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Atrophy

By: Administrator, Views: 9466

Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, excessive amount of apoptosis of c...

HIV replication/ Replication cycle of HIV

By: HWC, Views: 3804

Replication cycle of HIV, one of the retroviruses. The HIV virus is surrounded by a lipid envelope with embedded proteins. A coat of viral proteins surrounds two strands of RNA and the enzymes used during replication. The virus attaches to and enters the host cell. Viral reverse trans...

Mitosis step-by-step

By: HWC, Views: 4586

During interphase, the chromosomes will be duplicated in preparation for mitosis, which divides the chromosomes, and cytokinesis, which divides the cell's cytoplasm. In early prophase, the duplicated chromosomes begin to condense. Each chromosome consists of two sister chromatids joined at the...

Glycolysis - Introduction to ATP and the burning of sugar

By: HWC, Views: 6751

Do you use sugar with your coffee or tea? Or do you occasionally drink a sport or soft drink? As millions of people do each day, they obtain energy from the sugar added or contained in these drinks. How can we understand this concept of energy within a sugar molecule? Let's take a tablespoon ...

Rods and Cones Animation

By: Administrator, Views: 10081

A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes...

Body plan of euglena Animation

By: HWC, Views: 992

Euglenoids are single-celled organisms that live in lakes and ponds. A contractile vacuole pumps out the water that diffuses into the cell from its hypotonic surroundings. The body is covered by a translucent pellicle composed of flexible strips of a protein-rich material. Light passe...

Plant Defense Mechanisms from Pathogens

By: HWC, Views: 6103

Plants and pathogens have coevolved such that pathogens can recognize plants by the sugars, or other molecules, they produce. Plants, in turn, can recognize pathogens by the molecules they produce. The ability to recognize pathogens allows plants to activate defense systems that can prevent wides...

Membrane transport proteins - pores, gated channels and pumps

By: HWC, Views: 6754

• 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...

Gas exchange - partial pressure, locations, external and internal respiration

By: HWC, Views: 6813

▪ In a mixture, each individual gas exerts a pressure that is proportional to the concentration of that gas within the mixture. • This part of the total pressure is called a "partial pressure". • A gas moves along the part of the pressure gradient determined by its own concentration. ...