Nucleotides, DNA, and RNA

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Questions and Answers

Considering the chemical structures of nucleotide bases, which tautomeric form of guanine predominates under physiological conditions and how does this preference impact its base-pairing specificity?

The _amino_ form predominates, disrupting hydrogen bond formation with cytosine.
The _enol_ form predominates, favoring Hoogsteen base pairing with cytosine.
The _imino_ form predominates, leading to wobble base pairing with thymine.
The _keto_ form predominates, enabling canonical Watson-Crick base pairing with cytosine. (correct)

The presence of 2'-hydroxyl group in deoxyribose enhances DNA's resistance to alkaline hydrolysis compared to RNA.

False (B)

Describe how the interplay between enthalpy and entropy dictates the specificity and stability of nucleic acid hybridization, particularly in the context of varying GC content and salt concentrations.

Enthalpy favors hybridization due to hydrogen bond formation and base stacking interactions, while entropy opposes it due to decreased degrees of freedom. Higher GC content increases enthalpy due to stronger stacking, needing higher temperatures to denature. Salt concentrations neutralize phosphate backbones, decreasing electrostatic repulsion and favoring hybridization.

In the context of Sanger sequencing, the incorporation of a ______ results in chain termination due to the absence of a 3'-hydroxyl group necessary for phosphodiester bond formation.

dideoxynucleotide Signup and view all the answers

Match each restriction enzyme type with its corresponding cleavage pattern characteristics:

Type I = Cleaves DNA at random far from recognition site; requires ATP. Type II = Cleaves DNA within or at specific distance from recognition site; doesn't require ATP. Type III = Cleaves DNA at a specific distance from recognition site; requires ATP. Type IV = Targets modified DNA. Signup and view all the answers

Considering the structural dynamics of DNA, which factor most significantly contributes to the hyperchromic effect observed during DNA denaturation?

Unstacking of base pairs, leading to increased UV absorbance. (D) Signup and view all the answers

In gel electrophoresis, DNA migration speed is linearly proportional to the applied voltage, irrespective of the buffer ionic strength.

False (B) Signup and view all the answers

Explain the mechanistic differences between DNA polymerase I and DNA polymerase III in E. coli, focusing on their roles in replication and repair, and including their respective exonuclease activities.

DNA polymerase III is the primary enzyme for replication, possessing high processivity and 3'-5' exonuclease activity for proofreading. DNA polymerase I has 5'-3' exonuclease activity for removing RNA primers and a 3'-5' exonuclease activity as well but lower processivity; it is mainly involved in repair and completing Okazaki fragments. Signup and view all the answers

In the context of recombinant DNA technology, a ______ is a self-replicating DNA molecule used to carry foreign DNA into a host cell, enabling its replication and expression.

vector Signup and view all the answers

Match the components involved in protein synthesis with the function each performs:

mRNA = Carries the genetic code from DNA to ribosome. tRNA = Transports amino acids to the ribosome. Ribosome = Site of protein synthesis. Aminoacyl-tRNA synthetase = Catalyzes the attachment of amino acids to their corresponding tRNAs. Signup and view all the answers

Given the complexity of PCR, which modification to standard PCR cycling parameters would most effectively amplify a target sequence with high GC content?

Adding betaine to reduce secondary structure formation. (A) Signup and view all the answers

The Avery-MacLeod-McCarty experiment definitively proved that protein was the genetic material, disproving the role of DNA in heredity.

False (B) Signup and view all the answers

Describe the role of topoisomerases in DNA replication and transcription, detailing how they alleviate torsional stress and the consequences of their inhibition.

Topoisomerases relieve torsional stress by cutting and rejoining DNA strands, preventing supercoiling. Inhibition can halt replication and transcription, causing DNA damage and cell death. Signup and view all the answers

In the central dogma of molecular biology, the process of involves the synthesis of RNA from a DNA template, while involves the synthesis of protein from an RNA template.

transcription, translation Signup and view all the answers

Match each DNA sequencing technology with its key characteristic:

Sanger Sequencing = Chain termination using dideoxynucleotides. Next-Generation Sequencing = Massively parallel sequencing allowing for high throughput. Illumina Sequencing = Uses reversible terminators and fluorescence for base detection. Nanopore Sequencing = Involves passing a single DNA strand through a protein pore. Signup and view all the answers

Considering the ethical implications of gene editing, which CRISPR-based technology raises the most concerns regarding germline modification?

CRISPR-Cas9 for modifying embryos, leading to heritable changes. (D) Signup and view all the answers

In the context of gel electrophoresis, ethidium bromide intercalates into the DNA helix and decreases the overall fluorescence of DNA under UV light.

False (B) Signup and view all the answers

Explain the role of the Shine-Dalgarno sequence in prokaryotic translation initiation and how its absence or mutation affects protein synthesis.

