Search Results

Secondary and tertiary levels of protein structure Animation

By: HWC, Views: 1657

Amino acid sequence dictates a protein's final shape. The presence of certain amino acids favors a pattern of hydrogen bonding that causes part of the polypeptide chain to coil and twist into an alpha helix. The presence of other amino acids enables hydrogen bonding between strand like re...

Pores and Ion Channels

By: HWC, Views: 6922

Transmembrane channels, also called membrane channels, are pores within a lipid bilayer. The channels can be formed by protein complexes that run across the membrane or by peptides. They may cross the cell membrane, connecting the cytosol, or cytoplasm, to the extracellular matrix. Membrane po...

Major Elements in Biological Molecules: Carbohydrates

By: HWC, Views: 7279

Carbohydrates include simple sugars (monosaccharides) as well as large polymers (polysaccharides). Glucose is a hexose, a sugar composed of six carbon atoms, usually found in ring form. A starch macromolecule is a polysaccharide composed of thousands of glucose units. Glucose molecules can be ...

The Pressure Flow Model in a Plant

By: HWC, Views: 7121

The vascular system of plants has two transport tissues, called xylem and phloem. Xylem transports water and minerals, while phloem transports a variety of dissolved substances, including sugars and amino acids, throughout the plant. Water in the xylem always moves up, in the direction from th...

Status Epilepticus

By: Administrator, Views: 10723

Status epilepticus (SE) is a single epileptic seizure lasting more than five minutes or two or more seizures within a five-minute period without the person returning to normal between them. Previous definitions used a 30-minute time limit. The seizures can be of the tonic–clonic type, with a re...

Membrane transport proteins - pores, gated channels and pumps

By: HWC, Views: 7860

• a Three different types of membrane ion transport proteins are required to produce and carry electrical signals: • Pores • Gated channels • Na+/ K+ pump • Pores are always open and allow the diffusion of Na+ and K+ ions across the membrane, down their concentration gradients...

Neural Reflex Arc Animation

By: Administrator, Views: 10945

A reflex arc is a neural pathway that controls a reflex. In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the bra...

Electromagnetic Spectrum, Chlorophyll and Pigment & Light

By: HWC, Views: 7517

The sun gives off radiation that is called the electromagnetic spectrum. This is energy that travels as wavelengths and includes radio waves, X-rays and ultraviolet light. A portion of this radiation is known as visible light, and is the type of radiation that plants use to manufacture sugars. ...

Non-specific disease resistance mechanisms & Skin's defense barriers

By: HWC, Views: 7728

• Non-specific disease resistance acts quickly to fight a wide variety of invaders. • Mechanisms include: • Barriers • Antimicrobial substances • Cellular defenses • Inflammation • Fever Barriers - types • Physical and chemical bathers prevent invasion by micro...