Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

YEAR 1 - Organisation of the Body (Anton) > 1. Cellular & Molecular Structure & Function > Flashcards

1. Cellular & Molecular Structure & Function Flashcards

1
Q

What is the approximate size of the nucleus?

A

5-10μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the approximate size of a cell?

A

20-30μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the approximate size of a RBC?

A

7μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the smallest separation between two points that the eye can see?

A

0.1mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define a cell.

A
  • A single unit or compartment enclosed by a border or membrane.
  • Smallest metabolically functional unit of life.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Will extra magnification always help see the object in better detail?

A

No, because resolution depends on the wavelength of magnifying rays, so magnifying beyond a certain point will just “magnify the blur”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Give an example of a biological scale marker.

A

Red blood cells - They are usually exactly 7μm, so they give a good comparison for size in a magnified image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two types of sample section?

A
  • Transverse section (TS)
  • Longitudinal section (LS)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the difference between the two types of tissue section.

A
  • Transverse section - Cross section of a long structure
  • Longitudinal section - Cut parallel to long axis of structures inthe sample
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What things give need for section preparation before observing it under a microscope?

A
  • Tissue decay
  • Loss of structural detail
  • Autolysis (break down by own chemicals)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is fixation?

A

The process by which tissue decay and degradation is stopped. It often involves cross-linking proteins to give additional rigidity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the main steps of section preparation for observation under a light microscope?

A

Fixation, Sectioning, Staining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the two ways in which tissues being prepared for observation are stopped from decaying, autolysis and loss of structural detail?

A
  • Chemical cross-binding
  • Cryo (low temperature)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe how a sample may be sectioned.

A
  • Embed in wax block
  • Cut wax block into sections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the three routine staining techniques you need to know about?

A
  • Histochemistry
  • Immunohistochemistry (a.k.a. Immunocytochemistry)
  • In situ hybridisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is histochemistry?

A

Staining of cells with specific chemicals (such as with a H&E stain).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is another name for immunohistochemistry?

A

Immunocytochemistry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is immunohistochemistry?

A

Localisation of specific tissue antigens using labelled antibodies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is in situ hybridisation?

A

Localisation of a specific nucleic acid sequence by adding a complementary strand of RNA or DNA, then adding a labelled molecule similar enough to bind with it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the main types of microscope?

A
  • Light microscope (LM)
  • Electron microscope (EM) -> Transmission and scanning
  • Fluorescence microscope (FM)
  • (EXTRA) Confocal scanning laser microscope (CF)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe how a light microscope works.

A

Light from source:

  • focussed by condenser lenses
  • light passes through section
  • section detail magnified by objective lens
  • further magnified by eyepieces
  • eyes see the contrast in the magnified image
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Draw a diagram of how a light microscope works.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the resolution of a light microscope?

A

0.2µm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the significance of the resolution of light microscopy?

A

Can see:

  • Bacteria
  • Details within nucleated cells such as nuclei, mitochondria, ribosomes and storage ‘granules’.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Give an example of an artefact that often arises in light microscopy sample preparation.

A

Lipids are often dissolved in processing (when the wax is dissolved), leaving behind empty space.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe the staining process for light microscopy.

A
  • Cut section of wax
  • Dewaxed using chemical
  • Stained by H&E or trichrome stain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does H&E stain stand for?

A

Haematoxylin and eosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the colours seen in a H&E stain?

A

Purple and pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe the general histological appearance of a H&E stain.

A
  • Purple -> Nuclei and areas rich in nucleic acids
  • Pink -> Other structures, specially proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

EXTRA: Describe the principle on which H&E stains work.

A
  • Basophilic structures, such as nucleic acids, bind to basic dyes, in this case haematoxylin -> This turns them purple
  • Acidophilic structures, such as proteins, bind to acidic dyes, in this case eosin -> This turns them pink
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the full name for the trichrome stain?

A

Masson’s trichrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the advantage of trichrome staining over H&E staining?

A

It allows cells to be distinguished from surrounding connective tissue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Describe the colours and their significance in trichrome staining.

A
  • Blue/Green - Collagen
  • Pink - Cytoplasm
  • Dark red/Brown/Black - Cell nuclei
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is fluorescent microscopy a subset of?

A

Light microscopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Describe how fluorescence microscopy works.

A
  • Lamp produces light for excitation
  • Microscope focusses light on to section and collects fluorescence emission light
  • Sample is preserved, chemically or by freezing
  • Sample is labelled to tag/label specific molecules
    • Live fluorescent protein
    • Antibodies target specific protein (immunofluorescence)
  • Different dyes emit visible light of different colours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Can a fluorescence microscope sample be viewed through an eyepiece?

A

Yes, it is just like light microscopy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the two things that can be seen in fluorescence microscopy?

A
  • Live fluorescent proteins -> Proteins that are fluorescent, either naturally or by DNA modification to include a reporter protein
  • Immunofluorescence -> Labelling proteins using fluorescent antibodies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is immunofluorescence?

