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bio1140 > module 2 > Flashcards

module 2 Flashcards

1
Q

What structures does the cytoskeleton consists of?

A
  • network of microtubules
  • microfilaments
  • intermediate filaments within the cytoplasm.
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2
Q

What is the role of the cytoskeleton?

A
  • Mechanical support (resists pressure)
  • Structural maintenance
  • Cellular transport
  • Cell motility
  • Signaling support
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3
Q

What are the functions of the cytoskeleton?

A
  • Organizes cell structure and anchors organelles, facilitating cellular activities.
  • Allows organelles and enzymes to attach and move within the cell.
  • Maintains and modifies cell shape (especially in animal cells without cell walls).
  • Participates in cell division by separating and pulling apart chromosomes.
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4
Q

What is the structure of microtubules?

A
  • Thick, hollow rod composed of tubulin proteins.
  • Tubulin is a dimer consisting of two subunits: alpha tubulin and beta tubulin.
    (yhe term “dimer” refers to the combination of two subunits, specifically alpha tubulin and beta tubulin, )
  • Microtubules have polarity with a “plus end” and a “minus end.”
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5
Q

Where can a microtubule grow and shrink from?

A

microtubule can grow and shrink in length from its “plus end” through the processes of polymerization (growth) and disassembly (shrinkage) of the tubulin dimers.

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6
Q

The minus end of the microtubule is attached to:

A

the centrosome

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7
Q

Functions of Microtubules:

A
  • Maintenance of cell shape (acting as compression-resisting girders).
  • Facilitating cell motility (e.g., in cilia and flagella).
  • Assisting in chromosome movements during cell division.
  • Enabling organelle movements within the cell.
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8
Q

Microtubules are involved in the movement of what?

A

movement of organelles, vesicles and enzymes across the cell

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9
Q

What is the movement of microtubules is caused by?

A

aused by motor proteins powered by ATP (converts chemical energy to mechanical energy).

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10
Q

What are the two types of motor proteins?

A

kinesin and dynein

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11
Q

Kinesin moves cargo in what direction

A

towards the plus end of the microtubules

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12
Q

Dynein moves cargo in what direction

A

owards the minus end of microtubules

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13
Q

Describe polymerzation of microtubule

A

The process by which microtubules grow in length.
- It involves the addition of tubulin dimers to the “plus end” of the microtubule.

  • This elongation is critical for various cellular functions, including cell motility and intracellular transport.
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14
Q

What role do microtubules play during mitosis?

A
  • Microtubules play a crucial role in separating chromosomes during mitosis.
  • they radiate from the centrosome, helping to organize and segregate genetic material into daughter cells during cell division.
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15
Q

What is the centrosome?

A

A structure present in the cytoplasm of animal cells, typically located near the nucleus.

  • It functions as a microtubule-organizing center (MTOC) and plays a crucial role during cell division.
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16
Q

How many centrioles are in a centrosome?

A

2 centrioles that are perpendicular to one another

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17
Q

what’s a centriole

A
  • A cylindrical structure found in the centrosome of animal cells
  • composed of 9 microtubule triplets arranged in a “9+0” pattern
    = indicating that there are 9 microtubule triplets together but none at the center.
  • Centrioles play a role in cell division.
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18
Q

What happens to centrioles after mitosis?

A

the two centrioles separate, and each is replicated for the next cell cycle.

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19
Q

What is the hierarchal order for microtubule structure? (from low-high)

A
  1. Tubulin
  2. Tubulin dimer
  3. microtubule
  4. centriole
  5. centrosome
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20
Q

Microtubules are involved in the beating of:

A

flagella and cilia

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21
Q

What is the function of cilia/flagella?

A
  • Both cilia (short and numerous)
  • flagella (long and few) are cell appendages containing microtubules.
  • They are used in locomotion (flagella and cilia)
  • for moving fluids and facilitating feeding (cilia).
22
Q

What is the core of Cilia and flagella called + what is composed of?

A
  • The core of both cilia and flagella is called the axoneme.
  • The axoneme is composed of nine outer doublet microtubules and two inner single microtubules, arranged in a “9+2” pattern
    = meaning there are 9 pairs of microtubules surrounding 2 central microtubules.
    = These microtubules are covered by the plasma membrane.
23
Q

What does the sliding of microtubules depend on?

A

depends on a motor protein (dynein)

-> this creates the beating of flagella

24
Q

How does SARS-Cov-2 affect cilia in the respiratory system?

A
  • loss or shortening of cilia (axoneme) in tracheal epithelial cells.
  • Misorientation of the basal body
    = disrupting the proper alignment and function of cilia in the respiratory tract.
25
Q

How does SARS-Cov-2 affect mucociliary clearance?

