Module 2

  1. What is the equation for magnification?
    Magnification = size of image ÷ actual size
  2. How can resolution be increased?
    • Using a smaller wavelength
    • e.g. electron beam
  3. What is an artefact with reference to microscopy?
    • Visible structural detail caused by processing the specimen 
    • -e.g bubble under cover slip
  4. What are the key features of electron microscopy, what types are there, as well as the resolution and magnification?
    • Beam of electrons ~ less than 1nm
    • Black & White (digitally coloured)
    • Magnification: 500,000x

    • Transmission electron 
    • -through specimen
    • -resolution: 0.5nm
    • -2D image

    • Scanning electron 
    • -across surface
    • -resolution: 3-10nm
    • -3D images
  5. What are the key features of light microscopes, as well as the resolution and magnification?
    • 2D coloured image
    • Magnification: 1500x
    • Resolution: 200nm
  6. What type of image is produced by a laser scanning confocal microscope?
    • 2D or 3D depending on different focal planes
    • Laser light causes fluorescence from dye
    • High resolution
  7. What does gram staining show?
    • Crystal violet 
    • Gram positive bacteria retain the stain 
    • -blue/purple
    • Gram negative bacteria have thinner cell wall ⇨ lose stain


    Safranin dye counterstains G negative bacteria red
  8. What does the acid-fast technique of staining show?
    • Differentiates between mycobacterium and other bacteria
    • Myco ⇨ red
    • other bacteria lose stain and are exposed to a blue stain
  9. What is the Nucleus?
    • Contains DNA
    • Double membrane ~ nuclear envelope
    • Nuclear pores ~ allow molecules in & out of nucleus
  10. What is the Nucleolus?
    • Inside Nucleus
    • Produces Ribosomes
  11. What are Mitochondria? What is their basic structure like?
    • Site of final stages on cellular respiration
    • Produce ATP

    • Inner & outer membrane
    • Cristae
    • Matrix
  12. What are vesicles?
    Single membrane sacs for storage & transport
  13. What are lysosomes?
    • Vesicles
    • Contain hydrolytic enzymes
    • Break down waste & pathogens
    • Have a role in apoptosis
  14. What is the cell cytoskeleton?
    • Network of fibres for cell shape & stability
    • Aids transport within cells
    • Enables cell movement
  15. What are Centrioles?
    • 2 Centrioles form a centromere
    • ~used for assembly & organisation of spindle fibres
    • Found in most eukaryotic cells
    • -NOT flowering plants or most fungi
  16. What are flagella and cilia?
    • Flagella
    • Whip like
    • Cell mobility
    • Sensory organelle

    • Cilia
    • Large numbers
    • Beat in rhythmic manner
    • 9+2 arrangement ~ 2 central microtubules and 9 surrounding pairs
  17. What is the Endoplasmic Reticulum?
    Network of membranes connected to outer nuclear membrane

    • Rough ER 
    • -ribosomes bound to surface
    • -protein synthesis & transport

    • Smooth ER 
    • -lipid & carbohydrate synthesis & storage
  18. What are ribosomes?
    • Made of RNA molecules
    • Site of protein synthesis
    • Found free floating in cytoplasm or on rough ER
    • 70s in prokaryotes, 80s in eukaryotes
  19. What is the Golgi-apparatus?
    • Formed of cisternae 
    • -cis face & tans face
    • Modifying & packing proteins into vesicles
  20. What is the cell wall and what is it made of in different organisms?
    • Shape & support
    • Defense mechanism
    • Freely permeable
    • Plants ~ cellulose
    • Prokaryotic cells ~ peptidoglycan
    • Fungi ~ chitin
  21. What are vacuoles?
    • Membrane lined sacs in cytoplasm
    • Can play role in turgor pressure
    • have membrane called 'tonoplast' ~ selectively permeable
  22. What are chloroplasts? What is their basic structure?
    • Contain chloryphyll pigment
    • Photosynthesis 

    • Double membrane
    • Stroma ~ fluid enclosed
    • Thylakoids 
    • -form stacks called grana (singular granum)
    • -grana joined by lamellae 
    • Own DNA & ribosomes
    • Starch grains present
  23. For the following categories what are the differences between prokaryotic and eukaryotic cells?
    Feature | Prokaryotic | Eukaryotic

