Podcast
Questions and Answers
In what decade did doctors begin handwashing, though without understanding its impact on microbes?
In what decade did doctors begin handwashing, though without understanding its impact on microbes?
- 1950s
- 1780s
- 1900s
- 1840s (correct)
Which of the following processes completely eliminates all forms of life, including endospores?
Which of the following processes completely eliminates all forms of life, including endospores?
- Sanitization
- Sterilization (correct)
- Antisepsis
- Disinfection
Why are gamma rays and X-rays considered dangerous forms of radiation?
Why are gamma rays and X-rays considered dangerous forms of radiation?
- They create free radicals that can cause DNA damage and destroy cells. (correct)
- They emit non-ionizing radiation that is not strong enough to damage DNA.
- They create thymine dimers in DNA, blocking replication.
- They cause the vibration of molecules, leading to increased heat.
How does UV radiation primarily kill microbes?
How does UV radiation primarily kill microbes?
Which of the following is an example of moist heat treatment that sterilizes?
Which of the following is an example of moist heat treatment that sterilizes?
What is the primary mechanism by which alcohol kills bacteria?
What is the primary mechanism by which alcohol kills bacteria?
How do N95 masks effectively filter microbes?
How do N95 masks effectively filter microbes?
What is the function of chlorhexidine?
What is the function of chlorhexidine?
What is the main role of fluoride in preventing tooth decay?
What is the main role of fluoride in preventing tooth decay?
What are the primary functions that all cells must perform to facilitate growth?
What are the primary functions that all cells must perform to facilitate growth?
What is the overall purpose of metabolism in a cell?
What is the overall purpose of metabolism in a cell?
What is the direct consequence of enzyme denaturation?
What is the direct consequence of enzyme denaturation?
How does a competitive inhibitor affect an enzyme?
How does a competitive inhibitor affect an enzyme?
What best describes the process of fermentation?
What best describes the process of fermentation?
How does the amount of ATP produced by fermentation compare to that produced by aerobic respiration?
How does the amount of ATP produced by fermentation compare to that produced by aerobic respiration?
What is the role of DNA polymerase in DNA replication?
What is the role of DNA polymerase in DNA replication?
What is the main function of the mecA gene in S. aureus?
What is the main function of the mecA gene in S. aureus?
Which process involves making RNA from DNA?
Which process involves making RNA from DNA?
What best describes chemotaxis?
What best describes chemotaxis?
In genetics, what are induced mutations?
In genetics, what are induced mutations?
Flashcards
What is sterilization?
What is sterilization?
Removing all life forms, including endospores.
What is disinfection/antisepsis?
What is disinfection/antisepsis?
Reduces pathogens on a surface or tissue.
What is ionizing radiation?
What is ionizing radiation?
Gamma rays and X-rays which create free radicals that damage DNA.
How do N95 masks filter?
How do N95 masks filter?
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What do standard masks do?
What do standard masks do?
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How does alcohol kill bacteria?
How does alcohol kill bacteria?
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How does chlorhexidine work?
How does chlorhexidine work?
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How do halogens work?
How do halogens work?
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Where is fluoride found?
Where is fluoride found?
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Two tasks cells need to grow?
Two tasks cells need to grow?
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What is metabolism?
What is metabolism?
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What is ATP?
What is ATP?
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What is an enzyme?
What is an enzyme?
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Why is enzyme denaturation dangerous?
Why is enzyme denaturation dangerous?
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Transcription vs. Translation?
Transcription vs. Translation?
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What is chemotaxis?
What is chemotaxis?
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Mutation vs. horizontal gene transfer?
Mutation vs. horizontal gene transfer?
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What are thymine dimers?
What are thymine dimers?
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Transformation, Transduction, Conjugation?
Transformation, Transduction, Conjugation?
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Why is conjugation concerning?
Why is conjugation concerning?
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Study Notes
- Doctors started washing hands in the 1840s to reduce sickness, not to intentionally remove microbes.
Sterilization vs. Disinfection
- Sterilization removes all life forms, including endospores.
- Disinfection reduces pathogens.
- Disinfectants are for surfaces (e.g., bleach).
- Antiseptics are safe for living tissue (e.g., alcohol).
- Handwashing removes microbes through the physical action of soap and scrubbing.
