Metabolism, Cell Growth, and Experimental Design

Flashcards covering carbon source comparisons, cellular metabolism, cell growth phases, hypothesis testing, and experimental variables based on the lecture transcript.

What are the two carbon sources evaluated in this lab, and what are their respective acronyms?

The two carbon sources are glucose (G) and succinate (S).

How many total carbons does a glucose molecule have, and how many ATP molecules does it generate?

A glucose molecule has $6$ carbons total and generates ~ $32\text{--}36$ molecules of ATP.

Which metabolic pathways are involved in extracting energy from glucose?

The metabolic pathways are glycolysis, Krebs cycle, and oxidative phosphorylation.

What type of molecule is succinate, how many carbons does it contain, and how many ATP molecules can it generate?

Succinate is a (dicarboxylic) organic acid containing $4$ carbons total, generating up to $5$ molecules of ATP.

Which metabolic pathways are utilized during the breakdown of succinate?

The metabolic pathways utilized are the Krebs cycle and oxidative phosphorylation.

What three factors explain how glucose and succinate differ in how nutritious they are?

They differ in point of entry, energy yield (ATP), and number of Carbons.

What activities do cells carry out during the Lag phase of growth?

Cells enter a new environment and are busy synthesizing precursor metabolites, enzymes, and RNA to prepare for reproduction.

What characterizes the Exponential/Log phase of cell growth?

The cell population reaches its maximum growth rate, affected by nutrient availability and environmental conditions, while inhibitory factors like metabolic waste are still absent.

What defines the Stationary phase in a cell growth curve?

The rate of cell death equals the rate of reproduction, or reproduction overall ceases, because available nutrients are completely consumed or the environment is no longer suitable.

Why does the cell population decline during the Death phase?

The population declines due to the buildup of metabolic waste and nutrient depletion.

How is nutrition defined in metabolic terms?

Nutrition is the amount of energy that can be extracted from nutrient sources.

What are precursor metabolites, and what relies on them?

Precursor metabolites are 'building blocks' for making cellular components (like Amino Acids, nucleotides, and lipids). Nutrition and the number of precursor metabolites determine the rate of cell growth.

What is the sequence of breakdown for food sources during catabolism prior to entering the mitochondrion?

Food sources break down in the order: $\text{glucose} \rightarrow \text{pyruvate} \rightarrow \text{Acetyl CoA}$.

How many electrons do glucose and succinate send to the oxidative phosphorylation pathway?

Glucose sends $16$ electrons, whereas succinate sends only $2$ electrons.

What components make up the oxidative phosphorylation pathway?

The oxidative phosphorylation pathway is comprised of the Electron Transport Chain and chemiosmosis.

What is the conceptual difference between a hypothesis and a prediction?

A hypothesis is a proposed explanation for an observation that explains the 'WHY' and must be testable and falsifiable. A prediction is a statement about what you expect to see, stating the 'DIRECTION' and detailing expected trends between groups.

In the lab setup, what are the independent and dependent variables?

The independent variables are time, carbon treatment (Glucose and Succinate), and control variable (NoC). The dependent variable is cell growth (optical density).

What constitutes replication in this experiment, and how many replicates were used?

Replication occurs when there are multiple reads for the variables/treatment at the same point in time. There are $3$ replicates for G and G control, and $3$ replicates for S and S control.

What specific factors were kept constant across all treatments to limit experimental error?

Constants include the M9 solution, temperature of the incubator, and using the same spectrophotometer for each reading.