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Flashcards

CELLS AND THE MOVEMENT IN AND OUT OF THEM

ashiana121 AS AQA BIOLOGY A-Level Inglês 114 flashcards

CELLS AND THE MOVEMENT IN AND OUT OF THEM

Flashcards do conjunto (114)

  1. 1What instruments do we use to magnify images of objects?Microscopes
  2. 2What are the two types of microscope?Light microscope and electron microscope
  3. 3What is the equation used to calculate magnification?What is the equation used to calculate magnification?
  4. 4What is it important to ensure when calculating the magnification?The units are the same for the object size and image size
  5. 5How many nanometers are there in a millimeter?1,000,000
  6. 6So if an image was 10mm long and you knew the size of the object was 100nm, what calculation would you do to work out the magnification?10,000,000nm ÷ 100nm
  7. 7What is the definition of magnification?The degree to which something is enlarged under a microscope
  8. 8What is the definition of resolution?The minimum distance apart that two objects can be in order for them to appear as two separate objects
  9. 9What does resolution depends on?The wavelength or form of radiation used
  10. 10What is the process called in which cells are broken up and the different organelles they contain are separated out?Cell fractionation
  11. 11Before cell fractionation can begin, the tissue is placed in a cold, isotonic, buffer solution. Explain why each of these is necessary.Cold - to reduce enzyme activity that could break down the cells
    Isotonic - to prevent organelles bursting or shrinking as a result of osmosis
    Buffer - to maintain a constant pH
  12. 12What are the two stages of ultra centrifugation?Homogenation and ultracentrifugation
  13. 13What happens in homogenation?Cells are broken up by a homogeniser - this releases the organelles - the homogenate is filtered to remove any complete cells or large pieces of debris
  14. 14After this the homogenate is spun in an ultracentrifuge. First the tube of filtrate is spun at a low speed. What happens?The heaviest organelles - NUCLEI - are forced to the bottom and form a sediment
  15. 15The fluid at the top (supernatent) is filtered off and it is spun on a faster speed. What happens?The next heaviest organelles - MITOCHONDRIA - are forced to the bottom of the tube
  16. 16When the supernatent is removed and spun again, what organelles form the next sediment?Lysosomes
  17. 17Which are the smallest organelles that will from the last sediment?Ribosomes
  18. 18Why do light microscopes have a poor resolution?Due to the relatively long wavelength of light
  19. 19What does this mean the electron microscope has and why?A higher resolution due to the shorter wavelength of electrons
  20. 20Why can the beam of electrons be focused using electromagnets?Electrons are negatively charged
  21. 21Why does a vacuum have to be used in electron microscopes?Because electrons are absorbed by molecules in air
  22. 22What are the two types of electron microscope?Transmission electron microscope & scanning electron microscope
  23. 23Which out of the two produces a 3D image?Scanning electron microscope
  24. 24Which one out of the two has the higher resolution?Transmission electron microscope
  25. 25What are limitations of electron microscopes in general?- Vacuum needed and beam of electrons used so living specimens cannot be observed
    - Specimen must be extremely thin
    - Complex staining process required
    - Expensive to buy and to maintain
    - Lots of training required
  26. 26Name six organellesNucleus, ribsomes, ER, golgi, lysosomes, mitochondria
  27. 27What are the functions of the nucleus?- Act as a control center (production of mRNA and hence protein synthesis)
    - Retain the genetic information of the cell in the form of DNA and chromosomes
    - Make ribosomal RNA and ribosomes
  28. 28Which organelle is the site of respiration?Mitochondria
  29. 29What do mitochondria release?ATP
  30. 30The cristae inside the mitochondria are folded. This increases the surface area for what?The attachment of enzymes involved in respiration
  31. 31What are the two types of ER?Smooth ER and rough ER
  32. 32Which one has ribosomes on its surface?Rough ER
  33. 33What are the functions of rough ER?Provide a large surface area for the synthesis of proteins and glycoproteins & provide a pathway for the transport or materials throughout the cell
  34. 34How does the smooth ER differ in appearance to rough ER?No ribosomes on its surface, more tubular
  35. 35What are the functions of smooth ER?Synthesise, store and transport lipids and carbohydrates
  36. 36What are the three functions of the golgi apparatus?Produces lysosomes
    Processes, packages and secretes lipids, proteins and carbohydrates
    Vesicles to transport to the cell surface membrane
  37. 37Which organelle is the site of protein synthesis?Ribosomes
  38. 38How many subunits make up ribosomes?2
