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Histology Flashcards

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1
Q

How much water in a cell?

A 
average= 80%
range= 75-85%
comment= 90% free, 5% bound
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2
Q

How much protein in a cell?

A 
average= 15%
range= 10-20%
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3
Q

How much lipid in a cell?

A 
average= 2.5%
range= 2-3%
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4
Q

How much carbohydrate in a cell?

A 
average= 1.5%
range= 1%
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5
Q

How much inorganic in a cell?

A 
average= 1%
range= 1%
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6
Q

What cells contain the most water?

A

embryonic cells

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7
Q

What cells contain the least water?

A

old cells

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8
Q

What are common features to all eukaryotic cells?

A
  • outer membrane
  • an inner cytosol
  • a cytoskeleton
  • membrane bound organelles within the cytosol
  • inclusions
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9
Q

What is the cytosol?

A

a solution of proteins, electrolytes and carbohydrates. It has both fluid and gel-like properties

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10
Q

what is the cytoskeleton?

A

determines the shape and fluidity of the cell. Is made from thin and intermediate filaments and microtubules.

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11
Q

what are inclusions?

A

other structures within the cytoplasms which may or may not be bound by a membrane

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12
Q

What is the plasmalemma?

A

It is a bimolecular layer of amphipathic phospholipid molecules with their hydrophilic heads at the outer and inner surfaces and their hydrophobic fatty acid chains facing towards the middle of the 2 layers.

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13
Q

What does the plasmalemma do?

A

separates the cytoplasm from the outside environment

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14
Q

what does the plasmalemma contain?

A

integral proteins which the cells inserts into the membrane. These include receptors, channels, transporters, enzymes and cell attachment proteins.

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15
Q

What does the cell have the ability to do?

A

exocytose and endocytose material through the cell membrane

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16
Q

What can the cell membrane do?

A

it can change its shape easily as it is fluid.

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17
Q

What is the cell membrane permeable to?

A

It is selectively permeable

Highly permeable to: water, oxygen, small hydrophobic molecules

Virtually impermeable to charged ions

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18
Q

How can membrane proteins diffuse?

A

They can diffuse laterally, however many are anchored.

important to realise that many proteins are not distributed equally within the cell membrane

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19
Q

are all proteins distributed equally within the cell membrane?

A

no, as many are anchored

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20
Q

what are organelles?

A

small intracellular ‘organs’ with a specific function and structural organisation

they are essential to life

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21
Q

examples of organelles in the cytoplasm

A

Mitochondria - (energy production)
Rough endoplasmic reticulum - (protein synthesis)
Smooth endoplasmic reticulum - (cholesterol & lipid synthesis/detoxification)
Golgi apparatus - (modification & packaging of secretions)
Lysosomes – (hydrolytic enzymes for intracellular digestion)
Nucleus – (contains genetic code)

