Topic 7 Flashcards

Question

Why will the link reaction and the Krebs Cycle occur twice?

Answer 1

Every molecule of glucose produces two Pyruvate molecules, therefore the two steps will occur twice for every molecule of glucose. Thus, each molecule of glucose will produce - 2 molecules of acetyl CoA - 2 molecules of CO2 - 2 molecules of reduced NAD

Answer 2

• Occurs in the mitochondrial matrix • Complete oxidation of glucose to carbon dioxide • Produces 6 reduced NAD, 2 reduced FAD, 4 carbon dioxide and 2 ATP (for each glucose molecule) • Cycle of Acetyl co A binding to oxaloacetate 4C • Involves oxidation and decarboxylation reactions (and dehydrogenation)

Answer 3

• The enzymes needed are specific for each stage • The enzymes for each step are found in the matrix • So that the products (coenzymes) are available for the next stage (on the inner membrane of the mitochondria) ENZYMES •Each stage is catalysed by a different specific enzyme •The product of each stage becomes the substrate of the next stage

Answer 4

• Each reduced NAD makes 3 ATP • reduced FAD makes 2 ATP

Answer 5

• Speed up the reactions • By lowering activation energy • Each step produces the substrate for the next enzyme • Enzymes are specific for each stage • (gene expression) Allows control of each stage of respiration

Answer 6

On stalked particles on the inner mitochondrial membrane. 1. Hydrogen atoms are released from reduced NAD and reduced FAD as they are oxidised 2. Hydrogen atoms split into hydrogen ions (protons) and electrons 3. Electrons move along the electron transport proteins in the inner membrane of the mitochondria, releasing energy at each carrier 4. This energy is used to pump the Hydrogen ions (protons) into intermembrane space forming an electrochemical gradient 5. Hydrogen ions move down electrochemical gradient back to matrix via ATP synthase 6. Chemiosmosis 7. Movement of Hydrogen ions drives synthesis of ATP from ADP and Pi 8. Hydrogen ions, electrons and oxygen combine to form water, oxygen is the final electron acceptor (2H+ + 1⁄2 O2 + 2e- 􏰀 H20) 9. 26 ATP molecules are made (so 30 overall – but there is some debate)

Answer 7

NOTION = 38

Answer 8

- Oxygen acts as the final electron acceptor. - No oxygen = ETC cannot continue as electrons have no place to go. - No more ATP is produced via oxidative phosphorylation - Oxygen not accepting electrons (and hydrogen ions) reduced coenzymes NADH and FADH2 cannot be oxidised to regenerate NAD and FAD - Cannot be used in further hydrogen transport - Krebs cycle stops - Link reaction also stops

Answer 9

- Reduced NAD transfers hydrogen to pyruvate to form lactate - NAD can now be reused in glycolysis - Pyruvate is reduced to lactate by enzyme lactate dehydrogenase - Pyruvate = hydrogen acceptor - Final product lactate can be further metabolised - Small amount of ATP produced

Answer 10

- Can build up in the cells after a period of time - Can be oxidised to pyruvate, then channeled into the Krebs cycle for ATP production (needs extra oxygen - oxygen debt - explains why animals breathe deeper and faster after exercise) - Can be converted into glucose by the liver cells for use during respiration or for storage (glycogen)

Answer 11

• C - Either Temperature OR Mass of organisms (temp only up to 40 degrees - ethics of causing harm to an animal), 5 values stated • O - Germinating Seeds/ Maggots/ Any small respiring organism of same age, clones of each other or have same parents (plants can be cuttings, same genetic makeup) - to eliminate environmental and genetic effects on the results of the investigation • R – repeat 5 times at each temp/mass, calculate mean and s.d, stats test – Spearman’s rank, correlation coefficient • M - Change in volume of oxygen / volume of oxygen taken up - by measuring the distance moved by the liquid in the u tube and multiplying it by the cross-sectional area of the u-tube (πr2). Per unit of time. Per gram. • EG mm3s-1g-1 • S - Either Mass of organisms OR Temperature and then time left to respire, mass of soda lime, equipment used to measure th

Answer 12

- The heart has the ability to initiate its own contraction. - The heart can beat without any input from the nervous system as longs as its cells stay alive. This is due to myogenic contraction.

Answer 13

• Sinoatrial Node is the natural pacemaker - sends an electrical impulse • Sends a wave of depolarization across the walls of the atria • Atria contract – atrial systole • Depolarisation passes to the Atrioventricular Node & causes a delay • Atrioventricular Node is stimulated and passed the stimulation along the bundle of His to the bottom of the ventricles • Across the Purkyne fibres • Causes depolarization of the ventricular walls • Ventricles contract from the apex of the heart up – ventricular systole

Answer 14

- Means that the ventricles contract after the atria.