  39. 39What are the functions of lysosomes?1. Contain enzymes that digest worn out parts of cell
    2. Autolysis
  40. 40What are lipids soluble and insoluble in?Insoluble in water, soluble in organic solvents (alcohols, acetone)
  41. 41What elements do lipids contain?Carbon, hydrogen and oxygen
  42. 42What are the three main groups of lipids?Triglycerides, phospholipids and waxes
  43. 43What are the 5 main roles of lipids?Plasma membranes
    Energy source
    Waterproofing
    Insulation
    Protection
  44. 44What parts make up a triglyceride?Three fatty acid tails and glycerol
  45. 45In what reaction do the fatty acid tails make a bond with the glycerol?Condensation reaction
  46. 46Where does the different properties of the fats and oils come from?The variation of the fatty acids
  47. 47How many fatty acids are there?70
  48. 48If the hydrocarbon chain of the fatty acid has no double bonds it is __________Saturated
  49. 49What is the difference between triglycerides and phospholipids?Phospholipids have 2 fatty acids and a phosphate group
  50. 50What properties of phospholipids makes them suitable in the cell surface membrane?Hyrdrophilic head (phosphate) and hydrophobic tails (fatty acids)
  51. 51What is the test called that we use to test for lipids?The emulsion test
  52. 52What are the steps of the emulsion test?1. Add ethanol to sample
    2. Shake to dissolve sample
    3. Add water and shake
  53. 53What is the result of the test if a lipid is present?Any cloudy white colour
  54. 54What is the cloudy white colour due to?Due to any lipid in the sample being finely dispersed to form and emulsion - light passing through refracts across oil and water droplets
  55. 55In the plasma membrane, what are the functions of the phospholipid bilayer? (3)- Allow lipid soluble substances to enter and leave the cell
    - Keep water soluble substances from entering and leaving the cell
    - Make the membrane flexible
  56. 56What two types of proteins are there in cell surface membranes?Intrinsic and extrinsic
  57. 57There are six functions of the intrinsic and extrinsic proteins in cell surface membranes. What are these functions?Structural support - act as carries for water soluble substances - allow active transport by forming ion channels - form recognition sites - help cells stick together - act as receptors
  58. 58Why is the cell surface membrane described as 'fluid mosaic'?Fluid - because the individual phospholipid molecules can move relative to one another, making the membrane flexible
    Mosaic - because the proteins vary in size and it looks like a mosaic
  59. 59What is the definition of diffusion?THE NET MOVEMENT OF MOLECULES (OR IONS) FROM A REGION OF HIGH CONCENTRATION TO A REGION OF LOW CONCENTRATION
  60. 60What equation do we use to calculate diffusion?What equation do we use to calculate diffusion?
  61. 61What is diffusion also affected by?The nature of plasma membrane (composition/number of pores) and the size and nature of the diffusing molecule (small molecules diffuse faster than large ones)
  62. 62Is facilitated diffusion passive or active?Passive
  63. 63Diffusion and facilitated diffusion occur ______ a concentration gradientDown
  64. 64However what does facilitated diffusion involve that normal diffusion doesn't?Carrier proteins
  65. 65What type of molecules do the carrier proteins allow to diffuse?Water soluble
  66. 66What is the definition of osmosis?THE PASSAGE OF WATER FROM A REGION OF HIGH WATER POTENTIAL TO A REGION OF LOW WATER POTENTIAL THROUGH A PARTIALLY PERMEABLE MEMBRANE
  67. 67What is a solute?Any substance that is dissolved in the solute
  68. 68What is a solution?The solute and the solvent together
  69. 69What is water potential measured in?kPa
  70. 70What is the sign for water potential?What is the sign for water potential?
  71. 71What is the water potential of pure water?0
  72. 72What is an isotonic solution?A solution with the same water potential to the cell inside it
  73. 73When animal and plant cells are placed in an isotonic solution, what is the net movement of water?Neither enters or leaves the cell - there is no change
  74. 74What is a hypertonic solution?A solution with a lower water potential to that of the cell (high strength)
  75. 75What name is given to a solution with a higher water potential (low strength) to that of the cell?Hypotonic
  76. 76When a plant cell is placed in a hypertonic solution, what happens to it?Net movement of water out of the cell, cytoplasm shrinks from cell wall and cell plasmolyses
  77. 77What happens if a plant cell is placed in a hypotonic solution?Water enters the cell by osmosis and the cell swells and becomes turgid
  78. 78If an animal cell bursts when it is put into a solution, what must that solution be?Hypotonic
  79. 79Why is this?Water enters the cell so it swells and bursts
  80. 80What will happen to an animal cell if it is placed in a hypertonic solution?Water will leave the cell by osmosis and it will shrink