A
  • Decreased percentage of ciliated area in the respiratory tract.
  • Reduction in the mean clearance speed of viral particles.
  • These effects can hinder the effective clearance of mucus and viral particles from the airways.
26
Q

What are microfilaments (actin filaments)

A
  • Thin filaments composed of actin proteins.
  • They function alone or in conjunction with myosin to cause cell contraction
    = enabling various cellular processes such as muscle contraction and cell movement.
27
Q

What is the function of microfilaments?

A
  • Maintenance of cell shape.
  • Facilitating changes in cell shape.
  • Playing a crucial role in muscle contraction.
  • Promoting cytoplasmic streaming in plant cells.
  • Enabling cell motility, such as in amoeboid movement.
  • Assisting in the division of animal cells.
28
Q

What are microfilaments composed of?

A
  • double chain of actin subunits
29
Q

What are key features of microfilaments?

A
  • form a network and can branch within the cell.
  • Provide resistance to compression, maintaining the cell’s shape, especially in the cortex (thin region directly beneath the plasma membrane).
  • Can interact with the protein myosin to facilitate muscle cell contraction.
30
Q

What is the sliding of microfilaments powered by?

A

myosin

31
Q

what is myosin

A

a motor protein that powers movement in cells, particularly muscle cells, by converting chemical energy from ATP into mechanical work.

32
Q

what are the steps in muscle contraction

A
  • Nerve Signal: A nerve signal stimulates the muscle, leading to the release of calcium ions (Ca2+) from the sarcoplasmic reticulum.
  • Actin and Myosin Interaction: Calcium ions bind to troponin, allowing myosin heads to bind to actin filaments.
  • Cross-Bridge Formation: Myosin heads attach to actin, forming cross-bridges.
  • Power Stroke: ATP is hydrolyzed, causing myosin heads to pivot and slide actin filaments, contracting the muscle.
  • Relaxation: When nerve signals stop and calcium ions are pumped back into the sarcoplasmic reticulum, the muscle relaxes.
33
Q

What are intermediate filaments?

A
  • Strong and flexible filaments of intermediate size
  • They provide mechanical support to the cell
    = helping it withstand physical stress and maintain its structural integrity.
34
Q

What are the main functions of intermediate filaments?

A
  • Maintenance of cell shape, serving as tension-bearing elements.
  • makes sure nucleus and certain other organelles within the cell.
  • Formation of the nuclear lamina, a supportive network that surrounds the nucleus.
35
Q

Intermediate filaments are only found where?

A

mainly in the cytoplasm of animal cells.

36
Q

What differentiates intermediate filaments from microtubules/microfilaments?

A

Intermediate filaments are more permanent structures and do not undergo disassembly and reassembly to the same extent as microtubules and microfilaments.

37
Q

What is plasmodesmata?

A

plasmodesmata are tiny channels connecting plant cells, enabling communication and nutrient exchange.

38
Q

What are neighbouring cells in plants connected by?

A

Cytoplasmic channels called plasmodesmata

39
Q

What is the function of plasmodesmata?

A

facilitate the easier transport and communication of molecules and substances between plant cells.

They are tiny channels that connect cells, allowing things to move between them.

40
Q

What are the 3 different types of cell junctions in animals?

A
  1. tight junctions;
    2: desmosomes;
  2. gap junctions
41
Q

What are tight junctions?

A

protein-based structures that tightly bind the plasma membranes of adjacent animal cells, forming a strong barrier.

42
Q

What is the function of tight junctions?

A
  • act as barriers
    = preventing the leakage of fluid + selective passage of substances between cells in animal tissues.
43
Q

What is an example of tight junction?

A
  • Blood-brain barrier
  • Epithelial cells like skin cells (keratinocytes)
  • enterocytes in the intestine
  • Endothelial cells in blood vessel walls
44
Q

What are desmosomes?

A

cellular structures that firmly attach neighboring cells together using transmembrane proteins linked to intermediate filaments, promoting cell adhesion and tissue stability.

45
Q

What is the function of desmosomes?

A

Keeping neighboring cells tightly connected, particularly in stretchable tissues.

46
Q

What is an example of desmosomes

A

Muscle cells (myocytes) are held together by desmosomes, ensuring strong connections in contractile tissues.

47
Q

Cadherins

A

the proteins that link cells in desmosomes

48
Q

What are gap junctions?

A
  • specialized cellular junctions similar to plasmodesmata in plants.
  • They consist of channels formed by six proteins known as connexins, allowing for direct communication between neighboring cells.
49
Q

What is the function of gap junctions?

A

facilitating cell-to-cell communication by:
- allowing the passage of ions and small molecules
= (including amino acids and sugars ) between neighboring cells.

50
Q

What is an example of gap junctions?

A

heart muscle cells

bio1140 (4 decks)

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