Dr Bass
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
What are the 2 methods of cell motility?
• Swimming - Crawling
Which protein filaments are used for swimming?
Microtubules
Which protein filaments are used for crawling?
Actin
What proteins are microtubules made from?
Hollow tubes of α and β tubulin dimers (heterodimeric)
Which structures do microtubules form?
Cilia and flagella (same structure but cilia are shorter)
What energy source molecule does tubulin contain?
GTP (hydrolysed to GDP during polymerisation of microtubule)
How many protofilaments makes up a microtubule in a cell?
13
What is the axoneme?
Core microtubule structure of the flagella/cilia
What is the arrangement of microtubules in the axoneme called?
9+2 (9 outer doublets + inner pair)
What are the 9 outer doublets of the axoneme made from?
A fibre (13 protofilaments) and B fibre (10 protofilaments)
What is the motor protein associated with microtubules?
Dynein
How does dynein cause movement in cilia/flagella?
• Dynein arms connect adjacent doublets • Hydrolyse ATP to release energy • Doublets slide past each other • Linking proteins cause microtubules to bend
What is the basal body?
• Connects the flagellum to the inner cytoskeleton of the cell (avoids tearing the plasma membrane) • Modified centriole
What is the microtubule arrangement of the basal body?
9x3 (no central pair, 9 outer triplets)
What is a centrosome?
• Contains 2 centrioles - Organises microtubules
What is the structure of actin filaments?
• Not hollow • Polar (+ve/-ve ends) • ATP present in subunit (hydrolysed to ADP when polymerised to form a filament) • Actin monomers (homomeric)
What is the function of profilin?
Binds to ATP form of actin subunit to inhibit polymerisation
What is the function of cofilin?
Binds to actin filament and causes severing
What is the motor protein associated with actin?
Myosin
What are the ways that actin can cause movement?
• Treadmilling - Dragging with mysosin
Describe the interaction of actin and myosin to cause movement.
• Troponin/tropomyosin complex blocks myosin binding site • Calcium binds to t/t complex to= exposes binding site • Myosin head binds (cross-bridge) and hydrolyses ATP to ADP which causes the power stroke • ATP binds to myosin to break cross-bridge
What are the 4 actin structures?
• Filopodium • Lamellipodium • Stress fibres • Cortical actin
What are filopodia?
Membrane protrusions for exploration which extend beyond the lamellipodia (parallel bundles of actin) e.g. extending towards a growth factor stimulus
What are lamellipodia?
Wave-like actin cytoskeletal projections in a migrating cell (crosslinks of actin)