M1 MAJOR REVIEW

• Outline the roles of cholesterol in membrane structure and function.

  -maintain the fludity by preventing phospholipis from solidifying at low temperatures or becoming too fluid at high temperatures.

  -stabilizes the bilayer by binding to polar heads and non polar tails.
• Outline the roles of phospholipids in membrane structure and function.


  They provide a barrier to large polar molecules and ions, while permeable to non-polar molecules and small substances.
• Draw the dicotyledonous root and label the tissues and state how they assist in the function of the root.

  Parenchyma tissue-unspecialized

  
  

  Vascular tissues- transports material through plants cells: pericycle

  
  

  Xylem tissue- Transports water, cells: vessel elements

  
  

  Phloem tissue- transports substances the plant has made. Cells: Phloem sieve elements
• How is the dicotyledonous root an organ?

  The dicotyledonous root is made up of different types of tissues working together so that the root can absorb water and mineral ions.
• Define organ.

  An organ is a structure within a multicellular organism that is made up of different types of tissues working together to perform a particular function.
• Define tissue.

  A tissue is a group of cells grouped together to carry out the same function.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of cell walls.


  In prokaryotic cells the cell wall is always present and made up of peptidoglycan however in eukaryotic cells cellulose cell walls are present in plant cells.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of flagella.


  Prokaryotic cells sometimes have flagella but not of the 9+2 internal fibril arrangement, like that in eukaryotic cells.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of ribosomes.


  Ribosome in prokaryotic cells (70S/20nm)are smaller than the ribosomes in eukaryotic cells(80S/30nm).
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of chloroplasts.

  In prokaryotic cells there are no chloroplasts present but only photosynthetic lamellae however in eukaryotic cells there are chloroplasts usually presents normally in plants and algae.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of membrane bound organelles.

  In prokaryotic cells, there is no membrane bound organelles, however in eukaryotic cells there are membrane bounded organelles present.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of DNA.

  In prokaryotic cells, there are circular strands of DNA however in prokaryotic cells there is linear DNA is located.
• Compare the structure of prokaryotic cells with that of eukaryotic cells in terms of the nucleus.

  In prokaryotic cells, there is no distinct nucleus but only diffused areas of nucleoplasm with no nuclear envelope, however in eukaryotic cells there is a distinct, membrane bound nucleus.
• States the evidence which supports the endosymbiotic theory. (5)

  1.The outer membrane of the envelope of mitochondria and chloroplasts is similar to other membranes of eukaryotic cells, while the inner one has similarities with membranes of prokaryotes.

  2. Mitochondria and chloroplasts each have their circular DNA that is not enclosed in a nucleus like that of prokaryotes.

  3. Mitochondria and chloroplasts each have their own 70S ribosomes like prokaryotic cells.

  4. Mitochondria and chloroplasts reproduce by binary fission, like bacteria which are prokaryotes

  5. Mitochondria and chloroplasts are similar in size to prokaryotic cells.

  Mebiriside
• Outline the basis of the endosymbiotic development of eukaryotic cells.

  The theory states of that mitochondria and chloroplasts where once prokaryotic cells that invaded a eukaryotic cell and lived inside it. A symbiotic relationship was formed as the prokaryotes carried out complex metabolic reactions such as respiration and photosynthesis that provided the eukaryotic cell with energy. The eukaryotes provided the prokaryotes with nutrients.
• With the use of annotations describe the structure of a prokaryotic cell showing structures that may or may not be present. ...
• Comapre the structure of a typical animal and plant cell in terms of carbohydrate storage.

  Plant cells may contain starch grains in plastids while animal cells may contain glycogen granules.
• Comapre the structure of a typical animal and plant cell in terms of the structure lysosome.

  Lysosomes are not usually evident in plant cells but are usually present in animal cells.
• Compare the structure of a typical animal and plant cell in terms of the structures cillia and flagella.

  They are not present in most plant cells but they may be present in some animal cells.
• Compare the structure of a typical animal and plant cell in terms of the structure centriole.

  Plant cells have no centrioles while animal cells usually have a pair of centrioles present.
• Comapre the structure of a typical animal and plant cell in terms of the structure vacuole.

  Plant cells have large, permanent vacuoles often present surrounded by a single membrane called a tonoplast and the vacuole contains cell sap. On the other hand, animal cells have temporary small vacuoles or vesicles.
• Comapre the structure of a typical animal and plant cell in terms of the structure plastids (eg. Chloroplasts)

  Chloroplasts are present in some plant cells and leucoplasts are present in some plant tissues however animal cells have no plastids.
• Comapre the structure of a typical animal and plant cell in terms of the structure plasmodesmata.

  Plasmodesmata link adjacent cells, providing continuous membrane-lined passageway between them in plant cells, while animal cells have no plasmodesmata.
• Comapre the structure of a typical animal and plant cell in terms of the structure cell wall.

  The plant cell has a tough, elastic cell wall made of mainly cellulose, hemicellulose and sometimes lignin, while animal cells have no cell wall.
• What is the function of the nucleolus?

  It contains DNA that is used to make ribosomal RNA which is a component of ribosomes, thus producing ribosomes.
• What is the function of the nucleus?

  It contains store of genetic information as DNA in chromosones which are in chromatins.
• What is the function of centrioles?

  It assembles the spindle to move chromosones when the nucei divides.
• What is the function of the nuclear envelope?


  To separarte the nucleus from the cytoplasm and allow movement between the nucleus and cytoplasm.
• What is the function of the cell membrane?

  It controls what entires and leaves the cell. It retains the cell contents.
• What is the function of chloroplasts?

  It is the site of all the reactions of photosynthesis.
• What is the function of lysosomes?

  The destroy worn out parts of the cell and digest food particles and bacteria with enzymes by fusing with vesicles in the cell.
• What is the function of ribosomes?

  To assemble amino acids to make proteins.
• What is the function of the mitochondria?

  It is the site for aerobic respiration.
• What is the function of the golgi body?

  It modifies and packages proteins and it makes secretory vesicles and lysosomes.
• What is the function of the smooth endoplaismic reticulum?

  It is the site for the synthesis of lipids and the site for the production of steroid hormones and it is the site where toxins are broken down to make them harmless.
• What is the function of the rough endoplaismic reticulum?

  It is the site for protein synthesis.
• How does the structure of collagen relates to it being an extra cellular protein that provides toughness?

  The triple helices are joined together by covalent bonds which are very strong bonds forming fibrils and eventually a network of fibres. Also, the ends of the triple helices are staggered so it will not create a weak spot along the collagen fibrils.
• Collagen is a fibrous protein, what does this mean?


  It means that collagen is insoluble in water and have simple shapes, such as a helix.
• State the function of collagen.

  A collegen is an extracellular protein that provides toughness to skin, bone, cartilage, tendons, ligaments and muscles.
• Outline the molecular structure of collagen.

  Collagen consists of three identical polypeptide chains, each in the shape of a left handed helix. These three helical polypeptides wind around each other to form a rope like structure called a triple helix.