C2 - Basic components of living cells Flashcards

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1
Q

What is a light microscope?

A

Instrument that uses visible light and glass lenses to enable the user to see objects magnified

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2
Q

Image produced by light microscope

A

Blood smear

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3
Q

What is a compound light microscope?

A

Instrument that magnifies an object using two lenses.
-Eyepiece lens: closest to eye
-Objective lens: closest to specimen

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4
Q

Label a compound microscope?

A
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5
Q

What is a dry mount?

A

-Solid specimens
-Sectioned
-Specimen place on centre of slide
-Cover slip placed on top

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6
Q

What is a wet mount?

A

-Specimen suspended in liquid
-Cover slip placed on at angle

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7
Q

What is a squash slide?

A

-Wet mount prepared
-Lens tissue/ microscope slide used to press down cover slip

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8
Q

What is a smear slide?

A

-Edge of slide used to smear sample
-Creating thin, even coating
-Coverslip placed on top

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9
Q

How do you prepare a sample for staining?

A

-Placed on slide
-Allow to air dry
-Heat-fixed by passing through flame
-Specimen adheres to microscope and takes up stain

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10
Q

Rules for biological drawings

A

-Include a title
-State magnification
-Sharp pencil line
-White, unlined paper
-Use majority of space
-Smooth, continuous line
-No shading
-Draw clearly defined structures
-Label lines should not cross or have arrowheads
-Label lines should be drawn with a ruler, parallel to the top of the page

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11
Q

Examples of positively charged stains?

A

Crystal violet
Methylene blue
(attracted to positively charged materials in cytoplasm)

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12
Q

Examples of negatively charged stains?

A

Nigrosin
Congo red
(repelled by cytosol)

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13
Q

What is differential staining?

A

Using specific stains to distinguish between different types of cells

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14
Q

What is fixing?

A

Chemicals used to preserve specimens

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15
Q

What is sectioning?

A

Specimens dehydrated with alcohols
Placed in mould with wax/resin to form hard block
Can be thinly sliced with knife

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16
Q

What is mounting?

A

Specimens secured to microscope slide and cover slip placed on top

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17
Q

What is magnification?

A

To produce an image of an object at a scale larger than its actual size.

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18
Q

Formula for magnification

A

Magnification = size of image / actual size of object

M = I / A

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19
Q

What is resolution?

A

Shortest distance between two objects that are still seen as separate objects

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20
Q

1 micrometre in nanometres

A

1000nm

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21
Q

1 millimetre in micrometres

A

1000

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22
Q

What is an electron microscopy?

A

Microscopy using a microscope that employs a beam of electrons to illuminate the specimen
(higher resolution due to smaller wave length)

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23
Q

What is the measurement of each division on a micrometer slide?

A

100 divisions = 1mm
1 division = 0.01mm = 10 micrometers

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24
Q

What is a stage micrometer?

A

Microscope slide marked with an accurate scale in micrometers

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25
Q

What is an eyepiece graticule?

A

Glass disc marked with a fine scale from 1-100
Has no units

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26
Q

How do you use an eyepiece graticule to calibrate a light microscope?

A

1) Put stage micrometer in place and eyepiece graticule in eyepiece
2) Get the scale on the micrometer slide in focus
3) Align the micrometer scale with the scale in eyepiece
4) Take readings from the two scales
5) Calibrate the micrometer

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27
Q

What is ultrastructure?

A

Features of a cell that can be seen using an electron microscope

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28
Q

What are artefacts?

A

Objects/structures seen through a microscope that have been created during the processing of the specimen

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29
Q

What is a transmission electron microscope?

A

Beam of electrons transmitted through a specimen and focused to produce an image
Resolving power- 0.5nm

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30
Q

Image produced by TEM

A

wbc

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31
Q

What is a scanning electron microscope?

A

Beam of electrons sent across surface of specimen and reflected electrons focused to produce 3D image
Resolving power of 2-10nm

32
Q

Image produced by SEM

A
33
Q

What are the two types of electron microscope?

A

Transmission
Scanning

34
Q

Comparisons of different microscopes

A
35
Q

How are artefacts created?

A

Air bubbles trapped under cover slip

36
Q

What is laser scanning confocal microscopy?

A

Microscope that employs lase beam and a pin-hole aperture to produce an image with a very high resolution
2D images

37
Q

How are samples prepared for laser confocal microscopy?

A

Thin sections

38
Q

How can 3D images be produced from laser confocal microscopy

A

Create images at different focal planes

39
Q

What is laser confocal microscopy used for?

A

Non-invasive
Diagnosis of diseases in the eye

40
Q

What are prokaryotic cells?

A

Cells with no membrane bound nucleus or organelles

41
Q

Diagram of prokaryotic cells

A

Bacteriums

42
Q

What are eukaryotic cells?

A

Cells with nucleus and other membrane bound organelles
-Animals, plants, fungi, single-celled protocista

43
Q

Diagram of eukaryotic animal cells

A
44
Q

Diagram of plant cell

A
45
Q

What are organelles?

A

Membrane bound compartments with varying functions

46
Q

What does a eukaryotic cell consist of?

A

Microtubule network
Vesicles
Nucleolus
Nucleus
Golgi apparatus
Cell-surface membrane
Cytosol
Ribosome
Centriole
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Cytoskeleton
Secretory vesicles
Mitochondria

47
Q

What is the structure and function of the nucleus?

A

-Contains coded genetic information in the form of DNA molecules
-DNA contained within a nuclear envelope (double membrane)
-Nuclear envelope contains nuclear pores allowing molecules to move in and out nucleus

48
Q

What is the structure and function of DNA?

