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Questions and Answers
During DNA replication, which enzyme is responsible for initially synthesizing a short RNA sequence on both the leading and lagging strands?
During DNA replication, which enzyme is responsible for initially synthesizing a short RNA sequence on both the leading and lagging strands?
- DNA ligase
- DNA polymerase I
- Helicase
- Primase (correct)
The leading strand in DNA replication is synthesized in short fragments away from the replication fork.
The leading strand in DNA replication is synthesized in short fragments away from the replication fork.
False (B)
On the lagging strand, short DNA fragments called _________ are synthesized discontinuously.
On the lagging strand, short DNA fragments called _________ are synthesized discontinuously.
okazaki fragments
Which of the following enzymes is responsible for joining Okazaki fragments together during lagging strand synthesis?
Which of the following enzymes is responsible for joining Okazaki fragments together during lagging strand synthesis?
In what direction does DNA polymerase III synthesize new DNA strands?
In what direction does DNA polymerase III synthesize new DNA strands?
Match each type of RNA with its function:
Match each type of RNA with its function:
What is the relationship between the two polynucleotide strands in a DNA molecule?
What is the relationship between the two polynucleotide strands in a DNA molecule?
What is the role of DNA polymerase I in DNA replication?
What is the role of DNA polymerase I in DNA replication?
In the conservative model of DNA replication, the original DNA molecule is completely conserved, and the new DNA molecule consists of two newly synthesized strands.
In the conservative model of DNA replication, the original DNA molecule is completely conserved, and the new DNA molecule consists of two newly synthesized strands.
Briefly describe the semiconservative model of DNA replication.
Briefly describe the semiconservative model of DNA replication.
Only one primer is required for DNA polymerase III to synthesize the lagging strand.
Only one primer is required for DNA polymerase III to synthesize the lagging strand.
According to Chargaff's rule, the percentage of adenine (A) bases is approximately equal to the percentage of ______ bases in a DNA molecule.
According to Chargaff's rule, the percentage of adenine (A) bases is approximately equal to the percentage of ______ bases in a DNA molecule.
Which of the following models of DNA replication results in a daughter molecule containing a mix of parental and newly synthesized DNA segments interspersed on both strands?
Which of the following models of DNA replication results in a daughter molecule containing a mix of parental and newly synthesized DNA segments interspersed on both strands?
Match the level of DNA packaging with its corresponding diameter:
Match the level of DNA packaging with its corresponding diameter:
Given a sequence of one DNA strand is 5'-GATTACA-3', what would be the sequence of the complementary strand, considering the antiparallel nature of DNA?
Given a sequence of one DNA strand is 5'-GATTACA-3', what would be the sequence of the complementary strand, considering the antiparallel nature of DNA?
RNA molecules, like DNA, typically exist as a double helix structure.
RNA molecules, like DNA, typically exist as a double helix structure.
Which chemical linkage connects adjacent nucleotides in a single strand of DNA?
Which chemical linkage connects adjacent nucleotides in a single strand of DNA?
The 5' end of a DNA strand terminates with a hydroxyl (-OH) group attached to the sugar molecule.
The 5' end of a DNA strand terminates with a hydroxyl (-OH) group attached to the sugar molecule.
According to Chargaff's rule, if a double-stranded DNA molecule has 20% adenine (A), what percentage of guanine (G) would be expected?
According to Chargaff's rule, if a double-stranded DNA molecule has 20% adenine (A), what percentage of guanine (G) would be expected?
In the DNA double helix, the ______ forms the sides of the 'ladder', while the nitrogenous bases form the 'rungs'.
In the DNA double helix, the ______ forms the sides of the 'ladder', while the nitrogenous bases form the 'rungs'.
Match the following scientists with their contribution to understanding DNA structure:
Match the following scientists with their contribution to understanding DNA structure:
What type of bond stabilizes the double helix structure of DNA between complementary base pairs?
What type of bond stabilizes the double helix structure of DNA between complementary base pairs?
DNA strands in a double helix run parallel to each other, meaning their 5' to 3' directionality is the same.
DNA strands in a double helix run parallel to each other, meaning their 5' to 3' directionality is the same.
In the structure of a DNA nucleotide, which component contains nitrogen?
In the structure of a DNA nucleotide, which component contains nitrogen?
Which of the following best describes the primary advantage of an operon?
Which of the following best describes the primary advantage of an operon?
The regulatory gene within an operon directly codes for the structural genes.
The regulatory gene within an operon directly codes for the structural genes.
What would occur if the operator region of the lac operon were deleted?
What would occur if the operator region of the lac operon were deleted?
In the lac operon, the enzyme __________ hydrolyzes lactose into glucose and galactose.
In the lac operon, the enzyme __________ hydrolyzes lactose into glucose and galactose.
Match the following components of the lac operon with their respective functions:
Match the following components of the lac operon with their respective functions:
What is the role of allolactose in the regulation of the lac operon?
What is the role of allolactose in the regulation of the lac operon?
The lacA gene codes for permease, which facilitates the uptake of lactose into the cell.
The lacA gene codes for permease, which facilitates the uptake of lactose into the cell.
In the presence of both glucose and lactose, which carbon source will E. coli preferentially use, and how does this affect the lac operon?
In the presence of both glucose and lactose, which carbon source will E. coli preferentially use, and how does this affect the lac operon?
What is the direct effect of allolactose binding to the repressor protein in the lac operon system?
What is the direct effect of allolactose binding to the repressor protein in the lac operon system?
In the absence of lactose, the repressor protein of the lac operon is active and prevents RNA polymerase from binding to the promoter.
In the absence of lactose, the repressor protein of the lac operon is active and prevents RNA polymerase from binding to the promoter.
Why is the lac operon considered a negative control system?
Why is the lac operon considered a negative control system?
Enzymes involved in the lactose pathway are considered ______ enzymes because their synthesis is induced by a chemical signal.
Enzymes involved in the lactose pathway are considered ______ enzymes because their synthesis is induced by a chemical signal.
Match the following components of the lac operon with their function:
Match the following components of the lac operon with their function:
Which of the following is the most significant advantage of the lac operon system for bacterial cells?
Which of the following is the most significant advantage of the lac operon system for bacterial cells?
A mutation in the lacI gene results in a non-functional repressor protein. What is the likely effect on the expression of the lac operon genes?
A mutation in the lacI gene results in a non-functional repressor protein. What is the likely effect on the expression of the lac operon genes?
Mutations in somatic cells can be passed on to offspring and future generations.
Mutations in somatic cells can be passed on to offspring and future generations.
What is the direct consequence of a change in the sequence of bases in DNA?
What is the direct consequence of a change in the sequence of bases in DNA?
Large-scale mutations exclusively involve changes to a single nucleotide pair.
Large-scale mutations exclusively involve changes to a single nucleotide pair.
Which of the following is a type of point mutation?
Which of the following is a type of point mutation?
A nucleotide-pair substitution that results in a codon coding for a different amino acid is called a ______ mutation.
A nucleotide-pair substitution that results in a codon coding for a different amino acid is called a ______ mutation.
Why does a silent mutation have no observable effect on the phenotype?
Why does a silent mutation have no observable effect on the phenotype?
Match each type of mutation with its description:
Match each type of mutation with its description:
Insertions or deletions of nucleotide pairs do NOT usually cause frameshift mutations.
Insertions or deletions of nucleotide pairs do NOT usually cause frameshift mutations.
What is the immediate effect of a nonsense mutation on protein synthesis?
What is the immediate effect of a nonsense mutation on protein synthesis?
Flashcards
Antiparallel strands
Antiparallel strands
Two DNA strands oriented in opposite 5' to 3' directions.
DNA double helix
DNA double helix
A twisted ladder structure formed by two antiparallel polynucleotide strands
RNA structure
RNA structure
Consists of a single strand of nucleotides, unlike DNA's double helix.
Nucleotides
Nucleotides
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Nucleosomes
Nucleosomes
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Sugar-phosphate backbone
Sugar-phosphate backbone
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30-nm fiber
30-nm fiber
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5' and 3' ends
5' and 3' ends
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Chargaff’s rule
Chargaff’s rule
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Watson & Crick model
Watson & Crick model
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Semiconservative replication
Semiconservative replication
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Chargaff’s rule
Chargaff’s rule
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DNA replication models
DNA replication models
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Hydrogen bonding
Hydrogen bonding
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Phosphodiester linkage
Phosphodiester linkage
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Operon
Operon
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Components of an operon
Components of an operon
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Promoter
Promoter
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Operator
Operator
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Structural genes
Structural genes
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Lac operon
Lac operon
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Repressor protein
Repressor protein
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Allolactose
Allolactose
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Leading Strand Synthesis
Leading Strand Synthesis
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Lagging Strand Synthesis
Lagging Strand Synthesis
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Okazaki Fragments
Okazaki Fragments
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Primase
Primase
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DNA Polymerase III
DNA Polymerase III
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RNA Primer
RNA Primer
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DNA Ligase
DNA Ligase
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Types of RNA
Types of RNA
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Transcription in lac operon
Transcription in lac operon
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Proteins from lac operon
Proteins from lac operon
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Role of allolactose
Role of allolactose
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Repressor-operator complex
Repressor-operator complex
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Negative control in lac operon
Negative control in lac operon
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Inducible operon
Inducible operon
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Mutation
Mutation
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Small-scale mutations
Small-scale mutations
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Point mutation
Point mutation
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Nucleotide-pair substitution
Nucleotide-pair substitution
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Silent mutation
Silent mutation
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Missense mutation
Missense mutation
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Nonsense mutation
Nonsense mutation
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Nucleotide-pair insertions
Nucleotide-pair insertions
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Frameshift mutation
Frameshift mutation
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Study Notes
Chapter 1: Genetic Inheritance & Genetic Control, Part 2
- This chapter covers topics related to genetic inheritance and control, focusing on DNA structure, replication, protein synthesis (transcription and translation), mutation, and gene expression.
1. Terms in Genetics
- Terms related to genetics were introduced.
2. Mendelian Genetics
- Monohybrid inheritance: Describes inheritance patterns involving a single gene.
- Dihybrid inheritance: Explains patterns for two genes.
- Extensions of Mendelian Genetics: Addresses cases that don't follow the strict ratios of Mendel's laws.
- Human Pedigree Analysis: Using family trees to track traits through generations.
3. Population Genetics
- Terms in population genetics: Introduced relevant terms used in studying genetic diversity within populations.
- Hardy-Weinberg equation: Defines conditions determining whether a population's genotype frequencies are changing.
- Hardy-Weinberg equilibrium conditions: Specific conditions required for a population's genotype to remain constant.
4. DNA Structure and Replication
- DNA double helix: Describes the double-stranded, helical structure of DNA.
- Models of DNA replication: Explains various theoretical models, including the conservative, semi-conservative, and dispersive models.
- Meselson and Stahl's experiment: This experiment provided evidence that DNA replication follows a semi-conservative model.
- DNA replication: This process duplicates DNA.
5. Protein Synthesis: Transcription and Translation
- Types of RNA: Briefly described the different types of RNA (mRNA, rRNA, and tRNA), emphasizing their essential roles in protein synthesis.
- Basic principles of transcription & translation: Outlined fundamental processes involved in converting genetic code into proteins.
- Genetic code: The set of rules that determines how codons are translated into amino acids.
- Transcription of RNA: Detailed the process of creating RNA from a DNA template.
- Modification of pre-mRNA in eukaryotes: Description of modification in mRNA before it exits the nucleus.
