C1.2 Cell Respiration

ATP is

a nucleotide composed of adenine, ribose and three phosphate groups

ATP is required for:

• active transport across membranes

• synthesis of macromolecules by anabolism

• movements of cells using flagellum or cillia

• movemnt within the cells - chromosomes in mitosis or meiosis

endergonic reaction

requires energy

exergonic reaction

releases energy

Why is ATP good as an energy source

phosphor is negatiely charged and repels itself hence the bonds are unstable with a low activation energy and high in energy

ATP and ADP cycle

What in the repisration equation is reduction and what is oxidation?

C6H12O6 + 6O2 → 6CO2 + 6H2O

oxygen → water = reduction

glucose → carbon dioxide = oxidation

How many ATP produced by anaerobic respiration

2 ATP

Equation for anaerobic repisration in humans

glucose → lactic acid

Equation for anaerobic respiration in yeast

glucose → CO2 and ethanol

where does anaerobic repisration take place

cytoplasm

Equation for aerobic respiration

C6H12O6 + O2 → 6CO2 + 6H20

Where does aerobic repisration take place

First cytoplasm (glycolisys) then mitochondria (Krebs, link reaction and electron transport chain)

What can be used for aerobic respiration

carbohydrates fatty acids or amino acids

What can be used for anaerobic respiration

Only carbohydrates

How much ATP produced by aerobic respiration

30-34

What measured aerobic respiration

respirometer

Rate of cell respiration is affected by

• temprature

• pH

• tyep of cell

• glucose concentration

• oxygen concentration

• carbon dioxide concentraion

Glycolysis steps

1. Phosporylation → ATP is split attaching two phsophate groups to the 6 carbom molecule which is unstable / loss of 2 ATP

2. Lysis - the unstable 6 carbon molecule lyses into two seperate 3 carbon molecules (triose phosphate)

3. TP becomes oxides while NAD is reduce to NADH - the energy released add two more phosphate groups to the 3 carbom molecules (not from ATP)

4. ATP formtaion - enzymes take the phosphate groups and attach them to ADP froming ATP leaving two pyruvates

Glycolysis net gain

2 ATP, 2 NADH, 2 pyruvates

Anaerobic repisration after glycolysis

If no oxygen is present → regeneration of NAD as pyruvate needs to be reduced to become lactic acid so NADH is oxides

Link reaction

After glycosylis pyruvate moves to matrix

1. Pyruvate becomes decarboxylated forming a 2 carbon acetyl group and release of carbon dioxide

2. Acetyl group is oxides and NAD reduced to NADH

3. Acetyl group combines with a coenzyme A forming acetyl CoA which can enter Krebs cycle

→ Since two pyruvates two Acetyl CoA produced

Krebs cycle

in the matrix

1. Acetyl CoA enters the cycle and attaches to oxaloacetate - releasing CoA and forming citrate (6C)

2. Citrate becomes decarboxylated giving of CO2 and becomes oxides while NAD reduced to NADH forming a 5 Carbon molecule

3. 5C becomes decarboxylated giving of CO2 and its oxides and NAD reduced to NADH forming a 4 carbon molecule

4. ATP is produced

5. FAD reduced to FADH2

6. NAD reduced to NADH

7. oxaloacetate regenerated

8. This is repated as two acetyl coa

Krebs cycle net products

1 ATP, 1 FADH2, 3 NADH and 2 CO2

Electron transport chain

In the intermembrane space electron carriers are located

1. NADH and FADH become oxidised and pass their electrons onto the carriers

2. The electrons move along the chain releasing energy

3. The energy is used to transport hydorgen ions into the intermembrane space creating a proton gradient

4. The protons move back to the matrix via facilitated diffusion by ATP synthase and the harnessed energy is used to synthesize ATP

5. When the energy from electrons is used up oxygen accepts then and binds with the hydrogen ions which are found in high concentrations forming water

Chemiosmosis

movement of protons from high concetration to low through ATP synthase to convert ADP to ATP

Use of fatty acids instead of glucose for respiration

• yield 20% more energy

• more oxidasibale C-H bonds and less oxygen

• glycolysis then does not take place just starts at link reaction