MCB 3020 Exam 2 Study Guide with Complete Solutions
What is the most common mechanism for bacterial cell division? - ANSWER - Binary fission
List the 4 steps of Binary Fission - ANSWER - 1. Elongation of cell
2. Replication of chromosome
3. Separation of chromosomes into 2 parts of cell
4. Formation of septum in middle
Define 'Origin of Replication' - ANSWER - Where replication begins
How many origins of replication do bacterial chromosomes have? - ANSWER - 1
What is cytokinesis? Include brief overview of its four steps. - ANSWER - Division of a cell into two via a formation of a septum in the middle of cell
Penicillin-Binding Protein - ANSWER - Group of proteins that hydrolyze bonds in existing peptidoglycan strands and link together new strands
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) - ANSWER - Major components of peptidoglycan that bind to a membrane protein called bactoprenol
Obligate Anaerobes - ANSWER - Cannot survive in presence of oxygen
Facultative Anaerobes - ANSWER - Grow better with oxygen than without it (not needed)
Barotolerant - ANSWER - Survive increased pressures Autolysins - ANSWER - Degrade polypeptide where new units are to be added, and the new NAM-NAG units can then be inserted into peptidoglycan layer
What is crescentin? - ANSWER - A homologue or eukaryotic intermediate filaments
What are the other forms of asexual reproduction? Define each - ANSWER - - Budding: budding off daughter cells; seen in Listeria monocytogenes - Baeocyte formation: multiple rounds of cell division; seen in Cyanobacteria - Spore formation: form multinucleoid filaments that ultimately divide to produce spores with a single nucleus
Bacterial Growth Curve - ANSWER - - Lag phase: no net growth because; although the nutrients are abundant, the bacteria are adjusting to new conditions
- Log (exponential) phase: nutrients are abundant, and bacteria divide at their highest rate - Stationary phase: number of viable microorganisms is stable because the nutrients level off and waste products accumulate - Death phase: nutrients are depleted, and levels of waste products and toxins are high, so number of viable microorganisms decreases - Long-term stationary phase: nutrients are depleted, and waves of genetic variants come and go; natural
selection
T/F: When nutrient levels are low, limitation of microbial growth occurs as a result of saturation of transport proteins for nutrient uptake - ANSWER - False; should when levels are high
What is the generation time (GT)? - ANSWER - Time it takes the population to double What phase is it best to calculate GT? - ANSWER - Log phase
T/F: Cells typically exist in aqueous conditions - ANSWER - True
Define hypertonic and hypotonic. - ANSWER - - Hypertonic: one solution has higher concentration of solutes than another - Hypotonic: One solution has lower concentration of solutes than another
If a cell is in a hypertonic solution it will ______, while in a hypotonic solution it will _______ - ANSWER - Shrink, burst
What are the 3 distinct cardinal growth temperatures for organisms? - ANSWER - - Minimum: lowest temp at which an org can grow and survive
- Maximum: highest temp at which an org can grow and survive
- Optimal: most suitable temp for bacterial growth
Halophiles - ANSWER - Grow best in extremely salty environments
Xerophiles - ANSWER - Grow best in dry conditions
Psychrophiles - ANSWER - Grow between 0 C and 20 C - refrigeration temperatures
Mesophiles - ANSWER - Grow between 20 C and 45 C; most human pathogens
Thermophiles - ANSWER - Grow between 55 C and 85 C
What is the most common mechanism for bacterial cell division? - ANSWER - Binary fission
List the 4 steps of Binary Fission - ANSWER - 1. Elongation of cell
2. Replication of chromosome
3. Separation of chromosomes into 2 parts of cell
4. Formation of septum in middle
Define 'Origin of Replication' - ANSWER - Where replication begins
How many origins of replication do bacterial chromosomes have? - ANSWER - 1
What is cytokinesis? Include brief overview of its four steps. - ANSWER - Division of a cell into two via a formation of a septum in the middle of cell
Penicillin-Binding Protein - ANSWER - Group of proteins that hydrolyze bonds in existing peptidoglycan strands and link together new strands
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) - ANSWER - Major components of peptidoglycan that bind to a membrane protein called bactoprenol
Obligate Anaerobes - ANSWER - Cannot survive in presence of oxygen
Facultative Anaerobes - ANSWER - Grow better with oxygen than without it (not needed)
Barotolerant - ANSWER - Survive increased pressures Autolysins - ANSWER - Degrade polypeptide where new units are to be added, and the new NAM-NAG units can then be inserted into peptidoglycan layer
What is crescentin? - ANSWER - A homologue or eukaryotic intermediate filaments
What are the other forms of asexual reproduction? Define each - ANSWER - - Budding: budding off daughter cells; seen in Listeria monocytogenes - Baeocyte formation: multiple rounds of cell division; seen in Cyanobacteria - Spore formation: form multinucleoid filaments that ultimately divide to produce spores with a single nucleus
Bacterial Growth Curve - ANSWER - - Lag phase: no net growth because; although the nutrients are abundant, the bacteria are adjusting to new conditions
- Log (exponential) phase: nutrients are abundant, and bacteria divide at their highest rate - Stationary phase: number of viable microorganisms is stable because the nutrients level off and waste products accumulate - Death phase: nutrients are depleted, and levels of waste products and toxins are high, so number of viable microorganisms decreases - Long-term stationary phase: nutrients are depleted, and waves of genetic variants come and go; natural
selection
T/F: When nutrient levels are low, limitation of microbial growth occurs as a result of saturation of transport proteins for nutrient uptake - ANSWER - False; should when levels are high
What is the generation time (GT)? - ANSWER - Time it takes the population to double What phase is it best to calculate GT? - ANSWER - Log phase
T/F: Cells typically exist in aqueous conditions - ANSWER - True
Define hypertonic and hypotonic. - ANSWER - - Hypertonic: one solution has higher concentration of solutes than another - Hypotonic: One solution has lower concentration of solutes than another
If a cell is in a hypertonic solution it will ______, while in a hypotonic solution it will _______ - ANSWER - Shrink, burst
What are the 3 distinct cardinal growth temperatures for organisms? - ANSWER - - Minimum: lowest temp at which an org can grow and survive
- Maximum: highest temp at which an org can grow and survive
- Optimal: most suitable temp for bacterial growth
Halophiles - ANSWER - Grow best in extremely salty environments
Xerophiles - ANSWER - Grow best in dry conditions
Psychrophiles - ANSWER - Grow between 0 C and 20 C - refrigeration temperatures
Mesophiles - ANSWER - Grow between 20 C and 45 C; most human pathogens
Thermophiles - ANSWER - Grow between 55 C and 85 C
