Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Basic Principles Of Medicine 1-FTM 1 > Cells 2 > Flashcards

Cells 2 Flashcards

(51 cards)

Start Studying
1
Q

What are the components of cytoskeleton ?

A
  1. Actin filaments (microfilaments)
    - actin
    - 7nm diameter
  2. Intermediate filaments
    - 6 classes, numerous proteins
    - 8-12 nm diameter
  3. Microtubule
    - tubulin
    - 25 nm diameter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of the cytoskeleton?

A
  • structural support & stability
  • organization
  • cell division
  • cell movement
  • tracks for motor proteins to move organelles & vesicles within cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the structure of microtubules

A
  • Non-branching, rigid, hollow tubes
    • a and B tubulin protein subunits

Polar

  • minus (-) end
  • plus (+) end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the functions of microtubules ?

A

Intracellular transport
-movement of vesicles & organelles via motor proteins

Cell motility

  • movement of cilia and flagella via motor proteins
  • cell elongation and mivement

Mitotic spindle
-attachment of chromosomes & their movement during cell division

Rigid intracellular skeleton
-maintenance of cell shape & polarity

Assemble and disassemble as the needs of the cell change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the structure of centrioles

A

9 Triplets of microtubules arranged around a central axis

-Each triplet consists of 1 complete and 2 incomplete microtubules fused

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the functions of centrioles?

A

-Organize the centrosome

  • Basal body formation
    • provide basal bodies necessary for assembly of cilia and flagella
  • Mitotic spindle formation
    • formation of centrosome & alignment of the mitotic spindle during cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain the structure of the centrosome

A

Microtubule organizing center (MTOC)

Structure

  • contains a pair of centrioles
    • arranged such that one is perpendicular to the other
  • amorphous protein matrix
    • more than 200 proteins
  • Gamma-tubulin ring complexes
    • nucleation sites for microtubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of the centrosome?

A

-Organize microtubules

  • initiate microtubule formation
    • Microtubules are nucleases at the centrosome at their negative(-) ends
    • positive (+) ends point out and grow toward the cell periphery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the mitotic spindle poisons?

A

Colchicine

Taxol(palcitaxel)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is colchicine?

A

Anti cancer compound

  • prevents polymerization
    • binds to unpolymerized tubulin molecules
  • if given to dividing cells, mitotic spindle breaks down
    • programmed cell death

Related compounds

  • vinca alkaloids
    • vinblastine
    • vincristine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is taxol (palcitaxel)?

A

Anti cancer compound

- stabilizes and prevents microtubule disassembly
     - preferentially binds tubulin within associated microtubules 

 - Arrested dividing cells in mitosis
      - unable to achieve metaphase spindle conformation
      - programmed cell death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe microtubules

A

Polymerization

- organized & directed by microtubule organizing centers 
    - basal bodies
    - centrosome

GTP dependent

Highly dynamic (mitotic spindle) or relatively stable (cilia)

  • change in length
    • fast growing at positive end, slow growth or disassembly at negative end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe microtubule associated proteins (MAPs)

A

Tau proteins

  • abundant in neurons of the CNS
  • stabilize axonal microtubules
  • hyperphosphorylation of tau proteins can result in self-assembly of tangles
    • linked to Ahlzeimer’s disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the Dynein family as microtubule motors

A
  • move in the (-) direction along microtubules
    • retrograde

2 members

  • cytoplasmic dyneins
  • axonal dynein
    • located in cilia & flagella

Binding sites for vesicles, organelles or another microtubule

Largest & fastest of the known molecular motors
-dynein 14 um/sec vs kinesin 3 um/sec

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the kinesin family as a microtubule motors

A
  • Move in the (+) direction along microtubules
    • anterograde
  • binding sites for vesicles, organelles, microtubules
  • about 40 distinct kinesins humans
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the structure and function of the cilia & flagella

A

Motile structures
-highly specialized

  • Microtubules and axonemal dynein motor proteins
    • Characteristic arrangement found in almost all eukaryotic flagella and cilia

-Movement produced by the bending of the core (axoneme)

  • Accessory proteins cross-link adjacent microtubules together
    • As a result, dynein motors produce a bending movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The cilia is anchored to the …

A

Basal body

-thin, dark staining band at base of cilia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the function of the cilia?

