Bio6 Flashcards
Biological molecules
Nutrition is the science of how nutrients in food affect health. Macromolecules, needed in large amounts, are proteins, carbs, and lipids. Carbs are broken down into glucose and excess carbs are stored as fat. Lipids are made of a glycerol and fatty acid chain. They store energy for later use and provide insulation and even make up some hormones. Three types of lipids are saturated fats which are unhealthy, unsaturated fats which are healthy, and hydrogenated unsaturated fats called trans fat that is also unhealthy. Proteins are building blocks that are made of amino acids. They also function as enzymes. Micronutrients, needed in small amounts, are vitamins and minerals. Minerals are inorganic and vitamins are organic like the macronutrients. Minerals play a role in cell processes like bone formation or muscle contraction. Mg supports enzyme activity. Vitamins can be water soluble or fat soluble. Water soluble vitamins cant be stored in the body, and fat soluble vitamins are not easily eliminated. They are stored for later use. Water is not a source of energy many substances can dissolve in it and it does things like flushing toxins or lubricate tissues, so the body is 60 percent water.
The digestive system
Ingestion, digestion, absorption and elimination are four main steps of digestion. Simple animals have a digestive sac with a single opening for both ingestion and elimination, but more complex animals have a tract with two openings called a complete digestive system. mechanical digestion which occurs in the mouth and stomach is the physical breakdown of food into smaller pieces. It starts in the oral cavity which includes the pharynx, where the food surface area is increased. Chemical digestion which occurs in the mouth and stomach and intestine is the breakdown of macromolecules by enzymes. In the mouth, salivary glands secrete saliva to break down food. The cardiac sphincter connects the esophagus to the stomach and prevents food from going backward. The stomach, which can hold 1.5 L of food, is where bolus becomes chyme. Its churns food and its glands secrete enzymes to break food down. Pepsin digests proteins and rennin which is only in kids absorbs nutrients from milk. Smoking relaxes the cardiac sphincter and stimulates acid production contributing to heart burn. The small intestine is 6 meters long and has villi and microvilli that are filled with capillaries where blood absorbs the nutrients. The chemical digestion is done by enzymes that are added in the duodenum. They break molecules down so they can be absorbed in the ileum and jejunum.The acidity of chyme triggers the duodenum to release secretin, which signals the pancreas to release bicarbonate ions that neutralize the HCL in the duodenum. The pancreas also releases lipase which breaks down fats, amylase which breaks down disaccharides, and trypsin which breaks down protein. Sucrase, maltase and lactase digest sugars. The stomach and intestines have four layers: the mucosa, submucosa, muscularis externa and serosa. The liver is about 3 pounds and detoxifies blood of stuff like alcohol. By the time food gets to the large intestine most of the nutrients have been absorbed. The large intestine has a smooth mucus lining to help food move through it. It absorbs water and salt. It also contains about 500 species of bacteria that make important substances like vitamin B. Fibers is indigestible, but important beca they help us feel full and aid in egestion. Nerves in the gut wall initiate the defecation reflex. Stool is 75% water. Our bodies can make vitamin A, D, and K.
Bacteria
Bacteria have a flagellum, hairs called pili that transfer their nonessential DNA (plasmids) during conjugation and a cell wall surrounded by a capsule. Their cytoplasm has ribosomes and a nucleoid. They like warm environments and can be either autotrophic or heterotrophic. They are classified by cell shape (cocci or bacilli or spirochetes), cell wall (gram positive if purple in a gram stain gram negative if pink), motility (roll or glide or with flagella) or metabolism (obligate aerobes, obligate anaerobes or facultative anaerobes). Gram positive bacteria are used in food. Bacteria are essential for foods like cheeses and chocolate. They also make antibiotics to kill competing bacteria. bacteria have also developed resistance to antibiotics through mutation of horizontal gene transfer, the transfer of dNA between non related organisms. They reproduce via binary fission which is when a cell splits into two identical cells, conjugation which is when a cell passes a plasmid to another through pili, transformation which is when a cell picks pieces of DNA from its surroundings or transduction which is when DNA is injected into the cell by a virus. The last three increase genetic diversity. Reproduction can happen in twenty minutes. Six groups of bactérie are chlamydias, gram positive bacteria, Spirocetes, Proteobacteria, green bacteria And Cyanobacteria. The last three are photosynthetic, and Cyanobacteria photosynthesize most like plants. Photosynthetic bacteria are producers in marine ecosystems. Bacteria turn into dormant forms called endospores during periods of stress.