A
  • Antibody specific to a protein is labelled with a fluorescent marker (either directly or with another labelled antibody) so it can be traced
  • Therefore, the protein can be seen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

(EXTRA) What does GFP stand for?

A

Green Fluorescent Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What does GFP allow for?

A

Live imaging of cells and the function of their proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the resolution of TEM?

A

10nm to 0.5nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are the main differences of TEM compared to light microscopy?

A
  • In a vacuum
  • Electromagnets instead of lenses
  • No colour contrasts, just heavy metal salts, which scatter electrons, producing contrast
  • More careful fixation, because of need to preserve details that can be seen by electron beam
  • Resin used instead of wax -> Gives more support
  • Thinner sections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How does staining work in TEM?

A

Heavy metals salts (e.g. uranium), which are electron dense, act as “stains”. They scatter electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is the significance of the resolution of TEM?

A

Shows structure within organelles, lipid membranes, viruses and macromolecules e.g. DNA and proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Draw the structure of a TEM.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Describe the sample sections in TEM.

A

Thin plastic resin sections approx 50-100 nm thick.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is confocal microscopy and how does it work?

A

It is a technique used to produce 3D images of a sample thicker than in LM, with no need for taking several sections:

  • Often uses fluorescence microscopy
  • Scanned beam focussed at different levels of section
  • Image produced by detector and photomultiplier system
  • Cathode ray tube (CRT) screen used for imaging
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are 3 examples of methods used to study the surface of samples?

A

1) Light microscopy
2) Capsule endoscopy
3) SEM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the resolution of SEM?

A

2nm to 0.2nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Describe how SEM works.

A
  • Fixation as for LM or TEM
  • Sample may be very large; glued on to rivet or unsupported
  • Scanned with electrons, the scattering of which is detected
  • Conducting coating to minimise build-up of electrons which would produce areas lacking detail
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are eukaryotic cells?

A

Cells that have a true nucleus containing the DNA as well as various other membrane-bound organelles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What are the 4 tissue types?

A
  • Epithelium
  • Muscle
  • Connective tissue
  • Nerve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What details of the nucleus does light microscopy let you see?

A

Just the nuclei, when they are stained by H&E.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What details of the nucleus does TEM let you see?

A
  • Nuclear membrane/envelope
  • Nuclear matrix
  • Chromatin
  • Nucleolus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What are the two types of chromatin in an interphase nucleus?

A
  • Euchromatin
  • Heterochromatin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is the size of the nucleus?

A

5 - 10μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are the parts of the nucleus?

A
  • Nuclear membrane/envelope
  • Nuclear matrix
  • Chromatin
  • Nucleolus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What are the functions of the nucleus?

A
  • Gene replication and repair
  • Genetic transcription
  • Ribosome production
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What are the two types of DNA in the interphase nucleus?

A
  • Euchromatin
  • Heterochromatin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is euchromatin?

A

The finely dispersed, lightly stained form of DNA in the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is heterochromatin?

A

The clumped, coarse form of DNA in the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the function of the nucleolus?

A

Synthesis of rRNA -> Ribosome production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the function of the nuclear envelope?

A

Transport of substances into and out of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Describe how the structure of nuclear pores was discovered.

A
  • EM imaging showed 8-fold symmetry and petal-shaped structures
  • Then studied with sophisticated imaging techniques -> Showed they were 80nm across and showed more details
  • Later, protein analysis showed 30 other components
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

How do cell membranes appear in low and high power TEMs?

A
  • Low power -> Single line
  • High power -> Dark/Light/Light lines (called a unit membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What part of the nuclear envelope defines eukaryotes?

A

Nuclear envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What goes into and out of the nucleus through the nuclear pores?

A
  • In: Proteins
  • Out: RNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Describe the structure of the endoplasmic reticulum.

A

Network of membrane-limited channels called cisternae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What is the function of the RER?

A

Synthesis of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What is the function of the SER?

A

Specialised functions, such as production of lipids and hormones (e.g. secretion of steroid hormones).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Describe the structure of the Golgi apparatus.

A

Multi-layered network of membrane-bound cisternae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What are the names and functions of the two faces of the the Golgi apparatus?

A
  • Cis face -> Receives vesicles from the ER
  • Trans face -> Sends vesicles to cell membrane and endosomal pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is the function of the Golgi apparatus?

A

Packaging of material for transport out of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Practise drawing out the protein secretory pathway.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What is the function of lysosomes?

A

Intracellular digestion by acid hydrolases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What are the two stages of lysosome development?

A
  • Primary -> Smaller, Produced by budding from the Golgi
  • Secondary -> Larger, Produced when primary lysosomes fuse with endosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What happens to lysosomes after digestion is complete?

A

They become residual bodies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What are the two types of lysosomes and what are their functions?

A
  • Autophagosomes -> Recycling bits of cell no longer needed
  • Heterophagosomes -> Dealing with material brought into the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What are proteosomes?

A

Cytoplasmic organelles that degrade unwanted misfolded cytoplasmic proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

How do proteosomes know which proteins to break down?

A

They are tagged by ubiquitin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Are proteosomes visible by LM or TEM?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Describe the structure of proteosomes.

A
  • 4 stacked rings around a core
  • Proteases in central pore
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What is the function of mitochondria?

A

Generation of ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What is the shape of mitochondria?

A

Spherical or long.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

Describe the structure of mitochondria.

A
  • Outer membrane
  • Inner membrane -> Folds in to form cristae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

Are mitochondria acidophilic or basophilic (relevant in LM)?

A

Acidophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What is the length and width of mitochondria?

A

Length: 2 to 7μm
Width: 0.2 to 2μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

How can you easily tell apart a LM image from a EM image?

A

Although both have similar magnification, the EM has a much higher resolution so it appears sharper.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is an easy way of working out the scale of a microscope image?

A

Use reference markers, such as the size of RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What is the significance of the nucleus in microscope images?

A
  • Helps work out scale of image
  • Helps work out type of microscope (EM usually shows far more detail)
  • Shows type of cell
  • Shows cell activity (lots of heterochromatin = very transcriptionally active cell)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Label the following:

A
  • Mitochondrion
  • Nucleus
  • RER
  • Vesicles
  • Endocytic invaginations
  • Basal lamina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

Describe the structure of ribosomes.

A

Eukaryotic cells have 80S ribosomes which consist of:

  • Small 40S subunit
  • Large 60S subunits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

What are endosomes?

A

Vesicles that are formed by endocytosis. Essentially, the process is the reverse of exocytosis.

94
Q

What are peroxisomes?

A

Small organelles that have an oxidative role in, for example, lipid metabolism.

95
Q

What is the cytoskeleton?

A

A complex system of inter-linking protein filamnets that extends from the nucleus to the membrane.

96
Q

Why do cells require a cytoskeleton?

A
  • Cell motility
  • Cellular organisation -> Moving organelles and vesicles around
  • Mechanical strength
97
Q

What are the types of protein filament that form the cytoskeleton? (from thinnest to thickest)

Include their functions.

A

From thinnest to thickest:

  • Microfilaments (actin) -> Cell shape and motility
  • Intermediate filaments -> Strength and structure
  • Microtubules (tubulin) -> Position organelles and direct intracellular transport
98
Q

What is the diameter of microfilaments (actin)?

A

5-7nm

99
Q

Describe the structure of cytoskeleton microfilaments (actin filaments) and how they are arranged in the cell.

A
  • Two-stranded helical polymers of actin monomers with plus and minus end
  • 2D and 3D network throughout cell, concentrated just beneath cell membrane
100
Q

What are the functions of cytoskeleton microfilaments (actin filaments)?

A
  • Cell movement
  • Determine cell shape (e.g. in muscle contraction)
101
Q

Describe the polarity of actin filaments.

A
  • Plus end -> Growth and shrinkage are fast
  • Minus end -> Growth and shrinkage are slow
102
Q

Describe how actin filaments allow cell movement.

A
  • Rapid interchange of small soluble units and the large filament polymer allow for changes in shape and movement
  • The rapid polymerisation happens at the plus end of the filaments
  • This allows a directional response to a signal (e.g. a nutrient source)
103
Q

Give an example of cells using actin for cell motility.

A

Neutrophils (a type of WBC) can use the actin cytoskeleton to chase and engulf bacteria in response to chemical trails.

104
Q

Describe the importance of actin filaments in brain development.

A
  • Growth cone extensions (filopodia) carry bundles of actin filaments
  • These are used to assist with supporting dynamic directional growth in response to stimuli
105
Q

Actin combines with myosin to form…

A

Myofibrils

106
Q

What is the diameter of microtubules?

A

25nm

107
Q

Describe the structure of microtubules in the cytoskeleton and how they are arranged in the cell.

A
  • Long, hollow cylinders made of alpha and beta tubulin
  • Rigid and straight (unlike actin)
  • Often radiate out from a fixed point (MTOC)
108
Q

What are the functions of microtubules in the cytoskeleton?

A

Direct movement of organelles, vesicles and chromosomes intracellularly.

109
Q

Describe the polarity of microtubules.

A

They have a plus end and minus end (just like with actin) and growth is faster at the plus end.

110
Q

Describe the turnover of microtubules.

A
  • GTP -> Favours growth
  • GDP -> Favours shrinking
  • Subunits are recruited at plus end and lost from minus end, leading to a treadmill effect -> This is very active
111
Q

What are microtubules often centred around and how do these work?

A
  • Microtubule organising centres (MTOCs)
  • The stable minus end is embedded at the MTOC, while the plus end is free for growth and shrinkage
112
Q

Describe how different organelles can move along microtubules.

A
  • They associate with either kinesin motors or dynein motors
  • Kinesin motors -> Move towards plus end
  • Dynein motors -> Move towards minus end
113
Q

Describe the different arrangement of microtubules in different cell types.

A
  • Fibroblasts -> All microtubules head out from MTOC
  • Neuron axon -> Microtubule plus end at synapse, minus end in cell body
114
Q

What can affect the stability of microtubules?

A

MAP (microtubule associate proteins) -> Bind to and stabilise microtubules, resulting in longer tubules

115
Q

What is the clinical relevance of microtubules?

A
  • Tubulin mutations -> Lead to brain development abnormalities, such as cortical malformations
  • Different forms of the MAP protein MAPT allow for higher neuronal plasticity in the embryo and more stability in adults
116
Q

What is an example of an MTOC in human cells and how is it important?

A
  • Centrosome
  • It replicates at cell division, allowing the mitotic spindle to form
117
Q

What is the diameter of intermediate filaments?

A

10-12nm

118
Q

All all intermediate filaments the same? List the different types.

A

No, there are specific intermediate filament proteins in different cells:

  • Keratin
  • Desmin
  • Neurofilament
  • Nuclear lamin proteins
119
Q

What are the functions of intermediate filaments?

A

Mechanical strength and structure

120
Q

Describe the structure of intermediate filaments.

A

Multimers twisted into rope-like filaments.

121
Q

Where is keratin found and what is its function?

A
  • It is a group of intermediate filament proteins found in epithelial cells, as well as hair and nails
  • It provides mechanical support
122
Q

Where are neurofilaments found and what are their function?

A
  • They are intermediate filament proteins found in axons
  • They provide structure -> Level of NF gene expression determines axon diameter and therefore rate of conduction
123
Q

Where are lamins found and what are their function?

A
  • They are intermediate filament proteins that form the nuclear lamina (lining inner nuclear membrane)
  • They provide structure and provide anchoring point for chromosomes and proteins of nuclear pore complex
124
Q

What is the clinical importance of tubulin filament formation?

A

Tubulin microfilament formation can be targeted by anti-cancer drugs, since microtubules are required for cell division.

125
Q

What are all of the different types of abnormality of cell growth you need to know about?

A

Decreased growth:

  • Developmental
    • Agenesis
    • Hypoplasia
  • Progressive
    • Physiological
    • Pathological
      • General
      • Tissue-specific
      • Local atrophy
        • Disuse
        • Ischaemic
        • Neuropathic
        • Idiopathic

Increased growth:

  • Hypertrophy
  • Hyperplasia
  • Neoplasia
126
Q

What are the two types of decreased growth?

A
  • Developmental -> Occuring before the organ has reached maturity
  • Progressive -> Occuring after the organ has reached maturity
127
Q

What are the different types of decreased developmental growth?

A
  • Agenesis -> Complete failure to develop
  • Hypoplasia -> Partial failure to develop
128
Q

Define agenesis and give an example.

A
  • Agenesis is the complete failure of an organ to develop
  • Renal agenesis in the fetus can lead to decreased urine production
  • Since urine is a contributor to aminiotic fluid, there is decreased amniotic fluid
  • This can also lead to problems with pulmonary development (e.g. pulmonary agenesis)
  • This is known as Potter’s syndrome
129
Q

Define hypoplasia and give some examples.

A
  • Hypoplasia is the partial failure of an organ to develop

Example 1: Klinefelter’s syndrome

  • Partial failure of testes to develop
  • Caused by two or more X chromosomes in males

Example 2: Turner’s syndrome

  • Partial failure of ovaries to develop
  • Caused by a missing or partially X chromasome
130
Q

What are the different types of decreased progressive growth?

A
  • Physiological atrophy (involution) -> Natural shrinking of an organ, leading to a reduction in function
  • Pathological -> Diseased wastage of organs
    • General
    • Tissue-specific
    • Local atrophy
131
Q

Define physiological atrophy (involution) and give an example.

A
  • Physiological atrophy is the natural shrinking of an organ (after it has matured) due to a reduction in cell number, leading to a reduction in function -> It is NOT linked to disease
  • An example is the shrinking of the thymus at puberty
  • The thymus is where T-lymphocytes are trained, but strong immunity is required most when you are young, so the structure is replaced with fat over time
132
Q

What is the difference between agenesis, hypoplasia and atrophy?

A

They are all types of decreased growth, but:

  • Agenesis is the complete failure of an organ to form
  • Hypoplasia is the partial failure of an organ to form
  • Atrophy is the reduction is size and function of an organ after it had fully developed
133
Q

Define pathological atrophy and state the different types.

A
  • It is the wastage of an organ (after it has matured) due to a reduction in cell number, leading to a reduction in function -> It is caused by DISEASE

Types:

  • General -> Affecting many different tissues or organs
  • Tissue-specific -> Affecting many areas of the safe tissue type
  • Local atrophy -> Localised due to various reasons
134
Q

Define general pathological atrophy and give examples.

A
  • It is atrophy affecting many different tissues or organs throughout the body

Examples include:

  • Wasting during starvation
  • Malignant disease (cachexia)
135
Q

What is cachexia?

A

Weight loss due to muscle loss in patients with diseases such as cancer. It is an example of general pathological atrophy.

136
Q

Define tissue-specific pathological atrophy and give examples.