Answer 15

- The electrical activity of the heart can be monitored by an electrocardiograph. - Electrodes that are capable of detecting electric signals are placed on the skin - Produce an electrocardiograph (ECG) - Shows a number of distinctive electrical waves produced by the activity of the heart - Healthy heart produces a distinctive shape in an ECG.

Answer 16

1. P wave - caused by depolarisation of atria = atrial contraction (systole) 2. QRS complex - depolarisation of ventricles = ventricular contraction (systole) 3. T wave - repolarisation of ventricles = ventricular relaxation (diastole) 4. U wave - scientists are still unsure, may be caused by the repolarisation of the Purkyne fibres The BIGGER the wave, the GREATER the electrical activity passing through the heart, which results in a stronger contraction.

Answer 17

Tachycardia - heart beats too fast (>100) Bradycardia - heart beats too slow (60>) Ectopic heartbeat - easily heartbeat caused by a pause (due to earlier contraction of the atria or ventricles) Fibrillation - irregular heartbeat, disrupt rhythm of the heart - atria or ventricles stop contracting properly.

Answer 18

- the volume of blood that is pumped by the heart per unit of time. = heart rate x stroke volume Cm^3min^-1

Answer 19

Number of times a heart beats per minute - beats per minute (bpm)

Answer 20

The volume of blood pumped out of the left ventricle during one cardiac cycle. (Cm^3)

Answer 21

- Devices implanted in people whose heart’s electrical conduction system is not working properly. - Problems include - the SAN not firing - and the blockage or disruption of impulses between the SAN and AVN, or in the bundle of His. - Pacemakers monitor the heart’s electrical activity, stimulate the ventricles or atria to contract when necessary. - Impulses are transmitted down electrodes implanted in the muscular walls.

Answer 22

⚫ More oxygen to muscle cells ⚫ More glucose to muscle cells ⚫ More removal of carbon dioxide ⚫ More removal of lactate

Answer 23

- Hormones (adrenaline) - Neurotransmitter (Noradrenaline (binds to receptors on the SAN)) - Nerves (Parasympathetic nervous system, Sympathetic nervous system, Both part of the autonomic nervous system)

Answer 24

- Increase the rate and depth of breathing - Increase the heart rate

Answer 25

- controlled by the ventilation centres (respiratory centres) in the medulla oblongata - inspiration centre (air into lungs) - expiratory centre (air out of the lungs)

Answer 26

The inspiratory centre in the medulla oblongata has the following effect on breathing: • It sends nerve impulses along motor neurons to the intercostal muscles of the ribs and diaphragm muscles • These muscles will contract and cause the volume of the chest to increase • This lowers the air pressure in the lungs to slightly below atmospheric pressure • An impulse is also sent to the expiratory centre to inhibit its action • Due to the difference in pressure between the lungs and outside air, air will flow into the lungs. • lungs inflate, stretch receptors in lungs are stimulated. SR send nerve impulses back to the medulla oblongata. These impulses inhibit the action of the inspiratory centre. • The expiratory centre (no longer inhibited) sends nerve impulses to the diaphragm/inter coastal muscles to relax. Causes the lungs to deflate, expelling air. As the lungs deflate, the stretch receptors become inactive. The Inspiratory centre is no longer inhibited and the cycle starts again.

Answer 27

• Nerve impulses are sent back to the medulla oblongata which willinhibit the inspiratory • The expiratory centre is no longer inhibited and will bring about the following changes: • It sends nerve impulses to the intercostal and diaphragm muscles • These muscles will relax and cause the volume of the chest to decrease • This increases the air pressure in the lungs to slightly above atmospheric pressure • Due to the higher pressure in the lungs, air will flow out of the lungs • As the lungs deflate, the stretch receptors become inactive which means that the inspiratory centre is no longer inhibited and the next breathing cycle can begin

Answer 28

- in the lungs - are stimulated as they inflate with air

Answer 29

CHEMORECEPTORS - detect chemical changes in the composition of the blood, such as pH levels - located in the ventilation centre of the medulla oblongata - also present as clusters of cells in the aorta (aortic bodies) and carotid arteries (carotid bodies) BARORECEPTORS - found in the aortic and carotid bodies - stimulated by high and low blood pressure

Answer 30

The volume of air that moves in and out of the lungs during a set time period (e.g. a minute) INCREASES during exercise due to the increase in breathing rate and depth.

Answer 31

- Cardiovascular control centre in the medulla oblongata unconsciously controls the heart rate, by controlling the rate at which the sinoatrial node (SAN) generates electrical impulses.

