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Biology > Module 2: Foundations In Biology Cells > Flashcards

Module 2: Foundations In Biology Cells Flashcards

(92 cards)

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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
Disadvantage of using an electron microscope
Very expensive Require a controlled environment and dedicated space
26
TEM (transmission electron microscope)
Beam of electrons transmitted through specimen Focussed to produce an image Has best resolution with a resolving power of 0.5nm
27
SEM (scanning electron microscope)
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
28
Sample prep for electron microscopes
Involves fixation using chemicals or freezing, staining with heavy metals and dehydration with solvents
29
Sample prep for TEM
Set in resin then sometimes restained
30
Sample prep for SEM
May be fractured to expose the inside Cooked with heavy metals
31
Light microscope Expensive or inexpensive
Inexpensive to buy/operate
32
Electron microscopes Expensive/inexpensive
Expensive to buy/operate
33
Light microscope Small and portable or large and installed??
Small and portable
34
Electron microscopes Small and portable or large and installed???
Large and installed
35
Light microscope Simple or complex sample prep
Simple sample prep
36
Electron microscope Simple or complex sample prep
Complex sample prep
37
Light microscope Vacuum required or not required
Vacuum not required
38
Electron microscope Vacuum required/not required
Vacuum required
39
Magnification on light microscope
Up to x2000 magnification
40
Magnification on electron microscope
Over x500 000 magnification
41
Resolving power on a light microscope
200nm
42
Resolving power on an electron microscope
3-10 nm
43
Light microscope Specimens living or dead?
Either living or dead
44
Electron microscope Specimens living or dead??
Specimens dead
45
Artefacts
Visible structural detail caused by processing the specimen
46
Examples of artefacts
Air bubbles Loss of continuity in membranes Distortion of organelles Empty space in cytoplasm
47
Mitochondria function
Aerobic respiration Produce or release ATP Self replicate
48
How many mitochondria does a typical cell have
More than 1000
49
Where is mitochondria found?
In the cytoplasm of a cell
50
Where are there large numbers of mitochondria
In the muscle and liver cells
51
Chloroplasts
Photosynthetic organelle
52
Function of a chloroplast
Absorbs wavelengths of light for photosynthesis
53
Function of the Rough Endoplasmic Reticulum (REM)
Protein synthesis (translation 2nd stage)
54
Function of Smooth Endoplasmic Reticulum (SER)
Lipid synthesis Make steroid hormone (lipid based)
55
Examples of steroid hormones
Oestrogen Testosterone Progesterone
56
Function of the Golgi
Modifying and packaging the products
57
Transportation from RER to the Golgi
Protein uses vesicles Vesicles leave the cell via the cell surface membrane and a protein is contained within this vesicle
58
Where are ribosomes found?
Free in cytoplasm Attached to the cisternae
59
What do ribosomes do when they are free in the cytoplasm
They synthesise proteins to be used in a cell
60
What do ribosomes do when attached to cisternae
Used outside of the cell
61
1000mm = how many metres
1m
62
1000 ūm is how many mm?
1 mm
63
1000 nm is how many ūm??
1 ūm
64
What is the nucleus?
The information centre
65
Why does the nuclear membrane have pores?
The nuclear membrane is pitted with nuclear pores allowing transport of macromolecules from cytoplasm
66
What is the nucleolus?
The site of ribosome and RNA production
67
What is the chromatin?
Cells of DNA bound to protein in cell division The chromatin aggregates to form chromosomes
68
Function of the centrioles
Produce spindle fibres
69
Why is the production of spindle fibres important??
Made in meiosis and mitosis Separate chromosomes and chromatids
70
Cell surface membrane
Partially permeable Forms a barrier Controls what enters/leaves the cell Has receptors for molecules Recognition by immune system cells
71
How old are prokaryotic cells?
First appeared around 3.5 billon years ago May have been among the earliest forms of life on earth
72
Extremeophiles
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
Are prokaryotic organisms unicellular or multicellular
Unicellular with a relatively simple structure
74
Structure of a prokaryotic organism
DNA is not contained within a nucleus Few organelles Organelles they do have are not membrane bound
75
DNA in prokaryotes
Generally only have one molecule of DNA, a chromosome, supercoiled to make it more compact
76
What is a group of operons
Grouped genes on the chromosome
77
Ribosomes in prokaryotic cells
Ribosomes are smaller in prokaryotes than in eukaryotic cells They are necessary for protein synthesis
78
Cell walls in prokaryotic cells
Have cell walls made from peptidoglycan Complex polymer formed from amino acids and sugars
79
Where is the energy for the rotation of flagella from?
From the process of chemiosmosis
80
How is the flagella attached to the cell
Attached to the cell membrane By a basal body and rotated by a molecular motor
81
Function of a molecular motor on a flagellum
A molecular motor caused the hook to rotate giving the filament a whip like movement, which propels the cell
82
How old are eukaryotic cells?
Appeared 1.5 billion years ago
83
Structure of eukaryotic cells
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
Role of the cartilage
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
Goblet cells function
Secrete mucus, mucus traps pathogens, reducing the risk of lung infections
86
Ciliated epithelial cells function
Function of moving particles over epithelial surface in structures such as trachea, bronchi and nasal cavities Move trapped particles up to throat
87
Smooth muscle function
Allows lumen to constrict by contracting
88
Elastic tissue function
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
Blood vessels function
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
Squamous epithelial cells function
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
Why are there so many air sacs in the lungs??
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
What type of epithelium is in the walls of the air sacs
Squamous epithelium

Biology (7 decks)

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