Cell Cycle Flashcards
What is kineticore?
Protein complex that attaches to centromere region, contains motor proteins
Describe anaphase spindle 1
Sister chromatids separate, up replicated chromosomes move toward poles by dynien
What happens when the MT lengthen?
Mt polymerizaion
Use motor protein that moves away from the poles
Uses kinesin
What are the requirements for successful cell division?
Increase in cell size before dividing
Replicate DNA chromosome
Partition DNA chromosomes precisely
Partition cytoplasm
What are the ,another checkpoints during mitosis?
Spindle assembly checkpoint
G1 checkpoint
G/ checkpoint
Metaphase checkpoint
What happens during spindle assembly checkpoint?
Check for chromosome attachment to spindle
What happens during the G1 checkpoint?
Check for cell size Nutrients Growth factors and DNA damage Regulated by G1 cyclin and G1 CDK Cells can leave cycle Major decision point- start or restriction point
What happens during G2 checkpoint?
Check for Cell size DNA replication Completion of chromosome replication Coordinates entry into mitosis
What happens during the metaphase checkpoint?
Coordinates entry into mitosis
Chromosome alignment on spindle- makes sure all are present and accounted for
How is the G2 checkpoint regulated?
Controlled by MPF( mitosis promoting factor)
Regulatory subunit called cyclin
Catalytic subunit called CDK
Cyclin levels oscillate during cell cycle- hugest during M phase. Increase st G2
How is MPF activated
Cyclin synthesis
Regulation of MPF kinases and phosphotases
Degradation of cyclin in anaphase
CDK inhibitors
What are the functions of MPF?
Chromosome condensation phosphorylation of condensins
Nuclear breakdown
Spindle formation: phosphorylation of centrosome and microtubule associated proteins
Compare cytokinesis is plant cells and animal cells
Plant cells separate the two new cells using a cell plate made of cellulose. Vesicles containing building material fuse together to create plate
Animal cells: separate via a cleavage furrow contractile micro filaments pull the plasma membrane inward
What happens during an action potential
Secretion of ACh
ACh binds receptor on muscle,Na enters
Action potential along muscle membrane and T tubule
Conformation chafe in voltage sensor
Voltage sensor opens ca enters cytoplasm
Troponin moves tropomyosin
Myosin II binds to F actin causing a contraction
Describe MT organization
MTs originate from centrosome-may contain centriole
- end anchored to MTOC
+ end extends out
Some functions depend on stable MT, others on dynamic MT ( assembly and dissemblly)
Describe accessory proteins
MT associated proteins (MAPS)
They stabilize, cross link and are used in movement
Motor proteins
Describe motor proteins ( type of accessory protein)
Head binds tubules :hydrolyze ATP
Tail attaches to cargo
Describe micro filaments
Accessory proteins
Motility
Polymerization-driven
Motor protein- driven
Describe MF structure
Subunit: G actin(globular) Polymer- F actin( filamentous) Actin filament has polarity \+ end more rapid addition - end slower addition
Describe accessory proteins- actin binding
Influence organization assembly dissemblly and function
Describe MF motor protein
Myosin (uses ATP hydrolysis)
Two myosin groups:
Myosin 1
Myosin 2
Describe conventional myosin, myosin 2
Involved in muscle contraction
Myosin 2 tails associate with each other
Results in contraction.
Describe unconventional myosin- myosin 1
Tails associate with other cargo( vesicles or membrane )
Describe micro filaments motility
Two strategies
Polymerization- creates a pushing force
Motor protein driven- conformation change created force
Describe listeria bacterium
Example of polymerization driven MF motility
Propels itself across cytoplasm by polymerizaion groups actin behind it
Describe movement via a sarcomere?
Myosin 2 heads project in 2 directions to contract actin at both ends of the sarcomere
Myosin 2 tails are asscicated with other myosin tails
Describe the sliding filament model
Mechanism for muscle movement
ATP hydrolysis powers myosin 2 movement
Actin and myosin filaments slide past one another
Sarcomere shortens because myosin pulls in two direction
Contraction of multiple sarcomere shortens muscle
What is a centromere?
Region of DNA
