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How is osmosis different from simple diffusion?
Water movement is driven by the concentration of solutes rather than its own concentration.
What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane?
the cell will lose its interior water, causing it to shrivel up and possibly die
How is simple diffusion different from other types of passive transport?
Simple diffusion does not require a permease
Which of the following would not move freely across the cytoplasmic membrane?
positively charged hydrogen ions
What makes phospholipid membranes good at keeping some molecules out and allowing others to freely pass?
They have both hydrophilic ad hydrophobic regions
How does water enter and exit a cell?
By simple diffusion or by use of an integral transport protein
is a type of peripheral protein above that can be used as a receptor or in enzymatic functions
What is a hallmark of passive transport across a cell membrane?
It occurs along an electrochemical gradient, and may involve the use of transport proteins
A positively charged sodium ion
would require the use of integral protein channels to pass through a cell membrane
Sodium and potassium ions need to be pumped simultaneously against their concentration gradients. Which one of the transport proteins would be most effective at this?
Why are ATPases associated w/active transport proteins?
They provide transport proteins w/the energy needed to pump molecules against their concentration gradients
Efflux pumps can be used to pump antibiotics out of a cell once they enter to protect the cell. This will be done against the concentration gradient of the antibiotic. Which of the active transports would most likely be used?
Uniport b/c a uniport would pump the antibiotic out w/out needing to bring additional molecules into the cell, and would not allow the antibiotic to diffuse back in
Why is a ATP necessary for active transport?
ATP provides energy to transfer material against its concentration gradient
Which transport protein employs transporters that move molecules only in one direction?
uniport and symport
Which type of active transport protein uses one protein to pump two different molecules?
Antiport and Symport
What is part of the endomembrane system
Golgi apparatus, ER, lysosomes and vesicles; it manufactures, processes and transports lipids and proteins. The Golgi apparats processes and packages proteins
What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell?
What is the mechanism of action of penicillin in a prokaryotic cell?
Penicillin weakens the cell wall
Difference between Gram-Positive and Gram-Negative cells
only gram-negative cells have a lipopolysaccharide layer
Which type os solution would cause a bacterium w/a week or damaged cell wall to burst as water moves into the cell?
Structure or function of ribosomes
In eukaryotes, the ribosomes found in the chloroplasts and mitochondria are 70S ribosomes, which are similar to he size of the prokaryotic ribosome
Evidence of the endosymbiotic theory
-ribosomes contain w/in mitochondria and chloroplasts are very similar to prokaryotic ribosomes
-mitochondria and chloroplasts contain circular DNA, similar to the DNA in prokaryotes
-The same antibiotics that inhibit protein synthesis in prokaryotes also inhibit protein synthesis w/in mitochondria and chloroplasts
Distinguishing characteristics of Prokaryotic cells
-Their DNA is not associated w/histones
-Their DNA is not enclosed w/in a membrane
-They have cell walls containing peptidoglycan
-They lack membrane-enclosed organelles
What happens when a bacterial cell is placed in a solution containing 5% NaCl?
Water will move out of the cell
What structures are found in prokaryotic cells?
Flagellum, axial filament, pilus, peritrichous flagella
-is used to adhere to surfaces
-may be composed of polypeptide
-may be composed of polysaccharide
-may be responsible for virulence
Chemical components of a bacterial cell wall
The difference between simple diffusion and facilitated diffusion is that facilitated diffusion
requires transporter proteins
Considered to be microorganisms
-bacteria and viruses
-fungi (including yeasts and molds)
Which microorganisms are acellular and contain a nucleic acid core surrounded by a protein coat?
How did Pasteur's 1861 experiment disprove the theory of spontaneous generation?
Pasteur used open-ended, long-necked flasks w/necks bent into curves; other did not
Which of the following is the concept, proposed by the German scientists Virchow in 1858, that challenged the hypothetical process called "spontaneous generation"?
Which scientist, in 1876, established a sequence of experimental steps for directly linking a scientific microbe to a specific disease?
Human diseases can be caused by a complex aggregation of microbes known as a "biofilm"?
Emerging Infectious disease that is a spongiform encephalopathy caused by a prion
The presence of several types of bacteria on the surface of the tongue indicates the presence of
Statement regarding the experiments that "proved" spontaneous generation
microorganisms were already present
Regarding Pasteur's experiment w/the S-neck flask
-there was air involved
-all microorganisms were killed before beginning
-there was a food source involved
-any possibility of contamination was removed
Findings that were essential of Jenner's vaccination process?
a weakened microorganism may produce immunity
An agent that reproduces in cells but is Not composed of cells and contain RNA as its genetic material is a
Bacteria differ from viruses in that bacteria
-are composed of cells
-can live without a host
-have DNA and RNA
-on rocks provide food for animals
-in pipes black the flow of water
-on medical implants cause infections
-in your body protect mucous membranes from harmful microbes
What is the type of bond between carbon, hydrogen, and oxygen atoms in organic molecules?
