- the study of what genes are, how they carry information, how the information is expressed, and how genes are replicated and pass on
Genetics
- a segment of DNA, a sequence of nucleotides, that encodes a functional product, usually a protein
Gene
- all the genetic information in a cell. One complete copy of the genetic information in a cell
Genome
Principal molecule responsible for the storage of genetic information.
The nucleic acid of genetic material in all cells and some viruses.
Deoxyribonucleic acid (DNA)
structure containing DNA that physically carries hereditary information, contains genes
[in bacteria] single largest DNA molecule in a cell that contains the information necessary for the cell’s survival.
Chromosome
Any extra-chromosomal DNA that is capable of encoding its replication. In other words, non chromosomal replicons.
A small circular DNA molecule that replicates independently of the chromosome.
Plasmid
- Characteristics expressed by a cell in a given environment. Adaptable in response to environment changes.
- The expression of the genes: the proteins of the cell and the properties they confer on the organism.
- The external manifestations of an organism's genotype, or genetic make up.
Phenotype
- Collection of genes encoding the characteristics. Remains Unchanged.
- Is the genetic composition of an organism, its entire complement of DNA.
- The genetic make up of an organism.
Genotype
- Alternative forms of a gene on same chromosome, same location.
Allele
Polymer of nucleotides: adenine, thymine, cytosine, and guanine
Double helix, “Backbone” is deoxyribose-phosphate
Strands are held together by hydrogen bonds between AT and CG bases
Strands are antiparallel (5’ to 3’)
DNA structure
A mutagen that is incorporated into DNA in place of a normal base
Nucleoside analog
A mutagen that causes the formation of highly reactive ions.
Ionizing radiation
A mutagen that alters adenine so that it base-pairs with cytosine
Base-pair mutagen
A mutagen that causes insertions
Frameshift mutagen
A mutagen that causes the formation of pyrimidine dimers
Nonionizing radiation
The following is a code for a strand of DNA.
3' A T A T _ _ _ T T T _ _ _ _ _ _ _ _ _
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
mRNA C G U U G A
tRNA U G G
Amino Acid Met ___ ___ ___ ___
ATAT = Promoter sequence
a. Fill in the blanks to complete the segment of DNA shown using the genetic code.
b. Fill in the blanks to complete the sequence of amino acids coded for this strand of DNA.
c. Write the code for the complementary strand of DNA completed in part a.
d. What would be the effect if C were substituted for T at base 10?
e. What would be the effect if A were substituted for G at base 11?
f. What would be the effect if G were substituted for T at base 14?
g. What would be the effect if C were inserted between bases 9 and 10?
h. How would UV radiation effect this strand of DNA?
i. Identify a nonsense sequence in this strand of DNA.
a. A T A T T A C T T T G C A T G G A C T
b. met-lys-arg-thr-(end).
c. T A T A A T G A A A C G T T C C T G A
d. No change.
e. Cysteine substituted for arginine.
f. Proline substituted for threonine (missense mutation).
g. Frameshift mutation
h. Adjacent thymines might polymerize.
i. ACT.
When Iron i not available, E. Coli can stop synthesis of all proteins, such as superoxide dismutase and succinatee dehydrogenase, that require iron. Descride a mechanism for this regulation.
Iron deficiency could stimulate miRNA that is complementary to RNA encoding iron-requiring proteins
Identify when (before transcription, after transcription, before translation, & after translation) each of the following regulatory mechanisms functions.
a. ATP combines with an enzyme, altering its shape
b. a short RNA is synthesized that is complementary to mRNA
c. Myethylation of DNA occurs
d. An inducer combines with a repressor
a.after translation
b. after transcription
c. before transcription
d. before transcripiton
Which sequence is the best target for damage by UV radiation: AGGCAA, CTTTGA, or GUAAAU?
CTTTGA
Why aren't all bacteria killed when they are exposed to sunlight?
Endospores and pigments offer protection against UV radiation. Additionally, repair mechanisms can remove and replace thymine polymers.
You are provided with cultures with the following characteristics:
Culture 1: F+, genotype A+B+C+
Culture 2:F-, genotype A-B-C-
A. indicate the possible genotypes of a recombinant cell resulting from the conjugation of cultures 1 and 2
B. indicate the possible genotypes of a recombinant cell resulting from conjugation of the two cultures after F+ has become an Hfr cell.
a. culture 1 will remain the same. culture 2 will convert to F+ but will have its original genotype
b. The donor & recipient cells' DNA can recombine to form combinations of A+ B+ C+ and A-B-C-. If the F plasmid also is transferred, the recipient cell may become F+.
