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Biology > Module 2: Foundations In Biology Cells > Flashcards

Module 2: Foundations In Biology Cells Flashcards

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1
Q

What two lenses does a light microscope have?

A

Objective lens

Eyepiece lens

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2
Q

Objective lens

A

Produces magnified image

Magnified again by the eyepiece lens

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3
Q

What is illumination?

A

Provided by light underneath the sample

Opaque specimens can be illuminated from above

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4
Q

Sample prep: dry mount

A

Solid specimens can be viewed whole/cut into thin slices (sectioning)

Specimens placed on a slide and cover slip placed over

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5
Q

Sample prep: wet mount

A

Specimens suspended in a liquid such as water or oil

Cover slip placed at an angle

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6
Q

Sample prep: squash slides

A

Wet mount is first prepared

Lens tissue used to gently press down the cover slip

Squash slides are a good technique for soft samples

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7
Q

Sample prep: smear slides

A

Edge of slide used to smear sample

Creates thin, even coating on other slide

Cover slip then placed over sample

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8
Q

Diffraction

A

Bending of light as it passes close to the edge of an object

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9
Q

How do stains work?

A

Increase contrast as different components of a cell take up stains to different degrees

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10
Q

Thecytosol

A

Aqueous interior of cells - often transparent

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11
Q

Preparing a sample for staining

A

Place on slide

Air dry

Heat fixed via flame

Specimen will adhere to microscope slide and then take up stains

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12
Q

How do crystal violet/methylene blue stains work?

A

Positively charged dyes are attracted to negatively charged materials in cytoplasm

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13
Q

How do conga red/nigrasin stains work?

A

They are negatively charged and are repelled by negatively charged cytasol

These dyes stay outside cells, leaving cells in stained against a stained background

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14
Q

What is the purpose of differential staining??

A

Distinguish between two types of organisms that would otherwise be hard to identify

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15
Q

What is the gram stain technique?

A

Used to separate bacteria into two groups

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16
Q

What is the acid-fast technique

A

Used to differentiate species of Mycobacterium from other bacteria

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17
Q

Production of pre-prepared slides: fixing

A

Chemicals are used to preserve specimens in as near-natural state as possible

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18
Q

Production of pre-prepared slides: sectioning

A

Specimens dehydrated with alcohols

Placed in a mould with wax/resin to form hard block

Can then be sliced thinly with a knife (microtome)

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19
Q

Production of pre-prepared slides: staining

A

Specimens also treated with multiple stains to show different structures

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20
Q

Production of pre-prepared slides: mounting

A

Specimens then secured to a microscope slide and a cover slip placed on top

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21
Q

Risk management of stains

A

Many stains used in the preparation of slides are toxic or irritants

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22
Q

What is electron microscopy

A

A beam of electrons is used to illuminate the specimen

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23
Q

What is different about electron microscopy

A

More detail of cell ultra structure can be seen because electrons have a much smaller wave length than light waves

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24
Q

Can specimen be damaged when using an electron microscope

A

Yes

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25
Q

Disadvantage of using an electron microscope

A

Very expensive

Require a controlled environment and dedicated space

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26
Q

TEM (transmission electron microscope)

A

Beam of electrons transmitted through specimen

Focussed to produce an image

Has best resolution with a resolving power of 0.5nm

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27
Q

SEM (scanning electron microscope)

A

Beam of electrons sent across the surface of a specimen

Reflected electrons are collected

Resolving power is 3-10nm so resolution is not as good

3D images produced

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28
Q

Sample prep for electron microscopes

A

Involves fixation using chemicals or freezing, staining with heavy metals and dehydration with solvents

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29
Q

Sample prep for TEM

A

Set in resin then sometimes restained

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30
Q

Sample prep for SEM

A

May be fractured to expose the inside

Cooked with heavy metals

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31
Q

Light microscope

Expensive or inexpensive

A

Inexpensive to buy/operate

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32
Q

Electron microscopes

Expensive/inexpensive

A

Expensive to buy/operate

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33
Q

Light microscope

Small and portable or large and installed??

A

Small and portable

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34
Q

Electron microscopes

Small and portable or large and installed???

A

Large and installed

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35
Q

Light microscope

Simple or complex sample prep

A

Simple sample prep

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36
Q

Electron microscope

Simple or complex sample prep

A

Complex sample prep

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37
Q

Light microscope

Vacuum required or not required

A

Vacuum not required

38
Q

Electron microscope

Vacuum required/not required

A

Vacuum required

39
Q

Magnification on light microscope

A

Up to x2000 magnification

40
Q

Magnification on electron microscope

A

Over x500 000 magnification

41
Q

Resolving power on a light microscope

A

200nm

42
Q

Resolving power on an electron microscope

A

3-10 nm

43
Q

Light microscope

Specimens living or dead?

A

Either living or dead

44
Q

Electron microscope

Specimens living or dead??

A

Specimens dead

45
Q

Artefacts

A

Visible structural detail caused by processing the specimen

46
Q

Examples of artefacts

A

Air bubbles

Loss of continuity in membranes

Distortion of organelles

Empty space in cytoplasm

47
Q

Mitochondria function

A

Aerobic respiration

Produce or release ATP

Self replicate

48
Q

How many mitochondria does a typical cell have

A

More than 1000

49
Q

Where is mitochondria found?