Oil-degrading bacteria are naturally present in the environment but cannot degrade an oil spill fast enough to avoid ecological damage. How can the actions of these bacteria be sped up?
Provide nitrogen and phosphorus
Why do electron microscopes have higher resolving power than light microscopes?
electrons have a smaller wavelength than visible light, leading to higher resolution
Which type of microscope would allow the viewer to see ribosomes inside a cell?
a transmission electron microscope
Characteristic shared by both electron and light microscopes?
both employ the use of objective lenses
What is the fate of the electrons that interact w/a specimen in an electron microscope?
they may be absorbed, reflected, or refracted by the specimen
Why is a specimen smaller than 200 nm not visible w/a light microscope?
Anything smaller than 200 nm cannot interact w/visible light
What happens to the light rays wen they hit the specimen?
they are reflected, refracted, or absorbed by the specimen
What is the role of lenses in microscopy?
lenses focus either light or electrons to create a magnified image of a specimen
Why is cell growth typically graphed logarithmically?
Cell growth is rapid, and plotting the log of the number of cells versus the generation on a logarithmic graph produces a linear graph
Why might cells begin to die at a faster rate than new cells are made?
Lack of nutrients and an increase in cellular waste products
When the log of the number of cells is plotted versus the generation, the graph is linear
If you begin with six cells, how many cells would you have after three rounds of division?
Which step of binary fission is the reason for genetically identical daughter cells?
replication of the bacterial chromosome
What enables the copied chromosomes to separate during binary fission?
The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes
How long does it take for the daughter cells from one round of replication to replicate themselves?
no time is required-they are fully mature and ready to divide immediately after separation if conditions are right
Steps of bacterial replication in the correct order, starting from a parent cell
4.separation of daughter cells
What would happen if the septum did not form during binary fission?
The parent cell would now have two copies of the chromosome
Aerobic bacteria that have developed (or retain) the ability to continue growing in the absence of molecular oxygen are called
Which type of culture media is best for the growth of most chemoheterotrophic organisms?
During which phases of the bacterial growth curve are there no changes in the number of living cells
lag phase and stationary phase
Intense activity preparing of population growth occurs in which phase of the bacterial growth curve?
Represents an ideal number of colony-forming units for effective enumeration using the direct method?
A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies is call a
selective medium and differential medium
Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?
Patients with indwelling catheters are susceptible to infections because
biofilms develop on catheters
Microorganisms that are acellular and contain a nucleic acid core surrounded by a protein coat
How does noncompetitive inhibitor reduce an enzyme's activity?
The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site
What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor?
no change in enzyme activity would be observed
How is nevirapine used to treat HIV infections?
It alters the active site of reverse transcriptase, decreasing that enzyme's activity
How does a competitive inhibitor slow enzyme catalysis?
They compete w/the substrate for the enzyme's active site
What enables competitive inhibitors to bind to a specific enzyme?
competitive inhibitors have structures that resemble the enzyme's substrate
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected?
The enzyme will stop functioning
Why do all enzymatic reactions need activation energy?
Energy is required to disrupt a substrate's stable electron configuration
What is meant by the statement "Enzymes are biological catalysts"?
Enzymes speed up the chemical reactions in living cells
Why are enzymes important biological systems?
Enzymes decrease the amount of activation energy required for chemical reactions to occur
What is the fate of an enzyme after it dissociates from the products of the reaction?
The enzyme returns to its original configuration, ready to bind more substrate
features of a substrate that can be accommodated by an enzyme's active site?
and electron configuration of the substrate
A reaction that involves the transfer of electrons from one molecule to another is referred to as
a redox reaction
Why is a reduction the term used to describe the gain of an electron?
The electron acceptor's net charge decreases
What does the electron transport chain do to the concentration of hydrogen ions (protons)?
The concentration of protons is higher outside the membrane than inside
Why does lack of oxygen result in the halt of ATP synthesis?
The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained.
Why might some cells uncouple the electron transport chain?
Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation
How does cyanide poisoning result in the decrease of ATP production?
Cyanide permanently reduces cytochrome a3, preventing other components to change into the oxidized state. This causes the proton gradient to break down, stopping ATP synthesis.
What is he role of pyruvic acid in fermentation?
It takes the electrons from NADH, oxidizing it back into NAD+
What is the fate of the NAD+ newly regenerated by fermentation?
It returns to glycolysis to pick up more electrons.
Why is ATP required for glycolysis?
ATP makes it easier to break apart glucose into two three-carbon molecules.
What is the fate of metabolites during respiration?
They are oxidized completely to carbon dioxide and water
How food fuels cellular respiration
1.eating food provides fuel and building blocks for your body
2.after food is broken down the digestive system, it is transported to cells via the circulatory system
3.fuel molecules are broken down further in glycolysis and the citric acid cycle
4.ATP is produced with the help of the ETC
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