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Cell Biology and Signalling > L1- Cells and Organelles > Flashcards

L1- Cells and Organelles Flashcards

1
Q

Define the term cell

A

A cell is a semi-independent living unit within the body (in unicellular organisms, completely independent) in which are sited the mechanisms for metabolism, growth and replication (division). It consists of a aqueous solution of organic molecules surrounded by a membrane.

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2
Q

Define the term sub-cellular organelle.

A

A subunit within in a cell, with a defined structure and performing specific, integrated activities. Some are blinded by membranes, other are non -membranous.

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3
Q

Example of a non-membranous organelle

A

Ribosomes

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4
Q

Example of a membranous organelle

A

Mitochondria, Nucleus

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5
Q

Define the term tissue.

A

It is an organised assembly of cells and their extracellular products which carry out similar and coordinated activities within the body.

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6
Q

Example of a tissue.

A

Connective tissue; lymphoid tissue

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7
Q

Define the term organ.

A

An organ is an assembly of tissues coordinated to perform specific functions within the body.

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8
Q

Examples of an organ.

A

Eye, ear, hearts, lungs, liver

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9
Q

Define the term system.

A

It is an assembly of organs with specific, related activities, sharing regulatory influences (e.g. respiratory). Or it may be be diffuse functional network of cells situated in many parts of the body, sharing specific activities (e.g. immune)

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10
Q

Define the term Prokaryote.

A

A single-celled organism in which the chromosome is a circular strand lying free in the cell (i.e. no nucleus) and has no membranous organelles e.g. bacteria.

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11
Q

Define the term Eukaryote.

A

One or more cells in which chromosomes are enclosed in a nucleus; typically have -cytoplasmic, membrane-bound organelles, -DNA divided into a series of linear chromosomes
-considerable differences occur between cells within the same organism

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12
Q

Example of a prokaryote.

A

Bacteria

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13
Q

Example of eukaryotes.

A 
Plants
Fungi 
Animals 
Protozoa 
Algae
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14
Q

Define the term Virus.

A

An assemblage of nucleic acid (DNA or RNA) which is parasitic on prokaryotes/eukaryotes.

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15
Q

How do viruses replicate?

A

Viruses invade cells, subvert their protein synthesis machinery to make more viruses instead of normal cell proteins, then escape to infect others cells.

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16
Q

Why are viruses not cells/ organisms in the strict sense?

A

they lack a plasma and can only operate chemically within host cells

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17
Q

What is the cell theory?

A

All living things are made of cells and these arise through the division of pre-existing cells.

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18
Q

How is genetic material found in prokaryotic cells?

A

usually found in single circular chromosomes

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19
Q

How is genetic material found in eukaryotic cells?

