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organelles Flashcards

1
Q

Where is cytoplasm situated and what does it contain?

A

Contains all the cellular components between the plasma membrane and the nucleus

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2
Q

2 components of cytoplasm?

A
  1. The cytosol (intracellular fluid)

2. The organelles (specialised structure which co-operate to maintain homeostasis)

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3
Q

describe the cytosol

A

55% of cells total volume, between 75-90% water
Contains dissolved ions, glucose, amino acids, ATP, lipids and waste products
Is the site for a wide range of enzymatically controlled reactions

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4
Q

what are the three main types of filaments of the cytoskeleton

A

Microfilaments

Intermediate filaments and
Microtubules

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5
Q

whats the function of micro filaments?

A

Micro filaments
Surround the edge of the cell
Actin and myosin
Help generate movement (contraction, locomotion and cell division)
provide mechanical support needed for cell strength and shape
Create microvilli

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6
Q

functions and properties of intermediate filaments

A

Very strong
Are found in parts of the cell subject to mechanical stress
Help stabilise the positions of the organelles

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7
Q

what is intermediate filaments made of of ?

A

Proteins such as keratin, vimentin and lamin

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8
Q

what are Microtubules and what are they made of?

A

Long, unbranched hollow tubules made from tubulin

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9
Q

what are microtubules function

A

They form in the centrosome, then radiate outwards
Help with cell strength, shape and movement of organelles such as vesicles and during division
Help provide structure to flagella

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10
Q

steps involved in microtubules moving organelles .

A
  1. extension-focal adhesion to lamellipodium
  2. adhesion- new adhesion
  3. translocation-contraction- cell body movement
  4. De-adhesion- old adhesion detachment.
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11
Q

what does the Centrosome consist of :

A

2 Centrioles

  • Cylindrical structures composed of a circle of nine clusters of microtubule triplets, both at right angles to each other
  • Pericentriolar material surrounds the centrioles and consists of numerous rings of tubulin
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12
Q

function of centrosome

A

Growth of mitotic spindle during cell division

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13
Q

what occurs to the chromosomes when cell starts undergoing division.

A

In dividing eukaryotic cells, most microtubules spread out from the centrosomes,
When a cell is not undergoing division, a single centrosome is present.
However, when the cell does begin to divide the centrosome replicates early in the process.
The spindle apparatus then begins to form.

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14
Q

what is Cilia and flagella and what are they made of ?

A

Primarily made from microtubules

These are motile projections on cell surface

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15
Q

what is the cilia made of and how is it arranged .

what is its function

A

CiIia: Numerous, short hair like projections. Each cilium is anchored to a basal body and has a core of microtubules (Nine pairs microtubules encircle a central pair) enclosed in a membrane.
Function: transport of fluid along cells surface.

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16
Q

why do smokers cough persistently

A

Smoking destroys the cilia, resulting in a build up of mucus, dust and bacteria within the lungs. This must be removed by persistent coughing.

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17
Q

what is a Flagella, give an example of a cell that uses this .

A

Are similar in structure to cilia but are much longer and often only one is found on a cell
E.g. sperm tail

18
Q

Endoplasmic reticulum

A

ER is a network of membranes in the form of flattened sacs and tubules extending from the nuclear envelope into the cytoplasm
There are two types: The rough ER and the smooth ER

19
Q

function of Rough ER

A

Rough ER contains ribosomes attached, which are the site of protein synthesis
Proteins made by the ribosomes enter the ER space for processing and sorting
Enzymes may attach carbohydrate groups or attach the proteins to phospholipids

20
Q

what are the three things that happens to material made in RER?

A
  1. may be incorporated into membranes of organelles
  2. incorpprated in the plasma membrane,
  3. secreted via exocytosis
21
Q

what are ribosomes made of?

where are they made ?

A

It consists of a large subunit and small subunit synthesized separately in the nucleolus.
• They are rich in ribosomal RNA and contain over 50 proteins each.

22
Q

where are the ribosomes present ?

whats it function

A

The ribosomes are present free in the cytoplasm, within the mitochondria or attached to the endoplasmic
reticulum.

