BIOLOGY REVISION

• What happens in interphase (cell cycle)?

  • G1-Cell contents duplicated/cell growth
  • S- DNA unravelled/duplicated DNA
  • G2- continued growth, mitotic division preparation
  • G0- specialised cells
• Stages of mitosis:

  • Prophase- nuclear envelope breaks down, centrioles at opposite poles
  • Metaphase- chromosomes moved to spindle equator+ attach to spindle fibres
  • Anaphase- sister chromatids separated + pulled oppositely
  • Telophase- nuclear envelope reforms (cleavage furrow/plate cell)
• Sister chromatids are two identical chromosomes joined by a centromere
• Cytokinesis is the separation of cytoplasm into daughter cells
• Meiosis occurs in reproductive organs
• Mitosis produces genetically identical daughter cells
• Meiosis produces haploid gametes with half the number of chromosomes as somatic cells
• Mitosis produces diploid cells from diploid cells
• Homologous Chromosomes:

  • One maternal/paternal
  • Carries same genes
  • Different alleles
  • Same banding pattern
• Chromosomes structure:

  • Sister chromatids are identical
  • Contains same alleles
• Apologise is programmed cell death
• Interphase - DNA replication occurs during S phase
• Cell cycle consists of interphase (G1, S, G2) and mitotic phase (prophase, metaphase, anaphase, telophase)
• Prophase - nuclear envelope breaks down, centrioles move to opposite poles, spindle fibres form between them, chromatin condenses into visible chromosomes
• The four tissue types are:

  -Nervous

  -Epithelial

  -Muscle

  -Connective

  (In plants: epidermis, vascular)
• Specialised cell:

  Unique structures that allow it to carry out its function (G0)
• Organisation:

  Specialised cell, tissue, Organ, organ system, organism
• Organ: group of different tissues that carry out a specific function
• Stem cells:

  -undifferentiated

  -can undergo cell division over and over
• Potency:

  -Totipotent: can differentiate into any type of cell

  -Pluripotent: form all types of tissue, not whole organism

  -Multipotent: form a range of cells within certain tissue
• Meiosis:

  Nuclear division that results in the production of haploid cells from diploid cells
• Prophase I- chromosomes condense, nuclear envelope breaks down
• Metaphase I- homologous chromosomes assemble at middle, independent assortment and crossing over occurs
• Anaphase I-

  Spindle fibres pull chromosomes to opposite poles
• Telophase I- Chromosomes at opposite poles, nuclear envelope reforms
• Prophase II- chromosomes condense, nuclear envelope breaks down (x2)
• Metaphase II-

  Chromosomes line up at middle, spindle fibres attach
• Anaphase II-

  Sister chromatids are pulled apart
• Telophase II-

  4 genetically different haploid cells formed (nuclear envelope reforms)
• Anabolic reaction:

  monomers + energy = polymer
• Catabolic reaction:

  Polymers break down = monomers +energy released
• High temperatures increases enzyme reactivity:

  -more movement due to kinetic energy

  -more collisions

  -more enzyme substrate complexes
• Lock and key theory:

  -enzymes and substrate fit together, they're complementary
• Induced fit hypothesis:

  -active site not exactly complementary

  -changes shape in presence of specific substrate (change in tertiary structure of enzyme)
• Enzyme pH:

  -optimum pH= peak ROR

  -H ions interact w/ 'R' groups

  -change in H ions= denaturing
• Enzyme temp:

  -After optimum, protein bonds break

  -changes shape and denatures
• (Enzyme) substrate concentration:

  • More collisions = more reactions
  • Plateaus due to limiting factor
• Q10 (temperature coefficient)- How much ROR changes when temp Inc. By 10°c
• Q10= Rate at higher temp/ rate at lower temp
• Non competitive inhibition:

  • Inhibitor binds to allosteric site
  • Active site changes shape
  • Substrate can't bind