Lecture 5-Organelles Flashcards
1
Q
Cytoplasm
A
Contains all the cellular components between the plasma membrane + the nucleus
2
Q
What are the 2 components of the cytoplasm?
A
- The cytosol
- The organelles
3
Q
What is the cytosol?
A
The intracellular fluid of the cytoplasm
4
Q
What are organelles?
A
Specialised structures which co-operate to maintain homeostasis
5
Q
How much of the cell volume is cytosol?
A
55%
6
Q
How much of a cell is h20?
A
75-90%
7
Q
Function of the cytosol?
A
The site for a wide range of enzymatically-controlled reactions
8
Q
What is the cytoskeleton?
A
A network of protein filaments extending throughout the cytoplasm
9
Q
What are the functions of the cytoskeleton?
A
- Maintain cell shape + internal organisation
- Provide mechanical support (allows cell division + movement)
10
Q
What are the 3 types of cytoskeleton?
A
1) Microfilaments
2) Intermediate filaments
3) Microtubules
11
Q
Where are microfilaments found?
A
Around the edge of a cell
12
Q
Examples of microfilaments
A
ACTIN + MYOSIN
13
Q
What is the function of microfilaments
A
Help generate movement
14
Q
Describe the 3 types of movement microfilaments help generate?
A
1) contraction
2) locomotion
3) cell division
15
Q
How do microfilaments provide cell strength + shape?
A
Through mechanical support
16
Q
What role do microfilaments play in the small intestine?
A
They create microvilli
17
Q
How strong are intermediate filaments?
A
Very strong
18
Q
Where are intermediate filaments found?
A
In cells with a lot of mechanical stress
19
Q
What are the functions of intermediate filaments?
A
Help stabilise the positions of organelles
20
Q
Examples of intermediate filaments?
A
- KERATIN
- vimentin
- LAMIN
21
Q
What are microtubules?
A
Long, unbranched hollow tubules made from tubulin
22
Q
What do microtubules form and how are they positioned?
A
The centrosome
-They radiate outwards
23
Q
What are the functions of microtubules?
A
They help with cell #
- Strength
- Shape
- Movement
e. g. VESICLES DURING DIVISION - Structure to flagella + cilia
e. g. SPERMATOZOA
24
Q
What are centrosomes associated with?
A
The nuclear membrane during the PROPHASE STAGE
25
What cytoskeleton is the thinnest?
Microfilaments
26
What cytoskeleton is a more permanent fixture?
Inetrmediate filaments
27
What cytoskeleton is the thickest?
Microtubules
28
Where is the centrosome found?
CLOSE to the nucleus
29
What is the function of the centrosome?
The main microtubule organising centre + regulator of cell cycle progression
30
What 2 centrioles make up a centrosome?
1) Cylindrical structures
| 2) Pericentriolar material
31
Describe the cylindrical structures found in centrosomes?
A circle of 9 clusters of microtubule triplets , both at right angles to each other
32
Describe the pericentriolar material found in centrosomes?
Surrounds the centriole + consists of numerous rings of tubulin
33
What is the function of the centrosome?
Growth + movement of the MITOTIC SPINDLE during cell division
34
In dividing eukaryotic cells , how do microtubules spread?
They spread out from the centrosome
35
How many centrosomes are there when the cell is not dividing?
1
36
Upon division, what happens to the centrosome?
It replicates early forming the SPINDLE APPARATUS
37
What are cilia + flagella made of?
Microtubules
38
What are cilia + flagella?
Motile projections on the cell surface
39
Describe cilia?
Numerous , short hair-like projections
40
Describe the structure of cilia?
Anchored to a basal body + a crore of microtubules with 9 pairs of microtubules surrounding a central pair (all enclosed in a membrane)
41
What is the function of the cilia?
Transport fluid along cell surfaces
42
What does smoking do to the cilia?
Destroy them
43
What happens when the cilia are destroyed by smoking?
There's a buildup of mucus,dust+bacteria within the lungs
44
What does the cilia pass towards the uterus and what is the effect of this?
The oocyte
| -Increased risk of an ectopic pregnancy
45
What is the difference in structure between a cilia and flagella?
They are much longer + only 1 found in a cell
46
What is the endoplasmic reticulum?
A network of membranes composed of flattened sacs + tubules extending from the nuclear envelope into the cytoplasm
47
What do proteins synthesized by ribosomes enter the ER space for?
Processing + sorting
48
What are the role of enzymes in the ER?
Attach carb groups / proteins to phospholipids
49
How are molecules made in the ER incorporated into membranes?
Via exocytosis
50
Describe the structure of ribosomes?
Large subunit + small subunit synthesized separately in the nucleolus
51
What are ribosomes rich in ?
Ribosomal RNA (OVER 50 PROTEINS)
52
Where can you find ribosomes?
