MCB2010 Exam 1 Questions with Complete Solutions 100% Solved| Grade A+
What are the main products of the Kreb's Cycle? NADH and FADH2
What are the electron carrier molecules in the Kreb's cycle? NAD+ and FAD+
How much ATP is produced with the Kreb's Cycle? 2
Where in the cell is the electron transport chain located? Prokaryotes: Cell membrane
Eukaryotes: Membrane of the mitochondria
What are the electron carrier molecules in the electron transport chain? NADH and FADH2
What is the significance of the H+ gradient in the electron transport chain? Source of
potential energy
Where does the H+ gradient occur? Outside of the plasma membrane
What happens to the hydrogen atoms in the electron transport chain? They are pumped
across the membrane
What is the enzyme that synthesizes ATP in the electron transport chain? ATP synthase
How many energy molecules are produced in the electron transport chain? 32 ATP
How many glucose molecules are required to produce 36 ATP by fermentation? 36/2 = 18
glucose molecules
,What effect does oxygen have on an organisms that is strictly (obligate) fermentative? No
effect.
Fermentation will occur with or without oxygen, it is a completely anaerobic process not
influenced by oxygen availability.
What is the function of the pilus? A pilus is a thin, rigid fiber made of protein that protrudes
from the cell surface. T
The primary function of pili are to attach a bacterial cell to specific surfaces or to other cells
Conjugation mechanism with visual Conjugation diagram:
1. Donor cell produces pilus.
2. Pilus attaches to recipient cell and brings the two cells together.
3. The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient
cell.
4. Both cells synthesize a complementary strand to produce a double stranded circular plasmid
and also reproduce pili; both cells are now viable donor for the F-factor.
Describe the structure and function of bacterial glycocalyx The glycocalyx is a thick outer
covering of the plasma membrane. It is composed of strands of sugars and proteins bound
together. The result is a thick, sticky layer that helps cells stay put in environments with lots of
physical stress.
Bacteria use the glycocalyx to make thick films of bacteria in nature as well, called a biofilm.
What is a biofilm? A surface-coating colony of one or more species of prokaryotes that
engage in metabolic cooperation.
, Biofilms have important applications in breaking down toxic chemicals in our ecosystems and
have been used to clean up petroleum spills, as well as contamination in water supplies. The
bacteria in the biofilm break down the toxic chemicals, allowing the ecosystem to return to
normal.
What are some examples of bacteria with atypical cell walls? How do they do differ from other
bacteria? Bacteria that do not color with gram-staining but rather remain colorless: they are
neither Gram-positive nor Gram-negative. These include the Chlamydiaceae and the
Mycoplasmataceae (including mycoplasma and ureaplasma); the Rickettsiaceae are also often
considered atypical. They lack a peptidoglycan layer. Peptidoglycans are the site of action of
beta-lactam antibiotics such as penicillins and cephalosporins, so chlamydia and mycoplasma
are naturally resistant to these drugs
What is generation time? Generation time is the time required for a cell to grow and divide.
Length of generation time is a measure of the growth rate.
Describe how quorum sensing can lead to formation of a biofilm Biofilms form as a result of
quorum sensing, in which microorganisms respond to the density of nearby microorganisms.
To measure their population density, bacteria synthesize and secrete a small signaling
molecule. A protein receptor can detect their signal. At low density, the signal diffuses away
from cells. At high density, the signal reaches the receptor.
Explain how extremes of temperature and pH limit microbial growth. Temperature: If a
temperature is too extreme, the microbial growth is inhibited. Protein shapes can be altered by
the incorrect temperature. If the temperature is too low, cell membranes become very rigid
and feeble. If the temperature is too high, lipids become aqueous and the membrane is unable
to enclose the cell.
pH: Microorganisms display the best growth when it is in its proper pH. Most bacteria and
protozoa prefer a pH of around 7.
What are the main products of the Kreb's Cycle? NADH and FADH2
What are the electron carrier molecules in the Kreb's cycle? NAD+ and FAD+
How much ATP is produced with the Kreb's Cycle? 2
Where in the cell is the electron transport chain located? Prokaryotes: Cell membrane
Eukaryotes: Membrane of the mitochondria
What are the electron carrier molecules in the electron transport chain? NADH and FADH2
What is the significance of the H+ gradient in the electron transport chain? Source of
potential energy
Where does the H+ gradient occur? Outside of the plasma membrane
What happens to the hydrogen atoms in the electron transport chain? They are pumped
across the membrane
What is the enzyme that synthesizes ATP in the electron transport chain? ATP synthase
How many energy molecules are produced in the electron transport chain? 32 ATP
How many glucose molecules are required to produce 36 ATP by fermentation? 36/2 = 18
glucose molecules
,What effect does oxygen have on an organisms that is strictly (obligate) fermentative? No
effect.
Fermentation will occur with or without oxygen, it is a completely anaerobic process not
influenced by oxygen availability.
What is the function of the pilus? A pilus is a thin, rigid fiber made of protein that protrudes
from the cell surface. T
The primary function of pili are to attach a bacterial cell to specific surfaces or to other cells
Conjugation mechanism with visual Conjugation diagram:
1. Donor cell produces pilus.
2. Pilus attaches to recipient cell and brings the two cells together.
3. The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient
cell.
4. Both cells synthesize a complementary strand to produce a double stranded circular plasmid
and also reproduce pili; both cells are now viable donor for the F-factor.
Describe the structure and function of bacterial glycocalyx The glycocalyx is a thick outer
covering of the plasma membrane. It is composed of strands of sugars and proteins bound
together. The result is a thick, sticky layer that helps cells stay put in environments with lots of
physical stress.
Bacteria use the glycocalyx to make thick films of bacteria in nature as well, called a biofilm.
What is a biofilm? A surface-coating colony of one or more species of prokaryotes that
engage in metabolic cooperation.
, Biofilms have important applications in breaking down toxic chemicals in our ecosystems and
have been used to clean up petroleum spills, as well as contamination in water supplies. The
bacteria in the biofilm break down the toxic chemicals, allowing the ecosystem to return to
normal.
What are some examples of bacteria with atypical cell walls? How do they do differ from other
bacteria? Bacteria that do not color with gram-staining but rather remain colorless: they are
neither Gram-positive nor Gram-negative. These include the Chlamydiaceae and the
Mycoplasmataceae (including mycoplasma and ureaplasma); the Rickettsiaceae are also often
considered atypical. They lack a peptidoglycan layer. Peptidoglycans are the site of action of
beta-lactam antibiotics such as penicillins and cephalosporins, so chlamydia and mycoplasma
are naturally resistant to these drugs
What is generation time? Generation time is the time required for a cell to grow and divide.
Length of generation time is a measure of the growth rate.
Describe how quorum sensing can lead to formation of a biofilm Biofilms form as a result of
quorum sensing, in which microorganisms respond to the density of nearby microorganisms.
To measure their population density, bacteria synthesize and secrete a small signaling
molecule. A protein receptor can detect their signal. At low density, the signal diffuses away
from cells. At high density, the signal reaches the receptor.
Explain how extremes of temperature and pH limit microbial growth. Temperature: If a
temperature is too extreme, the microbial growth is inhibited. Protein shapes can be altered by
the incorrect temperature. If the temperature is too low, cell membranes become very rigid
and feeble. If the temperature is too high, lipids become aqueous and the membrane is unable
to enclose the cell.
pH: Microorganisms display the best growth when it is in its proper pH. Most bacteria and
protozoa prefer a pH of around 7.
