Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Mid-term > Flashcards

Mid-term Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Profilin

A
  • protein that accerlerates treadmilling
  • 有運輸ADP的作用 - binds to free ADP-actin

–> turns it into free ATP-actin

–> profilin-ATP-actin complex

  • so actin complex can bind efficiently to the (+) end, and profilin dissociates after the new actin subunit is bound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cofilin

A
  • protein that accerlerates treadmilling
  • 有運輸ADP的作用
  • binds to subunits of F-actin that contains ADP (older subunits toward (-) end - small twists

–> weaken ability to dissociate

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

Thymosin-β4

A
  • binds to ATP-G-actin monomer–>抑制both ends接合ATP-actin。
  • actin monomer sequestering protein
  • can also be reservoir of actin for polymerization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

capping proteins

A

阻止兩端actin的接合與解離，避免actin filaments不受控地無限生長

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

CapZ

A

binds to (+) end of F-actin, stopping it from addition of new G-actin monomer

  • present in skeletal muscle (near Z-disk)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Tropomodulin

A

binds to (-) end of F-actin, stopping it from addition of new G-actin monomer - present in skeletal muscle

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

Formin

A

(1) 形成長條型actin filaments，有FH1跟FH2(formin-homology domains 1&2)。

*** Promote polymerization of actin

(2) FH1充滿proline，會與profilin親合；此外還可以聚集出高濃度的profilin與G-actin接合，增加 profilin-G-actin-ATP complexes 濃度，藉此提高(+)end增長的速度。
(3) FH2則是兩個單體可以形成甜甜圈形狀的dimer(意即甜甜圈狀dimer由2個FH2構成)，可以吸引兩個actin subunits朝(+)端不斷兩兩疊加actin subunits。

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

Arp2/3 complex

A

形成分支網狀branched filament assembly is nucleated。

(1) Arp2/3本身作為nucleus的能力很弱，need to be activated by
1. NPF(nucleation promoting factor，主要成員皆有一個特殊序列region WCA (WH2, connector, acidic)
2. (performed)已生成的一條actin filament。
(2) Actin跟NPF的WH2 region結合後，再和Arp2/3結合，接到actin filaments的(+)端上。接合角度為70o

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

how listeria utilizes the power of actin polymerization for intracellular movement?

A
  • 在其表面具有ActA蛋白質，上面有actin-binding site和acidic region，可模擬NPF以活化Arp2/3 complex，聚合actin filaments推著自己到處移動。

Arp2/3 complex被活化會形成更多的filament協助移動，在電顯下面看起來像彗星尾巴。

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

What causes myosin head to unbind actin?

A
  1. When ATP is bound to myosin head (allosteric inhibitor) –> but if ATP is hydrolysized to ADP and Pi, then it is able to bind actin
  2. Removal of Ca2+ ions: Ca 2+ ions are essential for the conformational change of actin filament by
    i. displacement of tropomyosin
    ii. expose the myosin binding site on the actin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

nebulin

A

(1) extends along the thin actin filament (細肌絲，actin + associated proteins) all the way from Z disk (+ve end) to tropomodulin(-ve end)，
(2) nebulin的長度決定了thin filament的長度。

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

titin

A

(1) 頭部與Z disk接合並延伸到thick filament (粗肌絲，myosin II)的中間。

（2）Titin被認為是一種具有elastic molecules holds the thick filaments in the middle of the sarcomere (肌小節)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

tropomyosin

A

tropomyosin (TM, 原肌球蛋白): 40nm長的線型分子，可和actin filaments上七個actin subunits結合

  • 在沒有Ca2+（relaxed state）的情況下，tropomyosin阻斷myosin與F-actin的相互作用，肌肉鬆弛。

當Ca2+與TN-C結合後，觸發tropomyosin移動到actin filament上的新位點，從而暴露actin上的myosin-binding sites。

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

troponin

A

troponin (TN, 肌鈣蛋白): 由下列三個次單元組成、可和_tropomyosin_結合的一種複合物。

a. TN-T：推手
b. TN-I：推手
c. TN-C：Ca2+的結合位點，控制TM在肌動蛋白上的接合位置。當被鈣離子活化後會啟動TN-T跟TN-I，叫他們把actin filament表面的TM推開。

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

Regulation of contraction in smooth muscle and nonmuscle cells By Myosin-dependent mechanisms

A
  1. 脊椎動物平滑肌的收縮受到與myosin II neck domain相關的myosin regulatory light chain (LC)經歷phosphorylation和de-phosphorylation的途徑的調控。
    (1) 當LC未被磷酸化時，平滑肌的myosin II會折疊，並且其ATPase cycle無活性。
    (2) 當LC被myosin LC kinase(MCLK)磷酸化時，myosin II展開並組裝成active bipolar filaments，就可以活化並產生收縮。
  2. Calmodulin(攜鈣素)：可調控myosin LC kinase activity的Ca2+ dependent regulation。

Ca2 + first binds to calmodulin，誘導蛋白質的conformational change，然後Ca2+/calmodulin complex binds to myosin LC kinase –> myosin LC kinase is activated to phosphorylate myosin!!!

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

Cdc42, Rac, and Rho

A

Small GTP-binding proteins

  1. 與Ras superfamily中所有小GTPase一樣，Cdc42，Rac和Rho扮演著分子開關(molecular switches)，控制actin的排列與組織。
  2. Inactive in the GDP-bound state and active in GTP-bound state。
17
Q

What is microtubule made of? is it polarised? Give some egs

A
  • ab-tubulin heterodimers
  • both subunits can bind ATP, but only b subunit is able to undergo ATP hydrolysis and bind ADP
  • interchangeable –> microtubular dynamics It is polarised.
  • The (+) end of the microtubule favored for polymerization is the end with exposed β subunit.
  • The (-) end has exposed α subunit. mitotic spindle / flagella/ cilia/ axon
18
Q

秋水仙素Colchicine

A
  • to relieve the joint pain of acute gout.
  • A low level of colchicine r_elieves the inflammation caused in gout_ by reducing the microtubule dynamics of white blood cells, rendering them unable to migrate efficiently to the site of inflammation.
19
Q

taxol (紫杉醇)

A

a plant alkaloid from the Pacific yew tree, binds and stabilizes microtubules against depolymerization.

Toxol stops cells from dividing by inhibiting mitosis, it has been used to treat some cancers, such as those of the breast and ovary, where the cells are especially sensitive to the drug.

20
Q

Tau family protein

A
  • Function: Stabilizing the microtubule structure and dynamics
  • 由不同的side- 和end- binding protein所作用，使構型不會隨便被改變

Examples

  • (1) MAP2 (microtubule associated protein): 出現在dendrite中。
  • (2) Tau出現在axon以及dendrite中。
  • (3) 可以把MAP coat在outer wall of microtubule 以提升組合速率(growth rate) 並抑制catastrophe。
21
Q

Kinesin -13 family protein

A
  • end binding and severing proteins that dissembles microtubule - 結合後使之變成GDP-β-tubulin而彎曲，使其易從terminal end移除dimer，亦即增加catastrophe
  • Kinesin-13帶走1個dimer ; Stathmin帶走2個dimer
22
Q

Op18/ Stathmin

A
  • end binding and severing proteins that dissembles microtubule - 此蛋白和兩個tubulin dimers結合，形成如同GDP-β-tubulin的構型，增加 catastrophe
  • Kinesin-13帶走1個dimer ; Stathmin帶走2個dimer
23
Q

Katanin

A

Protein involved in dissembling the microtubules

直接破壞MTOC，令anchored在上面的microtubules脫離，- end裸露而易於分解

24
Q

kinesin

A

驅動蛋白 運送： (1) 不同Kinesin，有不同的移動方向。大部分由 - end往 + end移動。 (2) 運送需要ATP的能量才可以進行。 (3) Highly progressive: 以hand over hand的方式運送，一次能送很遠，且運送時不易從microtubule掉落，是非常有效率的運送方式。 (4) 步驟： a. 當ATP接上leading head，會改變構型讓trailing head被甩到前面。 b. 原本的trailing head被甩到前面後變成leading head，並釋出ADP。 c. ADP離開時，現在的trailing head水解ATP，產生ADP+Pi，然後Pi釋放。  所以一次運送結束時：leading head上沒有東西、trailing head上有一個ADP。  下一次circle開始，會有一個新的ATP接在leading head上把trailing head甩到前面新的leading head釋出原本的ADP新的trailing head水解ATP並釋出Pi。

25
Q

Dyneins

A

動力蛋白 1. two-headed molecule, built around 2 identical/nearly identical heavy chains 2. transport organelles toward the (-) end of microtubules 3. 每個單一重鍊結構： (1) Stem: other dynein subunits bind and associate with its cargo through dynatin。 (2) Linker: 涉及ATP-dependent motor activity (3) Head: 含有AAA ATPase domain(AAA: 與多種細胞活性相關的ATPase)，由6個重複序列組成，這些重複序列組成六個花瓣狀結構，其中間為ATPase的活性區域。 (4) Stalk: Protrudes from the structure and contains microtubule-binding region 4. 作用方式： 1. 原本的linker lies across第一跟第三個AAA domain上。 2. Upon ATP binding and hydrolysis，AAA稍微改變conformation(往左轉)讓linker纏在第一跟第五個AAA domain上。 3. This conformation change rotates the molecule to bring the stem and stalk closer 讓運送的物質往 - end端移動。 4. 有些cargo可以和兩種動力蛋白接合，所以運輸時可以轉變方向。(右下圖)

Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions