Cellular energy generation(week11)

Question 1

What happens when nonliving things are left to themselves?

Answer 1

They eventually become disordered.

Question 2

How do living cells generate order at every level on a holistic view?

Answer 2

Elaborate molecular mechanisms that extract energy from the environment and convert it into the energy stored in chemical bonds in cells.

Question 3

Give an example of how organisms extract energy from organic molecules(food)?

Answer 3

-Sugars that a plant has produced by photosynthesis as food for itself

-The mixture of large and small molecules that an animal has eaten.

Question 4

By what process do organisms extract chemical energy from food molecules?

Answer 4

Gradual oxidation

Question 5

What is the process of by which food molecules are gradually broken down to produce energy?

Answer 5

Cell respiration

Question 6

What is metabolism?

Answer 6

The term used to describe all the chemical reactions occurring in a cell (keep it alive).

Question 7

What is catabolism?

Answer 7

Chemical reactions where energy is released from chemical bonds of food molecules (breaking down molecules to release energy).

Question 8

What is anabolism?

Answer 8

Chemical reactions in which energy is used for synthesis of new molecules (requires energy).

Question 9

What do catabolism and anabolism have to do with life maintainence?

Answer 9

To ensure life is maintained the rates of catabolic and anabolic processes have to be balanced.

Question 10

What is the main carrier of energy? and its components?

Answer 10

ATP,

• Adenosine triphosphate.
  Chain of 3 phosphates, triosphosphate.
• Ribose sugar
• Adenine base.

Question 11

How do the interconversion of ATP and ADP occur?

Answer 11

There is an input of energy from sunlight or food and removal of water to form ATP from ADP.

To convert ATP to ADP available energy is release for intracellular work an for chemical synthesis.

Question 12

What are the other energy carriers aside from ATP?

Answer 12

NADH, NADPH are activated carriers of electrons.

NADH(Nicotinamide adenine dinucleotide)

NADPH(Nicotinamide adenine dinucleotide phosphate)

Both carry energy as two high energy electrons plus a proton(+) which together form a hydride ion(H-).

These activated cariers can pass their hydride ion(energy) to a donor molecule, they become oxidised to form NAD+ and NADP+ and the donor becomes reduced.

Question 13

What are the 8 functions of cell membranes?

Answer 13

1. Define boundaries of cell and organelles.
2. Aid organelle function(production of ATP).
3. Import and export of small molecules and ions.
4. Signal detection
5. Adhesion of cells to each other and to ECM(extracellular matrix)
6. Anchoring to the cytoskeleton
7. Cell movement and expansion
8. Cell division.

Question 14

How does oxidative phosphorylation create a proton gradient across a membrane to help produce ATP?

Answer 14

Using energy from the oxidation of food.

Question 15

How does photosynthesis generate a proton gradient across a membrane to help generate ATP?

Answer 15

Using an electron transport system using energy derived from the sun.

Question 16

Which process drives ATP synthesis?

Answer 16

A proton gradient

Question 17

What are the first step in synthesizing ATP?

Answer 17

Stage 1: Proton pump
proton gradient, high energy electrons from food or light.
Protons are from water, which is UBIQUITOUS in the aqueous environment of the cell.

Question 18

What are the second step in synthesizing ATP?

Answer 18

Stage 2: Chemiosmotic coupling.
Links the chemical bond-forming reaction that synthesize ATP(chemi) with the membrane transport processes that pump protons(osmotic(push))

Compartmentalisation is key.

Question 19

Where has mitochondria evolved from?

Answer 19

engulfed aerobic bacteria

Question 20

Where have chloroplasts evolved from?

Answer 20

engulfed photosynthetic bacteria.

Question 21

What features do mitochondria and chloroplasts share from their bacterial ancestors?

Answer 21

Both organelles contain their own DNA-based genome and the machinery to replicate DNA and make RNA and protein.

The mitochondrial matrix and chloroplast stroma contain DNA and a special set of ribosomes.

Membranes in both organelles contain the protein complexes involved in ATP production.

Question 22

What is the structure and function of mitochondria?

