Unit 2

• Mitosis


  The process where cells divide to produce new cells
• Mitosis


  • Provides new cells for growth
  • Provides new cells for repair of damaged cells
• DNA


  Carried on structures in the nucleus of a cell called chromosomes

  
• Mitosis


  1. DNA replication

  2. Each chromosome makes a copy of itself

  3. Copies are referred to as chromatids

  4. Chromatids remain attached by a centromere

  5. Chromatids separate and are then referred to as chromosomes

  
• Mitosis


  A type of cell division which produces daughter cells identical to the parent
• Chromatids


  The replicated copy of a chromosome visible during mitosis
• Centromere


  The region of a chromosome to which the spindle fibre attach to during mitosis
• Chromosome


  The structure made of DNA that codes for all the characteristics of an organism
• Replication


  The doubling of the chromosomes resulting from the copying of DNA to produce chromatids before mitosis
• Equator


  The middle position in a cell where the chromosomes line up and attach to the spindle fibres during mitosis
• Spindle fibres


  Protein threads or fibres produced to pull the chromatids apart during mitosis
• Poles


  The opposite ends of a cell to which chromatids are pulled during mitosis
• Haploid


  A cell that contains one set of chromosomes
• Diploid


  A cell that contains two sets of chromosomes
• Chromosome complement


  The number of chromosomes in a typical cell of an organism
• Unicellular Organisms


  An organism which only has one cell
• Multicellular Organisms


  An organism which has more than one cell
• Specialised


  A cell that has become differentiated to carry out a particular function e.g. red blood cell
• Stem cells


  A cell found in foetuses, embryos and some adult tissue that can give rise to a wide range of other cells
• Embryo


  An organism in the early stages of development
• Mitosis


  1. Parent cell chromosomes are replicated

  2. Chromosomes shorten and thicken to become visible

  3. Chromosomes line up at equator

  4. Chromatids are pulled apart to either pole by spindle fibres

  5. Parent cell divides to produce 2 new cells identical to parent cell
• Multicellular organisms


  • Have more than one cell type and are made up of tissues and organs
  • Organs perform different functions (e.g. Heart, stomach and lungs)
  • The cells in organs are specialised for their function and work together to form systems (e.g. digestive system and circulatory system)
• Diploid cells


  • All body cells (except gametes) are diploid cells
  • 2 sets of chromosomes
  • 46 chromosomes
• Haploid cells


  • Gametes (sex cells) are haploid cells
  • 1 set of chromosomes
  • 23 chromosomes
• Mitosis provides new cells for growth and repair of damaged cells (broken bones, wounds)
• Mitosis maintains the diploid chromosome complement
• Stem cells


  • Unspecialised cells which can divide in order to self-renew
  • Stem cells are involved in growth and repair
• How we obtain stem cells


  • From the embryo at a very early stage (cloned embryos, aborted foetuses and spare embryos - IVF)
  • From the body throughout adult life
• Stem cells have the potential to become different types of cells
• Nervous system


  Consists of central nervous system (CNS) and other nerves
• Central nervous system (CNS)


  Consists of brain and spinal cord
• Endocrine gland


  A gland that produces and releases a hormone directly into blood
• Diabetes


  A disease in which the blood is unable to regulate blood glucose
• Glucagon


  A hormone produced by the pancreas that promotes the breakdown of glycogen into glucose in the liver
• Insulin


  A hormone that regulates the level of sugar in the blood and can produced by genetically modified bacteria
• Glycogen


  Animals store glucose as glycogen in their liver and muscle tissues
• Glucose


  A simple sugar
• Sensory neurone


  The nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS
• Inter neuron


  Part of the CNS. Enables communication between the sensory and motor neurons
• Motor neuron


  The nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands