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Questions and Answers
Which enzyme stabilizes the unwound parental DNA during replication?
Which enzyme stabilizes the unwound parental DNA during replication?
- RNA polymerase
- Helicase
- DNA ligase
- Proteins (correct)
What polymerase is responsible for synthesizing a short RNA primer on the lagging strand?
What polymerase is responsible for synthesizing a short RNA primer on the lagging strand?
- RNA polymerase (correct)
- DNA polymerase
- DNA ligase
- Topoisomerase
Which enzyme is involved in continuously synthesizing the leading strand?
Which enzyme is involved in continuously synthesizing the leading strand?
- Helicase
- DNA polymerase (correct)
- DNA ligase
- RNA polymerase
What is the role of DNA ligase in DNA replication?
What is the role of DNA ligase in DNA replication?
Which fragments are formed on the lagging strand during DNA replication?
Which fragments are formed on the lagging strand during DNA replication?
Which process involves the synthesis of RNA from a DNA template?
Which process involves the synthesis of RNA from a DNA template?
What does DNA stand for?
What does DNA stand for?
How are the nitrogenous bases adenine and thymine connected in DNA?
How are the nitrogenous bases adenine and thymine connected in DNA?
Which component is not a part of a nucleotide?
Which component is not a part of a nucleotide?
What is the direction of the DNA strand on the left side of the double helix diagram?
What is the direction of the DNA strand on the left side of the double helix diagram?
What type of sugar is found in DNA?
What type of sugar is found in DNA?
Which enzyme is responsible for unwinding the DNA strands during DNA replication?
Which enzyme is responsible for unwinding the DNA strands during DNA replication?
In E. coli, approximately how long is the DNA relative to the cell?
In E. coli, approximately how long is the DNA relative to the cell?
Which enzyme is responsible for extending the RNA primer during replication on the lagging strand?
Which enzyme is responsible for extending the RNA primer during replication on the lagging strand?
What percentage of the total cell volume does the DNA take up in E. coli?
What percentage of the total cell volume does the DNA take up in E. coli?
Which of the following base pairings is correct in the structure of DNA?
Which of the following base pairings is correct in the structure of DNA?
Which enzyme is involved in the transcription process?
Which enzyme is involved in the transcription process?
What is the function of tRNA?
What is the function of tRNA?
Which type of RNA contains the codons?
Which type of RNA contains the codons?
During transcription, in which direction is the mRNA synthesized?
During transcription, in which direction is the mRNA synthesized?
Which of the following is NOT a component involved in the transcription process?
Which of the following is NOT a component involved in the transcription process?
How many amino acids are coded by the genetic code?
How many amino acids are coded by the genetic code?
How many possible combinations of 3-base codons exist?
How many possible combinations of 3-base codons exist?
What is the term used to describe genes that are always turned on?
What is the term used to describe genes that are always turned on?
Which of the following bases is NOT found in RNA?
Which of the following bases is NOT found in RNA?
What role do codons play in the genetic code?
What role do codons play in the genetic code?
Which type of mutation does not alter the function of the protein?
Which type of mutation does not alter the function of the protein?
Which process involves the uptake of naked DNA from the environment by a bacterium?
Which process involves the uptake of naked DNA from the environment by a bacterium?
Which of the following is necessary for evolution in bacteria?
Which of the following is necessary for evolution in bacteria?
Genetic transfer in bacteria does NOT occur through which of the following methods?
Genetic transfer in bacteria does NOT occur through which of the following methods?
Which process of genetic transfer in bacteria involves a virus?
Which process of genetic transfer in bacteria involves a virus?
What happens to the DNA of bacterial cells when they die?
What happens to the DNA of bacterial cells when they die?
Which process involves DNA being transferred from one bacterium to another by a virus?
Which process involves DNA being transferred from one bacterium to another by a virus?
In conjugation, what structure is used to pass DNA between bacteria?
In conjugation, what structure is used to pass DNA between bacteria?
During bacterial transformation, where does a living bacterium obtain new DNA?
During bacterial transformation, where does a living bacterium obtain new DNA?
Which of the following terms best describes a virus that infects bacteria?
Which of the following terms best describes a virus that infects bacteria?
What are the causes of genotypic variation in bacteria?
What are the causes of genotypic variation in bacteria?
Which type of mutation involves the substitution of one nitrogenous base for another?
Which type of mutation involves the substitution of one nitrogenous base for another?
What is an example of a transversion mutation?
What is an example of a transversion mutation?
Which statement is true about genotypic variations?
Which statement is true about genotypic variations?
By what mechanisms can a gene mutation be induced?
By what mechanisms can a gene mutation be induced?
What occurs in a deletion mutation?
What occurs in a deletion mutation?
What is a characteristic of phenotypic variation in bacteria?
What is a characteristic of phenotypic variation in bacteria?
Which substance interferes with the bacterial development of flagella?
Which substance interferes with the bacterial development of flagella?
What happens to bacterial cells with irregular staining when transferred to a fresh medium?
What happens to bacterial cells with irregular staining when transferred to a fresh medium?
Which factor influences the formation of capsules and spores in bacteria?
Which factor influences the formation of capsules and spores in bacteria?
What is the relationship between young multiplying bacterial cells and their susceptibility to disinfectants?
What is the relationship between young multiplying bacterial cells and their susceptibility to disinfectants?
When does Escherichia coli synthesize the enzyme beta-galactosidase?
When does Escherichia coli synthesize the enzyme beta-galactosidase?
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Study Notes
DNA Replication
- Occurs at the replication fork (5' to 3')
- Enzymes unwind the parental double helix
- Proteins stabilize the unwound parental DNA
- Leading strand is synthesized continuously by DNA polymerase
- Lagging strand is synthesized discontinuously by RNA polymerase and DNA polymerase
- RNA primer is digested and replaced with DNA
- DNA ligase joins the discontinuous fragments of the lagging strand
DNA Structure
- Double-stranded (double helix)
- Polymers of nucleotides
- 5' to 3' (strands are anti-parallel)
- Complimentary base pairing:
- A-T
- G-C
DNA and RNA
- DNA: deoxyribonucleic acid
- RNA: ribonucleic acid
- Nucleotides consist of:
- Phosphate group
- Pentose sugar
- Nitrogenous base
Genetic Code
- Codons code for a specific amino acid
- 20 amino acids
- 3-base code (4^3 = 64 possible combinations)
- Amino acids are coded for by more than one codon
Transcription
- One strand of DNA is used as a template to form a complementary strand of mRNA
- 3 ways RNA differs from DNA
- Promoter, RNA polymerase, and termination site are involved
- 5' to 3' direction
Types of RNA
- mRNA: contains codons
- rRNA: found in ribosomes (70S)
- tRNA: transfers amino acids to ribosomes for protein synthesis
- Anti-codon
Mutations
- Can be harmful, lethal, beneficial, or silent (neutral)
- Examples: UUU - Phe, UUC - Phe
Genetic Transfer in Bacteria
- Results in genetic variation, necessary for evolution
- 3 ways genetic transfer can occur in bacteria:
- Transformation
- Conjugation
- Transduction
Transformation
- Genes are transferred from one bacterium to another as naked DNA
- Bacterial cells uptake free DNA from the surrounding medium
Conjugation
- One bacterium passes some DNA (in a plasmid) to another bacterium
Transduction
- DNA is transferred from one bacterium to another by a virus (bacteriophage)
Genetic Variation
- Phenotypic variation:
- Changes in bacterial characters in response to environmental conditions
- Reversible when the environmental cause is removed
- Not heritable (no genetic changes)
- Genotypic variation:
- Changes in the bacterial characters due to changes in the genetic constitution of the bacterial cell
- Irreversible
- Heritable among bacterial generations
- Causes:
- Mutation
- Gene transfer
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