The response diminishes as deviations from this optimal length increases. These results are consistent with an optimal length of overlap, with associated cross-bridging, between actin and myosin filaments in the sarcomere as suggested by sliding filament theory. Introduction According to the sliding filament theory, (1) and (2), striated muscle contracts when cross-bridges between overlapping myosin (thick) and actin (thin) filaments initiate many independent filament micro-slides which result in shrinkage of the structural unit of the muscle fiber called the sarcomere. Evidence for this sliding theory was first observed in the constancy of the length of the sarcomere’s A-band under length variations of the sarcomere. The A-band has a region where actin and myosin filaments overlap.
| | | A) | endoplastic reticulum | | | B) | microtubules | | | C) | cytoplasm | | | D) | mitochondria | | | | | | Feedback: The cell's chemical processes take place in a semifluid material called the cytoplasm. This material provides an ideal environment for organelles because of its fluidity. | | 7 CORRECT | | This shows an example of endoplasmic reticulum. What is the significance of its structure? | | | A) | provides a location for DNA production | | | B) | helps decrease surface area | | | C) | allows selective permeability of cell membrane | | | D) | facilitates breakdown of chemical bonds | | | | | | Feedback: The pleats and folds of the endoplasmic reticulum provides a large surface area where cellular functions, such as breaking chemical bonds, can take place.
Cholesterol also makes the membrane less fluid by restraining the movement of phospholipids and lowers the temperature required to solidify the membrane. Complete depletion of cholesterol and sphingolipids results in cell death as their presence allows permeability to small molecules such as ions, glucose, and water. How does temperature affect lipid membrane? A membrane remains fluid as the temperature decreases, until it solidifies once it hits a critical temperature. The temperature at which a membrane solidifies depends on its fatty acid composition.
Drops of Liquid on a Penny Introduction: This experiment demonstrates the intermolecular forces between molecules of a substance. These forces are responsible for the observed surface tension in liquids. Surface tension is the phenomenon where strong forces between molecules cause the surface of a liquid to contract. Intermolecular forces result from the types of atoms bonded together in the compound and the shape of the molecule. When two different atoms are bonded together, each attracts the electrons differently like a tug-of-war between two unequal teams, producing a dipole.
Western Governors University UIT1- Task 2 Surface Tension Experiment Although we may not realize, surface tension plays a large role in our everyday life. Surface tension of a liquid refers to “the cohesive forces between molecules” in a given liquid (Surface Tension, n.d.). Basically, it is what holds the molecules in a liquid together. Different liquids have distinctive and dissimilar surface tensions. The question is, how can you determine which liquids have a strong surface tension and which have a weak surface tension?
Informative Essay on Earthquakes An earthquake, also known as a quake, tremor or temblor, is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are measured using observations from seismometers. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.
a. strain buildup only b. location of foci c. magnitude of P-waves [pic] d. reoccurrence rates of earthquakes in an area and the rate of strain buildup 2. What are most earthquakes associated with? a. rift valleys b. mid-ocean ridges c. divergent plate boundaries [pic] d. plate boundaries 3. At what point in the graph would a rock be permanently deformed? [pic] a. at the start of the stress [pic] b. past
This causes the rubber band to have an elastic limit which is caused when the molecules’ motion is stopped by these cross links. The disorder in the rubber band is described as its entropy, so when there is a high level of disorder of the molecules, there will be a high entropy level. When stretching occurs, the molecules line up and they uncoil from their original structures. This causes the molecules to become more ordered and so lowers the entropy. Heat is then given out when entropy decreases and therefore energy is lost.
The plates that are stuck become compressed and deform, this in turn builds stress and pressure (Murk, Skinner, & Mackenzie, 2010). The rocks eventually break or slip allowing the stuck plates to move (Murk, Skinner, & Mackenzie, 2010). When the rocks either break or slip the plates move once again (Murk, Skinner, & Mackenzie, 2010). This is what’s called elastic rebound and when they rube one another they produce what is known as “seismic waves that travel though the ground and shake the surface” (Lynch,
HSPs act as chaperones for other proteins and have two objectives: “Inhibit undesirable protein interactions and promote desirable protein interactions in order have stable bonds form between proteins”. HSPs bind to various proteins to perform a range of jobs by way of helping newly formed polypeptides to fold into their proper shape, disassembling polypeptides if they have been damaged and also chaperoning proteins to their intended associating proteins and keeping them from other interfering cellular processes and/or proteins. Primary role of HSPs: Keeping order is one way that HSPs maintain their key role of chaperoning other cellular proteins, guarding them from going astray. Two major families of molecular chaperones are HSP60 family and HSP70 family. HSP60 family (chaperonins): resembles a cage and has a highly hydrophobic inner rim that attracts amino acids with exposed hydrophobic regions of an unfolded protein to bind to it.