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Biology Module 1 > Chapter 2: Basic Components Of Living Systems > Flashcards

Chapter 2: Basic Components Of Living Systems Flashcards

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1
Q

Microscope

A

An instrument that allows you to magnify cells and see details of their ultrastructure

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2
Q

Advantages of light microscopes

A

Can observe living and dead things
Does not use harsh chemicals
Easy to setup and use
Cheap and portable

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3
Q

Disadvantages of light microscopes

A 
Low magnification (x2000)
Low resolution (200nm)
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4
Q

What is transmission electron microscopy?

A

Beam of electrons
Transmitted through a specimen
Focused to produce an image

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5
Q

Advantages of transmission electron microscopy

A 
High magnification (x 5 000 000)
High resolution (0.5nm)
Can see internal cell structure
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6
Q

What is scanning electron microscopy?

A

Beam of electrons
Sent across surface of specimen
Electrons reflected and collected to produce image

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7
Q

Advantages of scanning electron microscopy

A 
High magnification (x 500 000)
High resolution (3-10nm)
Can see the surface of cells
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8
Q

Disadvantages of transmission electron microscopy

A

Can only see dead material
Harsh chemicals used in prep
Expensive

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9
Q

Disadvantages of scanning electron microscopy

A

Can only see dead material
Harsh chemicals used (damaging to cell stature)
Expensive

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10
Q

What is laser scanning confocal microscopy?

A

Single spot of focused light
Moves across thin section of specimen
Light re-emitted is filtered through a pinhole aperture

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11
Q

Advantages of laser scanning confocal microscopy

A

Can see living cells - non invasive
Can observe cell processes - tracking
Higher resolution than light microscopy

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12
Q

Disadvantages of laser scanning confocal microscopy

A

Low magnification (x 2000)
More expensive than light microscope
Only a 2D image is produced

… 3D by creating images at different focal planes

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13
Q

Three cell theory statements

A

Plants and animals are composed of cells
Cells are the basic unit of all life
Cells can only develop from existing cells

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14
Q

What is brightfield microscopy?

A

Sample is illuminated from below

Observed from above

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15
Q

What is whitefield microscopy?

A

Whole sample is illuminated at once

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16
Q

Disadvantages of using microscopes

A

Organelles have low contrast in images

Cells do not absorb much light

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17
Q

How the general disadvantage of using microscopes can be overcome

A

Use stains

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18
Q

What is the purpose of staining cells?

A

Increase contrast
Different components absorb different amounts
Easier to differentiate between organelles

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19
Q

What are the four methods of preparation for sample light microscopy?

A

Dry mount
Wet mount
Squash slides
Smear slides

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20
Q

What is a dry mount?

A

Solid specimen
Sectioned
Placed between slide and cover slip

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21
Q

What is a wet mount?

A

Specimens are suspended in liquid

Cover slip is placed on top of slide

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22
Q

What is a squash slide?

A

Wet mount is prepared

Lens tissue is used to press down cover slip on slide

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23
Q

What is a smear slide?

A

Edge of a slide
Smears sample thinly and evenly on another slide
Cover slip is placed on top of slide with the smear

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24
Q

What are the two lenses in a compound microscope called?

A

Objective lens - placed near the object to produce a magnified image

Eyepiece lens - used to view the object and further magnify the object - reducing chromatic aberration

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25
Q

How do you prepare a sample for staining?

A 
Sample placed on slide
Allowed to air dry
Passed through flame
Sample adhered to slide
Able to take up stains
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26
Q

What happens when positively charged dyes are used to stain cells?

A

Attracted to negatively charged materials in the cytoplasm

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27
Q

Name two common dyes

A

Methylene blue

Crystal violet

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28
Q

What is the charge of cystosol in cells?

A

Negative

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29
Q

What happens when negative dues are used to stain cells?

A

Negative charged components in the cytoplasm repel the dye

Cells are left unstained and so stand out against stained background

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30
Q

What is the purpose of differential staining?

