Cells

• What is cell fractionation?

  The process where cells are broken up so that the organelles inside them can be observed.
• What is a homogeniser? 


  It is a special type of blender.
• What is the process of homogenation?


  
  

  1. It's where cells are broken up by a homogeniser which releases the different organelles inside the cell.
  2. The resultant fluid is then filtered to remove any whole cells or large pieces of debris.
• What is ultracentrifugation?


  It's where fragments in the filtered homegnate are separated in the centrifuge which spins the tubes of homogenate at very high speeds to create a centrifugal force.
• What are the two processes of cell fractionation?


  
  

  1. Homogenation
  2. Ultracentrifugation
• Why does the tissue sample size need to be placed in a cold solution?


  To reduce enzyme activity that might break down the organelles.
• Why does the tissue sample size need to be placed in a buffered solution? 


  So that the pH does not fluctuate. If a change in pH is present, then the structure of the organelle could be altered OR it could affect the functioning enzymes.
• Why does the sample size need to be placed in an isotonic solution?


  To prevent osmosis that could shrink or burst organelles.
• What does the mnemonic NMLERR represent? 


  The size order in which organelles are separated.

  N- nucleus (and whole cells)

  M- mitochondria (could be chloroplast but they come out first)

  L- lysosomes

  E R- endoplasmic reticulum

  R- ribosomes
• What is resolution?


  Resolution is the minimum distance two points can be separated and still distinguished as two separate points.
• Advantages of light microscopes? 


  -Can be used to view living specimens

  -Easy to use

  -Inexpensive
• Disadvantages of Light Microscopes?


  -Cannot make 3D images

  -Not very clear resolution
• Advantages of Transmission Electron Microscopy (TEM)?

  -High resolution and magnification

  -Can see internal features
• Disadvantages of TEM?


  -Specimen must go through an elaborate preparation process

  -Very expensive

  -Not portable
• Advantages of Scanning Electron Microscopy (SEM)?


  -A 3D image is obtained

  -Can be used to maintain images of viruses and large molecules

  -High resolution and magnification
• Disadvantages of SEM?


  -Specimen must go through an elaborate preparation process

  -Very expensive

  -Not portable
• What are organelles?

  Sub cellular structures found inside of cells
• The organelles in an eukaryotic cells are...

  membrane bound
• What is the role of the nucleus?

  Contains DNA and hereditary materials.
• What is the role of the nuclear pores?

  They allow the passage of large molecules out of the nucleus
• What is the nucleoplasm?

  A jelly like material that makes up the bulk of the nucleus.
• What is the role of the nucleolus?

  Manufactures ribosomal RNA and assembles the ribosomes.
• What is the role of the mitochondrion?

  Surrounded by a double membrane that controls the entry and exit of material.
• What is the cristae?

  Found in the mitochondria, they are extensions of the inner membrane which provides surface area for enzyme attachment and other proteins.
• What is the matrix?

  It contains proteins, lipids, ribosomes and DNA which allows the mitochondria to control the production of some of their own protiens.
• Label the mitochondria

  It is:

  A) Inner membrane

  B) Outer membrane

  C) Cristae

  D) Matrix

  
• Label the nucleus

  It is:

  A) Nuclear pore

  B) Nucleolus

  C) Nucleoplasm

  
• What is the function of the golgi apparatus?


  -Add carbohydrate to proteins to form glycoproteins.

  -Produce secretory enzymes such as those secreted by the pancreas.

  -Secrete carbohydrates, such as those used in making cell walls in plants.

  -Transport, modify and store lipids

  -Form lysosomes.
• What is the function of the lysosome?


  • hydrolyse material ingested by phagocytic cells, such as white blood cells and bacteria.
  • release enzymes to the outside of the cell (exocytosis) in order to destroy material around the cell.
  • Digest worn out organelles so that the useful chemicals they are made of can be re-used.
  • Completely break down cells after they have died. (autolysis)
• The two types of ribosomes are:


  80s ribosomes and 70s ribosomes
• Where are the 80s ribosomes found?


  Eukaryotic cells
• Where are the 70s ribosomes found?


  Prokaryotic cells and mitochondria
• What are the functions of the cellulose cell wall?


  • To provide mechanical strength in order to present the cell bursting under the pressure created by the osmotic entry of water.
  • To give mechanical strength to the plant as a whole.
  • To allow water to pass along it, contributing to the movement of water through the plant.
• What are the functions of vacuoles?

  • They support herbaceous plants and herbaceous parts of woody plants by making cells turgid.
  • The sugars and amino acids may act as a temporary food store.
  • The pigments may colour petals to attract pollinating insects.
• Label the cell.

  The cell:

  A) Endoplasmic reticulum

  B) Ribosomes

  C) Nucleus

  D) Nucleolus

  E) Nuclear membrane

  F) Golgi

  G) cytoplasm

  H) mitochondrion

  I) cytoplasmic membrane

  
• What types of vacuoles do humans and animals have?


  Temporary vacuoles
• Undifferentiated stem cells will switch off certain genes as they become specialised so that they only make the proteins needed to perform a particular function.
• bacteria cell

  A) cell surface membrane

  B) cell wall

  C) capsule

  D) ribosomes

  E) DNA

  F) plasmids

  G) flagellum

  H) pilli

  
• The bacteria cell wall is made from...


  murein
• What is the slime layer on bacteria made from?


  Protein