Genetics: DNA Replication, Transcription, and Translation, Schemes and Mind Maps of Microbiology

Download Genetics: DNA Replication, Transcription, and Translation and more Schemes and Mind Maps Microbiology in PDF only on Docsity! Exams genetics Exam 1: 1) A heterozygote is an individual carrying two different alleles of one gene  True 2) In a haploid organism, sister chromatids each carry different alleles of on gene.  False 3) The probability of a woman giving birth to three boys in a row is 1/6  False 4) In a cross between the genotypes AaBbCc and AaBbCc, what proportion of the offspring would be expected to be A_bbcc?  3/64 5) Why was the pea plant an ideal plant from mendel to use?  Simple traits that are easy to identify  Large numbers of offspring are produced 6) What is the role of the SRY gene in humans?  None of this answer are correct 7) In birds, males are homogametic sex and females the heterogametic sex. Which of the following is true in this system of sex determination?  The gender of the offspring is determined by the female parent 8) Match the following human sex chromosome:  XO: female 0 barr bodies  XXYY: male 1 barr bodies  XY: male: 0 barr bodies  XXXX: female 3 barr bodies 9) You have a wild-type (normal looking) ball python and want to determine if it is heterozygous dominant you decided to perform a testcross. Which cross below accurately reflects the potential outcome of this testcross  If your ball python is homozygous dominant, then 100% of the testcross offspring will be wild-type 10) Which nitrogenous base comprise RNA  Cytosine  Adenine  Uracil  Guanine 11) Tall pea plants (T) Is dominat to short pea plants (t). yellow seeds (Y) is dominant to green seeds (y). and both loci are autosomal in pea plants. A true-breading pea plant that is tall with yellow seeds is crossed to a true-breeding short plant with green seeds. The f1 progeny are allowed to self-fertilize. What is the probability of obtaining a short plant with green seeds in the f2?  1/16 12) Meiosis results in genetic variation among its products cells. One source of this genetic variation is the independent assortment of maternal and paternal chromosomes, and the other source of genetic variation is:  Crossing over occurring during at prophase 1 13) Which of the following characteristics are consistent with prokaryotic cell and not a eukaryotic cell  Lack of histones complexed with DNA  A short circular chromosome  Lack of nucleus 14) Match  Anaphase of mitosis: separation of sister chromatids to opposite poles  Metaphase I of meiosis: homologous chromosomes align along the metaphase plate  Anaphase I of Meiosis: separation of homologous chromosomes to opposite poles  Prophase I of meiosis: homologous chromosomes condense and repair 15) The human bone disease osteogenesis imperfect is caused by a dominant allele, D, and incompletely penetrant. After identifying 80 individuals with at least one D allele, only 50 show symptoms of osteogenesis imperfect. What is the penetrance of this disease?  63% 16) A playpus cell normally has 52 chromosomes (26 pairs) while it is in the g1 stage of the cell cycle. How many chromosomes and how many DNA molecules will it have in the G2 phase?  26 chromosomes and 52 DNA molecules 17) A mother with blood type AB has a child with blood type AB. Give all possible blood types (phenotypes) for the father of this child.  A  AB  B 18) In the snapdragon plant Antirrhinum, plants with the condition aurea have golden instead of green leaves. When two aurea snapdragon plants are crossed, the offspring’s phenotypes occur in an approximately 2:1 ratio of aurea seedlings to green seedlings. What best explains the inheritance of this trait?  The Aurea trait is caused by a lethal allele when homozygous 19) DNA replicates during anaphase, prior to entering the cell cycle  False 20) Select the property or event below that occurs in both mitosis and meosis.  DNA replication  Sister chromatids are separated 21) Which division of genetics focuses on the organism and is best described as studying mechanism of transmission of genes from generation to generation?  Transmission genetics 22) In the Norwegian snow kitten, the offspting of a tru-breeeding white parent and tre- breading black parent are all gary in color, after crossing the gray offspring with each other, the ratio of phenotypes in the offspring are: 1 black 2 gray 1 white. What is the most probable mode of inheritance of this trait?  one locus with incomplete dominance 23) The prune allele (pn) in drosophila simulans is X-linked recessive and produces dark purple-colored eyes. If a male (heterogmatic sex) with normal eyes is crossed with a heterozygous female (homogametic sex: normal0colored eyes), what is the ratio of phenotypes in the offspring?  