• Function: sites of protein synthesis

23
Q

what is smooth ER and whats its function

A

Contains no ribosomes but has a greater range of enzymes, making its functions more diverse
Synthesizes fatty acids and steroids such as estrogens and testosterone

24
Q

what function does Smooth ER have in the liver

A

In the liver it helps release glucose from gluc-6-p and detoxify lipid soluble drugs such as alcohol and pesticides

25
what function does Smooth ER in the muscle
Stores Ca2+ ions in muscle
26
Individuals who repeatedly take drugs such as the sedative phenobarbital must take more of the drugs over time to feel the effects. explain why?
Individuals who repeatedly take drugs such as the sedative phenobarbital, develop changes in the smooth ER in their liver cells. The cells produce more smooth ER to counteract the poison, meaning the person has to take more of the drug to feel the effect
27
describe the Golgi complex
Most proteins from the rough ER are transported to other regions of the cell It consists of 3-20 membranous cisternae(sac like structures) with bulging edges arranged in a stack.
28
describe the cis and trans entry of the golgi
The convex entry or cis face faces the ER and the concave exit(trans) face faces the plasma membrane. Sacs between are called medial cisternae
29
describe the process that occurs at the Golgi
1. Proteins surrounded by ER membrane and transported through the cell 2. Transport vesicles move to entry face 3. Fusion of several vesicles crates the entry face and releases proteins 4. Proteins are modified and move into medial cisternae, then either taken back to the entry face or to the exit face 5. Within the exit face proteins are modified and packaged 6-9. Proteins sent to their destinations
30
whats the function of lysosomes?
Digestion of substances entering the cell, worn out organelles (autophagy) and entire cells (autolysis)
31
why is autophagy importent
autophagy is required for renewal, cellular differentiation, control of growth & tissue remodelling
32
what is Tay- Sachs disease
Inherited condition affecting children. Caused by absence of a single lysosomal enzyme Hex A. It normally breaks down a glycolipid called ganglioside GM2, especially prevalent in nerve cells. It builds up, destroying nerves cell function. The patient suffers from seizures, muscle rigidity and become blind. Death is often before the age of 5
33
describe Peroxisomes
Similar to lysosomes but smaller. • Contains oxidases (oxidise substrates by removing hydrogen) They are involved with amino acid and fatty acid metabolism Oxidise toxic substances such as alcohol, high copy number in the liver • Also contain enzyme catalase to protection against toxic effects of hydrogen peroxide (made in oxidation reactions)
34
Name Peroxisomal disorders
Peroxisomal disorders form a heterogeneous disease group, with different degrees of severity. Zellweger syndrome (ZS), which is usually fatal within the first year of life, neonatal adrenoleukodystrophy (NALD), which is usually fatal within the first 10 years, rhizomelic chondrodysplasia punctata (RCDP), which in its most severe form is fatal within the first year or two of life.
35
what is proteasomes
lysosomes degrade proteins delivered in vesicles Proteasomes degrade cytosolic proteins (unneeded, damaged or faulty) Important in negative feedback (switch off a pathway once a resposne has been achieved) A typically cell contains thousand of these structures but they’ve only recently been discovered Contain protease enzymes
36
how is Alzheimers disease caused
Alzheimers disease is caused by the build up of misfolded proteins in brain cells. Ongoing research to look at why these proteins are not degraded
37
what is the mitochondria
Site of aerobic respiration ‘power house of the cell’-Produce ATP Cells have 100- 1000s depending on function
38
why is enzyme and cristae importent in the mitochondria.
Cristae provide a massive surface area for respiration | Enzymes needed for respiration are found in the matrix and on the cristae
39
describe the nucleus
Spherical or oval shaped, most cells only have 1 Surrounded by a double membrane (nuclear envelope) Many nuclear pores extend through the envelope In centre spherical bodies called nucleoli
40
whats the function of the nuclear pores ?
acts channels for ions, active transport for RNAs and proteins
41
nucleoli function
They are clusters of protein, DNA & RNA, responsible for producing ribosomes
42
Structure of cytoskeleton ?
It consists of a network of protein filaments extending throughout the cytoplasm

biology (25 decks)

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