Muscles and Movement part 1 Flashcards
What is the cytoskeleton?
Protein based intracellular network. Gives structure to the cell. Contains microtubules, microfilaments and actin filaments
What are motor proteins?
enzymes that use energy from ATP to move. Move along the cytoskeleton. Convert chemical energy into mechanical energy by the hydrolysis of ATP
Cytoskeleton elements
Microtubules, microfilaments (actin), intermediate filaments
How can the cytoskeleton move?
Cytoskeletal rope and motor protein carriers pull on the cytoskeletal rope
What are microtubules?
Tube-like polymers of the protein tubulin. Similar protein in diverse animal groups. Have multiple isoforms. Anchored at both ends
-Microtubule organization centre (MTOC) near the nucleus (-). Attached to integral proteins (+) in the plasma membrane
Function of microtubules
Motor proteins (kinesin and dyenin) can transport sub cellular components along microtubules -Microtubules form the spindles used in the segregation of chromosomes during mitosis or meiosis
Movement of pigment Granules
African frogs can change their skin colour based off of the environment theyre in as camouflage to hide
- through the movement of pigments using motor proteins along the microtubules cytoskeleton
- skin cells (melanophore) contain dark pigment at the centre of the cells
- melanocyte stimulating hormone cause them to move along microtubules to periphery until completely dark or it can move in the opposite direction
What are microtubules composed of?
Microtubules are polymers of the protein tubulin
- tubulin is a dimer of alpha-tubulin and beta-tubulin
- tubulin forms spontaneously: does not require enzymes
- composed of one - end and one + end at the periphery
How are microtubules assembled?
1) alpha tubulin and beta tubulin combine to form dimer, tubulin (activation of tubulin monomers by GTP)
2) Multiple dimers assemble end to end to form a protofilament
3) Protofilaments line up to form sheets
4) sheet of protofilaments roll up to form a tube
5) Microtubules grows by monomer addition to + end and shrinks by monomer removal from - end
What factors effect the growth and shrinkage of microtubules?
1) local concentrations of tubulin
2) Dynamic instability
3) Microtubule associated proteins (MAPs)
4) Temperature
5) chemicals that disrupt the dynamics
What is treadmilling?
When one end of the filament grows in length and the other end shrinks
-results in a section of the filament moving across the cytosol
What do MAPs do?
Microtubule associated proteins, regulate assembly and stability of microtubules. They stabilize the cell and attach to the positive end of microtubules
What direction does Kinesin move in?
+ positive direction
What direction does Dyenin move in?
- negative direction
What is required for movement?
ATP is required (fuelled by hydrolysis of ATP). The rate of movement is determined by the ATPase domain of motor protein and regulatory protein
Kinesis average step size
8.6 nm. Correction: 1.5um/sec
Dyenin average step size
8.9 nm. Correction textbook states that dyenin does not move faster and that they both travel the same speed
Correction: 1.7 um/sec
How does Kinesin walk?
Hand over and hand
How does Dynein walk?
More complex, was dragging the other foot
What are Cilia?
numerous, wavelike motion
What are flagella?
single or in pairs, whiplike motion. Composed of microtubules arranged into axoneme
Axoneme
Bundles of microtubules (hairs of microtubules) in the periphery of the flagella
-9 pairs of microtubules around the outside. IN the centre are pairs of microtubules. Dyenin can interact with these microtubules which causes movement on one side
What is the function of Cytokenesis?
Development and growth. Microtubules ensure the chromosomes are equally divided after mitosis
What is the function of the axon structure?
Nervous system. Microtubules support long axons
Function of vesicle transport?
Hormone and cell singling. Microtubules cary hormone from sites of synths to sites of release
What is the function of pigment dispersion?
Adaptive coloration, microtubules control the distribution of pigment granules throughout the cell to affect animal colour
What is the function of flagellar movement?
Reproduction. Flagella allow sperm to swim towards the egg
What is the function of cilia movement?
Respiration, digestion: cilia propel mucus and other fluids over the epithelial surface
What is Katanin?
Heterodimeric protein that destabilizes structure of microtubules and severes them
-KATNA1
