chapter 2 - Cell Structure And Microscopy Flashcards
(183 cards)
1
Q
Biological drawing checklist (10)
A
- sharp pencil
- take up at least half the page
- lines need to be clear and continuous (no shading/colouring)
- label lines in pencil
- label lines touch the actual part your labelling
- label lines don’t cross over each other
- ensure proportions are correct
- label all areas that you have shown
- no arrow heads
- LOW POWER TISSUE PLAN
2
Q
Define magnification
A
How much bigger a sample appears to be under the microscope than in real life
3
Q
Define resolution
A
The ability to distinguish between two points in an image - detail
4
Q
Resolution of light microscope
A
200nm
5
Q
What does it mean if something is closer together than 200nm on a light microscope
A
They will be seen as 1 object
6
Q
Why is the magnification 200nm on a light microscope
A
Due to the magnitude of the wavelength of light
Resolution tends to be half the wavelength of the energy source being used
7
Q
What is the resolution of human eye
A
100 micro meters
8
Q
Maximum magnification of a light microscope
A
X1500
9
Q
Type of samples for a light microscope
A
Thin, transparent samples
Living or dead
10
Q
What stains DNA
A
Acetic Orcein
11
Q
What colour does acetic orcein stain DNA
A
Dark red
12
Q
Why may some samples be sectioned (embedded in wax)
A
To help preserve structure while cutting
13
Q
How does a light microscope work
A
Has two convex glass lenses: objective (near specimen) and eyepiece lens.
Mirror/light source directs light through condenser (focuses light), diaphragm and through sample.
Image is magnified by the objective lens (usually 4x, 10x or 40x).
14
Q
Pros of light microscopes
A
• Lens configuration allows for reduced Chromatic aberration
• Inexpensive to buy and operate
• Small and portable
• Sample preparation does not usually lead to distortion
• Vacuum not required
• Natural colour is seen – unless stained
• Specimens can be living or dead
15
Q
Cons of light microscopes
A
• Lower magnification
• Lower resolution
• Bubbles in cover slips – artefacts
16
Q
What are artefacts
A
damage caused in specimen preparation
17
Q
Resolution of TEM
A
0.02-1nm
18
Q
Resolution of SEM
A
0.2-10 nm
19
Q
Resolution of LSCM
A
200nm
20
Q
Magnification of SEM
A
X100,000
21
Q
Magnification of TEM
A
X 500,000
22
Q
Magnification of LSCM
A
X 20000
23
Q
Types of samples SEM
A
- dead
- dries and coated with heavy metals
24
Q
Types of samples TEM
A
- dead
- dries and coated with heavy metals
25
Why do electron microscope samples need to be coated with heavy metals
to increase the level of contrast in the final image.
26
Types of samples in LSCM
Different layers at different depths
Living or dead
27
How does TEM work
A beam of electrons is passed through a vacuum to ensure electrons are traveling in a straight line,
with a wavelength less than 1mm is transmitted through the specimen and focused to produce and image.
28
How does an SEM work
A beam of electrons is sent across the surface of a specimen and the reflected electrons are collected
29
Pros of a TEM
• High magnification
• High resolving power
30
Cons of a TEM
• Specimen must be fixed in plastic
• Must be dead
• Expensive
• Must be used in a carefully controlled environment
• Problem with artefacts – structures that are produced due to the preparation process
• Complex sample preparation
• Vacuum required
• Sample preparation often distorts image
• Black and white images produced – but can be coloured digitally
31
Pros of an SEM
• They can be used on thick or 3-D specimens
• They allow the external, 3-D structure of specimens to be observed•
32
Cons of an SEM
- Lower resolution than TEMS
- Samples must be dead
- They don’t produce a colour image
33
Diagram of a LSCM
34
How does an LSCM work
• Uses lasers
• Cells are stained with a fluorescent dye
• A thick section of tissue, or a living
organism, can then be scanned with a
laser beam which can be reflected by
the dyes
• The laser beam is scanned at different
depths
35
Advantages of LSCM
• The laser beam is focussed at a specific
depth, which eliminates blur caused by out
of focus tissue above the focal point
• Images are taken at successive depths and
then put together into a 3D picture by
computers
• Can be used to see living tissue (the eye)
or distribution of individual molecules
within cells
36
How do LSCM limit the focal plane
employ a pair of pinhole apertures to limit the specimen focal plane to a confined volume approximately a micron in size.