Why are mutation and recombination important in the process of natural selection and the evolution of organisms?
Mutation and recombination provide genetic diversity. Environmental factors select for the survival of organisms through natural selection. genetic Diversity is necessary for the survival of some organisms through the processes of natural selection. Organisms that survive may undergo further genetic change, resulting in the evolution of the species
Normally a commensal in the human intestine, this bacterium became pathogenic after acquiring a toxin gene from a Shigella bacterium. Name IT
Escherichia Coli
Transfer of DNA from donor to a recipient cell by a bacteriophage
A. conjugation
B. Transcription
C. Transduction
D. Transformation
E. Translation
C. Transduction
Transfer of DNA from a donor to a recipient as naked DNA in Solution
A. conjugation
B. Transcription
C. Transduction
D. Transformation
E. Translation
D. Transformation
Feedback inhibition differs from repression because feedback inhibition
a. is less precise
b. is slower acting
c. stops the action of preexisting enzymes
d. stops the synthesis of new enzymes
e. all of the above
c. stops the action of preexisting enzymes
Bacteria can acquire antibiotic resistance by all of the following except
a. mutation
b. insertion of transposons
c. conjugation
d. snRNPs
e. transformation
d. snRNPs
Suppose you inoculate three flasks of minimal salts broth with E. coli. Flask A contains glucose. Flask B contains glucose and lactose. Flask C contains lactose. After a few hours of incubation, you test the flasks for the presence of Beta-galactosidase. Which flask(s) do you predict will have this enzyme?
c. C
Plasmids differ from transposons in that plasmids
a. become inserted into chromosomes
b. are self-replicated outside the chromosome
c. move from chromosome to chromosome
d. carry genes for antibiotic resistance
e. none of the above
B. are self-replicated outside the chromosome
Mechanism by which the presence of glucose inhibits the lac operon
a. catabolite repression
b. DNA polymerase
c. Induction
d. repression
e. translation
a. Catabolite repression
The mechanism by which lactose controls the lac operon
a. catabolite repression
b. DNA polymerase
c. Induction
d. repression
e. translation
c. Induction
Two offspring cells are most likely to inherit which one of the following from the parent cell?
a. a change in a nucleotide in mRNA
b. a change in a nucleotide in tRNA
c. a change in a nucleotide in rRNA
d. a change in a nucleotide in DNA
e. a change in a portein
d. a change in nucleotide in DNA
Which of the following is not a method of horizontal gene transfer?
a. binary fission
b. conjugation
c. integration of a transposon
d. transduction
e. transformation
a. binary fission
Compare and contrast the following terms
a. cDNA and gene
a. both are DNA. cDNA is a segment of DNA made by RNA-dependent DNA polymerase. It is not necessarily a gene; a gene is a transcribable unit of DNA that codes for protein or RNA
Compare and contrast the following terms
b. restriction fragment and gene
b. Both are DNA. A restriction fragment is a segment of DNA produced when a restriction endonuclease hydrolyzes DNA. It is not usually a gene; a gene is a transcribable unit of DNA that codes for protein or RNA
Compare and contrast the following terms
c. DNA probe and gene
c. Both are DNA. A DNA probe is a short, single-stranded piece of DNA. It is not a gene; a gene is a transcribable unit of DNA that codes for protein or RNA.
Compare and contrast the following terms
d. dDNA polymerase and DNA ligase
d. Both are enzymes. DNA polymerase synthesizes DNA one nucleotide at a time using a DNA template; DNA ligase jointspieces (strands of nucleotides) together.
Compare and contrast the following terms
e. rDNA and cDNA
e. Both are DNA. Recombinant DNA results from joining DNA from two different sources; cDNA results from copying a strand of RNA
Compare and contrast the following terms
f. genome and proteome
f. The proteome is the expression of the genome. An organism's genome is one complete copy of its genetic information. The proteins encoded by this genetic material comprise the proteome .
Differentiate the following terms. Which one is "hit and miss"-- that is, does not add a specific gene to a cell?
a. protoplast fusion
b. gene gun
c. microinjection
d. electroporation
In protoplast fusion, two wall-less cells fuse together to combine their DNA. A variety of genotypes can result from this process. In b, c, and d, specific genes are inserted directly into the cell.
