What raw materials are used in metabolism? The foods we eat, including carbohydrates, protein, and fat, are the sources of raw material that are metabolized inside the cell. What role does ATP play in anabolism and catabolism? Anabolism requires an input of ATP; catabolism releases energy that is eventually converted into ATP.
In Figure A, the raw materials arrive at the factory. Figure B illustrates anabolismamino acids are linked together to form a protein, like building a brick wall. Figure C illustrates catabolisma protein is broken down into individual amino acids, like knocking down a brick wall.
Carbohydrates are classified according to size. Monosaccharides and disaccharides are called sugars; polysaccharides include starches, glycogen, and cellulose.
Monosaccharides contain three to six carbons. What are the three six-carbon simple sugars? They are glucose, fructose, and galactose. Glucose is the most important of the three and is an immediate energy source. For what are the five carbon monosacharides used? They are used in the synthesis of DNA and RNA.
Disaccharides are made when two monosaccharides are linked together. They must be broken down into monosaccharides before they can be absorbed and used by the cells.
Polysaccharides are made of many monosaccharides linked together in straight chains or branched chains. Plant starch, glycogen, and cellulose are the three polysaccharides of interest to us. Glycogen is the form in which humans store glucose. It is also called animal starch and is stored primarily in the liver and skeletal muscle.
After you eat a sugary snack and your body digests and absorbs it, your body can use the sugars in one of the three ways listed on the slide.
Glycolysis is an anaerobic process and occurs in the cytoplasm. Aerobic metabolism occurs within the mitochondria.
In glycolysis, glucose is catabolized completely: a small amount of ATP is produced in the anaerobic process. In an aerobic situation, glucose is completely metabolized into carbon dioxide, water, and ATP. After glucose is broken into pyruvic acid, it moves into the mitochondria where enzymes break the pyruvic acid fragments into carbon dioxide and water. The mitochondria contains the enzymes of the Krebs cycle and those of the electron transport chain. A great deal of ATP is produced aerobically.
Oils are liquid at room temperature, and fats are solid at room temperature. Refer students Table 4-2 and ask them to identify other lipid types. Examples are types of steroids (cholesterol), fat-soluble vitamins (A, D, E, and K), and lipoproteins.
Triglycerides have three long chains of fatty acids attached to one small glycerol molecule. Phospholipids form when phosphorus-containing group attaches to one of the glycerol molecules. The third type of lipid is the steroid.
The body needs and uses lipids, but it can also put fats into long-term storage or deposit them inside blood vessels. Excess fat is deposited in adipose tissue throughout the body. Discuss LDL (bad cholesterol), VLDL, and HDL (good cholesterol).
Refer students to Table 4-4 and ask them to identify several physiological processes controlled by proteins. Examples include hemoglobin transporting oxygen and muscle proteins enabling the muscle to contract.
Every amino acid contains an amine group and an acid group. Ask students to identify the amine group and the acid group in Figure 4-5. Portion B of the slide illustrates the assembly of many amino acids to form peptides and polypeptides. Proteins are very large polypeptides. A peptide bond is formed when the amine group of one amino acid joins the acid group of a second amino acid.
More than half of the amino acids can be synthesized by the body. Both essential and nonessential amino acids are needed by the body; these terms refer to the body’s ability to synthesize them. Refer students to Table 4-3 and ask them to identify common essential and nonessential amino acids. Examples are tryptophan (essential) and alanine (nonessential).
Using protein as a source of energy for ATP production is not desirable. Carbohydrates and fats are better energy sources. Gluconeogenesis is the process of breaking down protein and converting it to glucose. Why is gluconeogenesis important in understanding blood glucose regulation? The body uses gluconeogenesis to ensure that the blood glucose level does not become too low.
The liver forms urea from the nitrogen released by the breakdown of amino acids. Blood transports urea to the kidneys, which eliminate it in the urine. It should be noted that ammonia (NH3) is toxic to the body.
Amino acids must be precisely arranged for protein synthesis. Where is the pattern of amino acid assembly coded and stored? It is coded and stored within the deoxyribonucleic acid (DNA) in the nucleus of the cell. The two strands of nucleotides form a double helix of sugar-phosphate molecules. The rungs are made of one base from each side.
Adenine pairs with thymine, and cytosine pairs with guanine Adenine and guanine are purines. Cytosine, thymine, and uracil are pyrimidines.
The code for protein synthesis is encoded within the sequence of bases in one strand of DNA. Figure 4-8 shows the base sequences for single amino acids. This is the code that will later be copied by messenger RNA (mRNA).
The slide shows the code on the DNA strand that will be copied by mRNA.
tRNA (transfer RNA) can read the code on the mRNA and transfers the amino acids in the proper order so that protein synthesis can be completed.
This slide and the next slide summarize the entire process of protein synthesis. DNA and RNA control protein synthesis by following the five steps listed on this slide.
Transcription is the copying of the separated DNA strand onto a strand of mRNA. Translation is the reading of the mRNA code by the rRNA. At the end of the process, a complete protein has been created and is ready for the cell to use or export to another site.
The Human Body in Health and
Illness, 4th edition