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80 Cards in this Set

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What is used to classify prokaryotes?
1. photosynthetic or nonphotosynthetic
2. motile or nonmotile
3. unicellular or colony-forming or filamentous
4 formation of spores or divison by transverse binary fission
A characteristic feature of the plasma membrane of prokaryotes is the prescence of what?
invaginated regions
Heterotrophs that harvest energy from organic molecules are called what?
chemoheterotrophs
Prokaryotes differ from eukaryotes in most characteristics besides what?
The plasma membrane
A microbiologist is investigating the effects of cold on a particular bacterium. He notices that as the temperature approaches zero degrees Centigrade, that the bacterium begins to
form endospores
Tuberculosis remains a serious world-wide health problem due to
1. Transmission through the air
2. Social factors such as crowding and poverty
3. The increasing prevalence of HIV infections
4. It is multi-drug resistant
A microbiologist is conducting a research project on chemoautotrophs. This means that the investigator is examining certain aspects of a bacterium that
can oxidize sulfur and other inorganic substances to get energy
The disease sometimes referred to as the "silent STD" because it is usually asymptomatic in women early on is
chlamydia
Chancre is a sore that is formed due to
nfection with Treponema pallidum
Most viruses form a capsid around their nucleic acid core. This capsid is composed of
a protein
Virulent viruses multiply within infected cells and eventually
cause lysis of the host cell, releasing new viruses
The genetic alteration of a cell’s genome by the introduction of foreign DNA is called
transformation
Recently a class of infectious proteins with no associated nucleic acid, have been identified. They are referred to as
prions
The HIV virus is considered a ______ virus, because after getting integrated into the host cell chromosomes, it does not begin replicating immediately.
latent
Each HIV particle possesses a ___________ on its surface that precisely fits a cell-surface marker protein called CD4 on the surfaces of the immune system cells called macrophages and T cells.
glycoprotein
Phages are viruses which can infect
bacteria
Viruses that become established as stable parts of the host cell genome are called
temperate
The infection cycle of HIV includes what steps?
attachment, entry into cells, replication, integration into the host cell's DNA, production of new viruses, and finally exit from the cells.
The onset of AIDS is often accompanied by
a steep drop in T cell numbers
A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the
envelope
What are the major characteristics of viroids?
1. Naked RNA molecules
2. Only a few 100 nucleotides long
3. Important infectious diseases in plants
Question 13 text Scientists have demonstrated that the cholera bacteria, Vibrie cholerae, exist in at least two forms. It usually exists in a rather harmless form, however a phage conversion can occur which produces a disease-causing, virulent form. This conversion is caused by
the phage introducing a gene into the bacterium's chromosome that codes for the cholera toxin which can cause death in humans
Viruses infect every organism that has been investigated for their presence. However, viruses can only replicate in
a very limited number of the host’s cells
Viruses may cause cancer by
triggering the expression of cancer-causing genes present in the genome
The _________________________ viruses have been linked with liver cancer in people with chronic infections.
Hepatitis B and C
Located on or within the cell are _________ proteins, each of which has a three dimensional shape complementary to that of a specific signal molecule.
receptor
The space into which neurotransmitters are released is called a chemical
synapse
Cyclic AMP and calcium ions are often used within a cell as
secondary messengers
The cells of multicellular organisms use a variety of molecules as signals which are
proteins, individual amino acids, nucleotides, steroids, other lipids, and dissolved gases
Signals with short-lived, local effects are called
paracrine signals
Synaptic signaling requires
neurotransmitters
The molecules that convert extracellular signals into intracellular ones are
cell surface receptors
Do chemically gated ion channels have genes incoded in them?
No
The class of cell surface receptors that act indirectly on plasma membrane-bound enzymes or ion channels are called
G proteins
A small number of surface receptors can ultimately generate a large intracellular response, as each step of the pathway is often expanded by
signal amplification
Most cells are in physical contact with other cells at all times by forming permanent connections called
cell junctions
In the digestive tract adjacent cells develop connections to form a sheet that prevents leakage of small molecules. These connections between cells are called
tight junctions
Small molecules or ions can pass from one cell to another through
communicating junctions
Junctions in which the cytoskeleton of a cell is attached to that of other cells or the extracellular matrix are called
anchoring junctions
A biochemist is designing a new drug that will mimic the shape of a particular signal molecule. She has to design the drug molecules so that they will be selected over the other “normal” molecules at the surface of the cell membrane. Therefore she must produce molecules that will bind to the receptor protein and
induce a change in the receptor molecule shape, which will ultimately produce a cellular response
What technique has recently aided the study of receptor proteins?
monoclonal antibodies
What occurs during autocrine signaling?
Signal molecules are released from a cell and bind to receptors on its own plasma membrane.
Intracellular receptors usually bind to
lipid-soluble signals.
What are the different types of cell surface receptors?
chemically gated ion channels, enzymic receptors, and G-protein linked receptors
What things are used as secondary messengers?
cyclic adenosine monophosphate, calcium ions, and cAMP
What does the amplification of a cellular signal require?
a second messenger,a signal molecule, and a cascade of protein kinases
MHC proteins are
identity markers present on the surface of an individual's cells.
Sheets of cells are formed from which type of cell junctions?
tight junctions
Cadherin can be found in what type of cell junction?
anchoring junctions
Plasmodesmata are a type of what junction?
communicating junction.
Viruses consist of a ________________ core surrounded by a protein coat.
nucleic acid
Phages infect bacterial cells by
poking holes in the cell and injecting their DNA.
The end result of the viral lytic cycle is
the release of new viruses.
The alteration of a cell's genome by the incorporation of foreign DNA is called
transformation.
What are the viral glycoproteins that play a role in the infection of human cells by HIV?
CD4 and CCR5
The HIV enzyme, ________________, produces a DNA copy of the viral genome once it is inside the host cell.
reverse transcriptase
The drug AZT and its analogs functions by
inhibiting the replication of viral nucleic acid.
What is the function of the CD8+ cell antiviral factor (CAF) in human white blood cells?
blocks replication of the HIV virus
New strains of flu viruses are most likely to arise in the Far East because
common hosts (ducks, chickens, pigs) live in close proximity to humans.
Which of the following infectious agents does not contain protein?
viroids
Once they evolved, _____________ forever changed the atmosphere on earth.
cyanobacteria
Are prokaryotic cells unicellular or multicellular?
unicellular
When bacterial cell walls are covered with an outer membrane of lipopolysaccharide, they are
gram-negative
The prokaryotic genome is contained in the
nucleoid region.
Archaebacteria and bacteria do not differ in their
presence in nonextreme environments.
Genetic recombination has led to antibiotic resistance through the transfer of
plasmids.
Prokaryotic organisms that obtain their energy by oxidizing inorganic substances are called
chemoautotrophs.
What disease is experiencing new outbreaks because of antibiotic resistance?
tuberculosis
The disease sometimes referred to as the "silent STD" because it is usually asymptomatic in women early on is
chlamydia
What tasks can be attributed to bacteria?
decomposition of dead organic matter, increasing oxygen levels in the atmosphere, and production of antibiotics
An atom gains energy when
it undergoes reduction.
Which of the following is concerned with the amount of energy in the universe?
the First Law of Thermodynamics
In a chemical reaction, if ΔG is negative, it means that
the reaction will proceed spontaneously.
A catalyst does what?
lowers the amount of energy needed for a reaction to proceed.
Do all the cells of an organism contain the same enzymes?
No, this is false.
A multienzyme complex contains
enzymes that catalyze a series of reactions.
What are factors that can have an effect on the rate of enzyme-catalyzed reactions?
temperature, ph, and concentration of substrate
How is ATP used in the cell to produce cellular energy?
ATP hydrolysis is coupled to endergonic reactions.
Anabolic reactions are reactions that
make chemical bonds.
How is a biochemical pathway regulated?
The end product inhibits the first enzyme in the pathway by binding to an allosteric site.