Anatomy of a cell Flashcards
1
Q
What are the levels of structural organisation?
A
Cell
Tissue
Organs
Organ system
Organism
2
Q
What are the contents of a typical cell?
A
plasma membrane
cytoplasm
cytoskeletal elements
nucleus
mitochondria
endoplasmic reticulum
ribosomes
golgi complex
3
Q
What are three characteristics of the cell membrane?
A
- Fluid in nature
- Can change its shape easily
- Separated the cytoplasm from the outside environment
4
Q
Under an electron microscope what is the structure of the cell membrane called?
A
trilaminar structure
5
Q
What does the trilaminar structure consist of?
A
Phospholipid bilayer
Cholesterol
Proteins
6
Q
What are the two different types of proteins in a cell membrane?
A
Integral and peripheral
7
Q
What do integral and peripheral proteins act as (5)?
A
Receptors
Channels
Transporters
Enzymes
Cell attachment proteins
8
Q
What does the cell membrane do?
A
Acts as a selective structural barrier between the cell and the outside environment
9
Q
What is the cell membrane highly permeable to?
A
Water
Oxygen
Small hydrophobic molecules
10
Q
What is the cell membrane virtually impermeable to?
A
Charged ions
11
Q
How do larger molecules pass through the cell membrane?
A
By utilizing transport mechanisms like exocytosis and endocytosis
12
Q
What does the cytoplasm consist of?
A
The cytosol and cytoskeleton
13
Q
What is the cytosol?
A
A solution of proteins, electrolytes and carbohydrates
14
Q
What is the size of microfilaments?
A
7nm
15
Q
What are microfilaments composed of?
A
Fine strands of protein actin
16
Q
What is the space inside the cell called?
A
Intracellular space
17
Q
What is the space between the cells called?
A
Intercellular space
18
Q
Where do you find microfilaments?
A
Under the cell membrane
19
Q
What do microfilaments do?
A
Form a network which provides mechanical support, determines cell shape and allows movement of the cell surface.
20
Q
What is the size of intermediate filaments?
A
10-15nm in diameter
21
Q
What is the physical description of intermediate filaments?
A
They form a network throughout the cytoplasm, that can extend a ring surrounding the nucleus towards the plasma membrane.
22
Q
What do the intermediate filaments do?
A
Bind intracellular elements together and to the cell membrane
23
Q
What is the size of microtubules?
A
24nm
24
Q
What are microtubules composed of?
A
Two types of tubulin subunits, alpha and beta in an alternating array
25
Where do microtubules originate from?
They originate from a special organising centre called the centrosome
26
What does it mean that microtubules are polar?
Polymerize in the central portion of the cell
27
What is Dynein when talking about microtubules?
Dynein is an ATPase that moves towards the cell centre
28
What is Kinesin when talking about microtubules?
Kinesin is an ATPase that moves toward the cell periphery?
29
Why are proteins Kinesin and Dynein important?
They are important in the movement of components in cells with long processes
30
What do dynein and kinesin do to microtubules?
They attach to the microtubules and move along them.
They associate with the membranes of organelles and vesicles and drag them along the microtubule
31
What is an example of microtubules and dynein and kinesin?
The long axonal process of many neurons
32
What best describes the purpose of microtubules?
They act as the motorway network of the cell.
33
What are intermediate filaments made of?
Keratin
34
What is a nucleus enclosed by?
A double layered nuclear envelope
35
What is a nucleus made up of?
Inner & outer nuclear membrane
Nuclear pores
36
What are the two types of DNA found in a nucleus?
Euchromatin and Heterochromatin
37
What is Euchromatin?
Dispersed DNA actively undergoing transcription
38
What is Heterochromatin?
Condensed DNA not undergoing transcription
39
What is the location of RNA synthesis?
The nucleus
40
Where is rRNA transcribed?
In the nucleolus
41
What is the nucleolus?
a 1-3um diameter dense area within the nucleus
42
Where is mRNA and tRNA transcribed?
In the nucleus
43
What are the nuclear pores doing?
They are in communication with Rough Endoplasmic Reticulum
44
How does the endoplasmic reticulum appear in micrographs?
As flattened membrane sheets or elongated tubular profiles
45
What does reticulum stand for?
Net like structure
46
What are the two types of endoplasmic reticulum?
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
47
What is an endoplasmic reticulum?
Network of intercommunicating channels and sacs formed by a continuous membrane
48
What happens in the rough endoplasmic reticulum?
Synthesis of proteins destined for insertion into membranes or for secretion
49
What is the membrane of the rough endoplasmic reticulum studded with?
Ribosomes
50
How does the amount of Endoplasmic reticulum in a cell vary with activity?
Prominent in cells specialized for protein
RER = little in metabolically inactive cells
SER = most cells contain little SER but in some it is extensive
51
Where are ribosomes synthesised and assembled?
In the nucleus
52
What happens to ribosomes once they've assembled?
They leave the nucleus and enter the cytoplasm to participate in protein synthesis
53
What are ribosomes composed of?
Two different sized subunits
54
Is the smooth endoplasmic reticulum continuous with Rough ER?
Yes
55
What does smooth endoplasmic reticulum do?