The Shine-Dalgarno sequence is a ribosomal binding site that ensures the ribosome is correctly positioned on the mRNA for translation initiation. Its absence or mutation significantly reduces or abolishes protein synthesis by preventing efficient ribosome binding. Signup and view all the answers

In PCR, the enzyme ______ is used because it is heat-stable and can withstand the high temperatures required for denaturation.

Taq polymerase Signup and view all the answers

Match each type of RNA with its primary function in eukaryotic cells:

mRNA = Carries genetic information from DNA to ribosomes. tRNA = Transports amino acids to ribosomes during translation. rRNA = Forms the structural and catalytic core of ribosomes. snRNA = Involved in splicing and other RNA processing events. Signup and view all the answers

Given a newly discovered bacterial species with an unusual DNA base composition, what experimental approach would best determine whether its DNA replication mechanism relies on a semi-conservative model?

Analyzing the buoyant density of DNA after multiple replication cycles in different isotopic media. (C) Signup and view all the answers

In DNA sequencing, chain-terminating inhibitors lacking both 2' and 3' hydroxyl groups are called dideoxynucleotides which allows for elongation of chains.

False (B) Signup and view all the answers

Describe the mechanisms of action of Type II restriction endonucleases, including their recognition sequences, cleavage patterns, and the chemical nature of the bonds they hydrolyze.

Type II restriction endonucleases recognize specific palindromic sequences in DNA, cleaving the phosphodiester backbone either within the sequence or at a defined distance, resulting in either blunt or sticky ends. They hydrolyze the phosphodiester bonds between the 3'-O and the phosphate group. Signup and view all the answers

The process of creating multiple copies of a DNA fragment in vivo is known as , typically involving the use of a to introduce the DNA into a host organism.

molecular cloning, vector Signup and view all the answers

Match the given genetic engineering tools with their specific applications in biotechnology:

CRISPR-Cas9 = Precise gene editing in living cells. Recombinant DNA technology = Creating genetically modified organisms by combining DNA from different sources. PCR = Amplifying specific DNA sequences for various applications. Gel Electrophoresis = Separating DNA fragments based on size for analysis. Signup and view all the answers

When analyzing a next-generation sequencing dataset, what statistical method would be most appropriate to identify differentially expressed genes between two experimental conditions, accounting for multiple hypothesis testing?

A t-test with Benjamini-Hochberg correction for false discovery rate. (C) Signup and view all the answers

In the context of transgenic organisms, a 'gene knockout' refers to the insertion of a functional, overexpressed gene to enhance a specific trait.

False (B) Signup and view all the answers

Explain the difference between orthologous and paralogous genes, and describe how their analysis contributes to understanding genome evolution and functional divergence.

Orthologous genes are genes in different species that evolved from a common ancestral gene through speciation, often retaining similar functions. Paralogous genes result from gene duplication within a species, leading to functional divergence over time. Analysis of these genes provides insights into evolutionary relationships and gene function. Signup and view all the answers

__________ is a method used to separate macromolecules, such as DNA, RNA and proteins, based on their size and electrical charge

Gel Electrophoresis Signup and view all the answers

Match the Cloned genes use case with their primary benefits:

Human insulin = Treatment of diabetes Human growth hormone = Red blood Stimulation of some endocrine disorders Erythropoietin = Stimulation of red blood cell production Hepatitis B surface antigen = Vaccination against hepatitis B Signup and view all the answers

Which of the following is the most direct application of recombinant DNA technology?

Producing human insulin in bacteria for treating diabetes. (C) Signup and view all the answers

Golden rice, genetically modified to produce beta-carotene, is intended to enhance the nutritional value, specifically Vitamin E

False (B) Signup and view all the answers

How are transgenetic animals like "knockout mice" created?

Transgenic animals, like knockout mice, are created by inactivating existing genes by replacing or disrupting it with an artificial piece of DNA Signup and view all the answers

______ sequences are removed during RNA Splicing

Intron Signup and view all the answers

Match each scientist with their discoveries:

Griffith = Showed how genetic material from dead type S bacteria can live as type R bacteria Macleod = The experiment demonstrated that DNA, not protein, was the genetic material responsible for transformation in bacteria Avery = The experiment demonstrated that DNA, not protein, was the genetic material responsible for transformation in bacteria McCarty = The experiment demonstrated that DNA, not protein, was the genetic material responsible for transformation in bacteria Signup and view all the answers

In a Polymerase Chain Reaction, which step is most impacted by DNA polymerase failure?

Signup and view all the answers

In semi-conservative replication, original strands are combined to create new dna

False (B) Signup and view all the answers

Describe a method for dealing with PCR reaction with high GC.

Adding betaine to reduce secondary structure formation. Signup and view all the answers

______ sequences are not directly translated into proteins.

dNTPs Signup and view all the answers

Match the different sequences with their corresponding purpose:

DNA replication = AGAGGTGCT RNA = AGAGGUGCU Signup and view all the answers

Flashcards

Discrete Units of Inheritance

Mendel found that traits are passed down as discrete units.

DNA Recipe

In molecular biology it is like a recipe or computer program, irreversible.