Biology

• Chromosome


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


  A type of cell division which produces two identical diploid daughter cells
• Gene

  The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production.
• Cancerous tumours

  • Can be either malignant or benign
• Each human body cell contains 46 chromosomes. These can be arranged into 23 pairs. Each chromosome in a pair carries the same types of genes.
• Specialised cells

  Formed when stem cells differentiate
• The 23rd pair is the sex chromosomes. In females, the two chromosomes are identical in shape. These are X chromosomes. Females are referred to as XX. In males, one of the chromosomes is different in shape. This is a Y chromosome. Males are referred to as XY.
• Cell division

  1. Occurs when:

  2. An organism grows

  3. An organism becomes damaged and needs to produce new cells for repair

  4. Organisms like bacteria reproduce asexually
• Mitosis

  Type of cell division which produces two identical diploid daughter cells
• Cancerous tumours

  Either malignant or benign
• Cell cycle

  The events that lead to cell division and DNA replication
• Specialised cells

  Formed when stem cells differentiate
• Synthesis

  Made or put together
• Specialised cells

  Formed when stem cells differentiate
• For most of the time, DNA exists in the nucleus as thin strands. When the cells containing nuclei are ready to divide, the DNA copies itself then coils and condenses to form chromosomes.
• Mitosis


  A type of cell division which produces two identical diploid daughter cells
• DNA

  Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being
• Each chromosome is made from a single molecule of DNA. Each section of this single molecule of DNA contains a code for the production of a particular protein called a gene.
• Chromosome


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

  Cells found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells
• Mitosis


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


  • Can be either malignant or benign
• When looking at cells with a microscope, the length of different stages of the cell cycle can be estimated using the formula: Length of time in phase = (observed number of cells at that stage/total number of cells observed) x total length of time of cell cycle
• Specialised cells

  Formed when stem cells differentiate
• Differentiation

  When an unspecialised cell becomes a more specialised cell type
• Stages of mitosis

  1. Interphase

  2. Prophase

  3. Metaphase

  4. Anaphase

  5. Telophase

  6. Cytokinesis
• Undifferentiated cells are called stem cells
• Enzymes

  Biological catalysts which speed up reactions
• An embryo develops from a fertilised egg
• Enzymes

  • They are specific for their substrate
  • They are denatured at extremes of temperature and pH
• In interphase, the cell spends most of its life and the DNA in chromosomes copies itself ready for mitosis
• Cells at early stages in the development of the embryo are stem cells
• Lock and key hypothesis

  Models how enzymes are specific for their substrate
• Enzymes are biological catalysts which speed up reactions
• In prophase, the DNA in chromosomes and their copies condenses to become more visible, and the membrane around the nucleus disappears
• If embryonic stem cells are removed from the embryo they will differentiate into any cell type
• Enzymes are specific for their substrate
• Enzymes


  Biological catalysts which speed up reactions
• Enzymes are denatured at extremes of temperature and pH
• Adult stem cell locations

  • Nose
  • Brain
  • Eyes
  • Blood
  • Heart
  • Liver
  • Bone marrow
  • Skin
  • Muscle