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Micro Exam Ch8
Microbial Genetics
| Question | Answer |
|---|---|
| What is the study of what genes are, how they carry information, how information is expressed, and how genes replicated? | Genetics |
| What is a segment of DNA that encodes a function product, usually a protein? | Gene |
| What is a structure containing DNA that physically carries hereditary information? | Chromosome |
| The chromosomes contain the ______ | Genes |
| All the genetic information in a cell | Genome |
| The genetic makeup of a cell -- the information that codes for all the particular characteristics of the organism -- are referred to as ______ | Genotype |
| ______ refers to actual, expressed properties, such as the organism's ability to perform a particular chemical reaction | Phenotype |
| ______ refers to actual, expressed properties, such as the organism's ability to perform a particular chemical reaction | Supercoiled |
| Bacterial chromosomes consist of no ______ proteins, but may be associated with other types of proteins | Histone |
| E. coli genome has __________ base pairs and is about 1 mm long if stretched out | 4.6 million |
| Human genome has _________ base pairs housed in 23 pairs of chromosomes and would stretch about 6.5 feet if linear | 3 billion |
| What are the four base nucleotides in DNA? | Adenine, thymine, cytosine, and guanine |
| What is the structure of the double-stranded molecules of nucleic acids in DNA referred to as? | Double helix |
| The strands of DNA each run from 5' to 3' and run in _______, or opposite, directions from each other | Antiparallel |
| This enzyme adds on nucleotides to the growing DNA strand in the 5' to 3' direction | DNA polymerase |
| This is the point at which DNA replication occurs | Replication fork |
| Because each new double-stranded DNA molecule contains one original (conserved) strand and one new strand, the process of replication is referred to as ________ ______ | Semiconservative replication |
| DNA replication has high _____, meaning mistakes happen only 1 in a billion bases | Fidelity |
| What new DNA strand is synthesized continuously in the 5' to 3' direction (from a template parental strand running 3' to 5')? | Leading strand |
| What new DNA strand is synthesized discontinuously in fragments of about 1000 nucleotides? | Lagging strand |
| What are the fragments of the DNA lagging strand referred to as? | Okazaki fragments |
| What enzymes unwind the parental double helix in DNA replication? | DNA helicases |
| What stabilize the unwound parental DNA in DNA replication? | Proteins |
| RNA primase is an enzyme that synthesizes short RNA sequences called ______. These start as a starting point for DNA synthesis | Primer |
| What enzyme joins the discontinuous fragments of the lagging strand? | DNA ligase |
| n what process is DNA transcribed to make RNA (mRNA, tRNA, and rRNA)? | DNA transcription |
| Transcription begins when RNA polymerase binds to the ______ ______ | Promoter sequence |
| Transcription stops when it reaches the ______ _______ on DNA | Terminator sequence |
| mRNA is translated in _____ (sets of 3 nucleotides) to make proteins | Codons |
| How many sense codons on mRNA encode the 20 amino acids? | 64 |
| Which RNA carries the complementary anticodon & its corresponding amino acids? | tRNA |
| True or False: There is no nucleus in prokaryotes to spatially separate transcription and translation | True |
| Do prokaryotic RNA transcripts require processing (splicing out introns) before translation? | No |
| Of the 64 codons, 61 are ______ codons which code for amino acids, and 3 are _______ codons (stop codons) which do not. | Sense, nonsense |
| The site of translation is the ribosome, and ________ ____ molecules both recognize the specific codons and transport the required amino acids | Transfer RNA (tRNA) |
| Prokaryotic organisms have how many chromomes? | 1 |
| Eukaryotic organisms have how many pairs of chromosomes in humans? | 23 |
| What shape is the DNA in prokaryotes? Is prokaryotic DNA housed in the nuclear envelope? | Circular, no |
| What form/shape are the DNA strands in eukaryotes? Where are DNA formed and stored in? | Linear, nucleus |
| True or False: Prokaryotic genes are comprised of introns and exons; only the exons will encode proteins | False |
| Where does transcription and translation occur in prokaryotes simultaneously? | Cytoplasm |
| Where does transcription occur in eukaryotes? | Nucleus |
| Where does translation occur in eukaryotes? | Cytoplasm |
| ________ genes (genes that are always active and are constantly transcribed because ribosomes are constantly needed for protein synthesis) comprise 60-80% of genes and are expressed at a fixed rate | Constitutive |
| ________ turn on the transcription of a gene | Inducers |
| ________ block the ability of RNA polymerase to initiate transcription from the repressed gene | Repressors |
| What is a group of genes that are transcribed together and controlled by one promoter? | Operon |
| What is the region of DNA where RNA polymerase, activators, and repressors may bind to regulate transcription? | Control region |
| What is like a traffic light that acts as a go or stop signal for transcription of the structural genes? | Operator |
| What is the system called for regulating lactose catabolism, originally described in E. coli? | Lac operon system |
| E. coli prefer to use glucose, but in the absence of glucose, they will use _______ if present | Lactose |
| When will the lac operon be expressed to regulate the enzymes needed for lactose catabolism? | When glucose is absent or lactose is present |
| The lac operon is an _________ operon. In the absence of lactose, the repressor binds to the operator site, thus preventing transcription | Inducible |
| This molecule accumulates in the cell when glucose is not available and binds to the allosteric site of catabolic activator protein (CAP). CAP binds to the lac promoter, which initiates transcription, making it easier for RNA polymerase to bind to the pro | cAMP |
| Mutations that disfavor microbial survival are just as likely, but those cells will die out; fittest organisms are selected by ________ ________ | Natural selection |
| What are some examples of new phenotypes made by genetic evolution? | Antibiotic resistance, enhanced resistance to other antimicrobial agents, increased enzyme efficiency, decreased sensitivity to pH or osmotic changes |
| True or False: Neutral mutations may persist without much impact | True |
| What are the three general sources of genetic diversity of microbes? | Mutation, transfer & recombination, transposons |
| What is a permanent change in the base sequence of DNA? | Mutation |
| What is the most common type of mutation in which a single base at one point in the DNA sequence is replaced with a different base and may cause the insertion of an incorrect amino acid in the protein? | Base substitution |
| If a base substitution results in an amino acid substitution in the synthesized protein, this change in the DNA is known as a _______ mutation | Missense |
| A base substitution resulting in a nonsense codon is thus called a _______ mutation | Nonsense |
| Mutations that are changes in DNA and result in one or a few nucleotide pairs being deleted or inserted in the DNA are called _______ mutations | Frameshift |
| _______ mutations occur in the absence of a mutagen | Spontaneous |
| Agents in the environment, such as certain chemicals and radiation, that directly or indirectly bring about mutations are called _______ | Mutagens |
| What mutation rate is relatively low with 1 in a billion replicated base pairs or 1 in a million replicated gene mutations? | Spontaneous mutation |
| New strains of a ________ can emerge through rare genetic alterations such as mutations | Pathogen |
| What refers to the exchange of genes between two DNA molecules to form new combinations of genes on a chromosome? | Genetic recombination |
| What is a process of genetic recombination where some foreign DNA may be inserted into a cell's chromosome and some of the genes carried by the chromosomes are shuffled? | Crossing over |
| What occurs when genes are passed from an organism to its offspring? (Process done by plants and animals) | Vertical gene transfer |
| What is the transfer of genes between cells of the same generation? | Horizontal gene transfer |
| This cell gives a portion of its total DNA to a RECIPIENT CELL | Donor cell |
| What are the three methods of horizontal gene transfer? | Transformation, conjugation, and transduction |
| What protein catalyzes the joining of the donor DNA strand and the recipient DNA strand? | RecA protein |
| In this process, genetic information is used within a cell to produce the proteins needed for a cell to function | Expression |
| In this process, genetic information can be transferred between cells of the same generation | Transfer and recombination |
| In this process, genetic information can be transferred between generations of cells | Replication |
| In what process is "free-floating" DNA taken up from the environment and enters a recipient cell (which can be integrated with recipient DNA by recombination). | Transformation |
| What process is the transfer of genetic material by direct cell-to-cell contact? | Conjugation |
| Conjugation is mediated by a _______, a circular piece of DNA that replicates independently from the cell's chromosome | Plasmid |
| Plasmids may contain ________ _____ that enable resistance to various antibiotics | Resistance factors |
| In conjugation, cells must generally be of opposite ________ type (donor cell has the plasmid; recipient does not | Mating |
| When an F factor (fertility factor) (a plasmid) is transferred from a donor (F+) to a recipient (F-), the F- cell is converted to a ____ cell | F+ |
| In conjugation by ____-_____ bacteria, the plasmid carries genes that code for synthesis of sex pili, projections from the donor's cell surface that contact the recipient and help bring the two cells in contact | Gram-negative |
| In conjugation by ____-______ bacteria, cells produce sticky surface molecules that cause cells to come into direct contact with each other | Gram-positive |
| In ________ by a Bacteriophage, bacterial DNA is transferred from a donor cell to a recipient cell via a virus that infects bacteria, called a BACTERIOPHAGE or PHAGE | Transduction |
| True or False: Viral DNA are more likely than host DNA to be packaged into phages | False (Both viral and host DNA are equally likely to be packaged into phages) |
| In transduction, _____ of the donor cell distributes the new phages | Lysis |
| What are small segments of DNA that can move (be "transposed") from one position of DNA to another | Transposons |
| What are small segments of DNA that can move (be "transposed") from one position of DNA to another | Insertion sequences |
| ______ may carry other genes that are not related to the transposition process (such as antibiotic resistance). They can also jump from one site to another on the same or other chromosomes or to a plasmid | Transposons |
| True or False: Transposition is relatively rare | True |
Created by:
malele-sedlacek
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