A

Used to differentiate between two types of organisms that are somewhat similar

Used to differentiate between different organelles of a single organism in a tissue sample

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31
Q

Describe the gram stain technique

A

Separates bacteria into positive and negative groups

Crystal violet used to stain cells -> Iodine fixes the dye -> Sample is washed with alcohol -> Positive bacteria retain the stain (thicker cell walls)

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32
Q

What does a counterstain do?

A

Safranin dye makes gram-negative bacteria turn red, whereas the crystal violet left them colourless

Due to their thinner cell walls, gram-negative bacteria do not retain due and are not susceptible to penicillin
… inhibits cell wall formation

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33
Q

Describe the acid-fast technique

A

Used to separate different species of Mycobacterium -> Lipid solvent carries carbolfusion dye into the cells -> Cells are washed with a dilute acid-alcohol solution -> Mycobacterium retain the stain and turn red -> Other bacteria are exposed to the blue methylene stain

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34
Q

What are the four methods of producing slides?

A

Fixing - chemical, preserve cells, near-natural state
Sectioning - alcohols, dehydrate cells, placed in mould, sliced thinly
Staining - dyes, multiple ones used to show multiple structures
Mounting - sample being secured between a slide and cover slip

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35
Q

What do scientific drawings include?

A 
Title
Magnification 
Smooth continuous line
No shading
Straight lines parallel to page
36
Q

What is an artefact?

A

A visible structural detail caused by processing the specimen but is not a feature of it E.g. Bubbles trapped under a cover slip

37
Q

What is the purpose of a dichroic mirror in a laser scanning confocal microscope?

A

It reflects one wavelength but allows other wavelength to pass through - non blurred image

38
Q

What is the purpose of antibodies with fluorescent tags?

A

Laser scanning confocal microscopy allows specific features to be targeted and studied with more precision than when using staining and light microscopy

39
Q

How do fluorescent tags work?

A

They emit bright green light when illuminated by UV light

Genetically engineered to fluoresce different colours so different structures can be studied

Non invasive technique - gene is isolated and attached to the genes coding for proteins

Allows study of production and distribution of proteins in cells and organisms

40
Q

Define magnification

A

By how many time the image has been enlarged

Objective lens

41
Q

Define resolution

A

How much detail the object can be viewed in - limited by diffraction

42
Q

Define diffraction

A

The tendency of light waves to disperse as they pass close to physical structures in the specimen being studied - causing loss of detail

43
Q

Define resolved

A

Seen separately

44
Q

How can resolution be increased?

A

Using beams of electrons which have wavelengths thousands of times shorter than light
… beams can be closer together before overlapping

45
Q

Magnification formula

A

Magnification = image / object

46
Q

What is the use of an eyepiece graticule?

A

Used to measure the size of a sample under a microscope

Glass disk marked with a fine scale of 1 to 100 which has no units and remains unchanged

Relative size of division increases with each magnification factor

47
Q

What is the use of a stage micrometer?

A

A microscope slide with a very accurate scale in micrometers (um)

100 divisions = 1mm
1 division a 0.01mm

48
Q

Measurement equation

A

Measurement = graticule divisions X magnification factor

49
Q

Define prokaryote

A

Single-celled organism

50
Q

Define eukaryote

A

Multicellular organism

51
Q

What is metabolism?

A

The rate at which molecules are synthesised or broken down

52
Q

What is a membrane?

A

Controls what substances enter and exit the cell

Selectively permeable to maintain the cell environment

53
Q

Definition of nucleus

A

Contains DNA

  • > directs synthesis of proteins
  • > controls metabolic activities
54
Q

What is the nuclear envelope?

A

Double membrane with pores

Protects DNA from damage from the low pH of the cytoplasm in a cell

55
Q

What is the nucleolus?

A

In the nucleus
Produces ribosomes
Composed of RNA (which make proteins)

56
Q

What is a mitochondrion?