A
  • It is atrophy affecting a particular type of tissue throughout the body
  • An example is osteoporosis
137
Q

What is local atrophy and what are the different causes?

A
  • Atrophy that affects only part of the body

Causes include:

  • Disuse
  • Pressure from cysts/tumours/aneurysms
  • Ischaemia
  • Neuropathy (nerve problems)
  • Idiopathic (unknown cause)
138
Q

Give an example of local atrophy due to disuse.

A

Bone and muscle wastage in an immbolised limb (due to fracture).

139
Q

Give an example of local atrophy due to ischaemia.

A
  • Vascular disease
  • Cerebral atrophy
140
Q

Give an example of local atrophy due to neuropathy.

A

Muscle wasting after nerve injury or poliomyelitis

141
Q

Give an example of local atrophy due to idiopathy.

A

Neuropathies such as Parkinson’s

142
Q

What are the different types of increased growth?

A
  • Hypertrophy -> Growth of organ/tissue due to increase in cell SIZE
  • Hyperplasia -> Growth of organ/tissue due to increase in cell NUMBER
  • Neoplasia -> Tumour growth
143
Q

What are some of the characteristics of hypertrophy/hyperplasia?

A
  • Occurs in response to stimulus external to affected organ
  • Normal histology
  • Often provides extra function
  • Usually self-limiting and often reversible

Hypertrophy:

  • Characteristic of ‘permanent’ tissues (notably muscle)
  • Increase in size WITHOUT increase in number

Hyperplasia:

  • Characteristic of ‘renewing’ tissues
  • Increase in number WITHOUT increase in size (cell growth must occur but the cells are the same size as before hyperplasia - ‘balanced growth’)
144
Q

Compare the tissues in which hypertrophy and hyperplasia occur.

A
  • Hypertrophy -> Permanent
  • Hyperplasia -> Renewing (+ some ‘resting’ tissues like endocrine glands)
145
Q

Give an example of healthy and pathological hypertrophy.

A
  • Healthy -> Skeletal muscle hypertrophy in response to exercise
  • Pathological -> Cardiac hypertrophy
146
Q

Describe when cardiac hypertrophy may occur.

A
  • May be an adaptive response to pressure or volume stress
  • Therefore it is a common consequence of many forms of heart disease
147
Q

Give some examples of healthy and pathological hyperplasia.

A
  • Healthy -> Skin (in response to abrasion), Bone marrow (increased in erythropoiesis at high altitude), Endocrine glands
  • Pathological -> Hyperplasia of the thyroid in Graves’ disease
148
Q

What is erythropoiesis and what process does it involve?

A
  • RBC production in the red bone marrow
  • At high altitudes, hyperplasia is increased to accomodate for a need for higher rate of RBC production
149
Q

What are the characteristics of neoplasia?

A
  • Excessive proliferation of one cell type
  • Results from cumulative genetic and epigenetic changes (usually clonal)
  • Abnormal, unbalanced histology
  • No useful function
  • Progressive; Spontaneous regression is rare
150
Q

What is neoplasia essentailly synonymous with?

A

Tumour growth

151
Q

Describe the nomenclature of tumour types.

A
  • Epithelial
    • Surface
      • Benign -> Papilloma
      • Malignant -> Carcinoma
    • Glandular
      • Benign -> Adenoma
      • Malignant -> Adenocarcinoma
  • Mesenchymal
    • Benign -> e.g. Fibroma, Lipoma, Haemangioma (reflect tissue of origin)
    • Malignant -> -sarcoma
  • Haematological (benign/maligant doesn’t really apply)
    • Lymphoid -> Lymphoma, Lymphoproliferative disorders
    • Bone marrow -> Myelodysplasia, Leukaemia
152
Q

What are the two main types of tumour resulting from neoplasia? What is their main difference?

A
  • Benign -> Grow by expansion
  • Malignant -> Grow by invasion, metastasis and progression
153
Q

Describe the characteristics of benign tumours.

A
  • Grow by local expansion
  • Do not invade adjacent tissue, cross basement membrane or spread to distant sites
  • Similar differentiation to normal tissue
  • May cause harm through pressure, obstruction or secretion of hormones
  • May progress to malignancy
154
Q

Are benign tumours always harmless?

A

No, they may cause harm through pressure, obstruction or secretion of hormones.

155
Q

Do benign tumours remain harmless?

A

No, they may become malignant due to additional mutations.

156
Q

Describe the main characteristics of malignant tumours.

A
  • Grow by invasion of adjacent tissue, traverse basement membrane and spread to distant sites
  • Differentiation is incomplete to some extent (pleomorphism, anaplasia)
  • Nuclei are often large, aneuploid; mitotic abnormalities
  • Cause harm through destruction of normal tissue function (+ may also induce cachexia)
157
Q

What is the difference between cell growth and proliferation?

A
  • Cell growth is the process by which cells increase in mass and size
  • Proliferation is the process of cell division

These processes are frequently co-ordinated and are therefore often used interchangeably.

158
Q

What is morphogenesis?

A

The process by which an organism develops a shape.