- Handwashing does not sterilize
Ionizing Radiation
- Gamma rays and X-rays are two examples of ionizing radiation.
- They are dangerous because they create free radicals that damage DNA and destroy cells.
UV Radiation
- UV light kills microbes by creating thymine dimers in DNA, which blocks replication.
- Microwaves are not reliably antimicrobial because they heat unevenly.
- Powerlines and cell phones do not cause cancer because they emit non-ionizing radiation, which is not strong enough to damage DNA.
Moist Heat Treatment
- Boiling and pasteurization disinfect but do not sterilize.
- Autoclaving (121°C, 15 psi, 15 min) sterilizes and kills endospores.
- Pasteurization is a brief heat treatment that kills spoilage bacteria in liquids like milk without damaging taste.
- N95 masks filter particles larger than 0.2 μm using static-charged fibers.
- Smaller filters aren't practical due to airflow restrictions.
- Standard masks block respiratory droplets carrying microbes, preventing the spread of disease.
- Alcohol kills bacteria by disrupting membranes and 70-95% concentrations are most effective.
- Chlorhexidine peels off cell walls and is used as an antiseptic in mouthwash, body wash, and pet shampoo.
Halogens
- Halogens like chlorine and iodine form free radicals that damage cells.
- Chlorine can destroy endospores.
- Iodine (e.g., Betadine) is used on the skin.
- Fluoride is found in toothpaste and water, strengthens teeth, kills bacteria, and prevents cavities. It is considered safe.
- Colloidal silver is an antiseptic silver solution.
- Overuse can cause silver to deposit in skin, turning it blue (argyria).
Cell Growth
- Cells must make energy (ATP) from food.
- Cells must use that energy to build new cellular parts (macromolecules).
- Metabolism is the sum of all chemical reactions in a cell to generate energy and build cell components.
- ATP is the energy molecule produced during metabolism, made by all living organisms.
- An enzyme is a protein that catalyzes chemical reactions, converting a substrate into a product at its active site.
Enzyme Denaturation
- It is dangerous because it changes the enzyme's shape, preventing it from functioning.
- Without enzymes, cells cannot survive.
- Competitive inhibition involves an inhibitor mimicking a substrate and blocking the active site.
- Amoxicillin blocks PBP enzyme, stopping cell wall formation.
- Fermentation is ATP production from sugar without oxygen, occurring in the cytoplasm of bacteria and human muscle cells.
- Only 2 ATP are made by fermentation, less than the 38 ATP produced during aerobic respiration.
- Lactic acid (yogurt, sauerkraut) and ethanol + CO2 (beer, wine, bread) are examples of fermentation products.
- Facultative anaerobes grow better with oxygen because they produce much more ATP via aerobic respiration.
- The four nucleotides of DNA are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
- The central dogma of biology is DNA -> RNA -> Protein, where genetic information flows from DNA to RNA to protein.
- DNA polymerase copies DNA during replication so that each new cell gets a copy.
- The mecA gene codes for PBP2, making S. aureus resistant to antibiotics (MRSA).
Transcription vs. Translation
- Transcription makes RNA from DNA.
- Translation makes protein from RNA using ribosomes.
- Ribosomes are made of protein and rRNA, and all life uses ribosomes to make proteins.
- Chemotaxis is movement toward or away from chemical signals.
- Bacteria swim toward food and away from toxins.
- Quorum sensing is a chemical communication system used by bacteria to detect population density and form biofilms.
- Life adapts to changes through mutations and horizontal gene transfer.
- These alter DNA and allow survival under new conditions.
Mutation vs Horizontal Gene Transfer
- Mutation is a change in DNA sequence passed to offspring
- Horizontal gene transfer is DNA received from another bacterium.
- Good mutations include white fur in polar bears (camouflage)
- Bad mutations include antibiotic resistance in bacteria.
Mutations
- Spontaneous mutations are random DNA changes during replication due to DNA polymerase mistakes.
- Induced mutations are caused by mutagens like UV light or X-rays that damage DNA.
- Thymine dimers are UV-induced bonds between thymine bases that block DNA replication.
- This can kill the cell.
Transformation, Transduction, and Conjugation
- Transformation is the uptake of external DNA.
- Transduction is DNA transferred by viruses.
- Conjugation is DNA transfer through pili.
- Conjugation is concerning because it easily spreads antibiotic resistance genes between bacteria.
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