50% of the male offspring will have prune eyes, and 10% of the female offspring will have normal eyes. 52) Wilkins' and Franklin: DNA is composed of helical structure w bases 90 degrees from backbone 53) Which of the following distinguishes DNA from RNA  DNA lacks a 2-OH group on its pentose sugar 54) 35% of bases in DNA are cytosine. What % are expected to be Thymines  15% 55) Both DNA and RNA consist of repeating units of nucleotides. Which is NOT a component of a nucleotide found in DNA?  uracil 56) A DNA molecule 500bp long has 70 complete rotations. The DNA is  +) supercoiled 57) Centromeres help control the cell cycle by:  Causing DNA without centromeres to be lost 58) Which of the following most likely contributes to decreased transcription  the addition of more positive charged groups to histone tails 59) If a chromosome experiences a break, which DNA fragment(s) will be lost?  The fragment without a centromere 60) In a 3point testcross the nonrecombinant progeny have phenotypes r+st+p+ and r st p. The double crossover progeny are phenotypes r+st+p. Which locus (r, st, or p). Is in the middle  P 61) The study of human genetics is challenging because:  Controlled mating are not possible  Humans have relatively few offspring  Humans have a long generation time 62) A women affected with an X-linked dominant trait will have what proportion of offspring affected with the trait    1/2 sons and 1/2 daughters   63) A man affected with an x-linked dominant trait will have what proportion of offspring affected with the trait?   all daughters and no sons 64) A heterozygous plant (AB/ab) is testcrossed to a homozygous recessive (ab/ab) plant. What will the progeny phenotypic ratio be if genes A and B are complete linked?   1AB:1ab 65) An individual fruit fly heterozygous for two traits D & R has genotype DdRr. A 2 point test cross happens with homozygous recessive for both traits and 100 progeny: 35 DdRr 37 ddrr 13 Ddrr 15rrDd How far apart are genes D and R in map units?  28 map units 66) Which of the following chromosomal rearrangements often suppresses recombination (crossing-over) between homologous chromosomes:  Inversion 67) Euchromatin differs from heterochromatin in that:  Euchromatin encodes more transcribeb gene sequences in its DNA 68) If the sequence of one stand of DNA is 5’-GRRAGCTAGCA-3; what is the sequence of the complementary strand?    5’TGCTAGCTAAC-3 69) Before the chemical nature of genetic material was known, scientists knew that genetic material must possess:  Ability to replicate accurately  Capable of storing large amounts of information  Encoded the phenotype 70) A linear chromosome that lacks a telomere at one end will  Be unstable and ultimately degrade 71) In a three-point testcross the nonrecombinant progeny have phenotypes r+ st+ p+ and r st p . the double-crossover progeny are phenotypes r+ st+ p+. which locus (r,st, or p) is in the middle?    p Exam 3: 1) The Central Dogma, or flow of genetics information, is generally described as information, coded in DNA, is transcribed into protein intermediates, which are subsequently translated into RNA products.  False 2) The replication of the linear DNA molecules in eukaryotes occurs bidirectionally in each replication  True 3) During DNA replication, Okazaki fragments are associated with the synthesis of.. ?  The lagging strand 4) Which if the following is Not required as part of DNA replication?  Small and large ribosomal subunits 5) Which factors contribute to the extremely low error rate of DNA replication? Select all that apply  The 3’> 5’ exonuclease activity of DNA polymerase  The base-pairing rules of DNA 6) Which of the following statements is true regarding tRNA?  Amino acids bind to the 3' end of the tRNA 7) Each individual tRNA molecule is able to attach several different amino acids  False 8) Which of the following statements about the genetic code is false ?  There are two possible reading frames on any mRNA transcript. 9) Ribosomes are composed entirely of ribosomal RNA (rRNA) molecules  False 10) During the elongated phase of translation, the formation of a peptide bond between amino acids is catalyzed by  rRNA 11) Due to the wobble effect, the anticodon 3'-CUU-5' can possibly base pair with which codon(s) in mRNA?  5'-GGA-3' 5'-GGU-3' 5'-GGC-3' 12) Both bacterial and eukaryotic ribosomes are composed of small and large subunits  true 13) The secondary structure of proteins refers to structures such as aloha helices and beta- pleated sheets formed by hydrogen bonding.  