Question

1.) Compare aerobic respiration, anaerobic respiration and fermentation. How are the processes similar? How are they different? How do these processes determine which environment the organism can live in?

[Key terms to use in answer: electron transport chain, cytochrome, ATP, glucose, glycolysis, obligate aerobe, facultative anaerobe, microaerophile, obligate anaerobe, oxidase, catalase, peroxidase, CO ₂ , organic acids and alcohols, alternative substrates (other than glucose)]

2.) Using your knowledge of DNA recombination events to complete the following:

(Use the following terminology in your answer: recombination, DNA, horizontal gene transfer, conjugation, transformation, transduction, pilus, F factor, transposable elements, transposons, pathogenicity islands)

1. Propose two ways in which antibiotic resistance may develop in a bacterium
2. Describe how bacterial cells acquire the ability to produce toxins

**References are appreciated.

Answer 1

1- Anaerobic respirationbegins the same way as aerobic respiration and fermentation. ... However, instead of ending with glycolysis, as fermentationdoes, anaerobic respiration creates pyruvate and then continues on the same path as aerobic respiration.

Anaerobic respiration is similar to aerobic respiration in that the molecules enter the electron transport chain to pass the electrons to the final electron acceptor. ... Anaerobic respiration and fermentation processes take place in the muscle cells during immediate contraction and relaxation.

Aerobic respiration is a set of metabolic reactions that take place in the presence of oxygen, occurring in a cell to convert chemical energy into ATPs. Anaerobic respiration is a process of cellular respiration where the high energy electron acceptor is neither oxygen nor pyruvate derivatives.

• Aerobic and anaerobic respiration each have advantages under specific conditions. Aerobic respiration produces far more ATP, but risks exposure to oxygen toxicity. Anaerobic respiration is less energy-efficient, but allows survival in habitats which lack oxygen.
• Within the human body, both aerobic and anaerobic respiration are important to muscle function.
• Muscle cells specialized for aerobic respiration provide endurance, and those specialized for lactic acid fermentation support short but intense energy expenditures.
• Both ways of making ATP play critical roles in life on earth.
• Aerobic respiration is far more energy-efficient than anaerobic respiration.
• Aerobic processes produce up to 38 ATP per glucose.
• Anaerobic processes yield only 2 ATP per glucose.

2-Some bacteria are naturally resistant to certain types of antibiotics. However, bacteria may also become resistant in two ways: 1) by a genetic mutation or 2) by acquiring resistance from another bacterium.

Bacteria develop resistance mechanisms by using instructions provided by their DNA. Often, resistance genes are found within plasmids, small pieces of DNA that carry genetic instructions from one germ to another. This means that some bacteria can share their DNA and make other germs become resistant.

Antibiotic resistance is a consequence of evolution via natural selection. The antibiotic action is an environmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspring, which will be a fully resistant generation.

2-B- Toxigenesis, or the ability to produce toxins, is an underlying mechanism by which many bacterialpathogens producedisease. ... Exotoxins are usually secreted by bacteria and act at a site removed from bacterial growth. However, in some cases, exotoxins are only released by lysis of the bacterial cell.

Bacterial toxins are toxic substances that are produced and released by bacteria to target other bacterial or host cells. Bacteria often have antitoxins to avoid the deleterious effects of toxins