AP Molecular Genetics Review

The goal of transcription is to make a copy of DNA using mRNA. Transcription is the process by which the DNA sequence is converted into an RNA molecule, specifically mRNA. This mRNA molecule carries the genetic information from the DNA to the ribosomes, where it is used as a template for protein synthesis. Therefore, the correct answer is to make a copy of DNA using mRNA.

The given DNA strand has the nitrogen bases T A G G C A T C A. In mRNA, the base thymine (T) is replaced with uracil (U). So, the mRNA sequence would be A U C C G U A G U.

translation takes place at the ribosomes in the cytoplasm

Eukaryotic organisms have their transcription occurring in the nucleus and translation in the cytoplasm. This is because eukaryotes have a distinct separation of the nucleus, where DNA is located, and the cytoplasm, where ribosomes are located. Transcription, the process of synthesizing RNA from DNA, occurs in the nucleus where the DNA is transcribed into mRNA. This mRNA is then transported out of the nucleus into the cytoplasm, where translation, the process of synthesizing proteins from mRNA, takes place on ribosomes. This separation allows for more regulation and control of gene expression in eukaryotes.

Chromosome contain genes and are essentially gene-carriers (it's easier to think about them like that). Genes are basically sections of DNA, however exons are part of a gene but not what a gene is and a regulatory sequence is a non-gene portion of DNA.

mRNA is a type of RNA molecule, it is not just an atom nor is it a chromosome. It also carries encoded information copied from the DNA template to be translated to synthesize proteins.

RNA polymerase binds to a site on DNA called the promoter. The promoter is a specific region of DNA that signals the beginning of a gene. It provides a binding site for RNA polymerase, allowing it to initiate transcription and start the process of gene expression. The promoter plays a crucial role in regulating gene expression by determining when and how much RNA is produced.

Hydrogen bonds form between complementary base pairs in DNA. These bonds occur between the nitrogenous bases, specifically adenine (A) with thymine (T), and guanine (G) with cytosine (C). Hydrogen bonds are relatively weak compared to covalent or ionic bonds, but they play a crucial role in stabilizing the DNA double helix structure. The hydrogen bonds between base pairs allow for the separation and replication of DNA strands during cellular processes like DNA replication and transcription.

PCR stands for Polymerase Chain Reaction. It is a laboratory technique used to amplify a specific DNA sequence. The process involves repeated cycles of heating and cooling to denature and replicate the DNA. This technique is widely used in various fields such as genetic research, forensic analysis, and medical diagnostics.

During DNA replication, each original strand of the double-stranded helix serves as a template for the synthesis of a new complementary strand. As a result, one original strand is conserved in each daughter cell, while a new strand is synthesized to pair with it. This process is known as semiconservative replication because it conserves half of the original DNA molecule in each daughter cell. The term "proofreading" refers to the error correction mechanisms during replication, "redundant" and "freeing of DNA" do not accurately describe the process, and "mutation positive" is not a recognized term in the context of replication.

The correct answer suggests that something inside the bacteria has the ability to instruct and control its behavior, which can change the behavior of other bacteria if they come into contact with it. This conclusion is supported by Griffith's experiment on mice, where he observed that the harmless rough strain of bacteria became deadly when mixed with heat-killed smooth strain bacteria. This indicates that something in the heat-killed bacteria transformed the rough strain bacteria, leading to a change in their behavior. Therefore, it can be inferred that there is a factor inside the bacteria that can control and instruct its behavior.

Restriction enzymes are proteins that can recognize and bind to specific DNA sequences. They act as molecular scissors and can cut the DNA at these specific recognition sites. This process is known as restriction digestion and is commonly used in genetic engineering and molecular biology to manipulate and study DNA. The correct answer, "cut DNA at specific sites," accurately describes the function of restriction enzymes.

The correct answer is 4 because restriction enzymes are used to cut DNA at specific recognition sites. If the DNA sample being digested is a bacterial plasmid, it is likely to have multiple recognition sites for the restriction enzyme, resulting in multiple cuts. Therefore, 4 cuts would be made by the restriction enzyme in this scenario.

DNA ligase is an enzyme that plays a crucial role in DNA replication and repair. It functions by catalyzing the formation of phosphodiester bonds between adjacent nucleotides, thus joining the DNA fragments together. In this context, DNA ligase binds nucleotides together, ensuring the integrity and continuity of the DNA molecule. It does not have any role in binding introns or exons, nor does it interact with polymerase or the promoter region. Therefore, the correct answer is nucleotides together.