Some commonly used restriction enzymes are listed in Table 9.1 on page 248.
a. Indicate which enzymes produce sticky ends.
b. Of what value are sticky ends in making recombinant DNA?
a. BamHI, EcoRI, and HindIII make sticky ends
b. Fragments of DNA produced with the same restriction enzyme will spontaneously anneal to each other at their stick ends.
Suppose you want multiple copies of a gene you have synthesized. How would you obtain the necessary copies by cloning? By PCR?
The gene can be spliced into a plasmid and inserted into a bacterial cell. As the cell grows, the number of plasmids will increase. The Polymerase chain reaction can make copies of a gene using DA polymerase and a primer for the gene.
Describe a recombinant DNA experiment in two or three sentences. Use the following terms: exon, DNA, mRNA, cDNA, RNA polymerase, reverse transcriptase.
In a eukaryotic cell, RNA polymerase copies DNA: RNA processing removes the introns, leaving the exons in the mRNA, cDNA can be made from the mRNA by reverse transcroptase
You are attempting to insert a gene for saltwater tolerance into a plant by using the Ti plasmid. In addition to the desired gene, you add a gene for tetracycline resistance (tet R) to the plasmid. What is the purpose of the tet R gene?
You probably used a few plant cells in a Petri plate for your experiment. You can grow these cells on plant-cell culture media with tetracycline. Only the cells with the new plasmid will grow.
How does RNAi "silence" a gene?
In RNAi, siRNA binds mRNA creating double-stranded RNA, which is enzymatically destroyed
Name it: This virus family, normally associated with AIDS, may be useful for gene therapy
Retroviridae
Restriction enzymes were first discovered with the observation that
a. DNA is restricted to the nucleus
b. phage DNA is destroyed in a host cell
c. foreign DNA is kept out of a cell
d. foreign DNA is restricted to the cytoplasm
e. all of the above
b. phage DNA is destroyed in a host cell
The DNA probe, 3'-GGCTTA, will hybridize with which of the following?
a. 5'-CCGUUA
b. 5'-CCGAAT
c. 5'-GGCTTA
d. 3'-CCGAAT
e. 3'-GGCAAU
b. 5'-CCGAAT
Which of the following is the fourth basic step to genetically modify a cell?
a. Transformation
b. Ligation
C. Plasmid Cleavage
D. restriction-enzyme digestion of gen
E. isolation of gene
B. Ligation
The following enzymes are used to make cDNA. What is the second enzyme used to make cDNA?
a. reverse transcriptase
b. ribozyme
c. RNA polymerase
d. DNA polymerase
b. Ribozyme
If you put a gene in a virus, the next step in genetic modification would be
a. insertion of a plasmid
b. transformation
c. transduction
d. PCR
e. Southern blotting
c. transduction
You have a small gene that you want replicated by PCR. You add radioactively labeled nucleotides to the PCR thermal cycler. After three replicatio cycles, what percentage of the DNA single strands are radioactively labeled?
a. 0%
b. 12.5%
c. 50%
d. 87.5%
e. 100%
d. 87.5%
Pieces of human DNA stored in yeast cells
a. antisese
b. clone
c. library
d. Southern blot
e. vector
c. Library
A population of cells carrying a desired plasmid
a. antisese
b. clone
c. library
d. Southern blot
e. vector
b. Clone
Self-replicating DNA for Transmitting a gene from one organism to another
a. antisese
b. clone
c. library
d. Southern blot
e. vector
e. Vector
A gene that hybridizes with mRNA
a. antisese
b. clone
c. library
d. Southern blot
e. vector
a. Antisese
Differentiate the terms in each of the following pairs:
a. Etiology and pathogenesis
a. etiology is the study of the cause of a disease, whereas pathogenesis is the manner in which the disease develops
Differentiate the terms in each of the following pairs:
b. infection and disease
b. Infection refers to the colonization of the body by a microorganism. Diseases is any change from a state of health. A disease may, but does not always, results from infection.
Differentiate the terms in each of the following pairs:
c. communicable disease and noncommunicable disease
A communicable disease is a disease that is spread from one host to another, whereas a noncommunicable disease is not transmitted from one host to another
Define symbiosis. Differentiate commensalism, Mutualism, and parasitism, and give example of each
Symbiosis refers to different organisms living together. Commensalism one of the organisms benefits and the other is unaffected; eg., corynebacteria living on the surface of the eye. Mutualism- both organisms benefit;eg., E. Coil receives nutrients and a constant temperature in the large intestine and produces vitamin K and certain B vitamins that are useful for the human host. parasitism-one organism benefits while the other is harmed; eg., Salmonella enterica receives. nutrients and warmth in that large intestine, and the human host experiences gastroenteritis or typhoid fever.
