Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BMSC 220 CELL BIOL > AbuArish Section > Flashcards

AbuArish Section Flashcards

(56 cards)

Start Studying
1
Q

What three structures make up the cytoskeleton?

A

Microtubules
Actin filaments
Intermediate filaments

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

What are microtubules made of?

A

Tubulin

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

How are microtubules arranged?

A

Longitudinal rows af 13 protofilaments

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

What two components make up protofilaments?

A

a tubulin and B tubulin
- + end by b tubulin and - end by a tubulin

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

What are MAPs and what do they do?

A

Microtubule associated proteins
- increase stability and promote microtubule assembly by linking tubulin subunits together

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

What determines the shape of the cell?

A

Microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the three kinds of motor proteins?

A

Kinesin and Dyein which move along microtubules
- Myosin which moves along actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which direction do motor proteins move?

A

Unidirectionally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain what kinesins do

A

Superfamily of 14 motor proteins
- tetramer of 2 heavy and 2 light chains
- most move outwardly from - to +

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

Does kinesin movement require ATP?

A

yes, one per step

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does kinesins being highly processive mean?

A

Means they can walk along microtubules for a long time without falling off because one of the kinesin heads is always attached to the microtubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain what dyneins do?

A
  • Massive protein
  • two identical heavy chains
  • varying intermediate and light chains
  • moves from + to - end, opposite of kinesins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is cytoplasmic dynein responsible for?

A

moving spindle and positioning chromosomes during mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are MTOCs? Give an example of one

A

Microtubule organizing centers - where nucleation of microtubules occurs
- control number and polarity of microtubules
- control numberof protofilaments
- control the time and location of assembly
- Centrosome is an MTOC

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

What is the centrosome?

A

MTOC
- two barrel shaped centrioles surrounded by electron dense PCM
- major site of microtubule initiation in animal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a basal body?

A

MTOC
- forms at the base of cilia and flagella
- identical to centrioles - can swap between them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the common factor all MTOCs share?

A

y-tubulin - protein for microtubule nucleation
- pcm serves as attachment point for y tubulin

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

What can cause the disassembly of microtubules?

A
  • posttranslational modification
  • cold
  • hydrostatic pressure
  • elevated Ca
  • variety of chemicals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens during assembly of tubulin dimers?

A

GTP is bound to Btubulin
- GTP hydrolyzed to GDP after dimer is incorportated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens during disassembly of tubulin dimers?

A

Dimer enters the soluble pool, GDP replaced by GTP- nucleotide exchange allows it to recharge to become a building block again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is dynamic instability of microtubules?

A

explains that growth and shrinkage of microtubules can coexist in the same region
- any given microtubule can flip between growing and shrinking unpredictably
- property of the plus end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are cilia?

A

Hairlike, sometimes motile organelles
- on many eukaryotic cells?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the single nonmotile cilia do on cells?

Study These Flashcards
A

Acts as a sensory organ monitoring changes in environment

24
Q

Are cilia and flagella structurally identical?

25
Do cilia and flagella have a plasma membrane?
yes, shared with the cell just extended
26
What is the axoneme? What is the array
core of the cilia -array of microtubules running thru entire organelle - axoneme consists of 9 peripheral doublet microtubules surrounding a pair of single microtubules (9+2 array)
27
What is intraflagellar transport (IFT)
Process through which material is transported along cilia or flagella - assemble into a protein complex called IFT particle - multiple IFT particles lign up to form IFT trains - Carry cargo proteins like tubulin out to + tip for assembly - inhibiting IFT prevents cilia and flagella from forming
28
Which motor protein generates swinging movement for ciliary movement?
Dynein
29
should you go back and look at the complicated shit for cilia movement?
probably
30
What are ciliopathies?
diseases that result from primary cilia defects - Polycystic kidney disease - Bardet Biedl syndrome
31
What are intermediate filaments?
Strong ropelike fibers 10-12nm - provide mechanical strength to cells under physical stress - chemically heterogenous - 70 genes - divided into 5 classes -4 classes are cytoplasmic, 1 is on the nuclear envelope (Lamins)
32
What connects intermediate filaments to other cytoskeletal filaements?
Plectin - wispy bridges - each plectin has a binding site for IF at one end and for any one of the three at the other end
33
5 common points for IF structure? 1 2 4 8
- each monomer has a pair of globular terminal domains sperated by a long fibrous alpha helical region - pairs of monomers are associated in parallel orientation to form dimers (polar) - dimers associate in an anti parallel staggered fashion to form tetramers (basic subunit) (nonpolar) - 8 tetramers associate to form a unit length of IF - Elongated IFs are formed from the end to end associated of the unit lengths
34
Does IF assembly require ATP or GTP?
No
35
What is different about IFs from the other cytoskeleton elements?
Assembly and disassembly are controlled by subunit phosphorylation and dephosphorylation
36
What are keratin containing IFs
IFs that contain keratin - structural proteins of epithelial cells - radiate through cytoplasm attached to nuclear envelope - anchored by desmosomes - also connected to the other 2 elements - function to absorb mechanical stress
37
What are neurofilaments?
Bundles of IFs located in cytoplasm of neurons - parallel to axons
38
What is F-actin?
Third major cytoskeletal element - flexible helical filament composed of actin monomers - two stranded structure with two helical grooves
39
What can actin filaments be organized into (3)
- ordered arrays - highly branched networks - tghtly anchored bundles
40
How are actin monomers arranged in an actin filament?
Pointing in the same direction - polar filament with barbed + end and pointed - end
41
How is an actin filament assembled and disassembled?
Actin monomer binds to ATP - actin is an ATPase - ATP is hydrolyzed to ADP after incorporation - initial nucleation occurs slowly - elongation is quick tho - both ends are labelled - barbed end grows 10x faster
42
What are the 5 steps in actin assembly? Type of exercise
- Actin filaments are added w atp - if ATP is high, subunits are added - as monomers are consumed, ATP drops until addition only continues as barbed end - as filament elongation continues free monomers drop, starts taking from pointed end to give to barbed - eventually growth and concentration become constant - treadmilling -
43
What is myosin?
molecular motors of factin - protein superfamily - two groups -- conventional type ii muscle cells -- unconventional in other cells - operate with actin - move towards barbed end of actin - all share head domain - head domain contains two sites - one that drives myosin motor by hydrolyzing ATP and one that binds the actin - tails are divergent
44
What are type ii myosins?
primary motors for muscle contraction - move towards + barbed end - required for cell splitting, generating tension and cell migration
45
Myosin filaments are bipolar, what does this mean?
reversal of polarity in center - myosin heads at the opposite ends of a myosin filament can pull actin filaments together
46
What is myosin V?
unconventional myosin - moves in a hand over hand motion similar to kinesin - transports various types of cytoplasmic vescicles and organelles
47
What is the structure of a skeletal muscle fiber?
- muscle fiber is a multinucleate cell - each fiber has many myofibrils -each myofibril consists of repeating arrays of sarcomeres
48
What is a sarcomere?
- exends from one Z line to the next Z line - dense M line in the H zone - I band has only thin filaments - H zone has only thick filaments -
49
What is the sliding model of muscle contraction?
shortening of sarcomeres consists of thin and thick filaments sliding over eachother - A band remains constant -H and I bands decrease - Z lines move inwards
50
What are the thin filaments composed of?
actin, tropomyosin and troponin
51
What is tropomyosin?
elongated molecule that fits into thin filament grooves and associates w 7 subunits
52
What is troponin?
globular protein complex composed of 3 subunits spaced apart, touches actin and tropomyosin
53
What are the 8 categories of actin binding proteins?
- nucleating - monomer sequestering - end blocking - monomer polymerizing - actin filament depolymerizing - cross linking and bundling - filament severing - membrane binding
54
What are actin binding proteins?
determins organization and behavior of actin filaments in cells
55
How do cell fibroblasts move?
flattens itself close to substratum and becomes fan shaped - extends small protrusion called lamellipodium from cell which adheres to substratum at focal adhesions providing anchor sites to pull itself forwards
56

BMSC 220 CELL BIOL (6 decks)

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