  81. 81What is the definition of active transport?THE MOVEMENT OF MOLECULES OR IONS INTO OR OUT OF A CELL FORM A REGION OF LOW CONCENTRATION TO A REGION OF HIGH CONCENTRATION, USING ENERGY AND CARRIER MOLECULES
  82. 82Does active transport differ from passive forms of transport such as facilitated diffusion?- Metabolic energy in the form of ATP is needed
    - Materials move against a concentration gradient
    - Process is v. selective
    - Involves protein 'pumps'
  83. 83In which two ways is ATP used in active transport?- Using it to directly move molecules
    - By using a concentration gradient that has already been set up by direct active transport (co-transport)
  84. 84In active transport, when molecules bind to carrier proteins on the outside of the cell, what attaches to the same protein on the inside of the cell?ATP
  85. 85What does this cause ATP to split into?ADP and a phosphate molecule
  86. 86What happens to the protein as a result of the phosphate molecule binding to the inside of the protein?It changes shape - opens to the opposite side of the membrane
  87. 87After the molecules or ions are released into the inside of the membrane, what happens to the phosphate molecule?It is released from the protein and combines with ADP to form ATP during respiration
  88. 88What does the protein then do?Revert to its original shape
  89. 89Give an example of an active transport system in which a molecule is being removed from a cell at the same time as one being moved in to the cellThe sodium-potassium pump
  90. 90Which molecules are actively moved where in the sodium-potassium pump?Sodium ions out, potassium ions in
  91. 91Glucose is absorbed in the wall of the small intestine. The walls of the small intestine are folded into finger like projections called _____Villi
  92. 92Give 4 reasons why the villi are well adapted for to absorption of molecules, such as glucose, by diffusion- They increase the s.a for diffusion
    - They are thin to reduce the diffusion pathway
    - Able to move and therefore maintain a conc. gradient
    - Supplied with a rich network of blood capillaries to help maintain a diffusion gradient
  93. 93What is situated on the epithelial lining of the villi?Microvilli
  94. 94What does this mean is increased further?The surface area
  95. 95In the sodium-potassium pump, which molecules are actively transported out of the epithelial cells (through a carrier molecule)?Sodium
  96. 96What does this mean about the concentration of sodium ions in the lumen of the intestine?It is high
  97. 97This means there is a ___________ _______ of the sodium ions between the lumen and the epithelial cells.Concentration gradient
  98. 98What does this mean sodium ions are able to do?Diffuse back in to epithelial cells
  99. 99What do the sodium ions bind with as they diffuse back into the cells, and through which molecules do they do so?They bind with glucose ions, and go through a co-transport protein
  100. 100What does the glucose then do?Move down its concentration gradient - it diffuses through the cell membrane and capillary walls and into the blood
  101. 101Why is the absorption of glucose molecules an indirect form of active transport?The sodium ion concentration gradient powers to movement of glucose molecules
  102. 102What is the name of the pathogen that causes cholera?Vibrio cholerae
  103. 103If vibro cholerae enters the digestive system, what are most of the bacteriums killed by?The HCl in the stomach
  104. 104However some may survive. When they reach the small intestine, what structure do they use to propel themselves through the mucus lining of the intestinal wall?Their flagella
  105. 105What does the bacterium release at this stage?A toxin
  106. 106What does this toxin cause to open?Ion channels
  107. 107What floods out of the epithelial cells as a result?Chloride ions
  108. 108What happens to the water potential of the lumen as a result?It is lowered (more negative)
  109. 109What does this make happen and by what process?Water floods out of the epithelial cells and into the lumen by osmosis
  110. 110This causes _________ and ___________Diarrhoea and dehydration
  111. 111How is cholera transmitted?Through the ingestion of water contaminated with the faecal material of infected individuals
  112. 112What is the name given to treatment for diarrhoea?Oral rehydration therapy
  113. 113What the the two reasons why just drinking water is ineffective in treating diarrhoea (/dehydration)?1. Water is not being absorbed by the intestine
    2. Electrolytes (ions) are not being replaced
  114. 114What 5 things are included in oral rehydration powder?Water - potassium - sodium - glucose - other electrolytes such as chloride and citrate ions

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A-Level AS AQA BIOLOGY FlashCards sobre CELLS AND THE MOVEMENT IN AND OUT OF THEM, criado por ashiana121 em 14-05-2015.
Criado por
ashiana121 · mai 2015
Atualizado
19 fev 2016
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