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22
Q

mitochondria function

A

energy production

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23
Q

RER function

A

protein synthesis

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24
Q

SER function

A

cholesterol and lipid synthesis/ detoxification

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25
Golgi apparatus function
modification and packaging of secretions
26
lysosomes functions
hydrolytic enzymes for intracellular digestion
27
nucleus function
contains genetic code
28
what are inclusions?
stored nutrients, secretory products and pigment granules
29
what do inclusions represent?
components that have been synthesised by the cell itself (pigment , glycogen stores, lipid droplets, presecretion products etc) OR components that have been taken up from the extracellular environment (endocytotic vesicle)
30
What are the cytoskeletal proteins?
a set of filamentous cytosolic proteins that maintain many cell functions
31
What are the three main classes of filaments?
Microfilaments - 7nm in diameter - composed of the protein actin Intermediate filaments - >10nm in diameter - composed of 6 main proteins which vary in different cell types Microtubules - 25nm in diameter - composed of 2 tubular proteins
32
How do filamentous proteins become attached to the cell membrane and each other?
They anchor and join proteins to form a dynamic 3d internal scaffolding in the cell
33
Microfilaments (MF)
One of the cytoskeleton proteins composed of fine strands of actin 7nm diameter (or 0.007µm) Actin molecules can assemble into filaments and later dissociate, making them very dynamic cytoskeletal elements.
34
What polymerises to form filamentous (F) actin?
Globular (G) actin
35
Intermediate Filaments
One of the cytoskeleton proteins Bind intracellular elements together and to the plasmalemma 10-15nm in diameter (0.01-0.015µm) More than 50 types, but divided into classes. they form a network throughout the cytoplasm
36
Types of intermediate filaments
neurofilaments are found in nerve cells glial fibrillary acidic protein are found in glial cells of nervous system design found in muscle cells cytokeratins found in epithelial cells vimentin found in mesenchymal cells filesin found in the lens of the eye lamina found in the nuclei of all cells
37
Microtubules
One of the cytoskeleton proteins Microtubules: hollow tubule composed of two types of tubulin subunits, α & β in an alternating array. Can be assembled and disassembled. Originate from a special organising centre called the centrosome. Include stabilizing proteins: microtubule-associated proteins (MAPS)
38
what are microtubules made up of?
hollow tubule composed of two types of tubulin subunits, α & β in an alternating array.
39
Are microtubules polar?
Yes as they polymerise in the central portion of the cell and radiate outwards
40
What two proteins attach to microtubules and move along them?
Dynein and kinesin
41
what is kinesin?
an ATPase that moves towards the cell periphery
42
what is dynein?
an ATPase that moves towards the cell centre
43
What is the centrosome also known as?
microtubule organising centre
44
where do microtubules radiate from?
centrosome/ special microtubule organising centre
45
what does the centrosome contain at its core?
centrioles which are composed of mainly specialised microtubule segments
46
what is the nucleus enclosed by?
nuclear envelope composed of an inner and an outer nuclear membrane which has nuclear pores which provides continuity with the cytoplasm
47
what does the nucleus contain?
chromosomes and is the location of RNA synthesis
48
where is mRNA and tRNA transcribed?
the nucleus
49
where is rRNA transcribed?
the nucleolus | - a 1-3µm diameter dense area within the nucleus. 
50
what is the perinuclear cistern?
the space between the membranes of the nuclear envelope
51
what is the perinuclear cistern continuous with?
the cistern of the endoplasmic reticulum
52
What is studded with ribosomes?
the outer nuclear membrane as it is engaged in protein synthesis it is also continuous with the cytoplasmic rough endoplasmic reticulum
53
What does the nucleus contain?
Euchromatin (DNA that is more dispersed and is actively undergoing transcription) Heterochromatin (DNA that is highly condensed and not undergoing transcription)
54
what is the nucleus surrounded by?
a double nuclear membrane
55
what is euchromatin?
DNA that is more dispersed and is actively undergoing transcription found in the nucleus
56
what is heterochromatin?
DNA that is not highly condensed and is not undergoing transcription found in the nucleus
57
Where are ribosomes formed?
nucleolus essential in protein synthesis
58
What is a ribosome made up of?
a small subunit which binds to RNA AND a large subunit that catalyses the formation of peptide bonds
59
What does the export of ribosomes depend on?
the nuclear pore complex
60
What are nuclear pore complexes (NPCs)?
they are the gateways connecting the nucleoplasm and cytoplasm
61
What is the endoplasmic reticulum (ER)?
a network of interconnecting membrane-bound compartments in a cell
62
what does reticulum mean?
net-like-structure
63
what are the two types of ER?
rough (RER) | smooth (SER)
64
what dopes the ER look like in micrographs?
flattened membrane sheets or elongated tubular profiles
65
What does the RER do?
plays a vital role in protein synthesis (why it is studded in ribosomes) It is destined for insert into membranes or for secretions
66
Why does the amount of ER present in a cell vary?
It depends on how active the cell is. Cells that are relatively metabolically inactive have relatively little ER
67
What is synthesised on a polysome? (floats free within the cytosol
proteins that are to remain unpackaged within the cytosol

Principals (2 decks)

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