DNA, RNA, and Proteins - AP Biology

Uracil in RNA bonds to adenine on the DNA template during transcription. These two nitrogenous bases form two hydrogen bonds.

mRNA contains uracil instead of thymine, therefore your answer should not contain the base thymine. Remember, DNA is read in the 3' to 5' direction and the corresponding strand is created in the 5' to 3' direction. It is important to pay attention to polarity of the strands. Adenine pairs with thymine, and/or uracil. Guanine pairs with cytosine.

mRNA is messenger RNA, it carries the genetic code that determines the protein. snRNA directs splicing of pre-mRNA. tRNA transports the amino acids used for assembling proteins. rRNA is a component of ribosomes (the other component is protein). pre-mRNA- single strand of RNA processed to form mRNA.

Uracil is bound to adenine in the production of RNA, while thymine is used in its place in the production of DNA. Adenine, guanine, and cytosine are all used in the production of both RNA and DNA.

Cytosine and guanine form three hydrogen bonds with each other, while adenine and tyrosine only form two hydrogen bonds. This means that strands of DNA with a higher percentage of cytosine and guanine will have higher melting points.

Since we are looking for the sequence with the lowest melting point, we want the lowest percentage of cytosine and guanine, and the highest percentage of adenine and thymine.

The operator region is the location where the repressor binds. Other parts of an operon include the promoter (where RNA polymerase binds), and structural genes.

Addition of 5’ cap, 3’ tail, and intron splicing occur in eukaryotes, not prokaryotes. Repressors bind to the operator region of the gene and prevent RNA polymerase from transcribing the gene, while activators bind to the promoter and increase transcription of the gene.

A repressor is a molecule that binds to the operator region of a gene and prevents RNA polymerase from transcribing the genes. An inducer can bind to a repressor, preventing the repressor from binding to the operator region, and thus allowing RNA polymerase to transcribe the genes.

Fingerprints are different in all individuals, even identical twins. Due to RNA processing, or post-transcription modification, the grooves of a finger are different even in individuals with identical DNA.

The other techniques are used for DNA analysis between individuals with different DNA. Identical twins will be indistinguishable under these techniques, because their DNA is the same.

snRNPs, or small nuclear ribonucleoproteins, are an essential part of the spliceosome complex. The spliceosome is responsible for the removal of introns from the primary transcript.

Anticodons are found on molecules of tRNA. Their function is to base pair with the codon on a strand of mRNA during translation. This action ensures that the correct amino acid will be added to the growing polypeptide chain. A tRNA molecule will enter the ribosome bound to an amino acid. The anticodon sequence will bind to the codon of the mRNA, allowing the tRNA to release the attached amino acid. This amino acid is then added to the peptide chain by the ribosome.

The protein quaternary structure is the highest level of protein architecture and refers to the arrangement of protein subunits and their interactions with one another. There is a range in the complexity in the quaternary structure of proteins from dimers, such as DNA polymerase, to tetramers, such as hemoglobin. These structures are always composed of more than one protein subunit.

Disruption of normal protein folding or denaturation—protein unfolding—occurs under certain environmental conditions. Denaturation is defined as the loss of quaternary, tertiary, and secondary folding through the disruption of protein subunits and bonds. The environmental conditions that cause denaturation include the following: extreme temperatures, chemical interference, and extreme pH levels. Denatured proteins may sometimes refold if conditions stabilize; however, this does not typically happen.

Histone proteins are highly basic proteins found in the eukaryotic cell nuclei that are integral proteins needed to package DNA tightly inside. They are the chief protein components of chromatin, acting as spools around which the DNA winds and plays an important role in gene regulation. Without histones, the unwound DNA in chromosomes would be very long and difficult to control.

Secondary structure is made up of alpha helix and beta pleated sheets. Linear sequence of amino acids is found in primary structure, 3D folding is found in tertiary structure, and two peptide chains joined by non covalent bonds are found in quaternary.

Amino acid sequence is determined by the sequence of codons on mRNA. tRNA is responsible for bringing new amino acids to the ribosome. Interactions between the codons on mRNA and the anticodons on tRNA are what allow the formation of the appropriate peptide bonds.

Chaperones are later used to facilitate the development of protein structure, but are not involved in checking protein sequence.

The start codon for any strand of RNA begins with the codon that codes for the amino acid methionine. This is the first amino acid in a polypeptide chain. The abbreviation for methionine is: Met.

Silent mutations will change a DNA sequence without affecting the phenotype of the organism. This can occur either in an intron, which will not be translated, or by replacing a single nucleotide with another nucleotide without changing the amino acid recruited by the codon. Silent mutations often result from the degenercy of codons.

Frameshift, missense, and nonsense mutations, however, change both an organism's genotype and phenotype by altering its DNA. A frameshift mutation results from the insertion or deletion of a nucleotide, causing a shift in the codon reading frame for every codon read after the mutation. Missense mutations replace one amino acid with another, and nonsense mutations result in a premature stop codon, terminating translation and resulting in a shortened protein.

Proofreading is a function of DNA polymerase III that helps prevent errors during replication. An immediate consequence of a cell that cannot proofread would be a higher rate of mutations during replication. The other options could potentially happen later in the cell's life, but they would only occur as indirect results of the new mutations.