UNIT 3 PART 1 STUDY GUIDE QUESTIONS

• why is DNA replication necessary: to ensure that each daughter cell gets the same DNA as the mother

  • growth
  • repair
  • regeneration
• what is the result of DNA replication:

  2 strands of identical DNA
• what does semi-conservative mean:

  1 strand is an original strand (conserved), one is not (new)
• topoisomerase:

  "relaxes" the DNA strand before helicase comes in to pull it apart
• helicase: enzyme that breaks apart the strand of DNA into two halves.
• primase: puts the RNA primer down onto the nucleotides
• DNA polymerase: builds new nucleotides off of the RNA primer

  • 5-3 direction
  • can't work without the primer
• ligase: works as a glue for the new nucleotide bonds

  • comes after DNA polymerase
• SSBP: holds apart the 2 strands of DNA and prevents them from re-attaching
• Okazaki fragments: small sections of synthesized DNA that are found on the lagging strand
• RNA primer is needed because DNA polymerase needs something to build off of
• DNA Replication occurs during interphase: S phase
• Cells must divide for repair and growth of the cells and tissue
• Cell cycle phases:

  G1: growth 1

  S: synthesis

  G2: growth 2

  M: mitosis
• G1: Growth phase, cell grows and replicates DNA and organelles

  • spends most time in
• S: DNA replication occurs

  • ends when there are sister chromatids.
• G2: second growth period, prepares for mitosis, cell grows and repairs damaged parts
• mitosis: the process of cell division that results in two identical daughter cells (4 phases)
• checkpoints:

  G1: getting ready to divide

  End of G2: makes sure rep goes well

  Metaphase: makes sure spindle fibers are attached

  
  

  IF ALL CLEAR, IT KEEPS DIVIDING
• Phases of mitosis:

  prophase

  metaphase

  anaphase

  telophase
• Prophase: 1st stage

  • DNA gets tightly wound (stringy to tight)
  • spindle fibers start growing
  • 46 chromosomes
  • nuclear membrane starts disappearing
• metaphase: 2nd stage

  • the chromosomes line up in the middle (equator)
  • spindle fibers are long and attached to centreome
• anaphase: 3rd stage

  • spindle fibers start shrinking
  • chromosomes get pulled apart into sister chromatids
• telophase: 4th stage (one cell)

  • nuclear membrane reappears
  • chromosomes relax again
  • spindle fibers are gone
  • begins to become two cells
  • cleavage furrow begins to grow
• chromatid is a single strand of DNA that has a sister chromatid

  chromosomes are two sister chromatids joined by a centromere

  centromere is the thing that holds two chromatids together into a chromosome
• chromosome looks like an x because there are two-pieces that are being held together (similar to an x)
• cytokinesis: splitting of cytoplasm into two daughter cells

  animals: cleavage furrow forms

  plants: golgi vesicles form cell plate (eventually becomes cell wall)
• benign tumor: an abnormal mass of normal cells, usually doesn't spread

  malignant: an abnormal mass of cancerous cells, can spread
• cancer: uncontrolled growth of cells
• metastasis: when cancer cells move from one part of body to another
• contact inhibition: when cells grow until they touch each other (fill the gap)
• protooncogene: a normal gene that tells the cell cycle when to divide
• oncogene: a mutated protooncogene that gets the signs mixed up (can be cancerous)
• proto onogene is similar to a car's breaks because it tells the cell (car) when to stop dividing (driving) or start dividing.
• cancer treatments:

  similarites: gets rid of the cancer, has a side effects

  differences: radiation - targets specific area, chemo - covers the whole body, surgery - just flat out removes it
• restriction enzymes: tell DNA when to cut into certain fragments
• gel electrophoresis: separates DNA fragments based on size and charge

  • DNA fragments are placed in a gel and then high voltage is sent to it
• gel electrophoresis used for separate mixtures of DNA, RNA, or proteins according to molecular size.
• meiosis vs mitosis

  meiosis: cell division for gametes in sexual reproduction

  reproduction

  mitosis: cell division for living cells in an asexual reproduction