate duplication of genetic information and proper functioning of cells. The process is complex, but is essential for maintenance of genetic information and the growth and division of cells. If DNA replication does not occur or has errors, Trisomies might occur.
• Protein Synthesis


  1. Transcription

  2. Translation
• Transcription


  • Occurs in Nucleus
  • Between DNA and RNA Polymerase
• RNA Polymerase


  • Unwinds and unzips from DNA
  • Reads DNA code from DNA template strand
• Messenger RNA


  • Produced by RNA polymerase during transcription
  • Has a similar sequence as the coding strand of DNA
  • Nitrogenous Base: Thymine is replaced with Uracil, U=A
  • Orientation is still the same
• Translation


  • Occurs in Cytoplasm and Ribosome (Free and attached)
  • Involves Mrna, Rrna, and Trna
• Transfer RNA


  • Decodes mRna
  • Holds anticodon (Base pairings) for codon in the mRNA
  • Codon: Sequence of 3 consecutive nitrogenous bases that code for a specific amino acid
  • Locates Start codon (AUG) Methionine ALWAYS
  • Will stop once encountered the Stop codon (UAA,UAG,UGA) ALWAYS
• Ribosomal RNA


  • Molecule that makes up the ribosome
  • Provide amino acid that was basis of codons
• DNA Template Strand


  • TAC | CCG | CTA | AGA | CTC | GTC | ATC
• DNA Coding Strand


  • ATG | GGC | GAT | TCT | GAG | CAG | TAG
• mRNA Strand


  • AUG | GGC | GAU | UCU | GAG | CAG | UAG
• Polypeptide chain


  • MET - GLY - ASP - SER - GLU - GLN
• Traits


  Specific characteristics determined by expression of one or more genes (Physical or behavioral)
• Factors


  Genes, Environmental factors, Combination of both
• Genetics


  Study of Heredity
• Heredity


  Transmission of traits from one generation to the next
• Gregor Mendel


  • Father of Modern Genetics
  • First explained on how Heredity might work
  • Studied Tall vs. Dwarf plants, Purple vs. White flowers, Round vs. Wrinkled seeds
• Monohybrid Experiment


  • Cross-pollinated tall with dwarf pea plants
  • Crossed plants were planted and observed
  • Hybrid: Offspring of 2 different varieties or species
  • F1 (First filial) Generation only for the offspring of pure-bred parents
  • F1 Hybrids then self fertilized and produced seeds
  • F2 (Second filial) Offspring of F1 generation
  • 3 tall: 1 dwarf
• Monohybrid Crossing


  • T: Tall, t: Short
  • TT
  • Tt
  • tt
• Mendel's Observations


  • One trait appeared in F1 Hybrids (Dominant: T)
  • Other trait disappeared (Recessive: t)
• Laws of Inheritance


  • Dominance
  • Segregation
  • Independent Assortment