A

Move fluid and particles along epithelial surfaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure of the cilia

A

Microtubule-based, hair like structure

- motile
   - beat in synchronous pattern

9+2 microtubule arrangement

Pair of dynein arms

- motor protein
- binds adjacent microtubule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain the primary cilia as a sensory antennae

A

Photoreceptors
-outer segment of rods derived from primarily cilia

Chemoreceptors
-odor detection by receptors on primarily cilia of olfactory neurons

Mechanoreceptors

  • primarily cilia of epithelial cells monitors the flow of fluid through kidney tubules
  • defects underlie a variety of disorders
    - polycystic kidney disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Briefly describe the structure of the primary cilia

Study These Flashcards
A
  • Microtubule based, antennae-like structure
    • 9+0 arrangement
  • Emanates from almost cells
  • Anchored to cell via the basal body
  • Develops from one centriole following cell division
22
Q

Describe the structure of the intermediate filaments

Study These Flashcards
A

Rope-like filaments

Structure: formed by non-polar & highly variable subunits

23
Q

What are the functions of the intermediate filaments ?

Study These Flashcards
A

Structural

  • stabilize cell structure
    • mechanical strength
    • maintain the position of the nucleus and other organelles
  • Resist shearing forces
    • extend across cytoplasm
    • connecting with desmosomes & hemidesmosomes

Essential for integrity of cell- cell & cell-ECM junctions

24
Q

What are the classes of intermediate filaments?

