unit 1-cell biology

• What is the structure of DNA?


  double helix
• What are the 4 bases DNA contains?

  Cytosine, guanine, adenine and thymine
• What do 3 bases code for?

  An amino acid, this is a codon
• What does the base sequence determine?

  The amino acid sequence
• Amino acids are joined together to form a ____

  polypeptide chain
• What is the bond between amino acids called?

  peptide bond
• What is a gene?


  A section of DNA that codes for a protein
• Where is genetic information found?

  nucleus
• What does DNA contain?

  genetic information
• What is protein synthesis?

  When mRNA carries a complementary copy of genetic code from the nucleus to a ribosome

  This protein can then be made using this genetic copy
• What is the difference between proteins?

  The order of amino acids
• What is stage 1 of protein synthesis?


  In the nucleus, mRNA makes a copy of the base sequence on the DNA and then travels to a ribosome
• What is stage 2 of protein synthesis?

  The copied base sequence is used to join together the correct amino acids to form a chain(protein)
• What is mRNA?


  A molecule which carries a complementary copy of the genetic code from the nucleus to a ribosome, where proteins are assembled from amino acids
• The 5 types of proteins


  Structural

  Hormones

  Antibodies

  Receptors

  Enzymes
• What is the function of a structural protein? Give an example


  Provide support to different cellular structures, for example collagen
• What is the function of hormones? Give an example

  Chemical messengers that travel through the bloodstream to cells in their target tissue, for example insulin
• What is the function of an enzyme? Give an example

  Biological catalysts that play an important role in all aspects of metabolism, for example amylase
• What is the function of a receptor?


  They allow different signalling molecules to bind to the cell
• What is the function of antibodies?


  Made by WBCs to defend the body against foreign bodies that could cause disease
• What is a substrate?


  The specific substance that an enzyme reacts on
• What is the active site?


  The part of an enzyme where the chemical reaction occurs
• What is an enzyme-substrate complex?


  Enzymes have an active site that is complementary to only one substrate
• What is an enzyme?


  Biological catalysts which speed up chemical reactions but remain chemically unchanged
• Enzyme equation


  Substrates----enzyme---products
• What is meant by the term 'enzymes are specific'?


  Each enzymes has its own unique shape which is complementary with its substrate. It can only work with 1 type of substrate
• What are the 2 types of enzyme controlled reactions?

  synthesis and degradation
• What is a synthesis reaction?

  When an enzyme builds up its substrates into a larger molecule
• What is a degradation reaction?

  When an enzyme breaks down its substrate into smaller molecules
• What factors affect enzyme activity?


  Temperature and pH
• What are optimum conditions?

  the temperature and pH where enzyme activity is highest
• What does denatured mean?


  When an enzyme is exposed to high temperatures or extreme pH, the enzyme will lose its shape, making it denatured as it can no longer function
• What is genetic engineering?


  The transfer of genetic material from one organism to another
• Why is bacteria often used in genetic engineering?

  They reproduce rapidly and their plasmids are easy to remove, alter or replace
• What are the stages of genetic engineering?

  1) required gene is located on chromosomes and extracted using enzymes

  2) plasmid is extracted from the bacterial cell

  3) plasmid is cut open using enzymes

  4) required gene is inserted into bacterial plasmid using enzymes

  5) modified plasmid is inserted into a host bacterial cell to produce a genetically modified organism
• What are stem cells?


  Unspecialised cells in animals that have the potential to become different types of cells
• What is self renewal of unspecialised cells?


  Reproducing by self division, while remaining unspecialised
• What can stem cells do?


  Reproduce by cell division while remaining unspecialised

  Differentiate to become specialised cells
• What are the 2 types of stem cells?

  Embryonic and tissue
• What is energy essential for?


  Muscular contraction

  Mitosis

  Active transport

  Transmission of nerve impulses

  Synthesis of proteins