Answer 32

⚫ Inhibits effectors ⚫ Controls actions under resting conditions ⚫ Slows down activity ⚫ Conserves energy ⚫ Releases the neurotransmitter acetyl choline which binds to receptors on the SAN ⚫ decreases the heart rate after exercise

Answer 33

⚫ Stimulates effectors ⚫ Controls conditions under stress or activity ⚫ Speeds us up (fight or flight) ⚫ Secretes noradrenaline ⚫ increase the heart rate during exercise

Answer 34

HIGH BLOOD PRESSURE - detected by baroreceptors which send impulses to cardiovascular control centre - sends impulses along parasympathetic neurones which secrete the neurotransmitter acetylcholine - Acetylcholine binds to receptors on SAN causing it to fire less frequently - Heart rate slows down and blood pressure decreases back to normal

Answer 35

Parasynthetic neurones secrete acetylcholine (neurotransmitter) High blood pressure, High blood O2, Low CO2, or High pH levels.

Answer 36

Sympathetic neurones secrete noradrenaline (neurotransmitter) Low blood pressure, Low blood O2, High CO2, or Low pH levels.

Answer 37

• C - Time spent performing a specific exercise or type of activity • O - Human. The same person so that the results don't vary from different levels of fitness. Perform repeats by allowing the perfromer to fully rest. If multiple people same age, fitness level. • R – Repeat 5 times at each time/activity, calculate mean and s.d. stats test, time = spearman’s rank, activity – t-test • M - A spirometer is used to measure the volume of air in an area. The graph then plotted allows measurements on specific areas (See next slide) • S – Time exercised/activity type, temperature, volume of water consumed

Answer 38

Physiological control systems maintain the internal environment within restricted limits despite external changes. The following have to be maintained; • Body temp • Blood glucose conc. • Blood salt conc. / ions • Water potential of blood • Blood pressure • Carbon dioxide conc.

Answer 39

• A change in the internal environment brings about a response that reverses that change • EG temperature increases, you sweat, temperature decreases • Change needs to be detected • Change must be signalled to other cells • Response to reverse the change

Answer 40

Stimulus —> Receptor —> Communication pathway (cell signalling) —> Effector —> Response

Answer 41

Blood glucose levels increase —> Chemoreceptors detect a change in the blood (located in the pancreas) —> cell signalling to pancreases glands —> insulin is produced/secreted from the pancreas glands —> blood glucose levels decrease and return back to normal (cells take up glucose and convert glycogen in the liver)

Answer 42

- not common - Increases original change detected by receptors - Usually harmful - E.g. hypothermia body temp falls, - enzymes become less active, less heat released, temp continues to fall!

Answer 43

• Labour!! • Cervix opens and stretches • Oxytocin released • Oxytocin increases contractions • Cervix stretches more

Answer 44

1.Receptors in hypothalamus detect increase in core temp/temp of blood —> Also temperature receptors in the skin 2. Heat loss centre stimulated of the thermoregulatory centre 3. VASODILATION of arterioles 4. Arterioles leading to capillaries in the skin dilate 5. SHUNT VESSELS CONSTRICT 6. More blood flows to skin surface (capillaries) / heat loss by RADIATION 7. Heat loss by EVAPORATION of sweat / by using energy. —> High(er) rate of sweating leads to a low(er) skin temp 8. VOLUNTARY CENTRE: remove clothing / seek cooler area / cold drink

Answer 45

1. Receptors in hypothalamus detect decrease in core temp/temp of blood 2. Heat gain centre stimulated 3. VASOCONSTRICTION of arterioles 4. Arterioles leading to capillaries in the skin narrow 5. SHUNT VESSELS DILATE 6. Less blood flows to skin surface / less heat is lost by RADIATION 7. Hair raising / greater insulation / humans have less dense hair \ no effect 8. Shivering / rapid contraction and relaxation of muscles / heat produced by RESPIRATION 9. Adrenaline INCREASES METABOLIC RATE of cells //Mammals in cold climates can increase secretion of thyroxine / hormone increases metabolic rate on a more permanent basis 10. VOLUNTARY CENTRE: put on clothes / seek warmer areas / warm drink

Answer 46

- Blood moves to surface so heat can be lost. - Shunt vessels constrict. - Sphincter muscles in arterioles are relaxed and open. - This allows blood to flow to the surface and heat is lost.

Answer 47

- A blood vessel that links an artery (arteriole) directly to a vein (venuole). - Allowing the blood to bypass the capillaries in certain areas. - Shunt vessels can control blood flow by constriction and dilation.

