Lewin's Genes XII: Chapter 1 Exam Questions With Verified Answers.

Lewin's Genes XII: Chapter 1 Exam Questions With Verified Answers. Acridine - answerMutagens that act on DNA to cause the insertion or deletion of a single base pair. They were useful in defining the triplet nature of the genetic code. Allele - answerOne of several alternative forms of a gene occupying a given locus on a chromosome. Annealing - answerThe renaturation of a duplex structure from single strands that were obtained by denaturing duplex DNA. Antiparallel - answerA term applied to two molecules that are side by side but run in opposite directions. Antisense Strand - answeri.e. Template strand: The DNA strand that is copied by the polymerase. Back Mutation - answerA mutation that reverses the effect of a mutation that had inactivated a gene; thus, it restores the original sequence or function of the gene product. Base Pairing - answerBinding of nucleotide bases such that each base pair consists of a purine and pyrimidine held together by one or more hydrogen bonds. In DNA, the purine adenine (A) binds to the pyrimidine thymine (T) and the purine guanine (G) binds to the pyrimidine II cytosine (C). In RNA, the pyrimidine uracil (U) is substituted for thymine. Bent DNA - answerCurves in DNA often associated with poly(A) stretches on the same side of the double helix that are thought to assist with both activation and repression of transcription Bivalent - answerThe structure containing all four chromatids (two representing each homologue) at the start of meiosis. Blocked (closed/blocked reading frame) - answerA reading frame that cannot be translated into protein because of the occurrence of termination codons. Central Dogma - answerInformation cannot be transferred from protein to protein or protein to nucleic acid but can be transferred between nucleic acids and from nucleic acid to protein. Chiasma - answerA site at which two homologous chromosomes synapse during meiosis. EXAM STUDY MATERIALS July 23, 2024 4:26 PM Chromatid - answerEither of the two threadlike strands formed when a chromosome duplicates during the early stages of cell division. The two strands are held together at the centromere and separate into daughter chromosomes during anaphase. Chromosome - answerA discrete unit of the genome carrying many genes. Each consists of a very long molecule of duplex DNA and an approximately equal mass of proteins (in eukaryotes). It is visible as a morphological entity only during cell division. Cis-acting - answerA site that affects the activity only of sequences on its own molecule of DNA (or RNA); this property usually implies that the site does not code for protein Cistron - answerThe genetic unit defined by the complementation test; it is equivalent to a gene. Closed - answersee closed(blocked) reading frame Coding (or sense) Strand - answerThe DNA strand that has the same sequence as the mRNA and is related by the genetic code to the protein sequence that it represents. Coding Region - answerA part of a gene that codes for a polypeptide sequence. Codon - answer(1) A triplet of nucleotides that codes for an amino acid. (2) A termination signal. Colinear - answerThe relationship that describes the 1:1 correspondence of a sequence of triplet nucleotides to a sequence of amino acids. Complementary - answerBase pairs that match up in the pairing reactions in double helical nucleic acids (A with T in DNA or with U in RNA, and C with G). Complementation Group - answerMutant genes that do not complement each other, thus indicating that the mutations occur on the same gene. Complementation tests are used to determine whether two mutations are in the same or different genes Complementation Test: - answerA test that determines whether two mutations are alleles of the same gene. It is accomplished by crossing two different recessive mutations that have the same phenotype and determining whether the wild-type phenotype can be produced. If so, the mutations are said to complement each other and are probably not mutations in the same gene. Denaturation - answerA molecule's conversion from the physiological conformation to some other (inactive) conformation. In DNA, this involves the separation of the two strands due to breaking of hydrogen bonds between bases. DNA polymerase - answerAn enzyme that synthesizes a daughter strand(s) of DNA (under direction from a DNA template). Any particular enzym