True 14) Match the following terms regarding transcription with their appropriate description. Sigma factor -prokaryotic protein that forms a complex with RNA polymerase to aid in promotor recognition Terminator -sequence in prokaryotic DNA that signals the end of transcription and facilitates release of RNA polymerase from the template. RNA polymerase II -transcribes eukaryotic protein-coding genes and some small RNA's RNA polymerase I -transcribes all eukaryotic large ribosomal RNA's 15) Meselson and Stahl grew bacteria from many generation in medium containing heavy 15^N, then shifted the bacteria into medium containing light 14^N for one, two, or three rounds of DNA replication. The DNA was extracted after each round and the density of the DNA molecules was determined by density gradient centrifugation. After the second sound of replication, Meselson and Stahl observed two bands: one of density of just 14^N. After this observation, which hypothesis for SNA replication could be eliminated ? Select all that apply.  -Conservative -Dispersive 16) Transcription in archaea is more similar to transcription in prokaryotes than in eukaryotes ?  False 17) in rho-independent transcription termination in bacteria, the RNA polymerase is destabilized by  -a hairpin loop in the RNA molecule formed inverted repeats 18) the rate of RNA synthesis during transcription is much slower than the rate of DNA synthesis during replication.  True 19) A newly transcribed RNA molecule is complementary and antiparallel to which stand of the DNA molecule ?  template strand 20) In eukaryotic transcription termination, the Rat1 protein binds to and degrades ...  RNA after cleavage of the pre-mRNA 21) In the lab you generated a strain of yeast with a mutation in a gene that generates a new 3' cleavage site upstream of the original site. Which would be the most likely effect on the gene ?  The mutated gene's mRNA will be shorter than the original.  False 14) sanger sequencing of DNA requires small amounts of dideoxvribonucleoside triphosphates (ddNTPs) to terminate the sequencing reaction at different positions in the growing DNA strands. ddNTPs differ from normal nucleoside triphosphates (dNTPs) because they  lack a hydroxyl (-OH) group at their 3' end. 15) Humans and chimpanzees are very different phenotypically, but very similar when compared genetically.  true 16) In E. coli, which of the following occur when glucose levels are low? Select all that apply.  cAMP levels increase  b-galactosidase levels increase  the lac operon is activated  permease levels increase 17) Which of the following is NOT part of normal eukaryotic RNA degradation pathways  lengthening of the poly(A) tail 18) Which mechanism(s) of gene regulation are specific to eukaryotic cells and NOT bacterial cells? Select all that apply  regulation by siNAs and miRNAs,  independent regulation of transcription and translation in different cellular compartments  chromatin remodeling 19) In a typical operon, RNA polymerase binds to which region?  promoter 20) Which mutation below is considered the most damaging or most likely to result in a nonfunctional protein product?  nonsense 21) The discovery of PC revolutionized molecular biology studies. Which of the following are limitations of PC? Select all that apply.  PCR can be extremely susceptible to contamination,  PC can only copy DNA fragments up to several thousand base pairs in length. 22) Which of the following are required for PCR amplification of a DNA fragment? Select all that apply.  Primers,  All four nucleotides (dNTPs),  DNA (Taq) polymerase  Template target DNA 23) There is a mutation in the CAP binding site upstream of lacO promoter  CAP-cAMP cannot properly bind DNA, reducing RNA polymerase's binding efficiency at the lacp promoter  glucose levels are very low 24) There is mutation in the LacO operator that prevents lac from binding  The Lac operon will be constitutively transcribed 25) Which of the following base substitution mutations is a transition?  adenine being replaced by guanine 26) Fluorescent in-situ hybridization (FISH) can be used to identify the chromosomal location of a gene and the expression pattern of target mRNA molecules.  True 27) Eukaryotic regulatory promoters often contain several different consensus sequences to bind various transcription factors that help to precisely regulate expression of a gene.  True 28) During mismatch repair in prokaryotes, the old DNA strand is distinguished from the newly synthesized DNA strand by acetylation on the newly synthesized DNA strand.  