Lipid biosynthesis
Detoxification of potentially harmful compounds
Degradation of glycogen
56
What is the golgi apparatus?
A group of flattened, membrane bound cisternae that are arranged in sub-compartments
57
What is the function of golgi apparatus?
Modification and packaging of proteins and macromolecules that were synthesised in the ER
Adds sugars
Cleaves some proteins
Sorts macromolecules into vesicles
58
What is the physical description of mitochondria?
Oblong, cylindrical organelles, typically 0.5-2um in length
59
What do mitochondria contain?
Their own DNA and system for protein production
60
What is the functions of mitochondria?
Generation of ATP
Synthesis of certain lipids and proteins
61
How do mitochondria generate ATP?
Via oxidative phosphorylation
62
What are the two layers of the mitochondria?
Outer membrane and inner membrane
63
Describe the outer membrane of the mitochondria?
Smooth
64
Describe the inner membrane of mitochondria?
Extensively folded to form cristae
65
What is the number of mitochondria related to?
The cells energy needs
66
What are the three types of tissue from embryological origin?
Ectoderm, endoderm and mesoderm
67
What makes up ectoderm?
Skin
Hair
Nails
Nervous system
68
What makes up endoderm?
Inner linings and organs (GI tract, respiratory tract)
69
What makes up the mesoderm?
Connective tissue
Blood vessels
Muscle
Fat
Bone
Cartilage
70
What are the four basic types of tissue in an organ?
Epithelium
Connective tissue
Muscle
Nervous tissue
71
What does adipo refer to?
Refers to fatty tissue
72
What are myocytes?
Muscle cells
73
What are Endothelium?
Cells lining blood vessels (inner lining)
74
What are cytes?
Cells
75
What does chondro refer to?
Refers to cartilage
76
What are chondrocytes?
Cells of cartilagem
77
What does osteo refer to?
Refers to bones
78
What are osteocytes?
Bone cells
79
What are the two main components of each tissue?
Cells and extracellular matrix
80
What is the main function of epithelial tissue?
Lining of surfaces or body cavities
Glandular secretion
81
What is the main function of connective tissue?
Support and protection
82
What is the main function of nervous tissue?
Transmission of nervous impulses
83
What is the main function of muscle tissue?
Movement
84
How much extracellular matrix is found in epithelial tissue?
Small amount
85
How much extracellular matrix is found in connective tissue?
Abundant amount
86
How much extracellular matrix is found in nervous tissue?
None
87
How much extracellular matrix is found in muscle tissue?
Moderate amount
88
Describe the cells in epithelial tissue
Cells are aggregated and tightly adherent to each other
89
Describe the cells in connective tissue
Several types of fixed and wandering cells
90
Describe the types of cell in nervous tissue
Cells are specialized to have cytoplasmic processes which transmit nerve impulses
91
Describe cells in muscle tissues
Elongated contractile cells
92
Where is muscle tissue derived from?
Mesoderm
93
Where is nervous tissue derived from?
Ectoderm (neuroectoderm)
94
Where is connective tissue derived from?
Almost all comes from mesoderm
95
Where is epithelium tissue derived from?
All three layers.
Ectoderm - skin and glands
Endoderm - inner lining epithelia
96
What are the three things epithelium tissue does?
Covers body surface
Lines hollow organs
Forms glands
97
How does epithelium tissue occur?
As sheets of cells
98
What can epithelium tissue vary in?
Size
Shape
Orientation
Function
99
What is a simple tissue?
One layer
100
What is a stratified tissue?
Several layers
101
What is a pseudostratified tissue?
Looks multi layered but is only one layer
102
What is squamous tissue?
Flat plate-like
103
What is cuboidal tissue?
Height similar to width
104
What is columnar tissue?
Heigh 2-5 times width
105
What is an occluding barrier?
junctions that form a diffusion barrier
106
What are the names of junctions that provide mechanical strength?
Anchoring and adherent junctions
107
What are communicating junctions?
Junctions that allow movement of molecules between cells
108
What do intercellular junctions do?
Link individual cells together into a functional unit
109
What are the two types of connective tissues?
Loose and dense
110
What are the two types of dense connective tissue?
Regular and Irregular
111
What does connective tissues play a role in?
Development
Growth
Homeostasis of tissues
Energy storage via fat
112
What are three examples of specialised connective tissue?
Bone
Cartilage
Fat
113
What are the three major types of muscle tissue?
Cardiac
Skeletal
Smooth
114
What do glial cells do?
Support cells
Nutrition and defence
115
What draws occluding junctions together?
Actin filaments
116
What do occluding junctions appear as?
Appear as a focal region of close apposition between adjacent cell membranes
117
Where are communicating junctions most often found?
In cardiac muscle cells as it allows free flow of ions for fast conduction of the excitatory period
118
What produces the pores in communicating junctions?
Connexon proteins
119
What is each communicating junction?
Each junction is a circular patch studded with several hundred pores
120
What is present in adherent junctions (zonula adherens) ?
E-Cadherin which are catenin complex with actin filaments
121
What is present in adherent junctions (desmosomes)?
Cadherin
Protein plaque
Intermediate filaments