Answer 22

Structure:
Found in all eukaryotic cells
Enclosed by two membranes, each a phospholipid bilayer with unique embedded proteins.

Function:
Site of cellular respiration
DNA in organelle programs protein synthesis on mitochondrial ribosomes.

Question 23

Compartments of the mitochondrion…

Answer 23

1. Outer membrane(large channel forming protein(PORIN)
2. Inner membrane(folding called cristae)
   Large SA for cellular respiration
   Proteins of the ETC
   Oxidative phosphorylation and ATP synthesis.
   Selectively permeable membrane-matrix stays specialised.
3. Intermembrane space(ATP production)
4. Mitochondrial matrix(enclosed by the inner membrane) contains enzymes that catalyse some steps in cellular respiration.

Question 24

Describe the dynamic nature of mitochondria…

Answer 24

They can adjust their location, shape and number for cell needs.

Can remain in fixed location for ATP supply.

In heart muscle cell located close to contractile apparatus for ATP supply.

In sperm wrapped tightly around the thrashing flagellum.

Question 25

What are the principle sources of ATP in non-photosynthetic cells?

Answer 25

Glucose and fatty acids.

Question 26

How many molecules of ATP does the aerobic degradation of a single glucose molecule generate?

Answer 26

32 molecules of ATP during cellular respiration.

Question 27

How many molecules of ATP does glycolysis produce?

Answer 27

2 molecules of ATP.

Question 28

Where does glycolysis occur?

Answer 28

Occurs in the cytoplasm.

Question 29

What is the next breakdown of glucose, post glycolysis and what is generated?

Answer 29

After glycolysis, there is further breakdown by the TCA cycle in the mitochondrial matrix generating NADH.

Question 30

Where does oxidative phosphorylation occur?

Answer 30

on the cristae of the inner membrane in the mitochondria, generating 30 molecules of ATP.

Question 31

Describe the process of glycolysis in depth?

Answer 31

2 molecules of ATP and 2 NADH produced per glucose. Substrate-level phosphorylation occurs to produce the 2 molecules of ATP. There is transfer of a phosphate to ADP from an organic molecule in catabolism of glucose.

Question 32

What happens to the energy stored in NADH?

Answer 32

It can be converted to ATP by the ETC(electron transport chain) and oxidative phosphorylation.

Question 33

What happens in the mitochondrial matrix in terms of energy production?

Answer 33

Pyruvate is converted into acetyl CoA and CO2, and also reduction of NAD+ to give NADH, by the pyruvate dehydrogenase complex in the mitochondrial matrix.

Question 34

Where does the citric acid cycle take place?

Answer 34

Mitochondrial matrix

Question 35

What happens in the citric acid cycle?

Answer 35

There are a series of reaction starting with acetyl Co-A. It generatres large amounts of NADH by oxidising acetyl groups derived from food molecules to CO2.

Question 36

What happens in oxidative phosphorylation?

Answer 36

Completes the catabolism of food molecule and generates bulk of the ATP made by a cell. Electron bearing cariers(NADH) produced by the citric acid cycle and glycolysis donate their high energy electron to an ETC- inner mitochondrial membrane. Electron transfer is couple by proton pump across the inner membrane. Proton gradient leads to drive of ATP synthesis through the process of oxidative phosphorylation.

Question 37

Where does oxidative phosphorylation occur?

Answer 37

Mitochondrial inner membrane.

Question 38

How is the proton motive force generated?

Answer 38

Intermembrane space is slightly more acidic than the matrix because the higher the concentration of protons. Both the membrane potential and the pH gradient combine to generate the proton-motive force, which pulls H+ back into the mitochondrial matrix.

Question 39

How do convoluted cristae enhance productivity for ATP synthesis?

Answer 39

Large surface area.

Question 40

What is the importance of compartmentalization for cellular respiration?

Answer 40

Compartmentalization in cellular respiration ensures efficiency and regulation by isolating processes in specific organelles. For example, glycolysis occurs in the cytoplasm, while the Krebs cycle and oxidative phosphorylation occur in mitochondria, maintaining optimal environments for enzymes and preventing interference between metabolic pathways.