Cell Processes

First law of thermodynamics

Energy cannot be created or destroyed, but it can be transformed

Second law of thermodynamics

Disorder (entropy) is always increasing in the universe

Ex of the 1st law relevant to cellular processes?

Oxidation of glucose or photosynthesis

Which chemical reaction below, with the indicated equilibrium constants, Keq, and changes in free energy (ΔG) is energetically favorable? 

1) K = 104, ΔG = -5.7

2) K = 10-4, ΔG = 5.7

What is the free energy change, ΔG, for an enzyme reaction with a Keq of 17?

ΔG = -1.42 log K

What chemical reaction in cells, which a large negative change in free energy, is coupled to make biosynthetic reactions?

ATP hydrolysis

Which is the gain of electrons in a chemical reaction: oxidation or reduction?

reduction

Glycolysis produces two molecules of what 3-carbon compound?

Pyruvate

How many molecules of ATP and NADH are produced during glycolysis?

2 ATP and 2 NADH

Common fermentation product in yeast cells?

Ethanol and CO₂

Common fermentation product in muscle cells?

lactate/lactic acid

What important carrier molecule is regenerated in its oxidized state during fermentation?

Electron carrier molecule (NAD+)

Under what conditions does fermentation occur, for example, in our muscle cells?

Lack of oxygen

During the oxidation of glucose in our cells, what do the C and H atoms of glucose combine with?

oxygen

What products does oxidation of glucose form?

CO₂ and water

Before pyruvate from glycolysis enters the Krebs cycle, it becomes decarboxylated, releasing CO₂. To which 4-Carbon compound are the two resulting C atoms (an acetyl group) joined?

oxaloacetate

What 6-C compound is formed during Krebs cycle

citric acid

What is the name of the first protein complex in the electron transport chain that NADH gives its electrons to?

NADH dehydrogenase complex

What acts as the final electron acceptor during cellular respiration? What is formed as a result of this?

Oxygen; and it turns into water

The electron transport chain in mitochondria pumps protons into which mitochondrial compartment and from which compartment?

from the matrix (pH 8) into the intermembrane space (pH 7)

Which large enzyme complex synthesizes ATP using the energy of the proton gradient established by the electron transport chain?

ATP synthase

How many protons need to pass through the enzyme to synthesize one molecule of ATP?

4 protons

Including the NADH made from the oxidation of pyruvate, how many NADH are made per glucose molecule in the citric acid cycle?

per glucose molecule = 20

How many FADH₂ and ATP (count GTP as ATP)?

2 and 2

 How many total ATP are made from one glucose molecule if it is completely oxidized? 

30

How does the weight loss drug DNP (dinitrophenol) work? 

proton ionophore; it allows protons to move along the membrane without the proton gradient. energy is dissipated as heat

What are the dangerous side effects of DNP?

• hyperthermia

• dehydration

• nausea

• dizziness

• fever

What are the names of the processes indicated by the arrows below:

DNA —> mRNA 

mRNA —> Protein 

transcription and translation

What is the splicing of eukaryotic mRNAs? What enzymes carry out splicing? 

Splicing of eukaryotic mRNAs is the process where non-coding sequences called introns are removed from a newly transcribed pre-messenger RNA (pre-mRNA) molecule, allowing the coding exons to be joined together to form a mature messenger RNA (mRNA) ready for translation; this process is carried out by a large protein-RNA complex called the spliceosome

What 3-letter sequence on an mRNA specifies one amino acid?

codon

What 3-letter complementary sequence on tRNAs binds this sequence?

anticodon

What two products are produced in the light reactions of photosynthesis?

ATP, NADPH

How many of each product are needed to produce one molecule of glyceraldehyde-3-phosphate during the dark reactions of photosynthesis?

9 ATP 6 NADPH

How many CO₂ molecules are needed to produce one molecule of glyceraldehyde-3-phosphate? 

3

What abundant enzyme catalyzes the joining of C0₂ to the five-carbon compound ribulose 1,5-bisphosphate during photosynthesis?

Rubisco

Write the equation for both the oxidation of glucose in cells and photosynthesis and show how they are complementary.

C₆H₁₂O₆ + O₂ —> CO₂ + H₂O + energy (ATP) 

CO₂ + H₂O+ energy (sunlight) <—--C₆H₁₂O₆ + O₂