Search Results

Type of Cell Junctions - Desmosome, Hemidesmosomes and Gap Junctions

By: HWC, Views: 8074

Cell Junctions: Cell junctions are found in some multi-cellular organisms. They exist of complexes and are found between cells and between cells and other structures. The junctions provide a way for cells to connect and exchange signals. What are tight junctions, desmosomes, and gap junctions...

What are the Parts of a Plant Cell?

By: HWC, Views: 6775

Every chloroplast in a plant cell is packed with stacks of flattened sacs called thylakoids. The thylakoid membranes contain chlorophyll, as well as most of the other components required for the light reactions of photosynthesis. The chlorophyll-containing structures within the membranes are c...

Types of Transport - Uniport, Antiport and Symport (Glucose and Na+K+ Transporters)

By: HWC, Views: 7388

Some transport proteins bind and transport molecules very selectively. Uniport is the transport of one solute molecule. Symport is the transports of two solute molecules in the same direction. Antiport is the transports of two solute molecules in opposite directions. 1. Glucose bin...

Bond in biological molecules (Ionic, Covalent and Hydrogen bonds)/ How atoms bond?

By: HWC, Views: 5062

Sodium atoms and chloride atoms have unfilled orbitals in their outer shells. The lone electron in the outermost shell of a sodium atom can be pulled or knocked out. This ionizes the atom. It is now a positively charged sodium ion. A chlorine atom has an electron vacancy in its outer shell and...

Oxygen transport: association and dissociation & Factors that affect hemoglobin's saturation with O2

By: HWC, Views: 7668

• The production of oxyhemoglobin can be illustrated through the following reaction: 02 + Hb-H --) Hb-02 + H+ • This equation represents the binding of oxygen to the iron ions in heme groups in hemoglobin molecules. • Oxygen binding or loading occurs at the lungs • The dissociatio...

Bone cells and tissues - tissue composition and cells

By: HWC, Views: 8556

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...

Nucleic acid digestion - brush border enzymes, end products & transport mechanism

By: HWC, Views: 7509

• Further digestion occurs at the microvilli (brush border) of the epithelial cells of the villi in the small intestine. • Two brush border enzymes complete nucleic acid digestion: • Phosphatases, which catalyze the cleavage of a phosphate to form a nucleoside (nitrogenous base and pent...

Angiotensin II - kidneys, adrenal glands and dehydration

By: HWC, Views: 7846

• Angiontensin II targets cells in the proximal convoluted tubule of the nephron. ■ The reabsorption of Na+ and Cl- ions sets up an osmotic gradient favoring the retention of water. • Decreases urine production and increases blood volume and pressure. • Angiontensin II targets zon...

Medullary osmotic gradient: countercurrent multiplier, urea recycling & vasa recta countercurrent exchange

By: HWC, Views: 8427

▪ The primary cause of the medullary osmotic gradient is the active transport of solutes. • In the ascending limb of the loop, active transport of Na+ ions drives passive reabsorption of Cl- ions. • Addition of these ions to the interstitial fluid of the medulla increases its osmolarity...