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Phase 1 > Cells and Organelles Pt 1 > Flashcards

Cells and Organelles Pt 1 Flashcards

1
Q

What is the difference between Prokaroytic and Eukaryotic cells?

A

Prokaryotic

  • bacteria
  • 1-10u
  • few/no organelles
  • small genome
  • no cytoskeleton
Eukaryotic cells 
- fungi, plants, animals
- 5-10u 
- complex set of organelles 
- large genome 
- extensive actin cytoskeleton 
ORGANISED & COMPARTMENTALISED
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2
Q

what is the plasma membrane?

A

Encloses the cell contents.
Provides a barrier between the extracellular environment and the inside of the cell.
Site of the cell’s interaction with the environment - any signal in or out cell mediated here.

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3
Q

What are the features of the Plasma membrane?

A
  • Phospholipid Bilayer = antipathic nature provides barrier. polar heads outwards and fatty acids tails inwards creating a hydrophobic barrier in an aqueous environment.
  • Cholesterol = contributes t fluidity.
  • lipid rafts = lipid bilayer organised into biochemical and functionally distinct regions. enriched in particular cholesterol and phospholipids and concentrate proteins in cell signalling.
  • Carbohydrates = attached to extracellular surface of membrane and allow cells to be recognised.
  • Proteins = attach peripherally to membrane or span across membrane.
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4
Q

What do Integral plasma membrane proteins do?

A
  • Allow transfer of small molecules across the membrane.
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5
Q

What are the classes of Integral plasma membrane proteins?

A
  1. Pumps
  2. Carriers/transporters.
  3. Channels
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6
Q

What are plasma membrane receptors?

A

These receptors interact with specific chemical signals and initiate a cascade of chemical signals in the cell.
EGF receptor example.

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7
Q

What are the two internal departments of a cell?

A
  1. Nucleus.

2. Cytoplasm.

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8
Q

What two categories are the cytoplasm?

A
  1. Cytosol

2. organelles

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9
Q

What is the Nucleus?

A
  • Control center of the cell containing its genomic DNA packaged as Chromatin.
  • carries out DNA expression and replication.
  • Primary and messenger RNA.
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10
Q

What are the features of DNA?

A
  • Bounded by a double membrane seperating nuceloplasm from cytoplasm.
  • Outer membrane continous with another organelle the endoplasmic reticulum.
  • inner membrane attaches to a scaffold of intermediate filaments called nuclear lamina
  • movement of molecules in and out of nucleus occurs in nuclear pores.
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11
Q

What are organelles?

A

Sub-cellular compartments that are a feature of Eukarotic cells.
Usually membrane bound apart from Ribosomes.
Specialised for unique functions.

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12
Q

Why are functions seperated into organelles?

A
  • permissive environment for a set of biochemical functions.
  • protect the cell by segregating destructive enzymes and chemicals.
  • localise cellular processes for efficient functioning.
  • Seperation of molecules required for specific functions.
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13
Q

What are mitochondria?

A
  • They are organelles that act as the power house of the cell through aerobic respiration producing ATP.
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14
Q

What occurs in mitochondrial dysfunction?

A
  • Cytochrome C released into cytoplasm to cause cell death.
  • clinically heterogeneous group of disorders resulting from dyfunction in mitochondrial respiratory chain.
  • multiple organ dysfunction
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15
Q

What is the Endoplasmic Reticulum?

A

A continuous system of flattened membranes continuous with the nuclear membrane.

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16
Q

What is Rough Endoplasmic reticulum?

A

ER with ribosomes covering it. Ribsomes are synthesising proteins for insertion or exportation from the cell.

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17
Q

What is Smooth ER?

A

This is the site of lipid synthesis and Calcium storage.

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18
Q

What is the Golgi Apparatus?

A

‘The sorting office.’

- Proteins are sent from the ER to the Golgi. They are sorted for their final location in the cell.

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19
Q

How does the Golgi work?

A

Proteins are carried in vesicles which fuse and become the cis cisterna in the ER.
They move through the golgi stack and as they do undergo enzymatic modification labelling them for a specific destination.

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20
Q

What are Lysosomes?

A

A small vesicle in the cytoplasm.

impermeable membrane used to contain hydrolytic enzymes used to degrade old/defective organelles or molecules.

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21
Q

What are Endosomes?

A

A small vesicle in the cytoplasm.

Deliver molecules from the plasma membrane to the lysosomes to deliver their contents.

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22
Q

What are Peroxisomes?

A

A small vesicle in the cytoplasm.
Contain oxidatives and catalates and are involved in fatty acid metabolism, biosynthesis of bile acids and detoxification.

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23
Q

What occurs if there is dysfuntion in Lysosomes?

A

The accumulation of undegraded molecules in lysosomes causing cell dysfunction and cell death.

24
Q

How does Tay-Sachs Disease occur?

A

Lysosomal dysfunction causing failure to degrade lipids and an accumulation in neurons.
It is a rare and usually fatal genetic disorder.
Progressive damage to the nervous system.

