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Questions and Answers
What characterizes a successful mutant?
Which of the following is the correct phase in DNA replication that involves the unwinding of the DNA strands?
What role does primase play in DNA replication?
What is the outcome of binary fission in bacteria?
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Which mechanism of gene transfer involves a bacteriophage infecting a bacterial cell?
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What is the role of topoisomerases during DNA replication?
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How does bacterial transformation increase genetic diversity?
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What is the primary goal of genetic engineering?
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What is the function of nucleic acids in organisms?
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Which of the following best describes a gene?
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What is the primary difference between genotype and phenotype?
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During translation, which process occurs?
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What characterizes a point mutation?
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What type of mutation converts a codon into a stop codon?
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What is a silent mutation?
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What is the role of deoxyribose in nucleotides?
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Study Notes
Microbial Genetics
- Microbial Genetics is the study of heredity in microbes.
- DNA is the biological molecule responsible for heredity, composed of nucleotides.
- Each nucleotide has three components: deoxyribose sugar, phosphate, and a nitrogenous base.
- There are four nitrogenous bases: adenine, thymine, guanine, and cytosine.
- Nucleic acids are responsible for information storage and transfer.
- DNA stores instructions for all proteins and metabolic reactions.
- DNA transfers information to offspring, replicates, and passes information from DNA to RNA for protein synthesis.
- Chromosomes are composed of DNA, circular in prokaryotes and linear in eukaryotes.
- A gene is a sequence of nucleotides on a chromosome called a locus.
- Alleles are different versions of a gene.
- Genotype is the complete collection of genes a cell or organism can have.
- Phenotype is the physical characteristics of an individual resulting from gene-environment interactions.
- Protein synthesis involves transcription and translation.
- Transcription reads a DNA section to create messenger RNA (mRNA).
- Translation interprets mRNA to produce a specific protein.
Protein Synthesis
- The codon table maps three mRNA bases to an amino acid.
Mutations
- Mutations are heritable changes in an organism's DNA sequence.
- A mutant may have a phenotypic change compared to the wild type (most common in nature).
Types of Mutations
- Point mutation: a single base is substituted or replaced.
- Insertion: addition of one or more bases.
- Deletion: removal of one or more bases.
Effects on Proteins
- Silent mutation: no effect on protein.
- Missense mutation: incorporates a different amino acid.
- Nonsense mutation: converts a codon to a stop codon, usually resulting in a non-functional protein.
Adaptation and Mutation
- A mutant can be successful (adaptive), neutral (no difference), or deleterious (less successful) compared to the non-mutant.
- Adaptation occurs when a successful mutation becomes prevalent in a population.
DNA/Chromosome Replication
- Occurs in three phases: initiation, elongation, and termination.
DNA/ Chromosome Replication: Initiation
- Locates the origin of replication site (oriC).
- oriC is a specific DNA sequence marking the start of DNA replication.
- DNA strand unwinds at oriC, creating two strands.
- Helicase unwinds the DNA, creating two replication forks.
DNA/ Chromosome Replication: Elongation
- Polymerase replicates the two strands.
- Polymerase can only extend an existing strand, not initiate synthesis.
- Primase primes the strands for replication by adding a primer that polymerase recognizes.
- Replication proceeds in both directions: leading and lagging.
- Okazaki fragments are created on the lagging strand, and ligase joins them to form a contiguous strand.
- Topoisomerases (gyrase) resolve winding issues.
DNA/ Chromosome Replication: Termination
- Polymerase encounters the termination (Tus-Ter) sequence.
- Replication stops at Tus-Ter.
- Two new DNA loops form and migrate to the ends of the bacterium.
- A septum forms to create two new cells.
Gene Transfer
- Binary fission: simple asexual cell division with no genetic diversity.
- Bacterial conjugation: donor cell transfers genetic information to a recipient, resulting in genetic diversity.
- Bacterial transformation: bacteria pick up genetic information from the environment, leading to new characteristics and genetic diversity.
- Bacterial transduction: bacterial cell infected by a bacteriophage.
- Viral DNA inserts into bacterial DNA, and the virus replicates.
- The virus picks up bacterial and viral DNA.
- The virus re-infects other bacteria.
Biotechnology
- The use of living systems to benefit humankind.
- Genetic engineering alters an organism's genetics to achieve desired traits.
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Description
This quiz covers the fundamental concepts of microbial genetics, focusing on DNA structure, replication, and the roles of genes and alleles. Explore how DNA serves as the hereditary material in microbes and its functions in protein synthesis and phenotype expression.