Study These Flashcards
A
  • keratins
  • vimentin & vimentin-like
  • neurofilaments
  • lamins
  • beaded filaments
25
Explain keratins as intermediate filaments
Acid & basic cytokeratins - diverse group - over 50 isoforms -found in all epithelial cells
26
explain vimentin & vimentin like as intermediate filaments
Diverse family -most widely distributed in the body Vimentin -most abundant in mesoderm-derived cells Vepimentin-like found in a variety cells - Desmin: muscle cells - Glial fibrillar acid protein (GFAP): glial cells & astrocytes
27
Explain neurofilaments as intermediate filaments
-Assembled from neurofilament proteins of different molecular weights - Extend from cell body into the ends of axons & dendrites - Provide structural support -Found primarily in neurons
28
Explain the lamins as intermediate filaments
Found in nucleus of all nucleated cells -nuclear lamina Lamin A & B proteins
29
Explain beaded filaments as intermediate filaments
-Eye lens-specific group
30
Contrast the types of actin
G-actin= free actin molecules in cytoplasm F-actin= polymerized actin in a filament, ATP dependent
31
Describe the structure if actin filaments
Made up of protein actin Polarized structures - fast growing (+) positive end - slow growing (-) negative end May exist as single filaments, in bundles, or in networks
32
What is the function of the actin filament?
Variety of cell functions - anchorage - structural core of microvilli & stereocilia - cell motility - locomotion - extension of cell processes
33
What are the actin & fungal toxins?
Phalloidin & cytochalasins
34
What is phalloidin?
- toxin found in Amanita phalloides - used in cytoskeleton research - disrupts normal function of actin - binds F-actin more tightly and G-actin - promotes excessive polymerization and inhibits de polymerization - inhibits cell movement ``` Other toxins (amatoxins) are responsible for the toxic effects following oral ingestion -liver and kidney failure & death 4-8 days after consumption ```
35
What are cytochalasins?
- other fungal products - block polymerization of actin - Can be used to inhibit cell movement, division, & induce programmed cell death
36
Describe microvilli
- cylindrical, membrane bound cytoplasmic projections - 1-3 um in length - core of 25-30 actin microfilaments - Cross linked by villain - Anchored into the terminal web
37
Describe the structure of stereocilia
Unusually long microvilli -up to 120 um in length Actin filament bundle anchored to terminal web
38
Where can stereocilia be found?
Limited distribution - Epidydmis - proximal Ductus deferens - sensory hair cells of inner ear
39
Describe myosin as an actin motor
Human genome includes about 40 different myosin genes Myosin II - Generates the force for skeketal muscle contraction - formed from 2 heavy chains & 4 light chains - tail-tail interactions result in formation of bipolar thick filaments - several hundred myosin heads Each head binds and hydrolyzes
40
What are the myosin structural changes for actin motors?
Stage 1: attachment- rigor conformation Stage 2: release- ATP binds, reduces myosin affinity for actin Stage 3: bending- ATP hydrolysis, cinfirmational change Stage 4: force generation - weak binding of myosin to actin causes release of inorganic phosphate - release triggers tight binding & power stroke - force-generating conformational change Stage 5: reattachment -rigor conformation
41
How is actin involved in cell movement?
- actin filaments mostly oriented with + end facing forward - -ends frequently attached to the sides of other actin filaments via actin- related protein (ARP) complexes Actin web as a whole undergoes treadmilling - Assembling at the front - Disassembling at the rear ARP complex highly concentrated near front of lamellopodia where actin nucleation most active - Actin filaments - ARP complex Dense actin filament mesh work at leading edge
42
How does actin help with plasma membrane protrusions?
Protrusions driven by actin Different types of protrusion structures based on organization of actin Filipodia - Finger like projections - Core of long, bundled actin filaments Lamellipodia-fibroblasts -Sheet-like structures Pseudopodia- white blood cells -3 dimensional projections
43
Explain the cell movement- lamellipodia
Common example- fibroblasts of connective tissue Complex & integrated process 1. Protrusion - Actin polymerization at plus (+) end protrudes lamellipodium 2. Attachment - Focal adhesions anchor the actin cytoskeleton to the extracellular matrix via integrins proteins 3. Contraction - Bulk of the training cell & cytoplasm is drawn forward
44
What is chemotaxis?
Movement within tissue along a chemotactic gradient towards the source of inflammation - N-formylated peptides - Peptides attached to extracellular matrix
45
Summarize neutrophil migration
Extravasion 1. Rolling 2. Activation 3. Adhesion 4. Transendothelial migration Process of diapedisis -Extension of a pseudopod between endothelial cells -Pass the basement membrane into the tissue.
46
What are inclusions?
Cytoplasmic or nuclear structures formed from metabolic products of the cell Pigments- membrane bound
47
Describe Lipofuscin as an inclusion
Brown-goldfish pigment Generally seen in non-dividing cells - Accumulating over years - “wear and tear” pigment -Accumulation of oxidized lipids, phospholipids, metals and other organic molecules as result of lysosomal digestion
48
Describe hemosiderin as an inclusion
- brown pigment - Iron-storage complex found in cytoplasm - Commonly found in macrophages - Likely formed by indigestible residues of hemoglobin following phagocytosis of red blood cells - Demonstrated in the spleen, liver, lung Deposits may be also be linked to diseases of iron overload
49
Describe melanin as an inclusion
- Dark brown/brown/ reddish pigment produced by the oxidation of tyrosine - Produced by melanocytes in the skin & responsible for color of skin/ hair pigmentation - Also produced by certain neurons of the brain
50
Describe glycogen as an inclusion
- Non-membrane bound, TEM dense bodies - single(beta) 20-30nm particles or rosettes (alpha) - Storage form of glucose - Catabolism releases glucose for energy
51
Describe lipids as an inclusion
-Non-membrane bound, TEM dense - fat droplets - spherical droplets of triglyceride - Liquid at body temperature -Energy store and source of short carbon chains for membrane synthesis Lipid storage diseases (lipodoses) -lipid droplets accumulate in abnormal amounts or locations

Basic Principles Of Medicine 1-FTM 1 (39 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions