24 Questions
What occurs after glycolysis in anaerobic respiration?
Lactic acid fermentation
What is the primary method of bacterial growth and replication?
Binary fission
What is the ideal temperature range for bacterial growth?
0 – 121°C
What type of bacteria require oxygen for growth?
Strict aerobes
What is the purpose of additives in culture media?
To enrich or inhibit certain bacteria
What is culture media?
A substance that supports the growth of bacteria
What is the difference between defined and complex culture media?
Defined media has an exact composition, while complex media does not
What is the pH range that bacteria can tolerate?
pH 0-11
What is the definition of metabolism?
The total of all biochemical reactions occurring inside the cell for survival and reproduction
What type of transport involves a nutrient gradient?
Passive transport
What is the purpose of siderophores?
To uptake iron
What is the term for the breakdown of glucose to produce ATP in the absence of oxygen?
Anaerobic respiration
What is the term for the process of generating energy from glucose in the presence of oxygen?
Aerobic respiration
What is the term for the process of breaking down glucose to produce ATP?
Glycolysis
What is the term for the process of generating ATP from the energy released from the electron transport chain?
ATP synthesis
What is the term for the process of breaking down glucose to produce ATP in the absence of oxygen, resulting in the production of lactic acid or ethanol?
Fermentation
What is the primary function of ATP in cells?
To store energy for cellular reactions
What is the byproduct of anaerobic respiration?
Lactic acid and ATP
Which process is involved in the generation of ATP during aerobic respiration?
Oxidative phosphorylation
What is the primary source of energy for ATP synthesis during aerobic respiration?
NADH and FADH2
Which of the following is NOT a stage of aerobic respiration?
Fermentation
What is the end product of glycolysis?
Pyruvate
Which electron acceptor is used during anaerobic respiration?
Nitrate
What is the purpose of fermentation?
To break down glucose in the absence of oxygen
Study Notes
Metabolism
- Metabolism consists of two opposing chemical reactions in cells: catabolism and anabolism
- Catabolism breaks down foodstuffs into smaller molecules to generate energy
- Anabolism uses the energy from catabolism to drive the synthesis of other molecules
Energy
- Energy is produced in cells in the form of ATP (Adenosine Triphosphate)
- ATP is the currency and store of energy in cells
- ATP drives various chemical reactions, such as pumping substances actively across membranes, reproducing, and moving cells
- ATP is formed from ADP (Adenosine Diphosphate) and phosphate in an energy-consuming reaction
- ATP releases energy when hydrolyzed back to ADP
Metabolic Tasks
- Chubukov et al. (2014) discuss metabolic tasks in Nat Rev Microbiol. doi: 10.1038/nrmicro3238
Aerobic Respiration
- Aerobic respiration is not to be confused with breathing
- The overall reaction is: C6H12O6 + 6O2 → 6CO2 + 6H2O + (energy)
- Aerobic respiration consists of 4 processes:
- Glycolysis (pyruvate generation)
- Acetyl-CoA generation (pyruvate to acetyl-CoA)
- Citric acid (Krebs) cycle
- Oxidative phosphorylation
Anaerobic Respiration
- Anaerobic respiration breaks down glucose when oxygen is lacking
- Some organisms can utilize different electron acceptors, such as SO42- or NO3-
- Fermentation is another pathway for breaking down glucose
- Fermentation occurs after glycolysis
- There are two types of fermentation: lactic acid fermentation and alcohol fermentation
Bacterial Growth
- Bacteria grow and replicate primarily by binary fission
- Binary fission is a process whereby one bacterium splits into two
- Bacteria require energy to grow
Conditions that Affect Bacterial Growth
- Temperature: most bacteria prefer 37°C, but can vary from 0°C to 121°C
- pH: most bacteria prefer pH 7-8, but can vary from pH 0 to 11
- Oxygen: bacteria can be classified as strict aerobes, facultative aerobes, facultative anaerobes, or strict anaerobes
Growing Bacteria in the Lab
- Culture media is a substance that supports the growth of bacteria in the laboratory
- Culture media can be either defined (exact composition known) or complex (extracts from plants or animals; exact composition unknown)
- Additives can be incorporated to media to either enrich or inhibit certain bacteria
Bacterial Metabolism
- Learning objectives include defining metabolism, catabolism, and anabolism, identifying sources of energy for bacterial metabolism, and describing how bacteria are grown in the laboratory and counted
How Bacteria Uptake Nutrients
- Bacteria can uptake nutrients through passive transport, which involves a nutrient gradient
- Bacteria can also uptake nutrients through active transport, which utilizes energy to bring in nutrients
- Iron uptake is an example of active transport, and siderophores play a role in this process
Learn about the two opposing chemical reactions in cells: catabolism, the breakdown of foodstuffs into smaller molecules to generate energy, and anabolism, the synthesis of other molecules using this energy.
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