- Translation: Processes involving converting the mRNA molecule sequence into the amino acid sequence.
6. Regulation of Gene Expression
- Regulation of gene expression: The process of controlling which genes are active in a cell.
- Components of an operon: Explaining the operon system, encompassing a promoter, operator, and multiple related structural genes.
- Lactose operon (lac operon): Explains this bacterial gene regulatory system that controls the production of enzymes for lactose metabolism under different conditions.
7. Mutation
- Mutation: Describes any change in the nucleotide sequence of DNA.
- Small-scale mutations: Describes small nucleotide changes impacting a gene and their effect on the encoded protein.
- Chromosome mutations: Outlined large-scale changes affecting the entire chromosome.
- Human disorders due to chromosomal alteration: Examples of human conditions linked to chromosomal abnormalities were mentioned.
1.4. DNA Structure and Replication
- DNA double helix: Discusses the fundamental double-helix structure.
- Meselson-Stahl experiment: This experiment strongly supported the semi-conservative DNA replication model.
1.4.1 DNA Double Helix
- DNA structure: A polymer of nucleotides with a sugar-phosphate backbone.
- Phosphodiester linkages: Connects nucleotides.
- DNA directionality: 5' to 3'.
1.4.3 Meselson-Stahl Experiment
- Experiment details: Bacteria grown in mediums with heavy and light isotopes of nitrogen were used to track DNA replication.
- Results supported semi-conservative model.
1.4.4 DNA Replication
- Origin of replication: Location where DNA replication begins in circular chromosomes.
- Replication bubble: The region where DNA is unwound during replication (eukaryotes).
- Replication fork: The Y-shaped region of replication. Process in bacteria was discussed
1.4.2 DNA Replication Models
- Overview of the three DNA replication models (conservative, semi-conservative, and dispersive).
1.5 Protein Synthesis: Transcription and Translation
- Types of RNA and their roles.
1.5.1 Types of RNA
- mRNA, rRNA, and tRNA
1.5.2 Basic Principles of Transcription and Translation
- The synthesis of RNA using a DNA template or copying information from DNA to RNA.
- The synthesis of a polypeptide using information in the mRNA.
1.5.3 Genetic Code
- Codons in mRNA are read in the 5' → 3' direction.
- Each codon specifies a particular amino acid.
- Complementary DNA base triplets are known as codons.
- Table of genetic code.
1.5.4 Transcription of RNA
- Stages: Initiation, elongation, and termination.
- RNA polymerase binds to the promoter region to initiate RNA transcription (eukaryotes).
1.5.5 Modification of Pre-mRNA in Eukaryotes
- mRNA processing in Eukaryotes: Capping and polyadenylation.
- RNA splicing: Removing introns and joining exons creates mature mRNA.
1.5.6 Translation: Building a Polypeptide
- 3 Stages: Initiation, elongation, and termination.
1.5.7 Structure and Function of tRNA
- tRNA is single stranded.
- tRNA has an amino acid attachment site and an anticodon.
- tRNA brings specific amino acids to the ribosome.
1.6 Regulation of Gene Expression
- How prokaryotes and eukaryotes regulate gene expression.
- Operon structure: Promoter, operator, and structural genes.
- Lactose operon structure and function: How it controls lactose metabolism in bacteria.
1.7 Mutation
- Changes in DNA nucleotide sequences are mutations.
- Small-scale mutations: Substitutions, insertions, deletions.
- Large-scale mutations: Deletions, duplications, inversions, translocations. Examples of human genetic diseases (e.g., Down syndrome, Klinefelter syndrome, Turner syndrome, and Cri du chat Syndrome) associated with chromosome mutations.
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Description
Test your knowledge of DNA replication. Questions cover enzymes like DNA polymerase and primase, Okazaki fragments, and the semiconservative model. Understand the roles of leading and lagging strands in creating new DNA.
