Cells

• What is the structure of the nucleus?

  Nuclear envelope (double membrane)

  Nuclear pores (within envelope, allow mRNA to go out)

  Nucleoplasm (granular jelly like material)

  Nucleolus (smaller sphere insides which is the site of rRNA production and makes ribosomes)
• What is the function of the nucleus?

  Site of DNA replication and transcription (making mRNA).

  Contains the genetic code for each cell.
• What is the structure of the endoplasmic reticulum?

  Rough and smooth ER both have folded membranes called cisternae.
• What is the function of the endoplasmic reticulum?

  RER: Protein synthesis

  SER: Synthesis and storing on lipids and carbohydrates.
• WHat is the structure of the Golgi apparatus?

  Folded membranes making cisternae

  Secretary vesicles pinch off from cisternae.

  Slight curve in the shape compared to SER.
• What is the function of the Golgi Apparatus and vesicles?

  Add carbohydrates to proteins to form glycoproteins.

  Produce secretory enzymes

  Secrete carbohydrates

  Transport, modify and store lipids

  Form lysosomes

  Finished products are transported to cell surface in Golgi vesicles where they fuse with the membrane and contents are released.
• What is the structure of a lysosome?

  Bag of digestive enzymes
• What is the function of lysosomes?

  Hydrolyse phagocytic cells

  completely break down dead cells (autolysis)

  Exocytosis- release enzymes to outside of the cell to destroy material

  Digest worn out organelles for reuse of materials
• What is the structure of the mitochondria?

  Double membrane

  Inner membrane called cristae

  Fluid centre called mitochondrial matrix

  Loop of mitochondrial DNA
• What is the function of the mitochondria?

  Site of aerobic respiration

  Site of ATP production

  DNA to code for enzymes required in respiration
• What is the structure of ribosomes?

  Small, made from 2 sub-units of protein and rRNA.

  80s are large ribosomes found in eukaryotic cells

  70s are smaller ribosomes found in prokaryotic cells, mitochondria and chloroplasts.
• What is the function of ribosomes?

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

  Filled with fluid surrounded by a single membrane called tonoplast.
• What is the function of the vacuole?

  Make cells turgid and therefore provides support.

  temporary store of sugars and amino acids

  Pigments may colour petals to attract pollinators
• What is the structure of chloroplasts?

  Surrounded by double membrane

  Contain thylakoid (folded membranes embedded with pigment).

  Fluid filled stroma contains enzymes for photosynthesis
• What is the function of chloroplasts?

  Site of photosynthesis
• What is the structure of the cell wall?

  Plants: made of microfibrils of the cellulose polymer

  Fungi: made of chitin a nitrogen containing polysaccharide
• What is the function of the cell wall?

  provide structural strength for the cell
• What is the structure of the plasma membrane?

  Phospholipid bilayer: molecules embedded within and attached on outside (proteins, carbohydrates, cholesterol- which affect fluidity of membrane).
• What is the function of the plasma membrane?

  Controls entrance and exit of molecules
• Prokaryotic/ Eukaryotic which is larger in size?

  Eukaryotic
• Prokaryotic/ Eukaryotic which one has no membrane bound organelles?

  Prokaryotic
• What are the size of prokaryotic ribosomes?

  70s
• What are the size of eukaryotic ribosomes?

  80s
• Do prokaryotic cells have nucleus?

  no
• What is the cell wall made from in prokaryotic cells?


  Murein
• What 3 structural differences can be present in prokaryotic cells compared to eukaryotic cells?

  Plasmids

  Capsule around cell

  Flagella
• What are plasmids?


  Small loops of DNA which only carry few genes
• What is the capsule?

  A slimy layer made of protein which prevents the bacteria from drying out and protects bacteria against host immune system by covering antigens on the outside of cell.
• What does the flagellum do?

  Rotates to enable bacteria to move.
• What are the 3 main things present in a virus cell?

  Genetic material (DNA or RNA)

  Attachment proteins

  Capsid

  Occasionally lipid envelope formed from hosts cell membrane
• What are the 3 types of microscopes?

  Light

  Transmission electron

  Scanning electron
• What is magnification?


  Magnification of a microscope refers to how many times larger an image is compared to the object.
• What is resolution?


  Resolution of a microscope is the minimum distance between 2 objects in which they can still be viewed as separate. The resolution in an optical microscope is determined by the wavelength of light and the wavelength of a beam of electrons determines the resolution in an electron microscope.
• How does an optical microscope work?

  A beam of light is condensed to create an image. It has poorer resolution due to light having a longer wavelength. Also has a lower magnification.

  Produces colour images

  Can view living samples.
• Explain electron microscopes?


  A beam of electrons is condensed creating an image.

  Electromagnets are used to condense the beam.

  Higher resolving power as electrons have a short wavelength.

  Higher magnification.

  Black and white images

  Sample must be in a vacuum therefore non-living.
• What are the 3 features of solution in cell fractionation?

  Ice cold, isotonic, buffered.
• Why is the solution cold in cell fractionation?

  To reduce enzyme activity when the cell breaks open, enzymes are released why could damage the organelles.
• WHy is the solution isotonic in cell fractionation?

  Must be the same water potential as the organelles to prevent osmosis as this could cause organelles to shrivel or burst.
• Why is the solution buffered in cell fractionation?

  Kept at a constant pH to prevent damage to organelles.