B/B 1

• The A-band is the region encompassing thick, myosin filaments. This region can also overlap with areas of thin actin filaments. The length of the A-band remains unchanged during skeletal muscle contraction. The I-band is the region exclusively containing thin, actin filaments. The H-zone is the region exclusively containing thick, myosin filaments. Both of these regions shorten in response to skeletal muscle contraction. The Z-line defines the boundaries of each sarcomere unit. It does not lengthen or shorten in response to skeletal muscle contraction.
• Microfilaments are composed of actin and are found in the cytoplasm of eukaryotic cells, as well as in muscle.
• Eukaryotic cilia and flagella are composed of bundles of microtubules.
• The unusual cyclic structure of proline creates a high degree of rigidity in the primary structure of a protein and disrupts the normal formation of alpha or beta secondary structures. Thus proline is much more likely to be found in the unstructured "turn" regions of a protein between the larger secondary structures.
• A low Kd (dissociation constant) value means that the ES complex does not readily dissociate into enzyme and substrate (in other words, it is relatively stable). The lower the Kd, the greater the enzyme-substrate binding affinity.
• A Hill coefficient that is greater than 1 indicates positive cooperativity.
• The cis double bonds impose a bent molecular shape. These bends make it more difficult for the fatty acid chains to stack, which decreases the amount of van der Walls forces and lowers the melting point.
• Temporal summation occurs when a single presynaptic neuron releases neurotransmitters to generate the action potential.
• Spatial summation occurs when multiple presynaptic neurons release neurotransmitters together to fire an action potential.
• Opsonization is the process by which antibodies bind to and recognize antigens on the surface of a pathogen. The antibodies then attract macrophages to phagocytose the invader.
• DNA is normally negatively supercoiled. This is naturally prevalent, because it prepares the molecule for processes that require separation of the DNA strands.
• TCA is another name for the Krebs, or citric acid, cycle. Increased concentration of ADP signals that more ATP is needed. Therefore, the citric acid cycle enzyme in question will be activated by the presence of ADP.
• Tubulin is the main constituent of microtubules.
• Capillaries are the smallest blood vessels in the body, with walls that are composed only of a single layer of endothelial cells. 
• In eukaryotic cells, where is the highest local concentration of phosphorus likely to be found? Nucleus
• Cholecystokinin (CCK) acts in the small intestine upon the entry of food into the duodenum from the stomach. This peptide hormone functions to aid a series of processes involved in digestion. Among these are stimulating pancreatic acinar cells to release digestive enzymes, stimulating feelings of satiety (fullness) to suppress hunger, inhibiting stomach emptying, and lowering gastric acid secretion. Somatostatin, aka growth hormone inhibiting hormone, is a hormone that inhibits the release of CCK.
• The cerebellum receives information from sensory systems and then regulates fine motor movements. Thus, it coordinates posture, balance, fine motor coordination (like opening a bottle), and speech.
• The introduction of a premature stop codon is a nonsense mutation.
• The stomach arises from the endoderm. The ovaries arise from the mesoderm.
• The ectoderm primarily gives rise to the nervous system and epidermis (skin), as well as related structures like hair, nails, and sweat glands, and the linings of the mouth, anus, and nostrils. 
• The mesoderm generates many of the structures present within the body, including the musculature, connective tissue (including blood, bone, and cartilage), the gonads, the kidneys, and the adrenal cortex.
• The endoderm is basically responsible for the interior linings of the body, including the linings of the gastrointestinal system, the pancreas and part of the liver, the urinary bladder and part of the urethra, and the lungs.
• In the pentose phosphate pathway, the oxidative phase begins with glucose 6-phosphate. During the oxidative phase, each mole of glucose 6-phosphate is converted to one mole of ribulose 5-phosphate, and one mole of carbon is lost in the form of CO2.
• The sense strand is never transcribed into RNA; only the antisense strand is. Transcription of DNA to RNA always takes place by transcribing DNA onto an antiparallel RNA strand.
• The conversion of fumarate to malate is a key step in the citric acid cycle, which occurs in the mitochondrial matrix of the cell.
• Controls in which we expect to see no change are called negative controls.
• Fermentation, gluconeogenesis, glycolysis take place in the cytosol.
• The cytochrome c oxidase complex (complex IV) is the last enzyme of the electron transport chain. It receives one electron from each of four soluble cytochrome C molecules, transferring them to a single oxygen molecule and thus converting one O2 molecule into two molecules of water.
• NADPH is produced only in the oxidative phase of the pentose phosphate pathway.
• Oxidative phase is irreversible in the pentose phosphate pathway.
• Non-oxidative phase is reversible in the pentose phosphate pathway.
• Ribulose 5-phosphate (pentose phosphate pathway)

  Product of both the oxidative and non-oxidative pathways
• Ribulose 5-phosphate can be converted to ribose 5-phosphate. Ribose 5-phosphate can be used to make nucleotides (pentose phosphate pathway).
• Oxidative phase (pentose phosphate pathway)

  1. Converts six-carbon glucose 6-phosphate to five-carbon ribulose 5-phosphate

  2. Loses a carbon dioxide molecule
• No carbon dioxide is lost in the non-oxidative phase of the pentose phosphate pathway.
• The non-oxidative phase of the pentose phosphate pathway yields more moles of ribulose 5-phosphate per mole of glucose 6-phosphate than the oxidative phase.
• Which cytoskeletal component forms the majority of the outer layer of skin? Intermediate filaments
• Somatostatin is a peptide hormone secreted by delta cells of the pancreas. It inhibits both insulin and glucagon and its release is triggered by high glucose and amino acid levels.
• Epinephrine, which is involved in the fight-or-flight response, provides the body more access to glucose. Specifically, epinephrine activates a G protein-coupled signal transduction pathway that activates glycogen phosphorylase (the enzyme involved in glycogen degradation) and inactivates glycogen synthase (the enzyme involved in glycogen synthesis). 
• Reliability refers to how consistent and repeatable an experiment or assessment is. Validity is a measure of how well a given experiment actually measures what it sets out to measure.