A

Double membrane organelle
Inner membrane is highly folded (cristae)
Cristae contain the matrix (fluid) and enzymes - for the production of ATP

57
Q

What is a vesicle?

A

Singular membranous sac with storage and transport roles

58
Q

What are lysosomes?

A

Specialised vesicle
Contains hydrologic enzymes
Break down waste materials and pathogens
Apoptosis ‘programmed cell death’

59
Q

What is the cytoskeleton?

A

Network of fibres
Provide shape and stability

Microfilaments - contractile fibres, made of protein actin, responsible for cell movement and contraction

Microtubules - compose spindles fibres (segregate chromosomes in cell division), formed by the polymerisation of globular tubular proteins

60
Q

What are intermediate fibres?

A

Fibres made of proteins
Provide mechanical strength
Help maintain cell integrity

61
Q

What are centrioles?

A

Components of the cytoskeleton that are composed of micro tubules

2 associated centrioles form a centrosome
…involved in the assembly and organisation of spindle fibres

62
Q

What is a flagella?

A

Primary function - cell movement

Secondary function - sensory organelle, fetch change in cell environment

63
Q

What are cilia?

A

Stationary - present on surface - sensory organelle

Mobile - beat in a rhythmic manner creating a current to move fluids with trapped pathogens

64
Q

Which four organelles coordinate the production of proteins in cells?

A

Ribosomes
ER
Golgi apparatus
Cytoskeleton

65
Q

What is the endoplasmic reticulum?

A

A network of membranes enclosing cisternae which is connected to the nuclear envelope

66
Q

What is the smooth ER?

A

Responsible for lipid and carbohydrate synthesis and storage

67
Q

What is the rough ER?

A

Has ribosomes bound to the surface

Responsible for the synthesis and transport of proteins

68
Q

What is a ribosome?

A

Organelle where protein synthesis occurs

Contrasted of RNA made in the nucleolus used to make proteins

69
Q

What is the Golgi apparatus?

A

Organelle which modifies and packages proteins into vesicles for transport

70
Q

Define exocytosis

A

Vesicles fuse with the cell surface membrane for secretion out of the cell

Some form lysosomes

71
Q

Define endocytosis

A

Movement of substances into the cell

72
Q

Define phagocytosis

A

Movement through solid e.g. Lysosomes engulfing something

73
Q

Define pinocytosis

A

Movement through liquid e.g. Vesicle through the cytoplasm

74
Q

Define transcription

A

The copying of DNA so mRNA can exit the nucleus and cell and go to the ER ribosomes

75
Q

Define translation

A

The assembly of amino acids into proteins in the ribosomes of the ER

76
Q

What is the cell wall?

A

Give plants shape and support (turgor from vacuole)

Freely permeable membrane made of cellulose which acts as a barrier

77
Q

What is a vacuole?

A

Membrane lined sacs in cytoplasm

Contains cell sap which maintains turgor

78
Q

What is a chloroplast?

A

Organelle with a double membrane (containing stroma, DNA and ribosomes)
Responsible for photosynthesis

Thylakoids -> Granum (joined by lamellae)

79
Q

What is chlorophyll?

A

A green pigment from which photosynthesis occurs and produces starch

80
Q

What are extremophiles?

A

Organisms that can survive in extreme environments

81
Q

How do flagella move?

A

Filament is attached to the cell me ante by a basal body and rotates by a molecular motor by the energy supplied by chemiosmosis

82
Q

What form is DNA in cells?

A

Supercoiled -> Histones -> Chromatin

83
Q

How does DNA structure differ in P and E cells?

A

P - circular (proteins fold and condense)

E - linear (associated proteins, Histones)

84
Q

What are cell walls made of?

A

P - peptidoglycon

E - chitin=fungi, cellulose=plants, none in animal

85
Q

How do the size of ribosomes differ in P and E cells?

A

70s - P

80s - E

86
Q

How do cells in P and E cells reproduce?

A

P - binary fission

E - asexual or sexual

Biology Module 1 (1 decks)

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