Understanding Biomembranes: Structure, Function, and Properties
Understanding Biomembranes
A necessary condition for life is the existence of a barrier separating cell contents from the environment, since the cells must retain an internal environment appropriate to carry out the numerous chemical reactions necessary to sustain life. Biomembranes are the place where many chemical reactions take place. They regulate the entry and exit of materials from the cell. Some membranes are selectively permeable barriers that regulate the flow of molecules inwards and outwards,
Read MoreSmall and Large Intestine: Composition, Function, and Models
Composition and Function of the Small Intestine
Digestion within the small intestine produces a mixture of disaccharides, peptides, fatty acids, and monoglycerides. The final digestion and absorption of these substances occur in the villi, which line the inner surface of the small intestine.
- The crypts at the base of the villi contain stem cells that continuously divide by mitosis, producing:
- More stem cells
- Cells that migrate up the surface of the villus while differentiating
- Columnar epithelial cells
Antioxidants and Oxidative Stress in Exercise
Sources of Oxidative Stress
- Uncoupling of the electron transport chain: 2-5% of the total electron flux escapes the respiratory chain to make O2-. Exercise increases ATP demand. O2 uptake can increase 20-fold. O2 flux through active muscle may increase 100-fold. So there is an increased possibility.
- Ischemia-reperfusion: Intense exercise can lead to tissue hypoxia. Hypoxia promotes an excess of electron donors, NADH. Xanthine oxidase. After a period of ischemia, an increased neutrophil infiltration
Human Digestion: Enzymes, Absorption, and Assimilation
Why is Digestion of Large Food Molecules Essential?
Firstly, the food we eat is made up of many compounds produced by other organisms. Not all of these are suitable for human tissues. Therefore, these compounds have to be broken down and reassembled so that our bodies can use them. Secondly, food molecules must be small enough to be absorbed by the villi in the intestine through diffusion, facilitated diffusion, or active transport. Consequently, large food molecules need to be broken down into smaller
Read MoreBiotechnology and Genetic Engineering: Applications and Impact
Biotechnology and Genetic Engineering: Applications and Impact
Biotechnology is the use of biological processes to obtain goods and services from living organisms. The oldest examples are fermentations, such as the production of alcohol in wine, lactic acid in milk, or acetic acid in vinegar.
Genetic Engineering: A Powerful Tool
Genetic engineering is a technology for obtaining goods and services that emerged following the discovery of DNA. Its applications are significant, including the synthesis
Read MoreCell Membrane Structure: Lipids, Proteins, and Fluidity
Cell Membrane Structure
The plasma membrane, a thin layer of lipids and proteins, separates a cell from its surrounding. To maintain their internal environment, the cells of all organisms must constantly exchange molecules and ions with the fluid environment that surrounds them. Transport proteins move particular ions and molecules, including water, in a directed way across the membrane.
Lipids in Biological Membranes
Biological membranes consist of lipids. Phospholipids and sterols (such as cholesterol)
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