RNA polymerase is the correct answer because it is the enzyme responsible for transcribing DNA into RNA. It recognizes and binds to the promoter site on the DNA molecule to initiate the transcription process. The promoter site contains specific sequences that signal the start of a gene and provide the necessary binding site for RNA polymerase. Therefore, RNA polymerase is the molecule that recognizes the promoter site and starts the transcription process.

The answer suggests that the defendant may be guilty because the bands from the blood on the clothes match with the ones from the victim's blood. This indicates that the blood on the clothes belongs to the victim, supporting the possibility that the defendant is responsible for the crime.

Deletions are more likely to cause mistranslations of proteins because they shift the reading frame and cause downstream amino acids to be changed. This alteration in the sequence of amino acids can disrupt the proper folding and functioning of the protein, leading to potential errors in its structure and function. Substitutions, on the other hand, may only affect a single amino acid and may not have as significant an impact on the overall protein structure and function. Therefore, deletions pose a higher risk of causing mistranslations of proteins.

The correct answer is "makes it possible to create huge numbers of copies of tiny pieces of DNA". PCR is a technique used to amplify a specific segment of DNA, allowing researchers to create millions or billions of copies of that segment. This is achieved through a series of temperature cycles that cause the DNA to denature, anneal with primers, and extend with DNA polymerase. This process can be used in various applications such as genetic testing, DNA sequencing, and cloning.

A bacterial gene regulatory system is unlikely to have one or more introns. This is because introns are non-coding sequences that are typically found in eukaryotic genes and are removed during the process of mRNA splicing. Bacterial genes, on the other hand, are usually composed of continuous coding sequences without introns. Therefore, the absence of introns is a characteristic feature of bacterial gene regulatory systems.

Restriction enzymes are proteins produced by bacteria to protect themselves from virus attacks. These enzymes recognize specific sequences of DNA and cut the DNA at those sites. By cutting up foreign DNA, the enzymes prevent the virus from replicating and taking over the bacterium's genetic material. This defense mechanism helps the bacterium to defend itself against viral infections and maintain its own genetic integrity.

A vector is used to carry foreign genes or DNA fragments. Vectors are commonly used in genetic engineering to transfer genes into host organisms. They act as vehicles to transport the desired DNA fragments into the target organism's cells. This allows scientists to introduce new genes or modify existing ones in order to study gene function, produce proteins of interest, or develop genetically modified organisms. Vectors can be derived from various sources, such as plasmids or viruses, and are engineered to have specific features that enable efficient gene transfer and expression.

For transcription to be initiated, RNA polymerase must have access to the DNA double helix and be capable of binding to the gene's promoter. Transcription is the process of synthesizing an RNA molecule from a DNA template. RNA polymerase is the enzyme responsible for this process and it requires access to the DNA double helix in order to bind to the gene's promoter region. The promoter region is a specific sequence of DNA that signals the start of a gene and provides a binding site for RNA polymerase. Therefore, RNA polymerase must have access to the DNA double helix and be able to bind to the gene's promoter in order for transcription to begin.

Hershey and Chase tested and confirmed the hypothesis that if DNA is truly the hereditary material emitted into the bacteria, then radioactively marked DNA will show up in the bacteria, not in the external liquid following the virus' activity. They conducted an experiment where they labeled the DNA of a virus with radioactive phosphorus and the protein coat of the virus with radioactive sulfur. They found that only the radioactively labeled DNA was present in the infected bacteria, providing evidence that DNA is the hereditary material.

Regulatory proteins shut off transcription by binding to a site immediately in front of the promoter and often even overlapping the promoter. This site is referred to as the "operator site." The operator site is a specific DNA sequence where regulatory proteins, known as repressors, can bind and prevent the RNA polymerase from transcribing the gene. By binding to the operator site, the repressor protein physically blocks the RNA polymerase from initiating transcription, effectively shutting off gene expression. Therefore, the operator site plays a crucial role in regulating gene expression by controlling the access of RNA polymerase to the promoter region.

The lac operon of E. coli is a regulatory system that controls the transcription of genes involved in lactose metabolism. When lactose is present in the environment, it acts as an inducer and binds to the lac repressor protein, causing a conformational change that prevents it from binding to the operator. This allows RNA polymerase to bind to the promoter and initiate transcription of the lac genes. Therefore, the correct answer is that the lac operon is transcribed when lactose is present.

Histones are proteins that help package DNA into a compact structure called chromatin. When histones bind to DNA, they can either promote or inhibit gene expression. In this case, histones are binding to DNA and turning off certain genes, indicating that this is an example of epigenome. The epigenome refers to the chemical modifications and proteins associated with DNA that can influence gene expression without changing the DNA sequence itself.

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The correct answer is 1, 2, and 3. This means that all three lanes have the longest sections of DNA.