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Tissue Biology > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

How could you describe the cell as a system?

A

A system of membrane bound compartments each with a unique biochemical environment

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2
Q

What does the phospholipid bilayer consist of?

A

A polar hydrophilic head and a non polar hydrophobic tail

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3
Q

What does amphipathic mean?

A

Contains a hydrophobic and hydrophilic side

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4
Q

What percentage of the phospholipid bilayer is made up of proteins?

A

Roughly 50%

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5
Q

What are the three types of proteins?

A

Intrinsic, peripheral and transmembrane

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6
Q

Why does the EM of a bilayer show it as a trilaminar layer?

A

The outer edges are electron dense due to the hydrophilic head of inner layer and lipid tails of each layer but the central is electron lucent

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7
Q

What does the nucleus contain?

A

DNA and protein called nucleoprotein

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8
Q

What percentage of the nucleus is DNA?

A

20%

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9
Q

What types of nucleoprotein are there?

A

Histone proteins and non-histone proteins such as RNA

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10
Q

The nucleus is said to be heterogeneous, why?

A

It has electron dense and electron lucent areas

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11
Q

What is the electron dense area in the nucleus?

A

Inactive coiled chromatin found in irregular clumps

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12
Q

What is the electron lucent area in the nucleus?

A

Euchromatin - DNA active in RNA synthesis

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13
Q

Cells that are involved in highly active protein synthesis are able to be distinguished by staining due to…

A

A very dense nucleoli is present

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14
Q

The ribosomes and ribosomal RNA are constructed in the

A

nucleolus

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15
Q

Once the ribosomes and ribosomal RNA have been constructed where are they transported to?

A

The cytoplasm

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16
Q

In protein synthesis, what is transcription?

A

The DNA template of a particular protein is copied to form RNA

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17
Q

mRNA has _____ spliced out. Fill the gap

A

Introns

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18
Q

The mRNA is translated into a protein at which site?

A

The ribosomes

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19
Q

What is an intron?

A

A segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes

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20
Q

Describe the general structure of the rough endoplasmic reticulum

A

A system of flattened tubules covered with ribosomes

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21
Q

What is the main function of the rough endoplasmic reticulum?

A

To export proteins

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22
Q

What continues on with the rough endoplasmic reticulum?

A

The smooth ER

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23
Q

What is the difference between RER and SER?

A

The smooth endoplasmic reticulum has no ribosomes

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24
Q

What is the main function of the smooth endoplasmic reticulum?

A

Synthesis of lipids and membranes; membrane repair

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25
Give a brief description of the golgi
Stacked membrane bound cisternae
26
What is a cisternae in the golgi?
refers to a flattened membrane disk that makes up the Golgi apparatus
27
What is the main function of the golgi?
Glycosylation of proteins and package of proteins into secretory granules
28
What is the main function of the mitochondria?
The site of energy production by oxidative phosphorylation
29
What are the four compartments of the mitochondria?
The outer membrane the inner membrane the mitochondrial matrix the inner membrane space
30
The inner membrane of the mitochondria folds to form
cristae
31
The inner membrane space of the mitochondria contains
enzymes
32
Lipids are found in all
cells
33
Why can lipids not be seen during normal tissue stains?
The lipids are leached from the tissue during the processing
34
How do we go about visualising lipids?
We use frozen tissues - stained with osmium tetroxide which stains the lipids black
35
What is the cytoskeleton?
A complex network of protein filaments providing scaffolding for the cell
36
Give the four main functions of the cytoskeleton
1. Structure and support 2. Intracellular compartmentalisation 3. Cell movement 4. Muscle contraction
37
What are the three types of cytoskeleton?
1. Microtubules 2. Microfilaments/actin 3. Intermediate filaments
38
What are microtubules?
Hollow cylinders made up of polymers of tubulin
39
What types of polymers of tubulin make up microtubules?
Alpha and beta tubulin
40
The alpha and beta tubulin structure can be referred to as a...
Heterodimer
41
The heterodimers of alpha and beta tubulin making up the microtubule are in the same orientation. This means there is a ____ structure
Polar
42
Where do microtubules extend from?
From the centrosome
43
The centrosome is an organelle that is the main place where
cell microtubules are organised
44
Which end of the filament do microtubules grow from and where is this end found?
They grow from the minus end of the filament which is embedded in the centrosome
45
Microtubules serve as lines of transport for example
for the movement of organelles
46
How is movement achieved by microtubules?
By motor proteins which bind to specific microtubules and move in a specific direction
47
Microtubules need energy in the form of ___ for ______
ATP and movement
48
What is another name for microfilaments?
Actin
49
Microfilaments/actin are the ____ filaments found in the cytoplasm
thinnest
50
What is the most abundant protein in eukaryotic cells?
Actin
51
What percentage of the total cell protein does actin make up?
5%
52
Describe the general structure of actin/microfilaments
Two stranded helical polymers of G-actin protein
53
Mammals have how many types of actin that are classified into how many groups?
6 types of actin classified into 3 groups
54
What are the three groups that actin is classified into in mammals?
alpha actin, beta actin and y-actin
55
Where is alpha actin, beta actin and y actin found?
a - in muscle cells/muscle differentiation - specialised to contract b and y - non muscle cells
56
Actin filaments are organised in different ways depending on?
The functional state of the cell
57
What type of actin composition is found in non-motile cells?
Loose gel like network of actin
58
What type of actin composition is found in motile or contractile cells?
Discrete structures or bundles in motile or contractile cells of actin
59
Why are intermediate filaments called what they are?
Their average diameter is between those of actin and microtubules
60
Describe the general structure of intermediate filaments
Elongated rope like fibrous molecules
61
From where to where do intermediate filaments form their extensive network?
Around nucleus and out to cell periphery; span cytoplasm from one cell-cell junction to another
62
What are the three classes that intermediate filaments fall into?
Keratin filaments, vimentin and vimentin related filaments and neurofilaments
63
What is the main function of intermediate filaments?
Providing mechanical stability to animal cells
64
Give an example of a disease caused by a mutation in the keratin gene in an intermediate filament
Epidermolysis bullosa simplex
65
How does epidermolysis bullosa occur?
Defective keratin assembles with normal keratins and disrupts the keratin filament network in basal cells
66
How do blisters form in patients with epidermolysis bullosa?
Loss of cohesion between basal epithelial cells and underlying basement membrane , blister formation and fluid loss

Tissue Biology (16 decks)

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