Cytology Flashcards
(119 cards)
1
Q
What do free ribosomes do?
A
Synthesise intracellular proteins.
1
Q
TRUE or FALSE: Are ribosomes basophillic? - why do they stain well?
A
TRUE. Acidic cell structures stain well with basic dyes and are called basophilic. In nerve calls basophil aggregation of ribosomes are called Nissl bodies. (one of the only times you can see it under the light microscope).
2
Q
What is Cell Theory?
A
Cells are membrane enclosed units filled with cytoplasm and DNA. Organisms consist of nothing but cells. All cells arise from pre-existing cells by division.
3
Q
What is Magnification?
A
The Ratio of image size to object size.
4
Q
What is Resolution?
A
The ability to produce separate images of closely positioned objects.
5
Q
What does Fluorescence Microscopy consist of?
A
Uses fluorescence dyes to highlight specific structures.
6
Q
What light source does confocal microscopy use?
A
A laser.
7
Q
What type of image does confocal microscopy produce?
A
3D Image.
8
Q
List the different types of microscopes.
A
Light, Fluoresence, Confocal, Transmission Electon, Scanning Electron.
9
Q
What does TEM stand for?
A
Transmission Electron Microscope.
10
Q
What are 4 characteristics of TEM.
A
- Beam of electrons instead of beam of lights.
- Magnetic coils instead of glass lenses.
- Specialised specimen preparation.
- Magnification 1 000 000x, resolution 1nm.
11
Q
How is SEM different to TEM?
A
Specimen is coated with a thin layer of heavy metal and scanned by a beam of electrons. The cell structure is made out by electron bouncing off specimen and being detected.
12
Q
What are the four main tissues?
A
Epithelia, Connective, Muscle, Nervous
13
Q
What does the Epithelia assist in and how (what is a main feature of it)?
A
Facilitate transport across the cell as the cells are closely adherent.
14
Q
Provided examples of the classifications of the tissue. ‘Function, Focation, Shape and Arrangement.’
A
Function: Absorptive, cilitated, and secretory cells.
Location: Epithelium, mesothelium, and endothelium.
Shape: Squamous, cuboidal and columnar.
Arrangement: Simple, pseudostratified, and stratified.
15
Q
What are the two surfaces of Epithelial tissue (sheet)?
A
Epithelial sheet is polarized with an apical surface (exposed to air or fluid) and an basal surface (exposed to other tissue).
The basal surface lies on a sheet of extracellular tissue called basal lamina.
16
Q
What is the function of the connective tissue?
A
It connects tissues, provides framework, supports the entire body (via bones and catilage).
17
Q
What is the subclassification of connective tissue based on?
A
The cells and the composition and organisation of the intervening intercellular material - loose, dense, regular, irregular.
18
Q
What is cartilage, bone and fat all examples of?
A
Specialised connective tissue.
19
Q
What are the two main types of extracellular protein fiber?
A
Collagen and elastin.
20
Q
What does nervous tissue consist of?
A
It consists of long highly specialised neurons (nerve cells) and their supporting neuroglia (connective tissue of the nervous system).
21
Q
What do neurons used to transmit electrical and chemical stimuli?
A
Dendrites and axons.
22
Q
What stains well with basic dyes?
A
Acidic cell structures (DNA, RNA).
23
Q
What pH stain, stains most things in the cytoplasm well?
A
Basic.
24
What is Eosinophilia/Acidophilia?
Tendency to bind acidic dyes.
25
What is Basophilia?
Tendency to bind basic dyes.
26
What does staining depend on?
The chemical characteristics, not the staining structure.
27
What does H&E stain stand for?
Hematoxylin and Eosin.
28
Where is Hematoxylin derived from?
Peruvian logwood tree.
29
Is Hematoxylin basic or acidic?
Basic.
30
Where does Eosin come from?
It is an acidic alcohol-based synthetic dye derived from coal tar.
31
What stain stains carbohydrate bright pink?
Periodic-acid Schiff stain (PAS)
32
What is the characteristic of Van Giesen's stain?
Muscle appears yellow and collagen red.
33
What dye, stains elastic fibres black?