    • Nucleus: No | Yes
    • DNA: Circular | Linear
    • DNA organisation: proteins fold & condense DNA | histones
    • Extra chromosonal DNA: plasmids | present in mitochondria & chloroplasts
    • Organelles: non-membrane bound | both non & membrane bound
    • Cell Wall: peptidoglycan | chitin ~ fungi, cellulose ~ plants
    • Robosomes: 70s | 80s ~ larger more complex proteins
    • Cytoskeleton: present | present, more complex
    • Reproduction: binary fission | asexual or sexual
    • Cell type: unicellular | uni or multicellular 
    • Cell surface membrane: yes | yes
  24. What are the following ions necessary for?
    • Ca2+: Nerve impulse transmission. Muscle contraction.
    • Na+: Nerve impulse transmission. Kidney function
    • K+: Nerve impulse transmission. Stomatal opening
    • H+: Catalysis of reactions. pH determination
    • NH4+ (ammonium): Production of nitrate ions by bacteria

    • NO3- (nitrate): Nitrogen supply for plants ~ amino acid & protein formation
    • HCO3- (hydrogen carbonate): Blood pH
    • Cl-: Balance of positive charge of Na+ and K+ ions in cells
    • PO43- (phosphate): Cell membrane formation. Nucleic acid & ATP formation. Bone formation.
    • OH-: Catalysis of reactions. pH determination
  25. What elements make up the following biological molecules?
    • Carbohydrates: Carbon, Hydrogen, Oxygen. Generally Cx(H2O)x
    • Lipids: Carbon, Hydrogen, Oxygen
    • Proteins: Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur
    • Nucleic Acids: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus
  26. What properties does the hydrogen bonding in water lead to?
    • Cohesion: it sticks to itself
    • Adhesion: water molecules get attracted to other molecules
    • ~solvent
    • ~transport medium
    • ~coolant (since large amount of energy needed to overcome H bonding)
    • ~stable environment
  27. Give the structure of α-Glucose, β-glucose and ribose.
    • ck_55f311ac700e0
    • (Just RIBOSE)
    • Image Upload 1
  28. What type of monosaccharides form the following disaccharides?
    • Maltose: 2x alpha glucose
    • Sucrose: Fructose + Glucose
    • Lactose: Glactose + Glucose
  29. Describe the structure of starch
    Formed from alpha glucose

    • Amylose:
    • 1-4 glycosidic bonds
    • helix shape supported by hydrogen bonds within molecule 
    • Compact
    • Less soluble than glucose

    • Amylopectin:
    • 1-4 glycosidic bonds
    • SOME 1-6 glycosidic bonds 
    • Branched structure
  30. Describe the structure of glycogen
    (equivalent storage molecule to starch, but found in animals & fungi)

    • More branched than amylopectin
    • More compact ~ needs less space
    • Many free ends for addition/removal of glucose
  31. What are condensation and hydrolysis reaction?
    • Condensation: removal of water molecule
    • Hydrolysis: addition of water molecule

    Catalysed by enzymes
  32. Describe the structure of cellulose
    • Beta Glucose
    • -alternate in orientation
    • Straight chain ~ unable to coil/branch
    • Hydrogen bond to other cellulose molecules
    • -Microfibrils ⇨ macrofibrils ⇨ fibres
  33. Give two examples of macromolecules
    Triglycerides and Phospholipids
  34. Describe the structure of a Triglyceride
    • 1 glycerol & 3 fatty acids (have a COOH group) 
    • Ester bonds form during condensation reaction ~ esterification 
    • Non-polar
    • Insoluble in water
    • triglycerides2
  35. Describe the structure of phospholipids
    • Modified triglycerides
    • 1 fatty acid replaced with phosphate ion (PO43-)
    • Hydrophilic Head
    • Hydrophobic tails

    • Act as surfactants ~ form a layer on water
    • Form Phospholipid bilayer
    • figure-05-01-03a
  36. What are the roles of lipids?
    • Membrane formation
    • Hormone Production
    • Electrical Insulation
    • Waterproofing 

    • Triglycerides:
    • Thermal Insulation
    • Cushioning to protect organs
    • Buoyancy
  37. What is the basic structure of an amino acid?
    amino_acid_structure

    • aminoAcidStruc
    • (Amino acid as a Zwitter ion)
  38. How are amino acids joined together to form proteins? How are polypeptides broken down?
    • Peptide bond forms between carbon & nitrogen
    • Catalysed by enzyme found in ribosomes

    Breakdown catalysed by proteases
  39. Describe the different levels of protein structure and the bonding involved
    • Primary:
    • Amino acid Sequence
    • -peptide bonds

    • Secondary:
    • Oxygen, Hydrogen and Nitrogen interact
    • α-Helix
    • β-pleated sheet
    • -Hydrogen bonding