A

In the cytoplasm of a cell

50
Q

Where are there large numbers of mitochondria

A

In the muscle and liver cells

51
Q

Chloroplasts

A

Photosynthetic organelle

52
Q

Function of a chloroplast

A

Absorbs wavelengths of light for photosynthesis

53
Q

Function of the Rough Endoplasmic Reticulum (REM)

A

Protein synthesis (translation 2nd stage)

54
Q

Function of Smooth Endoplasmic Reticulum (SER)

A

Lipid synthesis

Make steroid hormone (lipid based)

55
Q

Examples of steroid hormones

A

Oestrogen

Testosterone

Progesterone

56
Q

Function of the Golgi

A

Modifying and packaging the products

57
Q

Transportation from RER to the Golgi

A

Protein uses vesicles

Vesicles leave the cell via the cell surface membrane and a protein is contained within this vesicle

58
Q

Where are ribosomes found?

A

Free in cytoplasm

Attached to the cisternae

59
Q

What do ribosomes do when they are free in the cytoplasm

A

They synthesise proteins to be used in a cell

60
Q

What do ribosomes do when attached to cisternae

A

Used outside of the cell

61
Q

1000mm = how many metres

A

1m

62
Q

1000 ūm is how many mm?

A

1 mm

63
Q

1000 nm is how many ūm??

A

1 ūm

64
Q

What is the nucleus?

A

The information centre

65
Q

Why does the nuclear membrane have pores?

A

The nuclear membrane is pitted with nuclear pores allowing transport of macromolecules from cytoplasm

66
Q

What is the nucleolus?

A

The site of ribosome and RNA production

67
Q

What is the chromatin?

A

Cells of DNA bound to protein in cell division

The chromatin aggregates to form chromosomes

68
Q

Function of the centrioles

A

Produce spindle fibres

69
Q

Why is the production of spindle fibres important??

A

Made in meiosis and mitosis

Separate chromosomes and chromatids

70
Q

Cell surface membrane

A

Partially permeable

Forms a barrier

Controls what enters/leaves the cell

Has receptors for molecules

Recognition by immune system cells

71
Q

How old are prokaryotic cells?

A

First appeared around 3.5 billon years ago

May have been among the earliest forms of life on earth

72
Q

Extremeophiles

A

Scientists believe these early cells were adapted to living in extremes of salinity, PH and temperature

Today these organisms can be found in hydrothermal vents and salt lakes

73
Q

Are prokaryotic organisms unicellular or multicellular

A

Unicellular with a relatively simple structure

74
Q

Structure of a prokaryotic organism

A

DNA is not contained within a nucleus

Few organelles

Organelles they do have are not membrane bound

75
Q

DNA in prokaryotes

A

Generally only have one molecule of DNA, a chromosome, supercoiled to make it more compact

76
Q

What is a group of operons

A

Grouped genes on the chromosome

77
Q

Ribosomes in prokaryotic cells

A

Ribosomes are smaller in prokaryotes than in eukaryotic cells

They are necessary for protein synthesis

78
Q

Cell walls in prokaryotic cells

A

Have cell walls made from peptidoglycan

Complex polymer formed from amino acids and sugars

79
Q

Where is the energy for the rotation of flagella from?

A

From the process of chemiosmosis

80
Q

How is the flagella attached to the cell

A

Attached to the cell membrane

By a basal body and rotated by a molecular motor

81
Q

Function of a molecular motor on a flagellum

A

A molecular motor caused the hook to rotate giving the filament a whip like movement, which propels the cell

82
Q

How old are eukaryotic cells?

A

Appeared 1.5 billion years ago

83
Q

Structure of eukaryotic cells

A

Much more complex than prokaryotic cells

DNA present in a nucleus and exists as multiple chromosomes which are supercooled and each one wraps round a number of proteins called histones

84
Q

Role of the cartilage

A

Keep trachea and bronchi open

Prevent collapse under low pressure

C-shaped to allow expansion of oesophagus

Helps support the trachea whilst allowing it to move and flex during breathing

85
Q

Goblet cells function

A

Secrete mucus, mucus traps pathogens, reducing the risk of lung infections

86
Q

Ciliated epithelial cells function

A

Function of moving particles over epithelial surface in structures such as trachea, bronchi and nasal cavities

Move trapped particles up to throat

87
Q

Smooth muscle function

A

Allows lumen to constrict by contracting

88
Q

Elastic tissue function

A

When breathing in the fibres stretch to allow alveoli and airways to expand

When breathing out they recoil, helping to reduce the volume of alveoli and expel air from lungs

89
Q

Blood vessels function

A

Many blood vessels to take substances to and from the alveoli

Deliver CO2 to alveoli for exhaling, remove O2 from alveoli and deliver to tissues

Maintain concentration gradient for diffusion, short diffusion distance

90
Q

Squamous epithelial cells function

A

In alveoli

Allow oxygen from the air to enter the blood in the capillaries of the lung and provide thin surface for gaseous exchange

91
Q

Why are there so many air sacs in the lungs??

A

Many alveoli are needed because they have a large SA and there is a gaseous exchange between air sacs and surrounding capillary blood vessels

92
Q

What type of epithelium is in the walls of the air sacs

A

Squamous epithelium

Biology (7 decks)

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