Verhoeff.
33
What dye stains reticular fibres black?
Silver stain.
34
List 5 common stains.
Periodic-acid Schiff (PAS), Van Giesen's, Gomori's trichrome, Verhoeff, Silver.
35
Describe the structure of the cell membrane.
- About 8nm thick
- Composed of lipid molecules (phospholipids), cholesterols and associated proteins.
- Hydrostatic force of repulsion from the water holds them together.
36
What are the different types of membrane protein locations.
Transmembrane, Monolayer-associated, Lipid-linked and Protein-attached.
37
What are the different types of membrane proteins (function).
Transporters and channels, anchors, receptors and enzymes.
38
What are carbohydrates attached to?
Lipids and proteins (on the noncytosolic surface) to form a cell coat, called glycocalyx.
39
How does a cell function?
1. Receiving information
2. Import and export of small molecules.
3. Capacity for movement and expansion because the membrane is fluid like and can stretch/ change shape.
40
How is a cell formed?
ER grows by the direct incorporation of molecules of lipids and protein.
Other structures are derived either directly or indirectly from the ER. (except mitochondria - their number increases by growth and division of existing organelles).
Flow of membrane is largely through vesicles that bud or are pinched off from the donor structure ans then fuse with and become part of the recipient structure.
41
What is the average size of cells?
10 micrometres.
42
What types of microscopes are used in histology- how do they differ in relation to magnification, resolution and 2D vs 3D?
1. Light Microscope (Brightfield)
Magnification: Typically up to 1000x.
Resolution: Around 0.2 micrometers.
Image Type: 2D.
Use: The most common microscope in histology labs, used for viewing stained tissue sections. It provides an image of the tissue but lacks the ability to offer fine details of cell organelles.
2. Fluorescence Microscope
Magnification: Similar to light microscopes, usually up to 1000x.
Resolution: Around 0.2 micrometers.
Image Type: 2D.
Use: Used for observing specific structures within cells by staining them with fluorescent dyes. This type of microscope allows visualization of proteins, nucleic acids, and other molecules tagged with fluorophores.
3. Confocal Laser Scanning Microscope (CLSM)
Magnification: Up to 1000x.
Resolution: Better than conventional light microscopes, about 0.2 micrometers laterally and 0.5 micrometers axially.
Image Type: 3D.
Use: Offers higher resolution and contrast compared to traditional fluorescence microscopes. It uses lasers to scan samples and can generate high-resolution, optically sectioned images. These sections can be stacked to form a 3D image, allowing for detailed tissue analysis at different depths.
4.Transmission Electron Microscope (TEM):
Magnification: Up to 1,000,000x.
Resolution: About 0.2 nanometers.
Image Type: 2D.
Use: Provides detailed images of the internal structure of cells at an ultrastructural level. It's used to observe organelles and even molecules like proteins.
5. Scanning Electron Microscope (SEM):
Magnification: Up to 500,000x.
Resolution: Around 1–20 nanometers.
Image Type: 3D.
Use: Produces highly detailed 3D surface images of tissue, ideal for examining the texture and topology of the sample.
43
What are the challenges that the cell membrane faces?
- Transporting current proteins to correct organelles (vesicles have a code to get them to the right place).
- Retrieving and degrading old components.
- Controlling water flow and cell volume.
- Getting selected molecules through membranes.
- Distribution of cell organelles in cell division.
44
What type of fermentation is the process that takes place in the rumen of cows?
Anaerobic fermentation.
45
Provide an example of Aerobic fermentation.
Liberation of carbon dioxide.
46
Give 3 characteristics of cytosol.
- Largest component in eukaryotic cells and the only one in bacteria.
- Consists of a water based gel and contains large and small molecules.
- Location of a large number of chemical reactions. (e.g. early steps of breakdown of nutrient molecules, protein synthesis at ribosomes).
47
Describe the process of the invagination of plasma membrane.
It is a process where a portion of the cell membrane is folded inwards to create a small, noncoated structure that can internalize molecules.
48
What is the endosymbiotic theory?