A

-DNA associates with histones (proteins) to form chromatin
-Chromatin coils and condenses to from chromosomes

-Controls synthesis of proteins and metabolic activities of cell (proteins/enzymes necessary for metabolism)

49
Q

What is the structure and function of the nucleolus?

A

-Area within nucleus responsible for producing ribosomes
-Composed of proteins and RNA

-RNA produces rRNA which combines with proteins forming ribosomes for protein synthesis

50
Q

What is the structure and function of mitochondria?

A

-Site of cellular respiration
-Double membrane
-Inner membrane highly folded forming cristae and matrix (liquid interior)
-Membrane forming cristae contain enzymes used in aerobic respiration
-Contain small amount of mitochondrial DNA

-Energy stored in the bonds of organic molecules
-Made available for cellular use by the production of ATP

51
Q

What is the structure and function of a vesicle?

A

Membranous sacs used to transport or store materials in the cell

52
Q

What is the structure and function of a lysosome?

A

Specialised vesicles containing hydrolytic enzymes for the breakdown of waste materials in a cell

53
Q

What is the structure and function of the cytoskeleton?

A

Network of fibres in the cytoplasm of a eukaryotic cell (microfilaments, microtubules, intermediate fibres)

Provides mechanical strength to cell
Aids transport within cell
Enables cell movement

54
Q

What is the structure and functions of microfilaments

A

-Contractile fibres
-Formed from protein actin
-Responsible for cell movement and contraction during cytokinesis

55
Q

What is the structure and function of microtubules?

A

-Globular tubulin proteins
-Polymerise to form tubes that form scaffold structure determining the shape of cell
-Act as tracks for movement of organelles
-Form spindle fibres

56
Q

What is the structure and function of intermediate fibres?

A

-Fibres that give mechanical strength to cells to maintain their integrity

57
Q

What is the structure and function centriole?

A

-Part of cytoskeleton
-Composed of microtubules
-Two associated centrioles form centrosome
-Centrosome is involved in assembly and organisation of spindle fibres

58
Q

What is the structure and function of flagellum

A

-Whip-like extension that protrudes from cell
-Enables mobility and can detect chemical change in environment

59
Q

What is the structure and function of cilia?

A

-Hair-like extensions that protrude from cells
-Can be mobile/stationary
-Important function in sensory organs
-Rhythmic beats create currents causing fluids adjacent to cell to move

60
Q

What is the 9+2 arrangement?

A

2 central microtubules surrounded by 9 pairs of microtubules

61
Q

What is the structure and function of endoplasmic reticulum?

A

Network or membranes enclosing flattened sacs called cisternae

62
Q

What are the two types of ER and their functions?

A

-Smooth ER: responsible for lipid and carbohydrate synthesis and storage
-Rough ER: ribosomes bound to surface, responsible for synthesis and transport of proteins

63
Q

What is the structure and function of ribosomes?

A

-Site of protein synthesis
-Not membrane-bound
-Constructed of RNA molecules made in nucleolus

(mitochondria and chloroplasts contain ribosomes)

64
Q

What is the structure and function of Golgi apparatus?

A

-Interconnected network of flattened, membrane-enclosed sacs (cisternae)

-Plays a role in modifying and packaging proteins into vesicles

65
Q

How are proteins produced?

A

1) Proteins are synthesised on ribosomes bound to RER
2) They pass into its cisternae and are packaged into transport vesicles
3) Vesicles containing proteins move towards Golgi apparatus via cytoskeleton
4) Vesicles fuse with cis face of Golgi apparatus and proteins enter
5) Proteins are structurally modified and then leave from its trans face (curved)
6) Secretory vesicles carry proteins that are to be released from the cell. Vesicles fuse to cell surface membrane releasing their contents by exocytosis.
7) Some vesicles form lysosomes which contain enzymes for use in the cell

66
Q

What is the structure and function of plant cell walls?

A

-Rigid structure surrounding cell membrane
-Freely permeable
-Acts as a support, shaping and defence mechanism

67
Q

What are plant cell walls made of?

A

Cellulose

68
Q

What other organelles do plant cells have?

A

Vacuoles
Chloroplast
Cell wall

69
Q

What is the structure and function of a vacuole?

A

-Membrane lined sacs in cytoplasm containing cell sap
-Large permanent vacuole help maintain turgor

70
Q

What is the structure and function tonoplast?

A

-Membrane of vacuole in a plant cell
-Selectively permeable

71
Q

Can vacuoles appear in animal cells?

A

Yes, but they’re small and transient

72
Q

What are the structures and function of chloroplasts

A

-Responsible for photosynthesis

-Found in green part of plants
-Double membrane
-Stoma: fluid in closed in chloroplast
-Thylakoids: flattened sacs formed by internal network membranes
-Granum: several thylakoids stacked together, contain chlorophyll pigments (site of light dependent reactions)
-Grana joined by membranes called lamellae
-Starch produced is present in starch grains

(contains DNA and ribosomes)

73
Q

What do prokaryotic cells contain?

A

Pili
Cell wall
Cell surface membrane
Cytoplasm
Ribosome (70s)
Free chromosomal DNA
Flagellum

74
Q

What is DNA in prokaryotes?

A

-Consists of one molecule of DNA, a chromosome, supercoiled
-Genes grouped into operons so a number of genes are switched on or off at a time

75
Q

Flagella in prokaryotic cells

A

-Thinner
-Energy to rotate supplied by chemiosmosis
-Attached by basal body and rotated by molecular motor

76
Q

Prokaryotic vs eukaryotic

A
77
Q

Why do we use staining?

A

To increase contrast making features more visible