Biology chapter 2

• • Contains multiple sub units called nucleotides which are used to form a double helix.
  • Genetic information of the cell.
  • Nitrogenous bonds in the DNA are held lightly together so they can break apart during cell division.
• 3 components of a nucleotide:

  • 5 carbon sugars
  • phosphate group
  • nitrogen base
• A zygote is a diploid cell, made from the result of fusion of male and female gametes.
• (eukaryotic cells) DNA is found in the nucleus of the cell, bound to histone proteins.
• The bonding of the DNA and histone proteins found in the nucleus is called chromatin
• The centromere is the part in which both sister chromatids are linked together.
• Somatic cells are all the bodily cells excluding reproductive belonging to humans.
• Locus refers to the location of of a specific gene on a chromosome.
• Homologous chromosomes a set of sister chromatids whose genes sequence are the same, yet that are not identical as a result of their alternate alleles.
• Alleles are two or more alternate forms of a gene that arise via mutation.
• Cytokinesis: The final stage of mitosis or meiosis in which the cytoplasm of the parent cell divides to form 2 new cells
• MITOSIS:

  Interphase: The resting phase between phase between the meiotic division of a cell.

  • DNA replication
  • chromosomes are not seen.
• METOSIS:

  Prophase: The phase in which the genetic material duplicated within the nucleus begin to separate.

  • Spindle fibers begin to form.
  • Nucleus shrinks.
  • Chromosomes become short and thickened, also become visible.
• METOSIS:

  Metaphase: The phase in which chromosomes line up along the middle of the cell to form a metaplate.

  • spindle fibers attach to centrosomes.
• Anaphase: The phase in which spindle fibers pull apart the centromeres of the chromosome pairs. This causes them to move towards opposite poles of the cell.
• METOSIS:

  Telephase: The final stage of metosis in which chromosomes pull apart and the divide of the parent cell into two daughter cells is formed.

  • Cytokinesis occurs
  • spindle fibres degenerate
  • for plants the cell plate splits and for animals the cleavage furrow splits, both leaving behind two daughter cells
• MEIOSIS:

  Prophase 1:

  • Sister chromatids cross over
  • Chromosomes shorten, thicken and become visible
  • DNA condenses into chromosomes
• MEIOSIS

  Metaphase 1:

  • Tetrids(aka chromosomes in meiosis) line up across the equator
  • Held by spindle fibers attached to the centromere
• MEIOSIS:

  Anaphase 1:

  Homologous chromosomes are pulled apart and are moved to opposite ends of the cell.
• MEIOSIS:

  Telophase 1:

  • Spindle fibers break up and degrade
  • cytokinesis
  • 4 haploid daughter cells form
• MEIOSIS:

  PROPHASE 2:

  • similar to prohase 1 except no DNA replication and spindles form at right angles
• Metaphase 2:

  chromosomes align with metaphase plate
• MEIOSIS:

  Anaphase 2:

  • Sister chromosomes separate and move to opposite poles of the cell.
  • chromatids become haploid daughter cells
• Telephase 2:

  • Spindle fibers dissocytokinesis
• Cell cycle: A sequence of events occurring in a eukaryotic cell for the divide of one cell to another.
• Cell cycle:

  (underlined is where the explanation occurs)

  1. m-phase->g1: cell undergoes mitosis for nuclear division and cytokinesis
  2. g1->g0: cells like nerve, muscle and redial undergo extended g1(at g0) as they are unable to divide
  3. g1->s-phase: cells experience major growth and replication of DNA
  4. s-phase->g2: reproduction of organnelles, growth DNA replication and synthesis
  5. g2->m-phase: preparations for cell to divide, 2nd growth phase, proteins and organelles necessary for cell division are produced.
• Mitosis: A type of nuclear division that occurs in somatic cells which result in the production of 2 identical diploid daughter cells.
• Meiosis: A type of nuclear division that produces 4 non-identical haploid daughter cells from one diploid parent cell.
• Loss minimisation is a risk management strategy to reduce the impact of revenue losses in one area on the overall profitability in the long term. 

   

  Minimises losses by not concentrate all efforts and resources in one market, industry or economy – spread risk. 

  Diversifying: process of business varying range of products or field operations.  

  Seasonality: routine changing of climate characteristics 

  Hedging is a management strategy against possible loss by balancing/compensating risk e.g. Australia’s multiple markets