Aerobic and photosynthetic prokaryotes engulfed by pre-eukaryotic cell over time envolved into cellular organelles. (ancient cell that has evolved over time and incorporated into eukaryotic cells).
49
What is the evidence for endosymbiotic theory?
Mitochondria has its own DNA.
50
What are the 3 main parts of the nucleus?
Nuclear envelope, Chromatin and Nucleolus.
51
What is a nuclear envelope?
Two concentric membranes separated by a 25nm wide perinuclear space.
52
What is connected to the ER?
The outer nuclear membrane.
53
What does chromatin consist of?
DNA in association with histones (structural proteins), globular and acid proteins, and ribonucleic acid (RNA).
54
What does Interphase of Chromatin mean?
Chromosomes form a diffuse network of elongated threads.
55
What are the two phases of Chromatin?
Heterochromatin and Euchromatin.
56
What is Heterochromatin?
Condensed, densely stained inactive chromatin, often associated with the nucleolus.
57
What is Euchrochromatin?
Uncoiled, less stained chromatin, abundant in active cells.
58
What does Chromatin look like in moribund cells?
Moribund (cells that will die - bubble shaped nuclei). The nuclei are often small and stain densely.
As cells become older, they start to degrade and do not work properly anymore. They stop producing all the normal proteins that cells need for survival.
59
What type of Nucleolus does the nucleus contain?
Basophilic nucleolus.
60
How large is the nucleolus?
4 micrometers/
61
What are intercalated discs?
Complex structures that connect adjacent cardiac muscle cells.
62
What is an interdigitated membrane and how can it occur?
It is a cell membrane where the lipid tails of one layer interlock with the opposing layer. This can occur in different ways, including partial, mixed or complete interdigitation.
63
What is the function of the nucleolus?
Storage of genetic material, regulation of gene expression, (20% of cell mass is protein which is a product of gene expression (most abundant macromolecule found in cells), Assembly of ribosomes.
64
Are ribosomes visible under light microscopes?
No.
65
What subunits does the ribosome consist of?
mRNA and tRNA AND a small ribosomal subunit join together to synthesis the new protein during translation.
66
What are polyribosomes or polysomes?
Groups of ribosomes that translate the same mRNA and are being made at the same time because they are do long and repetitive.
67
What does the ER consists of?
A network of membrane bound channels. These are Cisternae, Tubules and Vesicles.
68
What is a Vesicle?
Round balls of membrane that have a space in the middle and help facilitate transportation.
Extra information: Different types of transport vesicles with distinctive surface proteins shuttle between various organelles. Coding --> The vesicle membrane and the target membrane have an interaction. (LOCK AND KEY)
69
What is a Cytozolic face?
It is the outside face of the ER and it buds off little pieces of membrane which are hollow (lipid bilayer and lumen). These proteins and lipids move to the Golgi apparatus.
70
What are the functions of the Rough and Smooth ER.
Rough ER: Membrane, lysosomal and secretory proteins (proteins that ar going to move somewhere such as being secreted out or being moved to another organelle) are synthesised by membrane bound ribosomes.
Smooth ER: Enzymes at the lumen surface of the membrane synthesis lipids. For example phospholipids for membrane formation. Can not see under the microscope due to the lack of ribosomes.
EXTRA info:
○ Storage and release of Ca2+ ions (= sarcoplasmic reticulum in muscle cells)
○ Enzyme mediated drug detoxification.
○ It is found in large amounts in liver (liver stores lipids and has the first shot of nutrients from the intestines) and adrenal cortex cells.
Shows no basophilia due to the lack of ribosomes (acidophilia-eosin).
71
What does the Golgi Complex/ Apparatus stain well with?
Silver nitrate and osmium.
72
What does the Golgi Apparatus consist of? (STRUCTURE)
Consists of several layers of about 3-20 cisternae and an associated network of associated tubules and vesicles. The vesicles allow directed transport of proteins and lipids.
73
What does the Golgi Complex do? (FUNCTION)
The Golgi complex recieves proteins and lipids from the ER for:
Chemical modification - Glycosylation: adding supers, Phosphorylation: inorganic phosphate, Sulfation: Sulphur atoms added, of proteins.
