Cells

• What is the function of the nucleus?


  Control centre, stores genetic material, and manufactures ribosomes
• What is the function of nuclear pores?


  They allow the transport of molecules across the nuclear envelope
• What are the main structures of the nucleus?

  Nuclear envelope, nuclear pores, nucleoplasm, chromosomes, nucleolus
• What is the function of mitochondria?

  Site of aerobic respiration and ATP production
• What is the function of cristae in mitochondria?

  Increases surface area for enzyme activity
• What is the structure of mitochondria?

  Double membrane, cristae, matrix, 70s ribosomes
• What is the function of chloroplasts?

  Site of photosynthesis
• What are the structures of chloroplasts?


  Double membrane, thylakoids, grana, lamellae, stroma, starch granules, 70s ribosomes
• What is the function of the Golgi apparatus?


  Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell, and makes lysosomes
• What is the structure of the Golgi apparatus?

  A group of fluid-filled membrane-bound flattened sacs
• What is the function of Golgi vesicles?

  Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell
• What is the structure of vesicles?


  Small fluid-filled sac surrounded by a membrane
• What is the function of the cell surface membrane?

  Regulates the movement of substances in and out of cells
• What is the function of lysosomes?


  To digest invading cells or to break down worn-out components of the cell
• What is the structure of lysosomes?

  Round, membrane-bound, containing lysozymes
• What is the function of ribosomes?

  Site of protein synthesis
• What is the structure of ribosomes?

  Made up of proteins and RNA, with no membrane
• What is the function of rough endoplasmic reticulum?

  Folds and processes proteins that have been made at the ribosomes
• What is the structure of rough endoplasmic reticulum?

  System of membranes with ribosomes on the surface
• What is the function of smooth endoplasmic reticulum?

  Synthesizes and processes lipids
• What is the structure of smooth endoplasmic reticulum?

  System of membranes with no ribosomes
• What is the function of the cell wall?

  Supports the cell and prevents it from changing shape
• What is the structure of the cell wall in plants and fungi?

  In plants, it is made of cellulose; in fungi, it is made of chitin
• What is the function of the vacuole?

  Helps maintain pressure inside the cell and keeps it rigid, and is involved in the isolation of unwanted chemicals
• What is the structure of the vacuole?

  Tonoplast and cell sap
• How do multicellular eukaryotes differentiate?

  All cells contain the same genes, but different genes are 'switched on' in different cells
• What is a prokaryote?


  Any organism, usually single-celled, where DNA is suspended freely in the cytoplasm
• What are the two groups of prokaryotes?

  Bacteria and archaea
• What is the structure of a prokaryotic cell?

  Cell wall, cell membrane, cytoplasm, genetic material, plasmid, 70s ribosomes, and sometimes capsule and flagella
• Why is a virus considered acellular?

  They are not considered alive or to be a cell
• What is the structure of viruses?

  Capsid, genetic material, attachment proteins
• How do prokaryotes reproduce?


  Binary fission
• How do viruses reproduce?

  By injecting DNA into the host cell, which then uses its own machinery to replicate the viral particles
• What do attachment proteins do in viruses?

  Allow the virus to identify and attach to a host cell
• What are the three processes of cell fractionation?

  1. Homogenisation
  2. Filtration
  3. Ultracentrifugation
• What happens during homogenisation?

  The cells are put in a homogeniser and blended to break up the cell membranes
• Why are cells filtered in cell fractionation?

  To remove cellular debris, such as fragments of cell membrane or wall
• What properties must the solution have in cell fractionation?

  It must be cold (to stop enzyme activity), buffered (to prevent changes in pH), and isotonic (to prevent osmosis)
• What happens in a centrifuge during cell fractionation?

  The cell fragments are spun in a tube at increasing speeds
• What is meant by the pellet and the supernatant in centrifugation?

  Pellet is the sediment of the organelle that has spun out of the solution, and supernatant is the other organelles that are yet to be spun out