    • Tertiary: 
    • Folding into final shape
    • R-groups interact (brought together by secondary structure)
    • -hydrophobic/hydrophilic interations (polar vs non-polar R groups)
    • -hydrogen bonding
    • -ionic bonds
    • -disulphide bonds (bridges between R groups with sulfur atoms)

    • Quaternary:
    • Association of 2+ proteins
    • "subunits"
    • -same bonding as tertairy
  40. Describe the structure and function of Haemaglobin
    • Globular
    • Quaternary Protein ~ 4 polypeptides ~ 2 α & 2 β subunits
    • Each contain prosthetic haem group
    • conjugated protein ~ globular with prosthetic group 
    • Iron II in prosthetic group bind reversibly with O2
  41. Describe the structure and function of Catalase
    • Globular
    • Enzyme
    • Quaternary protein
    • 4 haem prosthetic groups
    • ~interact with hydrogen peroxide to speed up breakdown
  42. Describe the structure and function of Insulin
    • Globular 
    • Hormone ~ blood concentration control 
    • Soluble ~ travel in blood
  43. Describe the properties and functions of Collagen
    • Connective tissue found in skin, tendons, ligaments & nervous system
    • Flexible
    • 3 polypeptides wound together
  44. Describe the properties and functions of Keratin
    • In hair, skin & nails
    • High amounts of amino acid containing sulfur 
    • ~ lots of disulfied bonds
    • Flexibility determined by proportion of disulfide bridges
  45. Describe the properties and functions of Elastin
    • Elastic fibres in walls of blood vessels & alveoli in lungs
    • Made of tropoelastin
  46. What types of bonds are involved in the following molecules?
    • Carbohydrates: Glycosidic bonds
    • Lipids: Ester bonds
    • Proteins: Peptide bonds
    • Nucleic Acids: Phosphodiester bonds
  47. How do you test for proteins?
    • Biuret Test
    • Liquid sample mixed with sodium hydroxide
    • Copper sulfate solution added drop by drop until solution turns blue
    • Stand for 5 mins

    Alkali & copper sulfate solutions are called biuret reagent

    Peptide bonds form violet complexes with copper ions in alkaline solutions
  48. How do you test for reducing & non-reducing sugars?
    • Liquid sample in boiling tube
    • Add Benedict's reagent (alkaline copper II sulfate)
    • Heat gently for 5 mins

    Cu2+ ions get reduced in presence of reducing sugars (e.g. maltose or lactose) turning red

    Reagent test strips for reducing sugars

    (Reducing sugars ~ all monosaccarides & some disaccarides) 
  49. How do you test for Starch
    • Iodine
    • Add iodine dissolved in potassium iodide solution
    • Yellow/Brown turns purple/black if starch is present
  50. How do you test for Lipids?
    • Mix sample with ethanol
    • Mix with water & shake

    White emulsion is positive result for lipids
  51. Describe the structure of Nucleic Acids
    • Monomers: Nucleotides
    • Polymer: Nucleic Acid

    • Pentose monosaccaride
    • Phosphate group PO42-
    • Nitrogenous Base

    nucleotide
  52. What are the differences between DNA and RNA
    • Deoxyribose vs Ribose
    • Double strand vs single strand
    • Thymine vs Uracil
  53. What are the bases of DNA
    • Thymine & Adenine: 2 Hydrogen bonds
    • Guanine & Cytosine: 3 Hydrogen bonds

    • Pyrimidines: smaller, single carbon ring (T & C)
    • Purines: larger, double carbon ring (A & G)
  54. What word describes the directions in which the strands of DNA run?
    Anitparallel
  55. What happens to the bonds in RNA when it breaks down after protein synthesis?
    Hydrolysed
  56. What does semi-conservative replication mean?
    Each new strand of DNA consists of one old and one new
  57. What enzymes are involved in DNA replication?
    • DNA Helicase: breaks hydrogen bonds ~ unzips DNA
    • DNA Polymerase: catalyses formation of phosphodiester bonds between nucleotides
  58. Describe the nature of genetic code?
    • Triplet Code: 3 bases form a codon
    • Universal: to all organisms
    • Degenerate: different combinations of bases can code for the same amino acid
    • Non-overlapping
  59. Describe the structure of ADP and ATP
    • Pentose sugar: ribose
    • Nitrogenous Base: Adenine 
    • Inorganic Phosphates

    Image Upload 2
Author
Hebe
ID
332120
Card Set
Module 2
Description
Foundations in Biology
Updated