Packaging of secretory proteins.
Routing of proteins to correct cellular compartments.
74
What are the 3 types of vesicles that leave the Golgi Complex?
Transport vesicles containing lysosomal enzymes destined to late endosomes.
Transport vesicles of the constitutive secretory pathway to the plasma membrane.
Secretory vesicles (always produced) of the regulated secretory pathway to the plasma membrane.
75
What is an example of a vesicle that leaves the Golgi complex?
Insulin being secreted from a particular group of cells in the pancreas. Specialised cells that sit and are part of cell aggregated called islets. Their job is to secrete insulin which is not constant.
Exocytosis of secretory vesicles (regulated secretion of insulin signalled by increase in glucose levels).
76
What are endosomes?
Polymorphic membrane-bounded tubes and vesicles.
77
IMPORTANT INFORMATION:
* Subclassified into early and late endosomes (vesicles).
* Transport between early and late endosomes through endosomal carrier vesicles (also called multivesicular bodies).
* Located close to plasma membrane (where they are derived from).
* Sorting compartment for endocytic vesicles (pinocytosis).
○ Receptor bound molecules dissolve and empty vesicles including receptors go back to plasma membrane.
○ Receptor bound molecules get transported through for transcytosis.
○ Receptor bound molecules get transported to late endosome to be degraded in lysosomes.
78
What do late endosomes do?
Recieve endocytic material or digestion from early endosomes (from pinocytosis - ingestion of liquid into a cell by the budding of small vesicles from the cell membrane).
Fuse with heterophagosomes or autophagosomes (from phagocytosis).
Fuse with transport vesicles containing lysosomal enzymes.
Become lyosomes after membrane characteristics change and pH is decreased to pH 5.
79
Where are late endosomes located?
Located close to the Golgi Complex
80
What are endosomes?
Endosomes are intra cellular sorting organelles that act as a key hub in the endocytic pathway, sorting and delivering proteins and lipids to various locations, including the cell surface, Golgi complex, and lysosomes.
81
What are lysosomes?
They are small (0.2-0.5mm) membrane brane organelles that are visible with special stains in light microscopy. They contain hydrolytic or digestive enzymes in a low pH environment (pH 5) and digest microogranism, senescent rythrocutes, damaged cells, cell debris, food, unwanted molecules and old organelles for recycling and excretion.
82
What type of cell has a large number of lysosomes.
Phagocytes ( A type of immune cell that can surround and kill microorganisms, ingest foreign material, and remove dead cells) such as macrophages and polymorphonuclear leukocytes.
83
What things do lysosomes digest?
Senescent erythrocytes, microorganisms, damaged cells, cell debris, food, unwanted molecules and old organelles for recycling and excretion.
84
What happens when lysosomes fail to function?
Substrates ca build up in the cell leading to clinical conditions known as lysosomal storage disease (e.g. neuronal ceroid lipfuscinosis/Batten disease --> Severe brain atrophy blindess and seizures, leading to premature death).
85
What are Peroxisomes?
Small membrane-bounded spheres that contain a finely granular electron-dense content.
86
Where are peroxisomes found in masses?
Cells of the liver and kidney.
87
List characteristics of the mitochondria.
* Mitochondria (singular, mitochondrion)
* About 0.2 um diameter and 12 um long.
* Double membrane
○ Inner membrane folded
* Contain its own DNA
○ Cytoplasmic inheritance.
* Divide
* Size and shape are highly variable.
* Move in cell.
* High number in active cells
○ ~800/mammalian hepatic cell.
○ Few in lymphocytes.
○ None in erythrocytes and terminal keratinocytes.
Contribute to the eosinophilic staining of the cytoplasm
88
What occurs at the sit of chemical energy generation on the mitochondrion.
Food molecules from the cytosol and oxygen are transformed into carbon dioxide and adenosine triphosphate (ATP).
89
Describe the outermembrane/intermembranous space of the Mitochondria.
Outer membrane is smooth and permeable to all molcules of 5000 daltons or less. This is due to the protein channels.
90
Describe the inner membrane of the Mitochondria.
