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Pores and Ion Channels

By: HWC, Views: 5871

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...

Structures of the Eye Animation

By: Administrator, Views: 1488

Orbit A cone-shaped cavity in the front of the skull that contains the eyeball. Formed by the combination of several bones and is lined with fatty tissue that cushions the eyeball. This cavity has several foramina (openings) through which blood vessels and nerves pass. Largest opening is the ...

Retina

By: Administrator, Views: 9820

Eye Composed of special anatomical structures that work together to facilitate sight: Cornea Pupil Lens Vitreous body Light stimulates sensory receptors (rods and cones) in the retina or innermost layer of the eye. Vision is made possible through the coordinated actions of nerves that co...

ribosome

By: HWC, Views: 6308

The trp operon in E. coli contains five structural genes corresponding to enzymes that convert chorismate into tryptophan. The trpE gene contains a 5' untranslated region that plays an important role in the regulatory mechanism called attenuation. The 5' UTR contains four regions. Region 1 en...

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

By: HWC, Views: 6552

• 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...

Stages of Mitosis - Prophase, Prometaphase, Metaphase, Anaphase & Telophase

By: HWC, Views: 6272

In mitosis, the nucleus divides to produce two nuclei that are genetically identical to each other and to the parent nucleus. To prepare for division, the DNA replicates in the preceding interphase. Although the chromosomes are not yet compacted and visible as discrete bodies, we illustrate them ...

Central Nervous System Animation

By: Administrator, Views: 9704

Consists of the brain and spinal cord. CNS receives impulses from throughout the body processes the information responds with an appropriate action Brain and spinal cord can be divided into: gray matter (unsheathed cell bodies and true dendrites) white matter (myelinated nerve fibers) ...

Contraction cycle of a sarcomere

By: HWC, Views: 7151

• A single nervous signal releases Ca2+ ions into the sarcoplasm and initiates the contraction cycle. step 1. ATP hydrolysis • ATP provides the to move myosin molecules back into the energized configuration necessary to perform the power stroke. Step 2. Crossbridge attachment • Myosin...

Proteins Defined, Hierarchy & Composition of Cells

By: HWC, Views: 6133

Proteins are long chains of amino acids linked together by peptide bonds. Together with the other three biological macromolecules—carbohydrates, lipids, and nucleic acids—proteins are the building blocks of cells. Proteins are the most complex and abundant biological macromolecules in cel...