Cellular Metabolism: Enzyme Activity, Metabolic Pathways, and More
Cellular Metabolism Exercises
Exercise 1: Autotrophs and Heterotrophs
Fotoautotrophs: Solar radiation light, CO2, algae, plant, cyanobacteria
Quimioautotrophs: Inorganic matter, CO2, sulfur bacteria
Quimioheterotrophs: Organic matter, animal, fish, fungi
2. True or False:
a) Cellular chemoheterotrophs are always aerobic. False, there are chemoheterotrophs that are anaerobic, like yeast in fermentation.
b) Photosynthesis and cellular respiration are mutually exclusive. False, all photosynthetic cells respire.
Exercise 2: Enzyme Activity and pH
1. a) (Represents the results in a graph)
b) The graph indicates that the enzyme has an acid pH optimum (around 4), which is likely to act in lysosomes (the only place where cell pH is acidic).
2. a) What are the independent and dependent variables? The independent variable is the acidity (pH). The dependent variable is the enzyme activity.
b) Why control pH and other factors? To ensure that the results depend only on the changes made by the experimenter.
Exercise 3: Salivary Amylase and Temperature
1. Biological Interpretation:
The enzyme activity increases with temperature because the kinetic energy of molecules increases. At higher temperatures, proteins are denatured, losing their biological activity.
2. Interpretation at -10°C: At low temperatures, enzymes have very low activity. Foods are kept frozen to prevent enzymatic activity.
Exercise 4: Metabolic Pathways
a) Metabolites:
In: B, Glycogen: Acids, C: Amino acids, D: Acetyl CoA, E: Oxygen
b) Metabolic Pathways:
1: Glycolysis, 2: Respiratory chain-oxidative phosphorylation, 3: Oxidation of fatty acids (β-oxidation), 4: Krebs Cycle, 5: Fermentation of glucose (LDH)
c) Catabolic and Anabolic Pathways:
Catabolic pathway: degrades compounds to produce energy (protein degradation, glycolysis). Anabolic pathway: builds complex molecules from simpler ones, requiring energy (esterification, Krebs cycle).
Exercise 5: Metabolic Pathways and Molecules
1. Pathways:
1 – Pathway, 2 – Gluconeogenesis, 3 – Krebs Cycle, 4 – Protein Synthesis, 5 – Respiratory chain.
2. Molecules:
A – glycogen, polysaccharide, carbohydrates, B – amino-ATP, C, D, E – CO2-H2O
Exercise 6: Cellular Respiration and Fermentation
Cells obtain energy from glycolysis via fermentation (LDH). Animal cells use glycolysis without oxygen because the Krebs cycle does not work. Therefore, they can only partially oxidize glucose (glycogen) to lactate.