Biology: Topic 7 Flashcards
Glycolysis: Aerobic system
Glucose is broken down into 2 glyceraldehyde-3-phosphate, which requires 2 ATP. This then converts into 2 pyruvate, producing 4 ATP and 2 NADH.
Anaerobic system
After glycolysis, the pyruvate is converted into lactate using the hydrogen from the NADH.
Link reaction
Pyruvate undergoes decarboxylation (releases CO2) and is converted into an acetyl group. This is carried into the Kreb cycle by coenzyme A. Produces 2 NADH.
Kreb Cycle
Acetyl are added to a 4 carbon compound to from citric acid (6 carbon). This converts to a 5 carbon compound then 4, then another 4 and back to the beginning. Overall, 3 NADH, 1 FADH2, 1 ATP and 2 CO2, for ever acetyl group that enters the cycle.
Electron transport chain.
NADH and FADH2 carry hydrogen ions to the inner membrane of the mitochondria. Hydrogen ions release electron into electron transport chain and are pumped across the membrane. Hydrogen ions go through ATP synthase (facilitated diffusion). ATP produced. Hydrogen ions and electrons combine with oxygen to form water.
Sliding filament theory
Actin and myosin proteins slide past one another to cause movement. Troponin and tropomyosin on the actin move around to expose or block myosin binding sites. Once an impulse arrives at the muscle, Ca2+ are released from the sarcoplasmic reticulum, which diffuses through the sarcolemma and attaches to troponin, causing it to change shape. The movement of troponin causes the tropomyosin to change position. This exposes myosin binding sites on the actin. The myosin head binds to the actin forming a cross-bridge. This releases ADP and Pi from the myosin head. This causes the myosin head to change position (it ‘nods’) pulling the actin across the myosin. ATP then binds on to the myosin head, causing it to detach from the actin. ATPase in the myosin head hydrolyses the ATP to form ADP and inorganic phosphate. This changes the myosin head back into its usual position - it is now primed for another power stroke.
Creatine
Creatine is a naturally occurring substance in the body. It is also found in some food such as meat and fish and can be taken legally as a dietary supplement. It is absorbed into the body and taken to muscle tissue, where it is thought to increase levels of creatine phosphate, which is used in the ATP-PC energy system. This will help aid a performer with quick, high intensity activities.
Testosterone
Testosterone is a steroid hormone that is produced in both males and females in the adrenal glands (only in small amounts) as well as in the testes of males. Testosterone is involved in the development of the male sexual organs as well as the development of secondary male characteristics. It has also been linked with increased aggression. Testosterone also increases anabolic reactions within cells, such as protein synthesis, thus helping to increase the size and strength of muscles. When injected into the body, it is quickly broken down and has little effect on the performer.
Erythroprotein
Erythroprotein (EPO) is a peptide hormone produced in the kidneys. EPO is used in the body to stimulate the production of red blood cells by the bone marrow. If the kidneys detect low blood oxygen levels, they start to produce erythroprotein, which is released into the blood stream. Bone marrow is stimulated and begins to produce more red blood cells, in turn, these are released into the blood stream and begin to carry oxygen around the body, increasing blood oxygen levels back to normal. EPO can also be used to treat anaemia. It is difficult to test for as it is naturally occurring, it can be difficult to know for sure if raised EPO levels are natural or due to doping. However, a technique has been developed that can distinguish naturally produced EPO from synthetically produced EPO.
Increased levels of EPO to above usual levels can cause to many red blood cells to be produced. This has been linked with the increased chances of thrombosis, causing heart attacks and strokes.
Steroid hormones
Pass through the cell membrane and bind to receptor molecules which act as transcription factors.
Peptide hormones
Cannot pass through the target organs cell membrane and so attaches to receptor molecule on the outside of the cell, activating a secondary messenger which acts as a transcription factor.
Hormones
Chemical messengers secreted into the blood stream by endocrine glands. They either inhibit or facilitate body functions.
Target organ
The organ in which the hormone is intended for, which will have complementary receptor molecules for the hormone to bind onto.