Free in the cytoplasm / within the mitochondria
53
Function of ribosomes?
Site of protein synthesis
54
Where does the smooth ER extend from?
The smooth ER
55
What is the difference between the rough + smooth ER?
No ribosomes
| -More enzymes (diverse functions)
56
Describe + explain the functions of the smooth ER?
- Synthesizes fatty acids + steroids
- Help release glucose in the liver from gluc-6-p
- Detoxifies lipid soluble drugs
57
Give an example of substances the Smooth ER synthesizes?
Estrogens + testosterone
58
Give examples of lipid soluble drugs the smooth ER detoxifies?
Alcohol + pesticides
59
What happens when people abuse phenobarbital?
There's a change in the smooth ER in liver cells
60
What does the change in the smooth ER caused by phenobarbital do?
Cells produce MORE smooth ER to counteract the poison + need more to feel the same effect
61
Where are most proteins form the rough ER transported to?
The golgi body
62
Describe the structure of the golgi complex?
3-20 membranous cisternae with bulging edges arranged in a stack
63
Where do the entry/cis + the exit/trans face face?
```
Entry/cis = the ER
Exit/trans = the Plasma membrane
```
64
The sacs between the golgi complex are what?
Medial cisternae
65
What does retrograde transport refer to?
The motion from the periphery of the cell -----> to the centre
66
What is the function of a lysosome?
Digestion of substances entering the cell
67
Describe the 2 ways that lysosomes digest substances?
```
Autophagy = worn out organelles
Autolysis = entire cells
```
68
What is autophagy required for?
- Renewal
- Cellular differentiation
- Control of growth
- Tissue remodelling
69
Describe Tay-Sachs disease?
- Affects children
- Mutation of lysosomal enzyme Hex A
- Causes build-up of glycolipid ganglioside GM2
- Destroys nerve cell function
- Seizures , muscle rigidity + blindness
70
What is the difference between lysosomes + peroxisomes?
Peroxisomes are smaller
71
What do peroxisomes contain?
Oxidases
72
What are peroxisomes involved in?
AA + fatty acid metabolism
73
What do peroxisomes do?
Oxidise toxic substances
74
What type of toxic substances do peroxisomes oxidises and ho does this relate to the liver?
Alcohol (High copy number in the liver)
75
Why does peroxisomes contain the enzyme CATALASE?
To protect against toxic effects of hydrogen peroxide (made in oxidation reactions)
76
What type of groups do peroxisomal disorders form?
Heterogeneous disease group (different degrees of severity)
77
What do metabolic diseases of dysfunctional peroxisomes lead to?
Brain disorders + respiratory infections
78
What do lysosomes degrade?
Proteins delivered in vesicles
79
What do proteasomes degrade?
Free cytosolic proteins
80
What are free cytosolic proteins?
Unneeded / damaged / faulty proteins
81
What are proteasomes important in?
Negative feedback
82
What is negative feedback?
Switch off a pathway once a response has been achieved
83
How many proteasomes does a cell typically have?
Thousands
84
What do proteasomes contain?
Protease enzymes
85
What causes Alxheimer's disease?
The build-up of misfolded proteins in brain cells
86
What is the function of mitochondrions?
Site of aerobic respiration (converts glucose to produce energy)
87
How many mitochondrias do cells typically have?
100-1000s
88
What are the other functions of mitochondria?
Signalling , cell differentiation , cell death
89
What does a mitochondrion contain?
- 2 Membranes made of PHOSPHOLIPID double layers
| - Proteins
90
Describe the layers that make up a mitochondria?
1) Outer mitochondrial membrane
2) Intermembrane space
3) Inner mitochondrial membrane
4) Cristae space
5) Matrix space
91
What are the three main steps to generating ATP from mitochondria?
1) Glycolysis
2) Citric acid cycle
3) Krebs cycle
* 4)ATP SYNTHESIS
92
Where are mitochondria not found?
Red blood cells
93
Where are enzymes needed for respiration found?
The matrix + on the cristae
94
What role do the nuclear pores on nucleus for?
Channels for ions + active transport for RNAs + proteins
95
What is the nucleolus?
Clusters of protein,DNA + RNA responsible for producing proteins
96
What is transcription?
The process of constructing a messenger RNA molecule using a DNA molecule as a template with resulting transfer of genetic info to the messenger RNA
97
Name 3 macromolecules?
Proteins, CHO + fats
98
FUNCTIONS?
1) Cytoskeleton
2) Rough ER
3) Smooth ER
4) Golgi body
5) Nucleus
6) Ribosomes
1) Cytoskeleton - support/structure
2) Rough ER - proteins
3) Smooth ER - makes fats/releases glucose
4) Golgi body - processing/packaging
5) Nucleus - transcription
6) Ribosomes - translation = synthesis of proteins