159
Q

Describe the different possible fates of undifferentiated cells.

A
  • Differentiate
  • Apoptosis
  • Proliferation
  • Growth

Note that proliferation and growth usually lead to the same point since they are usually co-ordinated. In other words, the cell may grow and then divide, or divide and then grow.

160
Q

What processes balance the process of cell growth and division?

A
  • Cell loss
  • Cell death
161
Q

What does cell growth require in order to occur?

A
  • Increase in cell mass and volume -> Macromolecule synthesis
  • Relative movement at cell surface
162
Q

Name some important times when growth occurs in humans.

A
  • Development (Egg -> Embryo -> Fetus -> Adult)
  • Adult
    • Hypertrophy -> Permanent tissues
    • Hyperplasia -> Renewing tissues + Resting tissues
  • Disease -> Neoplasia
163
Q

Describe the different adult tissue types depending on how they grow.

A
  • Renewing tissues -> Continually dividing stem cells (e.g. skin, gut epithelium, RBCs) -> Hyperplasia
  • Resting tissues -> Cells multiply only to repair damage (e.g. liver, thyroid) -> Hyperplasia
  • Non-dividing tissues (e.g. neurons)
164
Q

Name some important times when cell/tissue loss or hypoplasia occurs.

A
  • Development
    • Tissue patterning (e.g. digit formation)
    • Neural patterning
  • ‘Physiological’ atrophy
    • Thymus at puberty
    • Epithelial cells
  • Developmental/physiological disorders
    • Hypoplasia e.g. Klinefelter’s syndrome
    • Atrophy from disuse or disease
165
Q

Describe the coupling of cell growth and proliferation in the cell cycle.

A
  • Cyclin-dependent kinases are responsible for the progression of the cell cycle (e.g. they control the transition from G1 to S phase.
  • These kinases are controlled by growth regulators, suggesting that growth causes the cell cycle, not vice versa
  • So: Growth -> Proliferation
166
Q

Give some examples of when cell growth and proliferation are not coupled.

A
  • Proliferation but no growth -> Cleavage in development
  • Growth but no proliferation -> Skeletal muscle hypertrophy
  • Growth and DNA replication but no cytokinesis, so cells are big -> Many myocardial cells are 4N (tertraploid)
167
Q

What molecules control cell growth?

A
  • Growth inhibitors (not very well characterised though)
  • Growth factors
168
Q

Give some experimental evidence for growth inhibitors.

A

Myostatin deficiency in mice is linked to up to a 3-fold increase in mass. This shows that myostatin is a growth inhibitor.

169
Q

Describe how growth factors work.

A
  • Bind to cell-surface receptor
  • This triggers an intracellular signalling cascade, with intracellular signalling molecules becoming active
  • These change the properties of transcription factors, often by phosphorylation
  • So macromolecular synthesis is increased, triggering growth and therefore the cell cell
170
Q

What are the different types of growth factor?

A
  • Global with global effects -> Endocrine
  • Global with specific effects -> Endocrine
  • Local with local effects -> Paracrine or autocrine

Local tend to control growth of specific organs, while global tend to control organism-wide growth of multiple organs (e.g. nutrition-dependent).

171
Q

How is organ size regulated?

A
  • It is usually autonomous, which is demonstrated by transplanted organs usually growing to adult size
  • Certain organs may be controlled non-autonomously (e.g. spleen)
172
Q

What is generally important in patterning?

A

Growth factors

173
Q

How do terminally differentiated cells compare to undifferentiated cells?

A

Similarities:

  • Contain the same set of organelles
  • Express some common proteins (‘housekeeping genes/proteins’)

Differences:

  • Express cell type-specific proteins not expressed in non-differentiated cells -> Lead to specilised functions and structures (e.g. sarcomeres)
174
Q

Give an example of a protein that is specific to apoptotic cells and describe some experimental evidence for this.

A
  • Caspases
  • When caspase 9 is knocked out in mouse embryos, the brain appears very large. This is because caspase is required for modelling the nervous system and without it neurons do not die.
175
Q

When is a cell terminally differentiated?

A

It differentiates terminlly after it has exited the cell cycle and entered a quiescent phase (G0).

176
Q

Can a cell exit G0?

A

Yes, this process may be triggered by growth factors.

177
Q

At what point in the cell cycle do cells enter G0?

A

After mitosis has finished and the cell is entering G1.

178
Q

Can cells ever de-differentiate?

A

Mostly no, except for certain cells, such as hepatocytes which can re-enter the cell cycle for liver regeneration.

179
Q

Do cells only differentiate after the have exited the cell cycle?

A

No, they start to differentiate before they exit the cell cycle.

180
Q

Define differentiation.

A

A complex multistep process involving gradual specialisation of a cell.

181
Q

What happens to potency as a cell differentiates?

A

It becomes more restricted.

182
Q

Describe the basis of how cell differentiation occurs.

A

Cell-type specific gene expression is induced.

183
Q

What are stem cells?