Relatively thick specimens can be imaged in successive volumes by acquiring a series of sections along the optical (z) axis of the microscope
37
Uses of LSCM
• A use in optometry
Eg. Looking at scratches in the cornea
38
What does the pinhole do in LSCM
Prevents scattered light from being detected - would blur the image
39
What type of microscope produced these
TEM
- Golgi apparatus and the mitochondria
40
What type of microscope produced these
SEM
41
What do the magnets do in an electron microscope
The condenser lenses are magnets which
can focus and direct the electron beam
42
Sample preparation for electron microscopes - list
- Chemical Fixation:
- Cryofixation
- Dehydration
- Embedding
- Sectioning
- Staining
- Mounting
43
Sample preparation for electron microscopes - in full
44
dry mount
- Solid specimens are viewed whole or cut into thin slices (sectioning).
- Specimen placed on centre of slide, cover slip onto
45
Examples of dry mount
Hai, pollen, dust, insect parts –whole, muscle tissue or plants – sectioned.
46
Wet mount
Specimens suspended in liquid (water or immersion oil). Cover slip placed at angle, aquatic samples and other living organisms viewed.
47
Squash slides
Wet mount prepared first, lens tissue used to gently press down cover slip.
Two microscope slides can be used to avoid coverslip damage.
Squash slides – soft samples. Root tip squashes used to look at cell division.
48
Smear slides
Edge of slide - smear sample, thin, even coating on slide. Cover slip on top. Eg. Blood sample.
49
Purpose of stains
help to better visualise components
under the microscope
50
What is differential staining
can distinguish between two types of organisms that would otherwise be hard to identify.
It can also differentiate between different organelles of a single organism within a tissue sample.
51
Types of standing techniques
Gram stain + acid fast technique
52
What is a prokaryotic cell
usually unicellular, small cells with no membrane-bound internal structures and circular
DNA.
53
Examples of prokaryotic cells
Bacteria, E. coli, Archaea
54
What is a eukaryotic cell
those cells that contain a nucleus and organelles enclosed by a plasma membrane.
55
Examples of eukaryotic cell
Plants and animal cell
56
Cell wall in eukaryotic cells
made of cellulose/lignin in plants and made of chitin in fungi
57
Cell wall in prokaryotic cells
Cell wall made of peptidoglycan and Murein
58
Size of eukaryotic cell
Up to 100 micrometers
59
Size of a prokaryotic cell
0.5-5 micrometres
60
How does a eukaryotic cell divided
Mitosis or meiosis
61
How does a prokaryotic cell divide
Binary fission
62
Where is dna found in eukaryotic and prokaryotic
Nucleus and cytoplasm
63
Size of ribosomes in eukaryotic and prokaryotic
Eukaryotic - Ribosomes structurally larger – 80 S
Prokaryotic- Ribosomes structurally smaller – 70 S
64
Organelles in plant cells
Golgi vesicles
Golgi apparatus
Ribosomes
Endoplasmic reticulum
Nucleus
Nucleolus
Vacuole
Amyloplast
Cell wall
Cell membrane
Mitochondria
Cytoplasm
Chloroplast
65
Organelle found in animal cells
Golgi vesicles
Golgi apparatus
Ribosomes
Endoplasmic reticulum
Nucleus
Nucleolus
Vacuole ?? - small
Cell membrane
Mitochondria
Centrosome
Lysosome
Cytoplasm
66
Which organelle are found in an animal cell but not plant cell
Centrosome
Lysosome
67
Centriole
• a component of the cytoskeleton
• present in most eukaryotic cells but flowering plants and fungi
• Hollow fibres made of microtubules in a 9 + 2 arrangement
• Two centrioles at right angles to each other form a centrosome
68
What does a Centrosome do
which organises the spindle fibres during cell division - anaphase
69
Mitochondria
• The site of aerobic respiration
• Surrounded by double-membrane with the inner membrane folded to form cristae
• Liquid compartment = Matrix
• The matrix contains enzymes
- contains DNA + ribosomes
70
Ribosome
- Functions as the site of protein synthesis
- Formed in the nucleolus
- Found freely in the cytoplasm or as part of the rough endoplasmic reticulum
71
Nucleus
- Contains chromatin
- relatively large
- Separated from the cytoplasm by a double membrane – nuclear envelope
- Contain nucleolus
72
What is Chromatin
(a complex of DNA and histone proteins)
73
Function of the nucleolus
Site of ribosome production
74
Golgi body
- Function is to modify/ finalise proteins and lipids before packaging them into Golgi vesicles
- Produces secretary vesicles
75
Golgi vesicles
- transport the proteins and lipids
usually exported, put into lysosomes, or delivered to membrane bound organelles
76
Lysosomes
- Function is to break down waste materials such as worn-out organelles
- Specialist form of vesicle
- Contains hydrolytic enzymes (break down)
- Used by the immune system and in apoptosis
77
What is apoptosis
Programmed cell death
78
Chloroplast
- site of photosynthesis
- Larger than mitochondria
- Surrounded by a double membrane
- Thylakoids containing chlorophyll stack to form grana – grana joined together by lamellae
- liquid part = stroma
79
Plasma membrane
- Functions as a partially permeable membrane that controls the exchange of materials between internal and external environment
- Diameter 10nm
- Formed from a phospholipid layer
80
Flagellum
• Found in specialised cells
• Similar in structure to cilia
- made from the plasma membrane + a bundle of 11 microtubules
• Contract to provide cell movement for example in sperm cells
81
Nuclear envelope / membrane
- Separates the nucleus from the cytoplasm
- Contains nuclear pores – allows mRNA and ribosomes to travel out of nucleus and allows enzymes and signalling molecules to travel in.
82
We cannot call the cell membrane, cell membrane anymore at a level. What is it actually called
PLASMA MEMBRANE / CELL SURFACE MEMBRANE
83
Rough endoplasmic reticulum
- Function is to process proteins made by the ribosomes
- Found in plant and animal cells
- Surface covered in ribosomes
- Formed from continuous folds of membrane with the nuclear envelope
84
Smooth endoplasmic reticulum
- Does not have ribosomes on surface
- Function is involved in the production, processing and storage of lipids, carbohydrates, and steroids
85
Cilia
hair-like structures
Made from the plasma membrane and 11 microtubules
Allows the movement of substances over the cell surface eg. Mucus
86
Goblet cells
secrete mucus which helps to trap dust, dirt and microorganisms - preventing them from entering vital organs where they may cause infection
87
Nucleus where
Plant and animal cells
88
Nucleolus where
Plants and animal cells
89
Nuclear envelope where
Plant and animal cells
90
Rough and smooth endoplasmic reticulum where
Plant and animal cells
91
Golgi body where
Plant and animal cells
92
Ribosomes where
Plant and animal and prokaryotic cells
93
Mitochondria where
Plant and animal cells
94
Lysosomes where
Animal cells
95
Chloroplasts where
Plant cells
96
Plasma membrame where
Plant and animal cells
97
Centrioles where
Animal cells
98
Cell wall where
Plant cells and prokaryotic
99
Flagella where
Prokaryotic cells
100
Cilia where
eukaryotic
101
Function of the cytoskeleton
- Establishing cell shape
- Providing mechanical strength
- Locomotion (cilia and flagellae)
- Chromosome separation in mitosis and meiosis
- Intracellular transport of organelles
102
The structure of a cilia was
- 2 central micrutubules surrounded by 9 pairs of microtubules arranged
like a wheel
- The pairs slide over each other to make the cilia move
103
How is the flagella of a prokaryote different to flagella on eukaryotes?
Thinner
Doesn't have the 9+2 arrangement
Rotary movement
energy comes from chemiosmosis (proton driven), not ATP
104
How are proteins made + transported
- transcription = nucleus
- translation = ribosomes on rough ER
- This protein then passes into the lumen (the inside space) of the rough endoplasmic reticulum to be folded and processed
- Proteins are carried to the Golgi body by vesicles = which fuse with the Golgi apparatus, releasing the proteins
- Golgi body sorts + packages proteins
- secretary vesicles ship proteins to their final destination ( fuse with cell surface membrane) = lysosomes or out of the cell
105
Difference between eukaryotic and prokaryotic cells
- Prokaryotic cells are much smaller than eukaryotic cells (between 100 - 1000 times smaller)
Prokaryotic have…
- A cytoplasm that lacks membrane-bound organelles
- Their ribosomes are structurally smaller (70 S) in comparison to those found in eukaryotic cells (80 S)
- No nucleus
- A cell wall that contains murein (a glycoprotein)
106
What is Murein
A glycoprotein
107
Organelle unique to prokaryotic cells
Plasmid
Capsules
108
Purpose of the capsule
helps to protect bacteria from drying out and from attack by cells of the immune system of the host organism
109
Eukaryotic vs prokaryotic table
110
organelles involved in protein synthesis
Nucleus
Ribosomes
Rough endoplasmic reticulum (RER)
Golgi apparatus
Cell surface membrane
111
Protein formation + transport diagram
112
What is the cytoskeleton
an extensive network of protein fibres, within the cytoplasm
113
What is the cytoskeleton made up from
Microfilaments, microtubules and intermediate fibres
114
What are microfilaments
- are solid strands
- mostly made of the protein actin.
- can cause some cell movement and the movement of some organelles within cells by moving against each other
115
What are microtubules
- tubular (hollow) strands that are mostly made of the protein tubulin.
- Organelles and other cell contents are moved along these fibres using ATP to drive this movement
116
Examples of cytoskeleton being important for transport within the cell
the movement of vesicles and the movement of chromosomes to opposite ends of a cell during cell division
117
Structures only found in animal cells
centrioles and microvilli
118
Structures only found in plant cells
cellulose cell wall, large permanent vacuoles and chloroplasts
119
Size of flagellum
> 10 micrometers
120
Size of cilia
< 10 micro meters
121
Difference between cilia and flagellum
Cilia is short + flagella is long
122
What is Undulipodia
A projection from a prokaryotic cell.
Made from the plasma membrane and a spiral of protein called flagellin.
123
What are microtubule motors
A protein that transports organelles along microtubules.
It connects to the organelle and slides along the microtubule
124
What is an organelle
A structure within a cell with a specific role
125
126
127
What type of extra cellular protein is secreted at vesicles
enzyme / (peptide) hormone / glycoprotein ;
128
Outline the role of the Golgi apparatus
129
130
131
132
133
134
135
136
How can you tell the difference between Gogol body and ER in a diagram
Golgi body does NOT touch
137
What do you lower a cover slip with
A mounted needle
138
D
139
Are lysosomes membrane bound
Yes
140
Is the Golgi body membrane bound
Yes
141
Is the ER membrane bound
Yes
142
Are ribosomes membrane bound
No
143
Are centrioles membrane bound
No
144
Is the cytoskeleton membrane bound
No
145
You can’t just say vacuole anymore, when talking about the differences between plant and animal cells. What must you say
LARGE, PERMANENT VACUOLE
146
State the correct term for this definition
The detailed structure of cells visible only with an electron microscope
Ultrastructure
147
B
148
C
149
Light microscope + Graticule
150
Where is RNA found
Nucleolus
151
Where is dna found
Nucleus
152
Differential staining - table
153
Differences between differential staining and simple staining - table
154
Example of differential staining
Gram staining
155
How does gram staining work
All bacteria - positive or negative
Gram positive = purple
Gram negative = pink
156
D
157
B
158
A
159
C
160
A
161
C
162
D
163
2nd part
C
164
D
165
B
166
C
167
A
168
B
169
C
170
What is the plasmodesmata
small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells.
171
172
173
174
175
176
177
B
178
179
180
181
182
183