* Inner membrane is folded into cristae or tubuli:
○ To enlarge the surface area.
○ To produce partially separated compartments.
* Inner membrane is impermeable to ions (e.g. protons) and most small molecules.
* Very rich in three groups of proteins:
○ Highly specific transport proteins.
○ Enzymes that carry out the oxidation reactions of ETC.
The ATP synthase, that makes ATP.
91
What are cellular inclusions?
Cellular inclusions are non-membrane bound, cytoplasmic or nuclear structures that accumulate as metabolic byproducts, breakdown products, or as a result of cell injury, and include substances like glycogen, lipids, proteins, and pigments.
92
Characteristics of Glycogen
§ Storage form of carbohydrates
§ Abundant in liver (starving --> little) , cardiac, skeletal muscle cells (running --> little).
§ Unstained in conventional staining method.
□ Dissolved in H&E stains.
□ Characteristic unstained patterns in cell.
□ Nucleus of the cell is not displaced.
§ Stains pink in PAS stain.
§ Glycogen storage diseases
□ Caused by the inability to degrade glycogen.
□ Cells become enlarged.
□ Functional loss of glycogen as cell energy and as a blood glucose buffer.
E.g. Pompe disease occurs in Brahman and Shorthorn cattle (and in humans) and is characterised by poor growth, incoordination, muscle, weakness and eventual recumbency.
93
Characteristics of Lipids.
§ Energy reserve
§ Abundant in adipocytes and steroid hormone-producing cells.
§ Present as unstained gaps in most histologic techniques (use of fat solvents in tissue preparation) (lipid droplet can fill out the majority of the cell and displace the nucleus).
Special techniques involve osmic acid fixation (brownish or black colour) or Sudan III stained frozen sections (stain fat red).
94
Characteristics of Melanin.
§ Dark brown or black pigment responsible for skin/coat colour.
□ Dark brown pigment - eumelanin
□ Yellow red pigment - pheomelanin
§ Occurs in basal layer of epidermis, external root sheath and hair matrix of hair follicles, epithelium of retina, leptomeninx of central nervous system.
§ Is synthesised by melanocytes - specialised cells with long dendritic processes.
§ Membrane-bounded granules (melamosomes) migrate to the tips of the dendritic processes of the melanocytes --> pinch off and are phagocytized by surrounding cells (e.g. keratinocytes).
Serval melanosomes can aggregate and form a melanosome complex (an apical cap that protects the nucleus from UV light).
§ Skin/Hair colour depends on the form of melanin and the number, size, distribution of melanosomes.
§ Melanin production can be increased due to external stimuli.
Tyrosinase is required for the production of melanin - lack of tyrosinase causes albinism.
95
Characteristics of Hemosiderin.
§ Forms as the result of haemoglobin degradation, molecules that have some ion content.
§ Is a golden brown pigment.
§ Occurs as granular cytoplasmic inclusions (after phagocytosis of erythrocytes) in the spleen, liver, bone marrow.
§ Specific stains allow distinction of similar coloured pigments - e.g. lipofuscin.
§ If iron increases beyond normal levels, excess hemosiderin is deposited in the liver and heart. This can reach the point that the function of these organs is impaired.
□ Hemosiderosis (disorder caused by excessive deposition of iron - multiple blood transfusions.)
§ Hemochromatosis (inherited iron-storage disease).
Local hemorrhage (bruising)
96
Characteristics of Lipofuscin.
§ End product of lysosomal activity (indigestible residues of heterophagy, autophagy and crinophagy (phagocytosis of secretory vesicles).
§ Golden brown pigment.
§ Stainable with fat and lysosomal dyes.
Ore abundant in non-dividing cells (neurons; skeletal, smooth, and cardiac muscle) and increase with age.
97
Characteristics of other pigments (Pigments, Dusts, Crystals).
§ Pigments
□ Naturally coloured (colour may be altered by stains)
□ Exogenous and endogenous pigments.
® Carotenoid - yellow pigment carotene found in green leaves, carrots etc and can be deposited in the skin when excessive quantities of the pigment are ingested - skin will appear pale yellow-red and resembles jaundice.