A

Cells that are:

  • Undifferentiated
  • Capable of renewal
  • Able to divide without limit
184
Q

Describe all of the combinations of the types of the 2 cells that stem cell division produces.

A
185
Q

What are transit amplifying cells?

A

Transit-amplifying cells (TACs) are an undifferentiated population in transition between stem cells and differentiated cells.

186
Q

What is the difference between unipotent stem cells, progenitor cells and transit amplifying cells?

A

All 3 types can only produce a single type of cell:

  • Unipotent stem cells -> Have the potential to divide an unlimited number of times, but tend to divide rarely
  • Progenitor cells -> Have the potential to divide only a limited number of times, but tend to divide rapidly
  • Transit amplifying cells -> Check the difference between this and progenitor cells, because they seem the same
187
Q

What are the different types of natural stem cell and where are they found?

A
  • Totipotent -> Can become any embryonic cell, plus placental cells -> Found in fertilised egg
  • Pluripotent -> Can become any embryonic cell, but cannot become placental cells -> Found in inner cell mass of blastocyst
  • Multipotent -> Can become any of a given type of cell (e.g. any blood cell) -> Found in adults
  • Unipotent -> Fully “committed” to terminal differentiation -> Found in adults
188
Q

What are haematopoietic stem cells and what type of stem cell are they?

A
  • Stem cells in red bone marrow that give rise to all of the different mature blood cell types and tissues
  • They are multipotent
189
Q

Describe the stages of differentiation.

A
  • The cell undergoes multiple changes from totipotent to pluripotent, then multipotent(?), then unipotent
  • Each of these changes involves specification (where the cell differentiates autonomously, but can still be induced to change this) and then determination (where the cell differentiates autonomously in all ways and cannot be induced to change this)
  • Finally, the cell terminally differentiates

Remember to check how transit amplifying cells fit into this - it seems that they are the stage between unipotent stem cells and differentiated cells.

190
Q

Describe simply the difference between the processes of specification and determination in differentiation.

A
  • Specification -> Autonomous differentiation, where the cell is planning on differentiating into something but can still be made to change its mind
  • Determination -> Too late for the cell to change its mind
191
Q

Give an example of the difference between specification and determination.

A

Taking ectoderm-planning cells and placing them in the right environment causes them to form mesoderm by induction instead.

192
Q

According to the syllabus, what is the principle of the establishment of tissues?

A

Progressive restriction of developmental potential

193
Q

What are adult stem cells important for?

A

Maintaining cell populations that last long periods of time and must be renewed:

  • Epithelium
  • Blood
  • Muscle
  • Liver
  • Brain
194
Q

Is the genome affected by differentiation? Give some experimental evidence for this.

A
  • No
  • Animals can be cloned by activating an egg, then inserting a fully differentiated nucleus. Since all of the different cell types of that organism can be formed from this nucleus, it shows that all of the DNA is present in the differentiated nucleus.
195
Q

How is the differentiated state of cells produced and maintained?

A

Transcription factors:

  • Show positive autoregulation (where the product of the gene activates the gene itself - see diagram)
  • Block the cell cycle

Epigenetic control:

  • Inactive genes -> Promoter regions are often methylated, while histones are deactylated
  • Active genes -> Vice versa to above
196
Q

Describe how induced pluripotent stem cells may be produced.

A
  • Specific combination of transcription factors is expressed in cell
  • These are normally specifically expressed in stem cells
197
Q

Describe some experimental evidence for transcription factors maintaining the terminal differentiated state in some cells.

A

Conditional genetic removal of the Pax5 transcription factor in mature B cells of the immune system produces uncommitted progenitor cells that can differentiate into other immune cell types. This shows the role of Pax5 in maintaining the cells in the differentiated state.

198
Q

Aside from regulation of the transcription, describe how differential gene expression may occur in differentiated cells.

A
  • Alternative splicing
  • RNA editing (post-transcriptional modification)
  • Genomic rearrangements (placing different parts of the genome next to each other - NOTE: This is an exception to the rule about not changing the genome in differentiation)
199
Q

What is induction?

A

When one cell instructs another to become committed and differentiate.

200
Q

What are some mechanisms involved in induction?

A
  • Diffusible ligand binds to a cell surface or intracellular receptor -> Paracrine or juxtacrine
  • Cell surface ligand binds to a receptor -> Juxtacrine
  • Gap junctions -> Juxtacrine

Juxtacrine is when the cells are right next to each other.

201
Q

Does all development require cell-cell interactions (i.e. induction)?

A

No, sometimes mosaic development can occur in mammals, where a certain part of the embryo will produce a given part of the organism, regardless of the different cells next to them.

202
Q

Describe the assymetric division of stem cells.

A

A stem cell will produce two cells: Another stem cell and a cell that can go on to differentiate.

203
Q

Describe the process of skin renewal.

A
  • Skin: stratified squamous keratinised epithelium layer
  • Basal cell layer contains proliferating stem cells
  • Cells move through layers of skin to replace cells sloughed off at surface
  • Cells move through states of gene expression towards terminal differentiation
  • Cells express a series of different keratin proteins during differentiation
  • 30 days from stem cell division to cell sloughed off at surface of the skin
204
Q

Does the basal layer of skin contain many stem cells?

A

No, it only contains a few which produce transit amplifying cells that divide far more rapidly.

205
Q

Why do stem cells not divide very often?

A
  • Limit the potential for mutations during DNA replication
  • Potential for very rapid repopulation when required e.g. wound repair
206
Q

Name the different cells that can be derived from haemapoietic stem cells (HSC).

A
  • RBCs
  • WBCs
  • Platelets
207
Q

Describe an experiment to show that bone marrow contains stem cells.

A
208
Q

What is the full name for a bone marrow transplant and what is it used to treat?

A

Haematopoietic stem cell transplantation (HSCT) used to treat:

  • Severe aplastic anaemia (bone marrow failure)
  • Leukaemia (cancer of WBCs)
  • Non-Hodgkin’s lymphoma (cancer of lymphatic system)
  • Genetic blood and immune system disorders
209
Q

Describe cardiac and skeletal muscle tissue regeneration.

A
210
Q

Describe the action of stem cells in the brain.

A
211
Q

Describe liver regeneration.

A
212
Q

When do embryonic stem cells become pluripotent rather than totipotent?

A

At the 8 cell stage.

213
Q

Describe the process of reprogramming cells to be induced pluripotent stem cells (iPS).

A
  • 4 reprogramming factors originally used to convert primary cells into iPS cells: Oct4, Sox2, Klf4, c-Myc
  • Delivered by viral vectors
214
Q

Aside from treating diseases, what can iPS cells be used for?

A

Studying human diseases in vitro - “disease in a dish” models.

215
Q

Give some examples of stem cells being used to treat diseases.

A

Parkinson’s disease:

  • Dopamingeric neurons transplanted at site of cell loss or site of dopamine loss
  • Experiments in rats and monkeys very successful
  • In humans: anecdotal success at best

Muscular dystrophy:

  • Using muscle stem cells or muscle precursor cells to regenerate diseased muscle
  • Experiments in rats very successful
  • In humans: Unsuccessful (due to death of injected cells, immune response, etc.)
216
Q

What are two main types of cell death?

A
  • Apoptosis -> Programmed cell death
  • Necrosis -> Accidental cell death
217
Q

Describe briefly the mechanism of apoptosis.

A

Molecular pathway involves activation of proteases and caspases:

  • Nucleus condensation and fragmentation
  • Membrane blebbing (buldging) seen
  • Apoptotic cell fragments (called apoptotic bodies) engulfed by phagocytic cells before bioactive contents can spill out
218
Q

Name two situations where apoptosis is necessary.

A
  • Digit formation
  • Epiphyseal plate (apoptosis of hypertrophic chondrocytes)
219
Q

What type of cell is it very important to target in cancer therapy and why?

A

Stem cells, since they drive the formation of tumours (despite their small number).

220
Q

When a cell detects DNA damage, what are the different possible outcomes?

A
  • Cell cycle checkpoint arrest
  • DNA repair
  • Apoptosis
221
Q

Which parts of the EM spectrum may cause damage to DNA?

A
  • Ultraviolet
  • X-ray
  • Gamma
222
Q

Describe how ionising radiation can damage DNA.

A
  • It ionises and excites water so that free radicals are produced
  • These can then cause damage to biological molecules, including proteins, RNA and DNA
223
Q

Give an example of highly-targeted radiotherapy.

A

Iodine-131 therapy:

  • Radioactive iodine is ingested
  • After ingestion, the iodine tends to affect the thyroid
  • The iodine emits ionising radiation, which is used to treat thyroid cancer and hyper-thyroidism (Graves’ disease)
224
Q

How common is radiotherapy treatment?

A

60% of cancer patients in the UK receive radiation therapy.

225
Q

Describe the radiation and technology involved in most radiotherapy.

A
  • X-rays
  • Delivered by a linear accelerator -> Uses synchronised microwaves to accelerate electrons before they are stopped by a metal target
226
Q

What are ‘organs at risk’?

A

Organs surrounding a tumour with normal function. The radiation dose to these areas must be reduced as much as possible.

227
Q

How can the radiation dose in radiotherapy be conformed to the shape of the tumour?

A

Multi-leaf collimation

228
Q

How can the radiation distribution in radiotherapy be changed?

A

Using wedges.

229
Q

Describe the different body volumes involved in planning radiotherapy.

A
  • Gross tumour volume (GTV) -> Extent of disease detectable by imaging or other clinical methods
  • Clinical target volume (CTV) -> Contains GTV and surroudning areas considered likely to contain subclinical disease (e.g. lymph nodes)
  • Planning target volume (PTV) -> Contains CTV and a margin to allow for physiological and technical variations
230
Q

What is 3D conformal radiotherapy?

A

A method that uses up to 3 different intersecting beams to provide a highly shape-matched treatment that does not affect normal tissue very much.

YEAR 1 - Organisation of the Body (Anton) (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions