Maintaining A Balance Essays - Biology, Animal Physiology

Maintaining A Balance Most organisms are active in a limited temperature range Enzymes: Biological catalysts. A specific enzyme controls every reaction and process within a cell. Enzymes control all the chemical processes of living systems. Enzymes are proteins made up of amino acids that are linked and then folded to produce a three-dimensional protein structure. Most metabolic processes would not occur at an efficient rate without enzymes. One model used to illustrate the action of an enzyme is the lock-and-key model. Enzymes are unique to one substrate The enzyme combines with the substrate to form an enzyme-substrate molecule. This somehow alters the substrate so that a chemical reaction can occur. The substrate is then altered and no longer fits' the enzyme - the enzyme is released. -34290024193500 - Effect of temperature on enzymes: each has an optimum temperature for activity. High temperatures can denature enzymes. - Effect of pH on enzymes: each has an optimum pH (acidity level) for activity. Changing the pH from the optimum reduces the enzyme's activity. - Effect of substrate concentration on enzymes: substrate concentration means the amount of compound present that the enzymes catalyses. Beyond certain substrate concentrations, the rate of reaction is limited by the amount of enzyme. pH as a way of describing the acidity of a substance: A measure of the concentration of hydrogen ions that are released by acids, therefore a way of describing the acidity of a substance. A pH value of 0-6 indicates an acid solution, a pH value of 8 - 14 indicates a basic (alkaline) solution. A pH of 7 indicates a neutral solution. Procedures to investigate the activity of an enzyme: Aim: to demonstrate the effect of increased temperature on the enzyme, rennin Method: make a rennin solution by dissolving a junket tablet in distilled water. Add the same amount of rennin solution to a number of test tubes of milk. Place test tubes in different water baths with different temperature ranges (0-60), making sure each water bath is kept at its allocated temperature. Time the interval between adding the rennin and curdling of the milk for each temperature. Results: The optimum temperature for curdling milk is 30-40 degrees. Anything above that optimum temperature will denature the rennin, preventing it from curdling the milk. Anything below the optimum temperature won't work as effectively. Maintenance of an optimal internal environment: Enzymes control all the metabolic processes in the body. Despite the internal and external changes occurring in the body, organisms need to maintain a constant internal environment for optimal metabolic efficiency. Enzymes work optimally in an environment where their optimum temperature and pH conditions are met. At temperatures and pH values other than the optimum, the enzymes fail to work as they should or not at all. The maintenance of an optimal internal environment is important for optimal enzyme efficiency. Homeostasis: The process by which organisms maintain their internal environment regardless of the external environmental conditions. Through homeostasis, organisms maintain an internal equilibrium by adjusting their physiological processes. Homeostasis ensures that the organism operates at maximum performance. To maintain homeostasis, this involves: A receptor: constantly monitors the internal environment, which may reflect the external environment A control centre: monitors the information passed on from the receptor An effector: carries the message from the control centre. Hypothalamus: the control centre for maintaining homeostasis. Homeostasis as a two-stage process: Coordination in animals is controlled by two systems; the nervous system and the endocrine system A feedback mechanism is self-regulating, which maintains balance or homeostasis. For a state of homeostasis to exist, the body must have some way of detecting stimuli that indicate a change in the body's internal or external environment. - Stage 1 - Detecting changes from the stable state: A receptor detects a change in some variable in the organism's internal environment. If our body temperature rises, the temperature rise in the blood stimulates the brain's anterior hypothalamus. Alternatively, when a mammal is exposed to cold, skin receptors increase their activity, sending nerve impulses to the posterior hypothalamus. - Stage 2 - Counteracting changes from the stable state: An appropriate response occurs that counteracts the changes and thus maintains the stable environment. After detecting the rise in body temperature, the hypothalamus then stimulates heat loss by blood circulation through the skin, sweating and metabolic activity, thus