§ Dusts
□ Coal dust will accumulate in macrophages.
§ Crystals
Are occasionally observed in cells - little is known of their significance.
98
What are the three types of cytoskeletons?
Intermediate filaments, Microtubules and Actin Filaments.
99
What is the function of the cytoskeleton?
Cells mechanical strength, control the shape, drive and guides its movements, plays a major role in cell devision, dynamic in structure.
100
Which out of the 3 types of cytoskeleton has the most structure.
Microfilaments (Actin Filaments).
101
What does the Cytoskeleton consist of?
Microfilaments, intermediate filaments, microtubules, proteins that interconnect these three filaments to other cellular structures.
102
What are the characteristics of Actin filaments/ Microfilaments.
- Thinnest filaments: 7 nm in diameter - flexible.
- Helical polymers of identical globular actin molecules.
- Assemble and disasemble (free actin molecules in cytoplasm).
- Throughout the cell but most abundant beneath plasma membrane.
- Linear bundles.
- Two dimensional networks. (can be joined in different ways to facilitate different functions).
- Three dimensional gels.
- Depending on actin binding proteins.
103
What are the 5 different parts of a microfilament? (Best to look at a diagram and revise).
1. Micro-villi on the brush border cells.
2. Contractile bundles (e.g. muscle cells)
3. Protrusions in crawling cells (e.g. migrating neutophils).
4. Contractile ring in cell division.
5. Cell cortex.
104
What is the function of a microfilament/ actin filaments.
Actin associates with myosin to form contractile structures.
- movements of vesicles within the cell (cytoplasmic streaming).
- movement of actin filaments against plasma membrane (in phagocytosis).
- actin filaments slide against myosin filaments (muscle contraction).
105
What are the characteristics of intermediate filaments.
- Intermediate in diameter (10nm).
- Ropelike fibres - great tensile strength.
- Form network throughout the cytoplasm - often anchored to plasma membrane at cell-cell junctions.
- Form the nuclear lamina that strengthens the nuclear envelop.
- Enable cells to withstand mechanical stress (abundant in epithelial, muscle and peripheral nerve cells).
- helical arrays of tetramers each composed of filamentous protein monomer do not form and reform in the continuous manner of microtubules and microfilaments.
- have a N and C terminus (allows polarity in proteins). - hydro-pillic/phobic states.
106
What are the 4 types of intermediate filaments?
Keratin filaments (Cytoplasmic)
Protein (vimentin and vimentin-related filaments) (Cytoplasmic)
Neurofilaments (Cytoplasmic)
Nuclear lamins (Nuclear)
107
What filament is in epithelial cells?
Keratin filaments.
108
What filament is in connective tissue cells, muscle cells and glial cells?
Protein/ vimentin and vimentin-related filaments.
109
What filaments are in nerve cells?
Neurofilaments.
110
What filaments are in all animal cells?
Nuclear lamins.
111
What are the characteristics of microtubules?
- Long hollow cylinders with a diameter of 25nm.
- Made out of tubulin (two different subunits which fits together).
- Can rapidly disassemble and reassemble (dynamic).
- One end attached to a single microtubule-organizing centre (centrosomes or basal body - where microtubules grow from).
- Organise the cell interior.
- Alpha tubulin and beta tubulin form dimer tubulin. (line up in a particular orientation).
- Linear chains of tubulin dimer form protofilaments.
- 13 linear protofilaments form the wall of cylindrical microtubule.
- Continuous state of polymerisation and + end (growing) and depolymerisation at - end (unless stabilised)
112
Which end does the microtubule grow from?
The positive end.
113
What are the 3 different roles of Microtubules.
Position organelles
Mitosis
Supporting structure
114
How do microtubules position organelles?
They guide transport of organelles, vesicles and macromolecules in nerve cells.
115
What are the three types of supporting structures of Microtubules? - what do these look like?
Non dividing cell.
Dividing cell.
Ciliated cell.
116
Where are microtubule ciliated cells found most abundant in?
Respiratory tract, reproductive tract - motile and cilia move. (this is different from villi which are static structures - unable to move).
117
