Active transport requires energy in the form of ATP and protein carriers to move the molecules across the membrane. The ATP formed as part of respiration is used in a wide variety of contexts for biology. For example, in order for an animal to move and hunt for food within its environment, it has to contract muscle tissue. The tissue is composed of cells containing actin and myosin filaments which move relative to eachother to contract a sarcomere. For this to happen, actomyosin cross-bridges form between the actin and myosin.
One example of where this would occur is glucose absorption into the blood. In active transport, once molecules have bound to carrier proteins, ATP binds to the protein and is broken into ADP and Pi. This provides energy for the protein molecule to change shape and open to the other side of the membrane. This moves molecules against the concentration gradient. ADP and Pi then recombine and cause the protein to revert back to its original shape.
The myosin head stays bound until a new ATP molecule binds to it. The next ATP causes the head to be released from the actin, which results in another power stroke. The stimulus stops. Ach is diffused through the synaptic cleft, CA2+ is transported back into the sarcoplasmic reticulum, and tropomyosin shifts to conceal the myosin binding sites. The sarcomeres slide back to their initial
| | | |The protein ___myosin____consists of two twisted strands with globular cross-bridges projected outward along the strands. | |__actin___ is a globular protein with myosin binding sites. What two proteins are associated with it? Troponin and tropomyosin | |According to the sliding filament theory of muscle contraction, if allowed to, the myosin crossbridge attaches to the binding site on the actin filament | |and bends, pulling on the actin filament; it then releases and attaches to the next binding site on the actin, pulling again. What is preventing this from| |happening continuously?
Depending on if the cell is an animal cell or a plant cell. | | Cytoskeleton | Cytoskeleton has intercellular proteins that help the cell maintain its shape and with helps with movement. | The word skeleton in Cytoskeleton reminds me of the meaning. | K Key Idea | I Information | M Memory Clue | Ribosomes | Ribosomes are protein builders. | The word Ribosomes remind me of Ribs.
The Muscular System: Sliding Filament Theory 1. a. The thick filament is composed of what molecule? __________Myosin_____________ b. Flexing the head of this molecule provides what is known as the ________Power Stroke_________________. 2. The myosin head contains binding sites for what two molecules?
It is the general supporting or packing tissue of the body. The type is loosely woven & has a gelatinous (protein containing glue like substance) substance between cells. Fatty tissue or Adipose – this type is made up of globules of fat that are found in thin membranous envelopes. It is found under the skin around the kidneys, bone marrow & the heart. It can provide protection, insulation & reserve food.
In describing the cellular components of skeletal muscle, several specialized terms are used such as the plasma membrane of skeletal muscle is called the sarcolemma; its cytoplasm is known as sarcoplasm; the endoplasmic reticulum is called the sarcoplasmic reticulum. The term motor unit is used to describe a group of muscle fibers innervated by a single motor nerve, the fibers within a single motor unit contract simultaneously (Van and Marleen,2000). Each muscle cell is surrounded by a sarcolemma and has many nuclei occurring at intervals along its length. The nuclei are displaced peripherally within a cross section of the sarcoplasm while a large number of longitudinal myofibrils, groups of arranged contractile proteins, occupy most of the center space(Tortora and Derrickson,2011). Based on nerve stimulation studies, skeletal muscles are divided into two muscle fiber types, the first type is called Slow-twitch muscle fibers which mainly rely on aerobic metabolism.
They are attached through myristoylation, palmitoylation, or isoprenylation. What are the lipid rafts? How do they form and what is their function? A lipid raft is a membrane domain which is enriched in sphingolipids and cholesterol (liquid ordered phase). Rafts are postulated to grow by accumulation of cholesterol, sphingolipids, and GPI-anchored proteins.
These dimers add on to the ends of a microtubule allowing the molecule to increase in size (Campbell & Reece, 2004). GTP irreversibly binds to the GTP-binding site positioned on α-tubuline where it does not become hydrolysed. On the other hand GTP reversibly binds to the binding site on β-tubuline where hydrolysis converts GTP into GDP (W.H.Freeman & company, 2000). Microtubules are involved in various different cellular activities such as flagellar and ciliary motion, maintenance and determination of the shape of a cell, cell division and chromosome movement. Because they create movement within the cell, both the cell as a whole and its subcellular components have the ability to move from one place to another (Kleinsmith & Kish, 1988) [pic](W.H.Freeman & company, 2000) Patients who suffer from Parkinson’s disease have a protein called alpha-synuclein in their brain.