chapter 2- Basic components of living systems Flashcards

1
Q

max resolutions?

A

light microscope= 0.2um
TEM=0.0005um
SEM=0.003um- 0.01um
lower resolution= better image quality

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2
Q

Max magnification

A

light microscope= x1500
TEM= more x1,000,000
SEM= less than x1,000,000
higher magnification the better

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3
Q

how does staining enable cell components to become visible?

A
  • resolution is limited by wavelength of light as it passes through the sample
  • most cell structures have low contrast and do not absorb light
  • stains increase contrast as different cell components take up the stain by different amounts
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4
Q

Give examples of stains

A
  • Crystal violet/ methylene blue= positively charged dye, attracted to negatively charged materials in the cytoplasm, stains RNA/DNA.
  • Nigrosin/ Congo red= negatively charged dye, repels negatively charged cytosol. These dyes stay outside of the cell, leaving the cell unstained so it can stand out against a stained background.
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5
Q

units of measurement

A

1000nm= 1um
1000um= 1mm
1000mm= 1m
10mm=1cm

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6
Q

what are the 4 different ways a specimen can be prepared for light microscopy?

A
  • dry mount
  • wet mount
  • squash slides
  • smear slides
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7
Q

stages involved in the production of slides

A
  • fixing= used to preserve the specimen
  • sectioning= specimens are dehydrated with alcohols then placed in a mould with wax, which can be thinly sliced
  • staining= specimens are treated with multiple stains to show different structures
  • mounting= specimens are secured to a microscope slide with a cover slip on top
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8
Q

describe the acid- fast technique

A
  • used to identify bacteria
  • carbolfuchsin dye is carried into specific cells
  • the cells are then washed with a dilute acid alcohol solution
  • bacteria will retain the carbolfuchsin dye which is bright red
  • other bacteria will lose stain and appear blue*
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9
Q

what is the acid fast technique used for?

A
  • used to differentiate species of mycobacterium from other bacteria.
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10
Q

describe the gram stain technique.

A
  • crystal violet is added to the bacterial specimen on the slide, then iodine which fixes the dye
  • the slide is then washed with alcohol
  • the gram positive bacteria retain the crystal violet stain and will appear blue/ purple
  • the gram negative bacteria have thinner cell walls, and therefore lose the stain. so they are stained with a counter stain (e.g. safranin dye), which will make the bacteria appear red.
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11
Q

what is the gram stain technique used for?

A
  • used to separate bacteria into 2 groups, gram positive and gram negative bacteria.
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12
Q

describe the features of a laser micoroscope

A
  • also known as a confocal microscope
  • laser scans objects point by point to assemble an image
  • can focus on different structures at different depths
  • more expensive than light microscopes
  • can study whole living organisms
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13
Q

what are the structures of a prokaryotic cell?

A

it is a bacteria cell and contains:
- cell wall( made of peptidoglycan)
- cell membrane= to allow transport of substances in an out of the cell
- slime capsule= to protect the bacteria from detection
- cytoplasm= for chemical reactions
- no nucleus= DNA in a loop
- ribosomes
- mesosome= help in the synthesis of the cell membrane, replication of DNA, and protein synthesis.
- flagella= for movement
- cytoskeleton= contains microtubules involved in cell division
- contains plasmids
- glycogen granules as energy stored
- pili= made of protein, for attachment (adhesion) to host cells

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14
Q

what is ultrastructure?

A

the detailed structure of cells visible only with an electron microscope

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15
Q

describe the mitochondria.

A
  • oval shaped organelle
  • matrix contains enzymes needed for respiration
  • needed for ATP production
  • inner membrane folded to form the cristae
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16
Q

describe the Golgi apparatus

A
  • fluid filled, flattened sacs.
  • processes and packages new lipids and proteins into vesicles
  • makes lysosomes
17
Q

describe the function of the SER

A
  • synthesis and processes new lipids
18
Q

describe the function of the RER

A
  • folds and process proteins made by ribosomes
19
Q

describe the chloroplast

A
  • site of photosynthesis
  • small, flattened structure
  • surrounded by a double membrane, filled with a thick liquid called stroma
  • contains thylakoid membranes which stack up to form grana (linked together by lamellae).
20
Q

is sucrose a reducing sugar?

A

Sucrose is not a reducing sugar because it lacks an aldehyde group.

21
Q

what are some examples of reducing sugars?

A
  • glucose
  • fructose
  • galactose
21
Q

what is a reducing sugar?

A

A reducing sugar is a type of sugar that can donate electrons to another substance. This happens in the Benedict’s test, where reducing sugars react with the Benedict’s solution and cause a color change. Reducing sugars have a free aldehyde (-CHO) or ketone (-C=O) group.

21
Q

define magnification

A

magnification is the number of times larger the image is compared to the object

22
Q

describe how the ultrastructure (can only be seen with a high magnification) of a neutrophil is specialised to enable it to perform this function. (4)

A
  • many microfilaments/microtubules
  • many ribosomes
  • many mitochondria
  • lots of Golgi
  • many receptor sites on plasma membrane
  • many lysosomes
23
Q

state 3 roles of membranes inside cells

A
  • site of attachment for enzymes/ ribosomes
  • selectively permeable
  • compartmentalisation
24
Q

outline how vesicles are moved from one organelle to another (2)

A
  • cytoskeleton is used for movement
  • vesicles move along microtubule
  • microtubules extend and break down
  • uses ATP
25
Q

why must specimens be thin when viewing under a microscope? (2)

A

so light can shine through it (1) / details can be seen (1)

26
Q

why must a cover slip be placed onto a wet mount at an angle? (1)

A

reduce / prevent air bubbles being trapped (1)

27
Q

what are 4 examples of proteins?

A
  • enzymes ( catabolic/ anabolic)
  • structural e.g. fibrous
  • antibodies (produces an immune response)
  • transport protein e.g. channel proteins