25
Q

What is the Cytoskeleton?

A
  • This organises the cell strucutre to keep it the correct shape and make sure it’s strong.
26
Q

What are the roles of the Cytoskeleton?

A
  • supports fragile membrane.
  • provides mechanical linkags that let cell/tissue bear stress.
  • Facilitates movement of organelles.
  • Allows cell to adopt specific behaviours (growth, dividion, motility).
27
Q

What is the Cytoskelton made of?

A

There are three types of Cytoskeleton Filament made up of proteins.

  1. Microtubules - Tubulin, (dynein, kinesin).
  2. Microfilaments - Actin (myosin)
  3. intermediate filaments - Keratin, vimentin, desmin, lamins
28
Q

What are the functions of Microfilaments?

A

in cell projections -> microvilli/stereocilia for absorption.
Cytoplasm - > cell contraction and shape change.
Membrane extensions - cell motility.
Contractile ring -> cytokinesis

29
Q

What is the role of intermediate filaments?

A

They are used for structural support.
They are in skin to allow it to move and bend without breaking.
They are also in nuclear lamina - lamins. They support membrane.

30
Q

What are microtubules?

A

highly dynamic strucutres that continuously grow and shrink.
The Centrosome organises them.
They move organelles and vesicles around the cell.

31
Q

Where do Kinesins move microtubules?

A

Move cargo away from the centrosome.

32
Q

Where do Dyneins move microtubules?

A

Move cargo toward the centrosome.

33
Q

What are Axonemes?

A

Primarily composed of microtubules and dynein they are cytoskeletal components of cilia and flagella.
they allow for bending to beat and movement.

34
Q

What occurs if there is a defect in cilia and flagella?

A

Kartagener’s Syndrome. Result of mutations in dynein.

Causes recurrent resp infections and infertility in males.

35
Q

What are cell junctions?

A

The connections of cells to allow them to work together.

It connects cell together or to the ECM.

36
Q

how do cell junctions work?

A

Transmembrane protein complexes which interact with similar proteins on adjacent cells. They link adjacent cells, the basement membrane and cytoskeleton.

37
Q

What are the three types of cell junctions?

A
  1. Anchoring
  2. Occluding/tight
  3. Communication/gap
38
Q

What are anchoring cell junctions?

A

Provide mechanical stability to groups of epithelial cells so that they can work together.

39
Q

What occurs if there is a defect in anchoring cell junctions?

A

Epidermolysis Bullos Simplex - severe blistering of the skin.

40
Q

What are tight junctions?

A

a specialised cell to cell contact which create a seal preventing diffusion of molecules between adjacent cells. They create a barrier in epithelial cell membranes.

41
Q

What are GAP Junctions?

A

Present in most cells. Intracellular channels that connect the cytoplasm of adacent cells.
Permit passage of inorganic ions and small molecules.
Important in cardiac and smooth muscle as they pass signals to each other.

42
Q

What occurs if there is a defect in gap junctions?

A

Mutations in connexins in gap junction cause a range of different conditions.

43
Q

What occurs if Connexin-26 is mutated?

A
  • Inherited human deafness
  • Vohwinkel syndrome (disorder of skin causing thick honeycomb calluses and build up of fibrous tissue on hands and feet)
44
Q

What is the importance of Adherens junctions in skin?

A

Holds epithelial cells together.

45
Q

What is the importance of Desmosomes in skin?

A

Provides for integrity of epidermis.

46
Q

What is the importance of Tight junctions in skin?

A

Provide a seal: prevent fluid passing across an epithelial sheet.

47
Q

What is the importance of Hemidesmosomes?

A

Hold epidermis to the dermis.

48
Q

What is the importance of Gap junctions?

A

Provide a route for intercellular movement of small molecules.

49
Q

What is a phospholipid?

A

A group of polar lipids consisting of two fatty acids, a glycerol unit and a phosphate group.

50
Q

What does amphipathic mean?

A

a molecule that has a polar and non-polar end.

51
Q

What are fillopodia?

A

Very small spikes of micofilament-based protrusions of the plasma membrane involved in cell motility.

52
Q

What are lamellipodia?

A

Micorfilament based membrane protrusions that help cells move.

53
Q

What type of molecules determine the ABO blood grouping?

A

Carbohydrates

54
Q

What are the four compartments of mitochondria and their function?

A
  1. outer membrane - selective permeability.
  2. inner membrane - electron transport chain
  3. Matrix - enzymes for citric acid/ TCA cycle.
  4. Intermembrane space - important in the electron transport chain and other enzymatic reactions (location of cytochrome C)
55
Q

What is Apoptosis?

A

The controlled and ordered sequence of events initiated by the cell to kill itself.

56
Q

What occurs when one of the mitochondrial components, cytochrome c, leaks into the cytosol?

A

Apoptosis.

57
Q

What is Actin’s function?

A

it plays an important role in cell motility.

Phase 1 (4 decks)

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