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BIO YR1 > microscopes > Flashcards

microscopes Flashcards

1
Q

describe compound light microscope

A
  • objective lens : near specimen
  • eyepiece lens : specimen is viewed through
  • illumination by light underneath the sample
  • eyepiece magnifies, objective magnifies again
  • reduces chromatic aberration
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2
Q

dry mount prep

A
  • section solid specimen (cut/whole but thin)
  • placed on centre of slide
  • cover slip over
  • e.g hair , dust / sectioned muscle
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3
Q

wet mount prep

A
  • specimen suspended in a liquid(water)
  • cover slip over on an angle
  • ## no air bubbles
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4
Q

smear slides

A
  • edge of slide smears the sample
  • thin even coating
  • E.G blood
  • views cells
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5
Q

use of staining

A
  • increase contrast
  • diff components of cells take up stain to diff degrees
  • components more visible
  • sample on slide is air dried
  • heat fixed (passed through a flame)
  • specimen adheres to slide
  • will take up stains
  • E.G crystal violet/methylene blue(DNA)
  • Congo red = negative stain
  • eosin (cytoplasm)
  • in e- microscope stain = solution of heavy metals (lead) bc they scatter e- creating contrast.
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6
Q

differential staining

A
  • distinguishes between 2 type of organisms

- differentiate between diff organelles within a tissue sample

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7
Q

magnification equation

A

magnification = image size (with ruler)/ actual size

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8
Q 
nm = micrometre
micrometre = mm
mm = m
A
  • 1000nm = 1 micro
  • 1000micro = 1mm
  • 1000mm = 1m
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9
Q

electron microscopes

A
  • beam of e-
  • shows cell ultrastructure
  • over x500000 magnification
  • expensive
  • used inside controlled env
  • specimen can be damaged by e- beam
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10
Q

transmission e- microscope

A
  • beam of e- transmitted through a specimen

- produces an image

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11
Q

scanning e- microscope

A
  • beam of e- across a surface
  • collects reflected e-
  • 3D image of surface
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12
Q

light v electron microscope

- compare magnification/resolution

A 
L : inexpensive 
E : expensive
L : small + portable
E : large + installed
L: no vacuum
E : requires vacuum 
L : living/dead specimen
E : dead specimen 
L : 
- R = 0.2micrometres 
- M = x1500
TEM:
- R = 0.0002micrometres
- M = more than x1000000
SEM:
- R = 0.002 micrometres
- M = less than 500000
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13
Q

prokaryotes

A
  • single celled
  • simple structure
  • cytoplasm : no membrane bound organelles
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14
Q

eukaryotes

A
  • multicellular
  • complicated internal structure
  • membrane bound nucleus
  • cytoplasm : membrane bound components
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15
Q

nucleus

A
  • contain genetic info
  • DNA directs protein synthesis
  • control metabolic activities of the cell
  • DNA contained in double membrane = nuclear envelope
  • NE has nuclear pores (mol move in/out of nucleus)
  • DNA combines with histones to form chromatin
  • chromatin coils/condenses = chromosomes
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16
Q

nucleolus

A
  • in nucleus
  • produces ribosomes
  • composed of proteins + RNA
  • RNA produces rRNA
  • rRNA combines with proteins to form ribosomes
17
Q

mitochondria

A
  • cellular respiration
  • double membrane
  • inner membrane is folded = cristae
  • fluid interior = matrix
  • membrane of cristae has enzyme used in aerobic resp
  • ribosomes : produce own proteins
  • reproduce themselves
18
Q

vesicles

A
  • membranous sacs
  • storage/transport roles
  • single membrane with fluid inside
19
Q

lysosomes

A
  • specialised forms of vesicles
  • hydrolytic enzymes
  • break down waste material in cells
  • immune system : break down pathogens
  • role in cell death
20
Q

cytoskeleton

A
  • in cytoplasm
  • network of fibres
  • shape
  • stability
  • organelles held in place
  • control cell movement
21
Q

components of cytoskeleton

A 
microfilaments : 
- contractile fibres formed from actin(protein)
- cell movement 
- cell contraction during cytokinesis
-
microtubules :
- shape of the cell
- tracks for cell movement 
- make spindle fibres

intermediate fibres:

  • mechanical strength
  • maintain their integrity
22
Q

flagella/cilia

A
  • extensions
  • flagella enable cells movement
  • cilia = mobile or stationary
  • cilia : surface of sensory organs (nose)
  • cilia : move in rhythmic manner to move mucus
23
Q

endoplasmic reticulum

A
  • network of membranes
  • encloses cisternae (flattened sacs)
  • smooth ER : lipid/carb synthesis + storage
  • rough ER : ribosomes bound to surface + synthesis + transport of proteins
24
Q

ribosomes

A
  • no membrane
  • made of RNA mol (nucleolus)
  • site of protein synthesis
25
Q

golgi

A
  • formed of cisternae
  • no ribosomes
  • modifies proteins
  • packaging proteins into vesicles to leave cell
  • or into lysosomes to stay in cell
26
Q

protein productions - interrelationship of organelles

A
  • proteins synthesised on ribosomes
  • bound to RER
  • pass into cisternae
  • packaged into transport vesicles
  • vesicles move to golgi via cytoskeleton
  • vesicles fuse with cis face golgi
  • proteins enter
  • proteins structurally modified
  • leave golgi in vesicles from trans face
  • secretory vesicles carry proteins
  • move towards + fuse with CSM
  • releasing content by exocytosis
  • some vesicles form lysosomes
  • contain enzymes used in cells
27
Q

cell wall

A
  • cellulose
  • give it shape
  • rigid
  • defence mechanism protecting inside from pathogens
28
Q

vacuoles

A
  • membrane lined sacs
  • contain cell sap
  • maintain turgor
  • membrane = tonoplast
  • selectively perm
29
Q

prokaryotic DNA

A
  • one mol of DNA (chromosomes)
  • supercoiled
  • more compact
  • genes grouped in operons
  • number of genes switched on/off
30
Q

prokaryotic ribosomes

A
  • smaller than euk

- protein synthesis

31
Q

prokaryotic cell wall

A
  • made from murein

- complex polymer from amino acids + sugar

32
Q

prokaryotic flagella

A
  • thinner than euk
  • energy supplied by chemiosmosis
  • rotated by molecular motor
33
Q

euk/prokaryotes ultracellular structure comparison

A

nucleus : Euk
DNA : Pro(circular) + Euk(linear)
cell wall : Pro(murein) + Euk(cellulose in plants/chitin in fungi)
ribosomes : Pro(smaller 70S) + Euk(larger 80S)
reproduction : Pro(binary fission) + Euk(a/sexual)
cell membrane : Euk + Pro
organelles : Pro(non-membrane bound) + Euk(both membrane + non-membrane bound

BIO YR1 (7 decks)

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