Search results for: 'pH'

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By: Administrator, Views: 11800

The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is no...

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Embryonic development - week 1 and 2

By: HWC, Views: 7700

The first through eighth weeks after fertilization are called the embryonic. Week 1 • Within a day, the zygote begins mitotic cell division (cleavage) forming blastomeres. By the 4th day, the blastomeres have formed a solid ball called a morula. • The morula enters uterine cavity ar...

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Role of ATP in muscle movement

By: HWC, Views: 7829

• Muscle cells use ATP to power contraction and movement. • The hydrolysis of ATP to ADP releases • ATP can be regenerated by adding to ADP. • During muscular contraction, ATP molecules: • Energize the myosin head • Detach myosin from actin • ATP must be then regenerat...

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Energy sources - types

By: HWC, Views: 7924

• The amount of ATP stored in a skeletal muscle cell can only provide muscular activity for two to three seconds. • Muscle cells must be able to generate additional molecules of ATP to continue contracting. • Muscle cells can generate ATP from several processes: • Phosphogen syste...

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Simple Diffusion - gases and nonpolar compounds transport

By: HWC, Views: 8049

Gases and some molecules can diffuse through the phospholipid bilayer because they are small or non-polar. Oxygen gas. Carbon dioxide gas. Lipid based hormones. Plasma membranes are selectively permeable: The lipid bilayer is always permeable to small, nonpolar, uncharged molecules ...

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Osmosis - water transport

By: HWC, Views: 7861

Osmosis is the flow of water down its concentration gradient, across a semi-permeable membrane. Osmosis is an example of diffusion, which is when molecules tend to distribute themselves evenly in a space. what is a semi-permeable membrane? It is a membrane or barrier that allows some molec...

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Endocytosis -Types and Phagocytosis

By: HWC, Views: 7770

Endocytosis is the process by which a substance is brought inside a cell without having to pass through the cell membrane. It is the opposite of endocytosis, the process by which substances exit the cell without having to pass through the cell membrane. Exocytosis – membrane-enclosed secret...

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Endocytosis - pinocytosis, receptor mediated and Transcytosis

By: HWC, Views: 7623

Pinocytosis is the process in which a cell "drinks" a tiny droplet Of extracellular fluid, including its solutes. Pinocytosis (Cell Drinking) is the process by which the cell takes in fluids (as well as any small molecules dissolved in those fluids). • The plasma membrane folds inward to...

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Bone cells and tissues - tissue composition and cells

By: HWC, Views: 8571

Bone tissue consists of bone cells secreting bone matrix. • The extracellular bone matrix is a connective tissue that is hard, yet flexible. • Collagen fibers provide flexibility. • Inorganic mineral salts (primarily calcium phosphate, or hydroxyapatite) provide hardness. • Togethe...

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