Untitled Quiz

The components of a DNA molecule are nucleotides, composed of a deoxyribose sugar bonded to a phosphate and a nucleotide base (adenine, thymine, cytosine, or guanine). The three-dimensional structure of DNA is a double helix.

The evidence included Rosalind Franklin's X-ray diffraction photo of a crystal of DNA, plus Erwin Chargaff's work that showed that DNA contains equal amounts of adenine and thymine and equal amounts of cytosine and guanine.

The 5' end has the 5th numbered carbon in deoxyribose facing out with a phosphate group attached, and the 3' end has the 3rd numbered carbon leading with an OH group attached.

<p>A gene is a strand of DNA that encodes a protein.</p> Signup and view all the answers

<p>Transcription and translation.</p> Signup and view all the answers

<p>Messenger RNA (mRNA) carries DNA instructions for building protein, transfer RNA (tRNA) carries appropriate amino acids to the ribosome, and ribosomal RNA (rRNA) is a major component of ribosomes.</p> Signup and view all the answers

<p>The steps of transcription are initiation, elongation of the RNA molecule, and termination.</p> Signup and view all the answers

<p>Transcription occurs in the nucleus.</p> Signup and view all the answers

<p>RNA polymerase uses the DNA template to bind additional RNA bases into the growing RNA chain.</p> Signup and view all the answers

<p>The promoter signals the start of a gene, and the terminator signals the end of a gene.</p> Signup and view all the answers

<p>A cap is added to the 5' end, a poly A tail is added to the 3' end, and introns are removed while exons are spliced together.</p> Signup and view all the answers

<p>Researchers reasoned that the genetic code could not reflect 1-base or 2-base 'words' due to insufficient combinations for 20 amino acids, finding that a triplet code could encode for 64 possible combinations.</p> Signup and view all the answers

<p>The steps of translation are initiation, elongation of the polypeptide, and termination.</p> Signup and view all the answers

<p>Translation occurs at ribosomes, which can be found free in the cytoplasm or attached to the rough ER.</p> Signup and view all the answers

<p>Polypeptides must be folded into proteins; sometimes amino acids are cut out, and sometimes multiple polypeptides join together.</p> Signup and view all the answers

<p>Cells regulate gene expression to avoid unnecessary protein production, saving energy.</p> Signup and view all the answers

<p>A repressor protein binds to an operator and prevents the genes in the operon from being transcribed.</p> Signup and view all the answers

<p>Transcription factors bind to certain DNA sequences to regulate transcription, while enhancers are sequences that help transcription factors enhance gene expression.</p> Signup and view all the answers

<p>An operon is a stretch of DNA found in bacteria that controls gene regulation, comprising a promoter, an operator, and structural genes.</p> Signup and view all the answers

<p>Cells can keep DNA coiled, attach methyl groups, splice out different introns, or degrade mRNA and proteins.</p> Signup and view all the answers

<p>A mutation is a change in the DNA sequence of a cell.</p> Signup and view all the answers

<p>Point mutations change one or a few base pairs; include substitutions, insertions, and deletions, each potentially altering the encoded protein.</p> Signup and view all the answers

<p>Mutations are caused by DNA replication errors, errors in meiosis, chromosome inversions and translocations, or exposure to chemicals or radiation.</p> Signup and view all the answers

<p>A germline mutation occurs in cells that will become sperm or egg cells; a somatic mutation occurs in a non-germline body cell.</p> Signup and view all the answers

<p>Mutations are used to learn how genes function, develop new crop varieties, trace virus evolution, and are important for evolution.</p> Signup and view all the answers

<p>The genome can make 400,000 proteins from about 25,000 genes by changing which introns are removed prior to splicing together mRNA.</p> Signup and view all the answers

<p>It encodes rRNA, tRNA, regulatory sequences, contains pseudogenes, transposons, and tandem repeats.</p> Signup and view all the answers

<p>Recombinant DNA is the combined DNA from two or more organisms.</p> Signup and view all the answers

<p>The order from smallest to largest is nitrogenous base, nucleotide, codon, gene, chromosome, nucleus, and cell.</p> Signup and view all the answers

<p>RNA has ribose sugar, uracil as a nitrogenous base, can be single-stranded, and can catalyze reactions; DNA has deoxyribose, thymine, is double-stranded, and cannot catalyze reactions.</p> Signup and view all the answers

<p>Transcription copies DNA into mRNA in the nucleus, while translation translates mRNA into proteins at ribosomes in the cytoplasm.</p> Signup and view all the answers

<p>mRNA carries genetic information, rRNA forms the ribosome, and tRNA carries amino acids to the ribosome.</p> Signup and view all the answers

<p>The cell can keep DNA coiled, attach methyl groups, splice out different introns, or degrade mRNA and proteins.</p> Signup and view all the answers

<p>A mutation can lead to a non-functional protein, regardless of its location, blocking the expression of relevant traits.</p> Signup and view all the answers

<p>A mutation may change a codon but result in the same amino acid due to codon redundancy.</p> Signup and view all the answers

<p>Restriction enzymes cut DNA at specific sites; fragments are joined by DNA ligase to create recombinant DNA, resulting in transgenic organisms.</p> Signup and view all the answers

<p>Cell structure and function depend on proteins, which are necessary for metabolic processes.</p> Signup and view all the answers