Answer 48

Area of the brain that is responsible for controlling many functions in the body, including - hormones - sleep - growth - body temperature - blood pressure

Answer 49

• Increases number and activity of Natural Killer cells. • These target cells which do not display “self” markers/antigens. • ( these can be cells invaded by viruses, bacteria and cancer cells) • They attack the cell membrane by making pores in it • ( make protein perforin). • Proteases can invade cell and cause apoptosis. • Give non-specific protection.

Answer 50

After exercise the number of these immune system cells falls • Natural killer • Macrophages • B cells • Helper T cells. • The specific immune system is depressed. • Debate about whether physical or psychological. • Stress of training could release adrenalin and cortisol both known to suppress the immune system.

Answer 51

- wear and tear on joints - suppression of the immune system

Answer 52

- Increased risk of obesity - Increased risk of CVD - Increased risk of diabetes - Suppression of the immune system - Increased levels of LDLs

Answer 53

E.g. knees • Cartilage worn away • Patellar tendonitis – kneecap does not move easily over femur • Bursitis – fluid filled sacs around joints swell up with extra fluid. Inflammation and tenderness. • Ligament damage. • Tendon damage

Answer 54

- less invasive procedure, only small incisions - small video camera inserted into the incision, along with special medical instruments

Answer 55

• Less tissue damage • Less bleeding • Less scarring • Less pain • Less anaesthetic • Lower risk of infection • Faster recovery rate • Cheaper • Faster – so more patients can be treated

Answer 56

—> EG Dynamic response prosthetic foot. —> Changes shape with body weight but returns to its original shape when off the ground. —> Can replace the joint, allow the person to move without pain & potentially play sport again —> Some prostheses may be connected to electronic devices that can “read” information from the nervous system in order to operate the body part. (E.g. hand prostheses enabling the user to move the fingers)

Answer 57

Performance enhancing drugs Anabolic steroids - increase muscle size, increased strength, speed and stamina, may lead to organ damage and increased aggression. Stimulants - more alert and able to react faster, greater endurance, may lead to aggressive behaviour Narcotic analgesics - strong painkillers, used to maintain their performance.

Answer 58

Rationalists - think there may be times when their use is justified. Absolutists - think that they are morally wrong and should be banned from all sports.

Answer 59

• Against: • Damaging effect on synapses • Leads to abnormal behaviour • Unfair advantage • May have long-term side effects on body eg heart disease – cost to NHS • Poor role model to youngsters

Answer 60

• Individual choice / responsibility; • Helps you win

Answer 61

•Transcription factors are proteins that help activate or deactivate specific genes by binding to nearby DNA. •Activators boost a gene's transcription. •Repressors decrease transcription. •Transcription factors help ensure that the right genes are expressed in the right cells of the body, at the right time.

Answer 62

• Normal body temperature – thyroid hormone receptor binds to the start of the gene • Reduces transcription (blocks RNA polymerase) • Cold temperature causes thyroxine to be released • Binds to thyroid hormone receptor • Activates gene • RNA polymerase binds • Transcription rate increases • Making an enzyme which increases metabolism • More exothermic reactions, so more heat produced • Body warms up

Answer 63

• Bind to receptors on the cell membrane • Activate messenger molecules in the cytoplasm • Messenger molecules activate enzymes called protein kinases • A chain of reactions called a cascade is triggered • Transcription factors are activated by the cascade

Answer 64

• Preventing them from binding to the DNA; • Binding and blocking their DNA-binding site • Promoting the degradation of these proteins

Answer 65

The movement of ions across a partially permeable membrane, down their electrochemical gradient

Answer 66

the process in which ATP is formed as a result of the transfer of electrons from reduced NAD or reduced FAD to Oxygen by a series of electron carriers

Answer 67

production of ATP in glycolysis & Krebs

Answer 68

the movement of electrons down a series of electron carriers

Answer 69

- The enzyme which makes ATP when H+ ions move through it.

Answer 70

• Human cells do this by converting pyruvate to lactate (reduction). • This reaction uses reduced NAD by oxidising it to NAD once more. • NAD is now available again to accept electrons and protons so glycolysis continues. • If NAD was not regenerated, even glycolysis would have to stop • Pyruvate + reduced NAD Lactate + NAD

Answer 71

• Anaerobic respiration occurs mostly in the muscles when oxygen is being used up quicker than it can be supplied, • In the absence of oxygen glycolysis would usually stop as there would be a build up of reduced NAD. • For glycolysis to continue, reduced NAD must be converted into NAD. • This happens when pyruvate takes up hydrogen from reduced NAD to make lactate. • Lactate causes reduced pH & fatigue in muscle tissue so this must be removed. • An oxygen debt occurs. • Lactate can be oxidised back to pyruvate and enter the Krebs cycle • Or taken to the liver converted to glucose & stored as glycogen.