A

found in paired chromosomes

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20
Q

Location of genetic material in prokaryotic cells

A

Nuclear region called nucleoid

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21
Q

Location of genetic material in eukaryotic cells

A

Membrane bound nucleus

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22
Q

Presence of nucleolus in prokaryotes

A

Absent

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23
Q

Presence of nucleolus in eukaryotic cells

A

Present

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24
Q

Presence of histone proteins in prokaryotic cells

A

Absent

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25
Presence of histone proteins in eukaryotic cells
Present
26
Where is extrachromosomal DNA found in prokaryotic cells?
Plasmids
27
Where is extrachromosomal DNA found in eukaryotic cells?
Mitochondria and plasmids
28
Mitotic spindle present in Prokaryotic cells?
Absent
29
Mitotic spindle present in Eukaryotic cells?
Present
30
Membranous organelles in Prokaryotic cells
Only in photosynthetic organisms
31
Membranous organelles in eukaryotic cells
Numerous membrane enclosed organelles
32
Endoplasmic reticulum presence in prokaryotic cells
Absent
33
Endoplasmic reticulum presence in eukaryotic cells
Present
34
Site of respiration in prokaryotic cells
at cell membrane
35
Site of respiration in eukaryotic cells
in mitochondria
36
Presence of Golgi in prokaryotic cells
Absent
37
Presence of Golgi in eukaryotic cells
Present
38
Presence of lysosomes in prokaryotic cells
Absent
39
Presence of peroxisomes in prokaryotic cells
Absent
40
Presence of peroxisomes in eukaryotic cells
Present
41
Size of ribosomes in prokaryotic cells
70S
42
Size of ribosomes in eukaryotic cells
80S in cytoplasm and on ER | 70S in mitochondria
43
Presence of cytoskeleton in prokaryotic cells
Absent
44
Presence of cytoskeleton in eukaryotic cells
Present
45
Structure of cell wall in prokaryotic cells
peptidoglycan, LPS and teichoic acid
46
Structure of cell wall in eukaryotic cells
Absent in most eukaryotic cells | -chitin in fungal cells
47
External layer in prokaryotic cells
capsule or slime layer
48
Present of cilia in prokaryotic cells
Absent
49
Presence of cilia in eukaryotic cells
Present in certain cell types
50
Presence of pili in prokaryotic cells
Present
51
Presence of pili in eukaryotic cells
Absent
52
Presence of flagella in prokaryotic cells
Present
53
Presence of flagella in eukaryotic cells
Present in certain cell types
54
Cell division type in prokaryotic cells
Binary fission
55
Cell division type in eukaryotic cells
mitosis or meiosis
56
Reproductive mode in prokaryotic cells
Asexual
57
Reproductive mode in eukaryotic cells
sexual or asexual
58
Define Cell theory
All living things are made of cell and these arise through the division of pre-existing cells
59
Approximate dimension of a plant cell
Around 100um
60
Approximate dimension of an animal cell
Around 50um
61
Approximate dimension of a bacterial cell
Around 1um
62
Approximate dimension of a virus
Around 80nm
63
What is the use of electron microscopes?
Only EM imaging can reveal sub-cellular details
64
What is a transmission electron microscope used for?
to look inside a cell (electrons go through the specimen)
65
How does TEM work?
electrons go through the specimen
66
What is a scanning electron microscope use for?
to see the cell surface (electrons scattered off the cell surface by a heavy metal coating e.g. Au)
67
How does SEM work?
electron scattered off the cell surface by a heavy metal coating e.g. Au)
68
Preparation of cells to be viewed under TEM and SEM
elaborate preparation and can only evaluate dead cells
69
Explain what limits the maximum size of a cell
as cell increases in size volume increases more than surface are; distance from nucleus to periphery influences movement of products; diffusion more than 50um inefficient
70
What type of cells may not fit the 50um maximum cell size?
specialised cells e.g. that have thin process, giant multinucleate cells, gaps junctions
71
How do specialised cells with thin processes overcome the maximum diffusion size problem?
directed transport of substances around cell via cytoskeleton e.g. neurons and oligodendrocytes
72
How do giant multinucleate cells overcome the maximum diffusion size problem?
gene expression can occur in more than one place e.g.skeletal muscle cells
73
How do cells connected by gap junctions overcome the maximum diffusion size problem?
channels between cells to allow movement of substances between cells
74
What is the purpose of membranes in cellular organelles?
- allows specialised environments to exist within them - different functions can operate under different condition e.g. pH - single cell can have numerous different functional compartments
75
Define the term cytoskeleton.
protein filaments (actin, microtubules and intermediate filaments) which contribute to mechanical strength, control shape, drive and guide movement of materials
76
Define the term cytosol.
aqueous environment within the plasma membrane
77
Define the term cytoplasm.
cytosol + organelles
78
Define the term nucleus.
contains genetic material, DNA, organised as chromosomes
79
What is the approximate size of the nucleus?
3-10um
80
Length of 'naked' DNA
1.8m
81
What are chromatin complex?
complex of DNA/histone and non-histone proteins
82
What is a nucleosome?
DNA wound around histones
83
Nature of SER.
location for biosynthesis of membrane lipids and steroids | -start of N-linked glycosylation, detoxification of xenobiotics
84
Nature of RER.
(coated with ribosomes) translation of proteins for secretion or insertion into cell membrane -proteins are folded (formation of Cys-Cys bridges) -vesicles are budded from RER and transported to Golgi body
85
Describe the golgi complex.
4-8 closely stacked membrane-bound channels (cisternae)
86
Function of mitochondria
Sugars oxidised to generate ATP in Krebs cycle, contain DNA (encodes ~1% of its proteins), Krebs cycle enzymes/Electron transport chain located different parts of membrane structure
87
Size of peroxisome
large (0.5-1.5um)
88
Nature of mitochondria
Two layer membrane, 0.5-2um long, number reflects metabolic activity of cell, Inner membrane folds- cristae increase surface area
89
Nature of nuclear pore
allows transport in and out of nucleus
90
What are secretary vesicles?
bud off from Golgi complex fuse with the inner surface of the plasma membrane and release their content (exocytosis) e.g. hormones and neurotransmitters
91
What content can secretary vesicles carry?
hormones and neurotransmitters etc.
92
What are the functions of the lysosome.
-consists of >50 different hydrolytic enzymes which can hydrolyse all major cellular macromolecules, involved in organelle turnover/replacement (autophagy)
93
Nature of lysosomes
electron dense spheres under EM, membrane bound, low pH
94
Describe the function of the peroxisome.
detoxification, phospholipid synthesis, oxidation of Very Long Chain Fatty Acids (VLCFA), enzymes which generate and degrade hydrogen peroxide
95
which organelle creates lysosomes
Golgi complex
96
Function of Golgi complex
modifies proteins delivered from RER via vesicles (modifying N-linked carbohydrates, glycosylation of O-linked carbohydrates and lipids) -synthesise/package materials to be secreted
97
Identification of peroxisome under EM imaging
not electron dense
98
Identification of lysosomes under EM imaging
electron dense
99
Nature of peroxisomes
large (0.5-1.5um), not electron dense
100
54. Which organelle is affected in in Adrenoleukodystrophy (ALD) and how?
affects protein that imports VLCFA into peroxisomes
101
Which organelle is affected in Zellweger Syndrome and how?
inherited absence of peroxisomes due to defects in targeting
102
Which organelle is affected in Zellweger Syndrome and how?
inherited absence of peroxisomes due to defects in targeting.
103
Which organelle is affected in in Adrenoleukodystrophy (ALD) and how?
affects protein that imports VLCFA into peroxisomes

Cell Biology and Signalling (2 decks)

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