Test Your Protein Synthesis Knowledge

Proteins are composed of long chains of amino acids. These amino acids are the building blocks of proteins, as they are linked together through peptide bonds to form polypeptide chains. Nucleic acids, such as DNA and RNA, are responsible for storing and transmitting genetic information. The endoplasmic reticulum is an organelle involved in protein synthesis and lipid metabolism. Therefore, the correct answer is amino acids, as they are the fundamental units that make up proteins.

RNA is a nucleic acid that contains ribose, a sugar molecule, and is single-stranded. It differs from DNA, which contains deoxyribose instead of ribose. Therefore, the correct answer is Deoxyribose because it is not a component of RNA.

Translation occurs at the ribosomes in the cytoplasm of the cell. Ribosomes are the cellular structures where proteins are synthesized. During translation, the genetic information in mRNA is decoded and used to assemble amino acids into a protein chain. This process takes place at the ribosomes, which are located in the cytoplasm of the cell. Therefore, the correct answer is "at the ribosomes in the cytoplasm of the cell."

tRNA, or transfer RNA, is responsible for picking up amino acids and delivering them to the ribosome during protein synthesis. It has a specific anticodon sequence that matches with the codon sequence on the mRNA molecule. This allows tRNA to recognize and bind to the correct amino acid, ensuring that the amino acids are brought to the ribosome in the correct order to form the protein. Therefore, tRNA plays a crucial role in the translation of genetic information from mRNA into proteins.

During the termination phase of translation, the stop codon on mRNA reaches the A site. Termination is the final step of protein synthesis, where the ribosome recognizes the stop codon (UAA, UAG, or UGA) on the mRNA. This signals the release of the newly synthesized protein and the disassembly of the ribosome from the mRNA template. Therefore, during termination, the stop codon reaches the A site, indicating the end of protein synthesis.

The RNA strand that would be produced from the given DNA strand is GGAGUACCG. RNA is synthesized from DNA through a process called transcription. During transcription, the DNA strand is used as a template to produce a complementary RNA strand. In RNA, thymine (T) is replaced by uracil (U). Therefore, the DNA sequence CCTCATGGC would be transcribed into the RNA sequence CCUCAUGGC.

Introns are noncoding sections of RNA. These sections do not contain the instructions for producing proteins and are removed during the process of RNA splicing. After the removal of introns, the remaining coding sections of RNA, known as exons, are spliced together to form the final mRNA molecule. This mRNA molecule can then be translated into a protein. Therefore, introns do not contribute to the coding sequence of RNA and are considered noncoding sections.

A plasmid is a small circular piece of DNA that is found outside the main chromosome in bacteria. It is separate from the bacterial genome and can replicate independently. Plasmids often carry additional genes that can provide advantages to the bacteria, such as antibiotic resistance. They can be transferred between bacteria through processes like conjugation, allowing for the spread of these advantageous genes. Therefore, plasmids play a crucial role in bacterial genetics and are an important tool in genetic engineering and biotechnology.

Ribosomes have 3 binding sites (A, P, and E). This means that during protein synthesis, the ribosome has three locations where tRNA molecules can bind. The A site (aminoacyl site) is where the incoming aminoacyl-tRNA binds. The P site (peptidyl site) is where the growing polypeptide chain is held. The E site (exit site) is where the tRNA that has released its amino acid exits the ribosome. This allows for the efficient and accurate assembly of proteins during translation.

RNA polymerase is an enzyme responsible for transcription, the process of synthesizing RNA from a DNA template. It adds RNA nucleotides to the exposed bases on DNA, creating a complementary RNA strand. This RNA molecule can then be used for various functions, such as protein synthesis or as a regulatory molecule. Forming peptide bonds between amino acids is the function of ribosomes, while producing the RNA primer required for DNA replication is the role of primase. Producing amino acids is not a function of RNA polymerase.

The correct answer is "Promoter". The promoter is the region of DNA where RNA polymerase binds and transcription begins. It contains specific DNA sequences that attract transcription factors and help position the RNA polymerase enzyme. The promoter plays a crucial role in initiating the transcription process by providing the necessary signals and binding sites for the transcription machinery.

RNA polymerases are not involved in DNA replication. DNA replication is the process by which DNA is synthesized to create an identical copy of the original DNA molecule. It involves several enzymes, including helicase, DNA ligase, DNA polymerases, and primase. Helicase is responsible for unwinding the DNA double helix, DNA ligase joins the Okazaki fragments on the lagging strand, DNA polymerases synthesize new DNA strands, and primase synthesizes RNA primers that are necessary for DNA replication. However, RNA polymerases are responsible for transcribing RNA from DNA, not for DNA replication itself.

An mRNA actively being translated in the cytoplasm would have all of the following except introns. Introns are non-coding regions of DNA that are transcribed into pre-mRNA but are removed during the process of splicing to form mature mRNA. In the cytoplasm, mRNA undergoes translation to produce proteins, and during this process, only the coding regions called exons are translated into amino acids. The mRNA would have a poly-A tail, a 5' cap, exons, and RNA nucleotides, all of which are essential for translation and stability of the mRNA molecule.

During initiation, mRNA binds to the small ribosomal subunit. This is the first step in the process of translation, where the genetic information encoded in the mRNA is used to synthesize a protein. The small ribosomal subunit binds to the mRNA at a specific sequence called the start codon, which signals the beginning of the protein-coding region. This binding allows for the recruitment of the large ribosomal subunit and the assembly of the complete ribosome, which then proceeds with the elongation phase of translation. Therefore, initiation is the correct answer.

Gerard Johann Mulder is credited with coining the term "Protein." Mulder was a Dutch chemist who conducted extensive research on the chemical composition of living organisms. In 1838, he identified a class of nitrogenous compounds found in both plants and animals, which he named "Proteins" from the Greek word "proteios," meaning primary or of prime importance. Mulder's discovery and naming of proteins laid the foundation for further exploration and understanding of these essential macromolecules in the field of biochemistry.

mRNA undergoes processing or modification before translation in eukaryotic transcription. This includes steps such as capping, splicing, and polyadenylation, which are essential for mRNA stability, transport, and efficient translation. Prokaryotic transcription, on the other hand, typically does not involve such extensive mRNA processing.

The TATA box is a short sequence in the promoter region of a gene where transcription factors bind. This binding helps to initiate the process of transcription by recruiting RNA polymerase to the promoter. The TATA box is crucial for the accurate initiation of transcription and is found in the majority of eukaryotic promoters. It is recognized by specific transcription factors, which then recruit RNA polymerase to the promoter to start transcription. Therefore, the TATA box plays a vital role in regulating gene expression.

Wobble refers to the relaxation of base pairing rules between the third base of a codon in mRNA and the corresponding base of an anticodon in tRNA during translation. This relaxation allows for flexibility in the genetic code, as multiple codons can code for the same amino acid. It is important for efficient and accurate translation of mRNA into proteins.

The lac operon in E.coli is involved in regulating the expression of a gene. It consists of three structural genes that are responsible for the metabolism of lactose. The lac operon is regulated by a repressor protein that binds to the operator region, preventing the transcription of the structural genes in the absence of lactose. When lactose is present, it binds to the repressor protein, causing a conformational change and allowing transcription to occur. This regulation ensures that the genes involved in lactose metabolism are only expressed when lactose is available as a nutrient source.

A single addition of a nucleotide in a DNA strand that codes for an mRNA would most likely cause a mutation with the greatest deleterious effect. This is because an addition of a nucleotide would shift the reading frame of the mRNA, leading to a completely different sequence of amino acids being produced during translation. This can result in a nonfunctional or malfunctioning protein, which can have severe consequences for the organism. In contrast, the other options (deletion of a nucleotide, single substitution in the third codon position, single substitution in the first codon position) would cause a change in only one amino acid, which may or may not have a significant impact on the protein's function.