Final (comprehensive, ch 26,21,22) Flashcards
In the history of classification of microbes, who were the key historical contributors and what were their key contributions?
robert hooke built the first compound microscope, and robert koch founded the scientific method, lady montegue and louise pastor invented the first vaccines.
Globally where are microbes able to grow and not grow?
everywhere, they are ubiquitous
What are the typical size ranges of each major type of microbe?
eukaryote 2um - 20cm, prokaryote 0.4 - 10um
What microscopes most easily visualize moving flagella?
dark field microscopy
What number of starting cells would produce any given number of final cells in log phase growth after a specific number of generations?
log phase: the phase where organisms are actively dividing and the generation time is constant.
This is the steep upward slope of the bacterial growth curve, where organisms are rapidly multiplying.
Nt=N0x2^n: Nt is the final cell number, N0 is the original cell number n is the number of generations.
How is glucose transported into cells occur when energy sources (ATP/PEP etc) are not available?
passive transport: simple diffusion, facilitated diffusion, and osmosis
When and how can oxygen be toxic to cells, and how do cells mediate this toxicity?
oxygen is toxic to aerobic cells that reqire enzymes to destroy reactive oxygen species (ROS)
What is the starvation response of cells?
enzymes can be produced to increase the efficiency of nutrient gathering, there can be programed cell death and TA (toxin-antitoxin) that is released to inactivate the toxin such as MazE and MazF
How are petri plates sterilized before we use them?
they are heated to kill bacteria that can interfere with tests
Why don’t bacteria grow in concentrated sugar solutions?
Sugar raises the solution’s osmolarity which increases ADH secretion, leading to reabsorption of water
What is the appearance and molecular structure of the sac around bacterial cells (based on an image)?
peryplasmic space?
Based on an image, how do some drugs function as weak acids or bases to enter cells?
Small molecules tend to penetrate membranes more rapidly than larger ones. Most drugs are weak organic acids or bases, existing in un-ionized and ionized forms in an aqueous environment. The un-ionized form is usually lipid soluble (lipophilic) and hydrophobic and diffuses readily across cell membranes.
What coupled processes allow bacteria to function and divide so rapidly compared to eukaryotes (based on an image)?
bacteria do not have a distinct nucleus that separates DNA from ribosomes, so there is no barrier to immediate translation and they have a singal recognition particle
What is polar aging?
Polar aging can cause members of the population to die as they accumulate damaged proteins at the “old” end of the cell. Some types of cells overcome this issue by alternating fast and slow extension of the poles.
What are the mechanisms of the different types of topoisomerases?
type I: single protein enzymes cleave one DNA strand and pass either one or two strands through the break before resealing it, releaves super coiling
type II: molecules cleave both DNA strands in concert and pass another double strand through the break followed by religation of the double strand break and uses ATP to introduce super coiling
What are the processes plasmids can use to get into new cells?
Plasmids are usually transferred from one bacterium to another via the process of conjugation (cell to cell) but they can also use transformation (environmental), and transduction (phage)
What are the error-proof and error-prone repair pathways?
prevent mutations:
a) methyl mismatch repair
b) photo reactivation
c) nucleotide excision repair
d) base excision repair
e) recombinational repair
cause mutations:
risk introducing mutations…operate only when damage is so severe that the cell has no other choice but to die
Why would error-proof pathways be maintained, in the face of evolution?
they prevent mutations and are favored in evolution
What are the processes and applications of CRISPR (based on an image)?
CRISPR is important because it allows scientists to rewrite the genetic code in almost any organism. It is simpler, cheaper, and more precise than previous gene editing techniques. Moreover, it has a range of real-world applications, including curing genetic disease and creating drought-resistant crops.
How and why do cells take up environmental DNA?
Many bacteria are naturally competent, able to actively transport environmental DNA fragments across their cell envelope and into their cytoplasm as a way to build their immunity.
What cell process(es) are sigma factors involved in?
Sigma factors are multi-domain subunits of bacterial RNA polymerase that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis.
What is the structure and function of ABC transporters (based on an image)?
ABC transport is powered by ATP when a solute binding protein binds to the solute and then to the membrane transporter and ATP is used to bring the solute across the membrane of the cell
Why should cells control gene expression?
expressing genes that are not necessary is a waste of energy
What is the basic function of the control of the lac operon?
Lacl binds to the tetramer to the operon region and represses the lac operon. beta-galactosidase or LacZ cleaves lactose to make the inducer allolactose which binds to Lacl and allowing induction of the operon.
How is the trp operon expression controlled?
The trp operon is expressed (turned “on”) when tryptophan levels are low and repressed (turned “off”) when they are high. The trp operon is regulated by the trp repressor. When bound to tryptophan, the trp repressor blocks expression of the operon.
What are the common signaling molecules used in biofilm formation by E. coli, and what do they do within cells?
free swimming cells,
How are energy consuming and producing reactions coupled in terms of delta G?
is delta G is greater than 0 then you are using energy for the reaction to occur but if delta g is less than zero then you are gaining energy and the reaction is favorable
How do we define fermentation?
is the completion of catabolism without the electron transport system and a terminal electron acceptor.
What are the names and features of the three major pathways for glucose breakdown (based on an image)?
glycolysis(emp), Krebs cycle and electron transport chain (oxidative phosphorylation). In this process, the glucose is converted to pyruvate during glycolysis and the same pyruvate produces carbon dioxide and water, along with the generation of energy.
What are the net outcomes (products and energy carriers) for the major pathways of glucose breakdown (based on an image)?
Glycolysis: Glucose breakdown to 2 pyruvates is coupled to net production of 2 ATP and 2 NADH.
kreb: 3 CO2 are produced by decarboxylation, 4 NADH (starting from Acetyl-CoA, just 3), 1 FADH2 are produced by redox reactions, 1 ATP is produced by substrate-level phosphorylation.
electron:
