110 Questions
What is the main objective of studying microbial genetics?
To understand the universal mechanism of gene function
What percentage of an organism's genome is expressed?
1%
What is the term for the complete set of genetic information in a cell?
Genome
What is the shape of a chromosome in prokaryotes?
Circular
What is the term for the genes of an organism?
Genotype
What is the role of microbial genetics in the production of value-added products?
To increase the production of antibiotics and growth hormones
Which of the following is an example of a non-protein gene product?
RNA
Which organism was the first to have its whole genome sequenced?
E. coli
What is the role of DNA helicase enzymes in the replication process?
To unwind the DNA, creating a replication fork
What is the result of the semiconservative replication process?
One DNA molecule with one original and one newly synthesized strand
What is the purpose of DNA repair systems in bacteria?
To maintain the integrity of their DNA
What is the relationship between the genetic information and the protein produced in a cell?
The genetic information is used to produce the protein needed for the cell to function
What is the role of the amylase enzyme in bacteria?
To break down starch as a food source
What is the prerequisite for the production of the amylase enzyme in bacteria?
The presence of the gene or DNA sequence
What determines the metabolic pathways available to a bacterium?
The presence of the enzyme and genetics
What is the term for the transfer of genetic information between cells of the same generation?
Recombination
What is the primary function of plasmids in bacterial cells?
To carry genes associated with specialized functions
What is the size range of a genome?
50kb - 13mn
What is the function of an operon?
To simultaneously regulate the expression of a cluster of genes
What is the role of the repressor in the lac operon?
To bind to the operator and block transcription
What is the function of the permease enzyme in the lac operon?
To catalyze the transport of lactose into the cell
What type of genes are typically carried on plasmids?
Specialized function genes
What is the result of lactose binding to the repressor in the lac operon?
The repressor changes its conformation
What determines the genome size of an organism?
The size of the ecological niche
What is the primary mechanism of horizontal gene transfer between cells of the same generation?
Conjugation
What is the purpose of DNA replication in cell division?
To make an exact copy of DNA before cell division
What is the significance of Chargaff's ratio in DNA structure?
It shows the ratio of A to T and G to C is always equal
What is the function of RNA polymerase in transcription?
To synthesize a complementary mRNA molecule
Why did Rosalind Franklin's work contribute to Watson and Crick's model of DNA?
She provided X-ray crystallography data
What is the result of transcription in terms of DNA and mRNA?
The DNA double helix is unwound and mRNA is synthesized
What is the function of specific DNA sequences called promoters in transcription?
To initiate the transcription process
What is the outcome of cell division without DNA replication?
One daughter cell receives DNA and the other doesn't
What is the primary function of the 5' cap and 3' poly(A) tail added to the mRNA molecule?
To increase the stability of the mRNA and facilitate its translation
What is the advantage of coupled transcription and translation in bacteria?
It enables the cell to respond more efficiently and rapidly to changes in its environment
What is the role of the ribosome during translation?
To read the mRNA sequence and recruit the appropriate tRNA molecules
What is the function of the tRNA molecules during translation?
To recognize the codon on the mRNA and bring the corresponding amino acid to the ribosome
What is the outcome when the ribosome reaches a stop codon on the mRNA?
The polypeptide chain is released from the ribosome
What is the enzyme responsible for synthesizing mRNA molecules from the DNA template in bacteria?
RNA polymerase
What is the term for the process of synthesizing proteins from the mRNA template?
Translation
What is the composition of the ribosome?
Both ribosomal RNA (rRNA) and proteins
What is the size of the plasmid after digestion with EcoRI?
20 Kb
What is the number of fragments produced by digestion with BamHI?
3
What is the size of the fragment produced by digestion with EcoRI and BamHI?
1.48 Kb
What is the size of the fragment produced by digestion with EcoRI and PstI?
1.74 Kb
What is the size of the fragment produced by digestion with BamHI and PstI?
1.74 Kb
What is the total size of the plasmid after digestion with EcoRI?
26 Kb
What is the size of the fragment produced by digestion with PstI?
1.94 Kb
What is the number of restriction sites for EcoRI in the plasmid?
1
What is the typical length of a recognition site usually recognized by a Restriction Enzyme?
4 base pairs
What type of ends are produced when Restriction Enzymes cleave the DNA molecule?
Either sticky or blunt ends
What is the purpose of Bovine Serum Albumin (BSA) in a Restriction Enzyme digest?
To stabilize the reaction by preventing enzymes from sticking to the sides of the container
What is the optimal condition for storing Restriction Enzymes?
On ice or in thermoresistant containers
What is a characteristic of a direct recognition site?
It is a palindromic sequence
What is the purpose of a specific buffer in a Restriction Enzyme digest?
To provide optimal conditions for the enzyme
What is the result of a Restriction Enzyme digest?
The DNA molecule is cleaved
What is the purpose of incubation temperature in a Restriction Enzyme digest?
To provide optimal conditions for the enzyme
What is the purpose of mixing DNA samples with a loading buffer in Agarose Gel Electrophoresis?
To increase the density of DNA samples and help them settle at the bottom of the well
What is the primary factor that affects the size separation of DNA molecules in Agarose Gel Electrophoresis?
The concentration of agarose
What is the reason behind the formation of two fragments of 3 Kb in the restriction enzyme digestion?
The restriction sites are not unique
What is the purpose of leaving the agarose solution undisturbed?
To allow the formation of a porous matrix
What is the result of increasing the agarose concentration in Agarose Gel Electrophoresis?
Smaller pore size is formed
Why do larger DNA molecules move more slowly than smaller molecules in Agarose Gel Electrophoresis?
Because they have a larger size
What is the role of the agarose molecules in Agarose Gel Electrophoresis?
To form a porous matrix for the separation of DNA molecules
What is the purpose of adding a polysaccharide like agarose to a buffer in Agarose Gel Electrophoresis?
To form a solid matrix for the separation of DNA molecules
What is the purpose of adding salt to the DNA sample during DNA precipitation?
To stabilize the negatively charged backbone of DNA
What is the result of cutting a plasmid DNA with a restriction enzyme?
A linear DNA fragment is formed
What is the purpose of adding a nucleotide stain to the agarose gel during DNA gel electrophoresis?
To visualize the DNA fragments
Why do smaller DNA fragments migrate more quickly than larger fragments during DNA gel electrophoresis?
Because they have a smaller molecular weight
What is the purpose of using a combination of different restriction enzymes in DNA fingerprinting?
To generate a unique pattern of DNA fragments
What is the role of the DNA ladder during DNA gel electrophoresis?
To provide a standard size reference for DNA fragments
What is the result of DNA precipitation with ice-cold alcohol?
A white precipitate is formed
What is the direction of DNA migration during DNA gel electrophoresis?
From the cathode to the anode
What is the function of di-deoxynucleotides (ddNTPs) in sequencing?
To limit their ability to form phosphodiester bonds with adjacent nucleotides
What is the primary advantage of High Throughput Sequencing?
It is a cost-effective and rapid method for sequencing DNA and RNA
What is the purpose of DNA adapters in sequencing?
To ligate to both ends of DNA fragments
What is the first step in the sequencing process?
Fragmentation of genomic DNA
What is the purpose of labeling each deoxynucleotide with a different fluorescent label?
To make detection of the DNA sequence easier
What is the term for sequencing from different species or groups of individuals?
High Throughput Sequencing
What is the advantage of Reversible Terminator sequencing?
It is a type of sequencing that uses modified bases to terminate the reaction
What is the outcome of the sequencing process?
A DNA sequence with fluorescent labels
What is the purpose of the Bridge amplification process?
To create a double-stranded DNA fragment
What is the role of the modified dNTPs in sequencing?
To allow for the addition of only one dNTP at a time
What is the purpose of washing off the reverse complementary strands after Bridge amplification?
To remove the reverse strands from the chip
What is the result of each round of dNTP addition to the growing strand during sequencing?
The chip is imaged and the emission wavelength is used to identify the base
What is the purpose of the phylogenetic tree?
To depict evolutionary relationships among organisms
What is the result of the cycles of Bridge amplification and sequencing?
Thousands of copies of the DNA fragment
What is the term used to describe a group of organisms that share a common ancestor and all of its descendants?
Monophyletic
What is the method of determining relationships based on the least amount of change between organisms?
Maximum parsimony
What is the term used to describe a group that includes a common ancestral species and some of its descendants?
Paraphyletic
What is the purpose of multi-locus sequence typing?
To characterize bacterial isolates into known groups
What is the term used to describe the most common recent ancestor of a group of organisms?
Basal Node
What is the term used to describe a group that does not share an immediate common ancestor?
Polyphyletic
What is the term used to describe the relationships between sister taxa?
Closest relatives
What is the primary shape of the head or capsid of a bacteriophage?
Icosahedral
What is the function of lysozyme in the lytic cycle of bacteriophages?
To open the cell wall of the host bacterium
What is the significance of the Hershey-Chase Experiments in molecular biology?
They confirmed that DNA is the genetic material in living organisms
What is the role of the tail of a bacteriophage in the infection process?
To inject the nucleic acid into the host bacterium
What is the primary advantage of using bacteriophages as a model in microbial genetics?
They are easy to culture and manipulate
What is the final step in the lytic cycle of bacteriophages?
Release of the mature phage from the host cell
What is the function of endolysin in the lytic cycle of bacteriophages?
To break down the host cell wall
What is the significance of bacteriophages in the history of molecular biology?
They were used to explore the mechanisms of life and led to the birth of modern molecular biology
What conclusion did Hershey and Chase draw from their experiment?
Genetic information is DNA, not proteins.
What is the difference between antibiotics and phages in terms of specificity?
Antibiotics are carpet bombing, while phages are guided missiles.
Why did phage-based therapies make a comeback?
Due to the emergence of antibiotic-resistant bacteria.
What is the advantage of phages over antibiotics in terms of resistance?
Phages are less prone to resistance development.
What is the application of phage therapies in skincare products?
To promote skin health.
What is the role of phages in the lysogenic cycle?
Phages integrate into the host genome.
Why did the development of phage-based therapies lag behind?
Due to the discovery of antibiotics.
What is the significance of the emergence of multi-antibiotic resistant bacteria?
It led to a renewed interest in phage-based therapies.
What is the difference between the lytic and lysogenic cycles?
The lytic cycle involves lysis, while the lysogenic cycle involves integration into the host genome.
Study Notes
Restriction Enzymes and Digestion
- Restriction enzymes recognize specific DNA sequences (4-6 base pairs) and cut the DNA at those sites.
- Recognition sites are usually palindromic, meaning they read the same forwards and backwards.
- Restriction enzymes can leave different types of ends, such as sticky ends (with 3' and 5' overhangs) or blunt ends.
- The type of end determines how the DNA fragment is isolated and recombined with other fragments during ligation.
Plasmid Mapping
- A plasmid is a circular piece of DNA that can be found in bacteria.
- Digestion with a single restriction enzyme (e.g. EcoRI) produces a specific number of fragments.
- Digestion with multiple enzymes (e.g. EcoRI and PstI) produces a combination of fragments, which can be used to create a plasmid map.
Agarose Gel Electrophoresis
- Agarose gel electrophoresis is a technique used to separate DNA molecules by their size.
- Negatively charged DNA molecules migrate to the positive electrode.
- The size of the DNA molecule determines how quickly it migrates through the agarose gel.
- Agarose gel electrophoresis is used to analyze the fragments produced by restriction digestion.
DNA Fingerprinting
- DNA fingerprinting involves using restriction enzymes to cut DNA into specific fragments.
- The fragments are then analyzed using agarose gel electrophoresis.
- DNA fingerprinting can be used to identify specific individuals or organisms.
PCR and Sequencing
- PCR (Polymerase Chain Reaction) is a technique used to amplify specific DNA sequences.
- PCR involves denaturing the DNA, annealing primers, and extending the primers to create a new DNA strand.
- Sequencing involves determining the order of nucleotides in a DNA molecule.
- Reversible terminator sequencing is a technique used to sequence DNA molecules.
Phylogenetic Trees
- Phylogenetic trees are used to depict the evolutionary relationships among organisms.
- The relationships are represented as a tree, with tips representing extant or living taxa.
- Branches represent evolutionary changes between ancestors and descendants.
- Sister taxa are groups that share an immediate common ancestor.
Phage Genetics
- Bacteriophages are viruses that infect bacteria.
- Phages have a specific host range and can be used as a model system to study the mechanisms of life.
- The Hershey-Chase experiments (1952) demonstrated that DNA is the genetic material in phages.
- Phages can be used as a therapeutic tool to target specific bacteria.
Microbial Genetics
- Microbial genetics is the study of the mechanisms of heritable information in microorganisms.
- Microorganisms include bacteria, archaea, viruses, and some protozoa and fungi.
- Microbial genetics provides a relatively simple system for studying genetic phenomena.
- Microbial genetics is used to understand gene function, develop new products, and control diseases.
DNA Replication
- DNA replication is the process of creating a new DNA molecule from an existing one.
- The process is semiconservative, meaning that each new DNA molecule contains one original strand and one newly synthesized strand.
- DNA replication is essential for the transmission of genetic information from one generation to the next.
Gene Expression
- Gene expression is the process of using genetic information to produce a protein or functional product.
- Gene expression involves transcription, translation, and regulation.
- Transcription is the process of synthesizing mRNA from a DNA template.
- Translation is the process of synthesizing proteins from mRNA.
Operons
- An operon is a functioning unit of DNA that contains a cluster of genes under the control of a single promoter.
- Operons allow for simultaneous regulation of gene clusters.
- The lac operon is an example of an operon that regulates the genes involved in lactose metabolism.
Microbial Genome Organization
- Microbial genomes can be organized into chromosomes, plasmids, and episomes.
- Chromosomes are structures made up of DNA and are usually linear in eukaryotes and circular in prokaryotes.
- Plasmids are extrachromosomal, autonomous, and can be linear or circular.
- Episomes are plasmids that can integrate into the host genome.
Genome Size
- Genome size varies among microorganisms, from 50kb to 13mb.
- Genome size is influenced by the organism's ecological niche and developmental cycle.
Operons and Gene Regulation
- Operons are controlled by promoters, operators, and repressors.
- The lac operon is an example of an operon that is regulated by a repressor.
- The lac operon is induced by lactose and repressed by glucose.
Microbial Metabolism
- Microorganisms have a variety of metabolic pathways, including glycolysis, the pentose phosphate pathway, and the citric acid cycle.
- Microorganisms can use different carbon sources, such as glucose, lactose, and starch.
- Microorganisms can also use different energy sources, such as ATP, NADH, and FADH2.
Explore the basics of microbial genetics, including the mechanisms of heritable information in microorganisms such as bacteria, archaea, viruses, and fungi. Learn about the importance of studying gene function in microorganisms and its applications in higher organisms.
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