Indicate whether each of the following conditions is typical of subacute, acute, chronic
a. The patient experiences a rapid onset of malaise; symptoms last 5 days
a. Acute
Indicate whether each of the following conditions is typical of subacute, acute, chronic
b. The patient experiences cough and breathing difficulty for months
b. Chronic
Indicate whether each of the following conditions is typical of subacute, acute, chronic
c. The patient has no apparent symptoms and is a known carrier
C. Subacute
Of all the hospital patients with infections, one-third do not enter the hospital with an infection. How do they acquire these infections? What is the method of transmission of these infections? What is the reservoir of infection?
Hospital patients may be in a weakened condition and therefore predisposed to infection. Pathogentic microorganisms are generally transmitted to patients by contact and airborne transmission. The reservoirs of infection are the hospital staff, visitors and other patients.
Distinguish symptoms from signs as signals of disease
Changes in body function that the patient feels are called symptoms. Symptoms such as weakness or pain are not measurable by a physician. objective changes that the physician can observe and measure are called signs
How can a local infection become a systemic infection?
When microorganisms causing a local infection enter a blood or lymph vessel and are spread throughout the body, a systemic infection can results
Why are some organisms that constitute the normal microbiota described as commensals, whereas others are described as mutualistic?
Mutualistic microorganisms are providing a chemical or environment that is essential for the host. Commensal organisms are not essential ; another microorganism might serve the function as well
Put the following in the correct order to describe the pattern of disease; period of convalescence, prodromal period, period of decline, incubation period, period of illness.
Incubation period, prodromal period, period of illness, period of decline (maybe crisis), Period of convalescence
Name it: this microbe is acquired by humans as infants and is essential for good health. Acquiring a closely releated strain cause sever stomach cramps, bloody diarrhea, and vomiting. what is this microbe?
E. coli (Escherichia coli)
The emergence of new infectious diseases is probably due to all of the following except:
a. the need of bacteria to cause disease
b. the ability of humans to travel by air
c. changing environments (e.g. flood, drought, pollution)
d. a pathogen crossing the species barrier
e. the increasing human population
a. The need of bacteria to cause disease
All members of a group of ornithologists studying barn owls in the wild have had salmonellosis (Salmonella gastroenteritis). One birder is experiencing her third infection. What is the most likely source of their infections?
a. The ornithologists are eating the same food
b. They are contaminating their hands while handling the owls and nests
c. one of the workers is a Salmonella carrier
d. Their drinking water is contaminated
b. They are contaminating their hands while handling the owls and nests
Which of the following statements is false?
a. E. coli never cause disease
b. E. coli provides vitamin K for its host
C. E. coli often exists in a mutualistic relationship with humans
d. E. coli gets nutrients from intestinal contents
a. E. coli never cause disease
Which of the following is not one of Koch's postulates?
a. The same pathogen must be present in every case of the disease
b. The pathogen must be isolated and grown in pure culture from the diseased host
c. The pathogen from pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal
d. The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact
e. The pathogen must be isolated in pure culture from an experimentally infected lab animal
d. The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact
Which one of the following diseases is not correctly matched to its reservoir?
a. influenza-Human
b. rabies- animal
c. botulism-nonliving
d. anthrax- nonliving
e. toxoplasmosis-cats
a. influenza- human
Compare pathogenicity with virulence
The ability of a microorganism to produce a disease is called pathogenicity. The degree of pathogenicity is virulence
How are capsules and cell wall components related to pathogenicity? give specific examples
Encapsulated bacteria can resist phagocytosis and continue growing, Streptococcus pneumoniae and Klebisella pneumoniae produce capsules that are releated to their virulence. M protein found in the cell walls of Strepococcus aureus help these bacteria resist phagocytosis
Describe how hemolysins, leukocidins, coagulase, kinases, hyaluronidase, siderophores, and IgA proteases might contribute to pathogenicity
Hemolysins Lyse red blood cells; hemolysis might supply nutrients for bacterial growth. Leukocidins destroy neutrophils and macrophages that are active in phagocytosis; the decreases host resistance to infection. Coagulase causes fibrinogen in blood to clot; the clot may protect the bacterium from phagocytosis and other host defense. Baterical kinases break down firbin; Kinases can destroy a clot that was made to isolate the bacteria, thus allowing the bacteria to spread. Hyaluronidase hydrolyzes the hyaluronic acid that binds cells together; this could allow the bacteria to spread through tissues. Siderophores take iron from host iron-transpot proteins, thus allowing bacteria to get iron for growth. IgA proteases destroy IgA antibodies; IgA antibodies protect mucosal surfaces
Explain how drugs that bind each of the following would affect pathogencity:
a. iron in the host's blood
a. would inhibit bacteria
Explain how drugs that bind each of the following would affect pathogencity:
b. neisseria gonorrhoeae fimbriae
b. would prevent adherence of N. gonorrhoeae
Explain how drugs that bind each of the following would affect pathogencity:
c. Streptococcus pyogenes M protein
c. S. pyogenes would not be able to attach to host cells and would be more susceptible to phagocytosis
Which of the following genera is the most infectious?
Legionella or Salmonella
Legionella
How can viruses and protozoa avoid being killed by the host's immune response?
Viruses avoid the host's immune response by growing inside host cells; some can remain latent in a host cell for prolonged periods. Some protozoa avoid the immune response by mutations that change their antigens.
Name it: The Opa gene is used to identify this endotoin-producing bacterium that grows well i the high-CO2 conditions inside phagocytes
Neisseria gonorrhoeae
The removal of plasmids reduces virulence in which of the following organisms?
a. Clostridium tetani
b. Escherichia Coli
c. Salmonella enterica
d. Streptococcus mutans
e. Clostridium botulinum
d. Streptococcus mutans
Which of the follwoing is not a portal of entry for pathogens?
a. mucous membranes of the respiratory tract
b. mucous membranes of the gastrointestinal tract
c. Skin
d. blood
e. parenteral route
d. Blood
All of the following can occur during bacterial infection. Which would prevent all of the others?
a. Vaccination against fimbriae
b. Phagocytosis
c. Inhibition of phagocyitc digestion
d. destruction of adhesins
e. alteration of cytoskeleton
a. Vaccination against fimbriae
The ID 50 for Campylobacter sp. is 500 cells; the ID 50 for Cryptosporidum sp. is 100 cells. Which of the following statements is false?
a. both microbes are pathogens
b. both microbes produce infections in 50% of the inculated hosts
c. cryptosporidum is more virulent than Campylobacter
d. Campylobacter and Cryptosporidum are equally virulent; they cause infections in the same number of test animals
c. cryptosporidum is more virulent than Campylobacter
An encapsulated bacterium can be virulent because the capsule
a. resists phagocytosis
b. is an endotoxin
c. destroys host tissues
d. interfers with physiological processes
e. has no effect; because many pathogens do not have capsules, capsules do not contribute to virulence
a. resists phagocytosis
A drug that binds to mannose on human cells would prevent
a. the entrance of Vibrio enterotoxin
b. the attachment of pathogenic E. coli
c. the action of botulinum toxin
d. streptococcal pneumonia
e. the action of diphtheria toxin
b. the attachment of pathogenic E. Coli
The earliest smallpox vaccines were infected tissue rubbed into the skin of a healthy person. The recipient of such a vaccine usually developed a mild case of smallpox, recovered, and was immune thereafter. What is the most likely reason this vaccine did not kill more people?
a. Skin is the wrong portal of entry for smallpox
b. The vaccine consisted of a mild form of the virus
c. Smallpox is normally transmitted by skin-to-skin contact
d. Smallpox is a virus
e. The virus mutated
A. Skin is the wrong portal of entry for smallpox
Which of the following does not represent the same mechanism for avoiding hose defenses as the others?
a. Rabies virus attaches to the receptor for the neurotransmitter acetylcholine
b. Salmonella attaches to the receptor for epidermal growth factor.
c. Epstein-Barr (EB) virus binds to the host receptor for complement
d. Surface protein genes in Neisseria gonorrhoeae mutate frequently
e. none of the above
d. Surface protein genes in Neisseria gonorrhoeae mutat frequently
Which of the following statements is true?
a. The primary goal of a pathogen is to kill its host
b. Evolution selects for the most virulent pathogens
c. A successful pathogen doesn't kill its host before it is transmitted
d. A successful pathogen never kills its host
c. A successful pathogen doesn't kill its host before it is transmitted