false 29) acetylate histone tails which reduces the positive charge, decondenses chromatin, and activates transcription  histone acetyltransferases 30) DNA rich in methvlated cytosines, often associated with the repression of transcription  methylated dna 31) found in newly synthesized DNA and often attracts chromatin modifying proteins or methyltransferases  hemi-methylated dnA 32) ATP-dependent protein complexes that reposition nucleosomes to either activate or repress transcription  chromatin remodeling complexes 33) Germ-line mutations often affect the entire organism, whereas somatic muttaions generally only affect a small region of tissue:  True 34) A structural gene encodes a product that interacts with other sequences and affects the transcription or translation of those sequences:  False 35) transcription of a negative inducible operon is normally activated by a repressor, but in the presence of an inducer is turned off.  False 36) Select the cis-acting factors from the yeast GAL4 galatcose metabolism system:  USASg enhancer  Regulatory promoter 37) Restriction enzyme A has the recognition sequence 5'-GGCC-3'. Restriction enzyme B has the recognition sequence 5'-GGATCC-3'. Based on this information, you can infer that  enzyme A will cut the genome into MORE pieces than will enzyme B. 38) Match  AP endonucleases: cleaves phosphodiester bonds between nucleotides  Base-excision repair: first removes a damage base, generating a AP site, then the sugar back bond is removed prior to replacement  CpG islands: regions of DNA with a high concentration of CG dinucleotides, often found in promoters 39) Because humans and chimpanzees are genetically very similar. The extensive phenotypic differences between them can largely be attributed to changes in gene regulation.  True 40) Which of the following is NOT part of normal eukaryotic RNA degradation pathways  Cleavage at the termination site 41) In a typical operon, a regulator protein binds to which region?  Operator 42) Which mutation below is considered the most damaging or most likely to result in a nonfunctional protein product?  Frameshift deletion 43) The LAC operon is a negatively inducible operon with core components…. Match:  Glucose levels are very high: little CAP-CAMP is available reducing RNA polymerase’s binding effeiciency  There is mutation in the lacO operator that prevents lacI from binfinding: The lac operator will be continuously transcribed  There is a mutation in the CAP binding site upstream of lacP promoter: CAP- CAMP can not properly bind DNA 44) Which of the following base substitution mutations is a transition?  Cytosine being replaced by thymine 45) Fluorescent in-situ hybridization (FISH) can be used to identify the chromosomal location of a gene and to sequence the bases of mRNA moelcules  False 46) Eukaryotic core promoters often contain a single consequence to help bind the basal transcription apparatus and set the basal expression level of a gene.  True 47) Third-generation DNA sequencing technologies can sequence single DNA molecules whereas other DNA sequencing technologies require prior amplification by PCR:  TRUE 48) NOT part of a typical operon?  Catalyst 49) Which of the following base substitution mutations is a transversion?  Thymine being replaced by guanine Extra: 1) Which of the following mechanism does not result in multiple types of mature RNA molecules?  Shuffling the order of the exons in the mRNA relative to their order in the DNA 2) DNA polymerase III: primary enzyme that adds new DNA nucleotides to the 3’ end of the growing daughter strand 3) Primase: forms RNA primase to initiate replication Which of the following factors did not contribute to Mendel’s success in his study of heredity?  a. his use of the pea plant  b. his study of plant chromosomes                    Autosomal recessive traits often appear in pedigrees in which there have been consanguine mating because these traits  a. appear only when both parents carry a copy of the gene for the trait, which is more likely when the parents are related.      When might you see an autosomal dominant trait skip generations?  It might skip generations when a new mutation arises or the trait has incomplete penetrance.      How could you distinguish between an autosomal recessive trait with higher penetrance in males and an X-linked recessive trait?  X-linked recessive traits are only passed to sons from mothers, not from fathers.      A male affected with an X-linked dominant trait will have what proportion of offspring affected with the trait?  a. all daughters and no sons      What features of a pedigree would distinguish between a Y-linked trait and a trait that is rare, autosomal dominant, and sex-limited to males?  If the trait were Y-linked, an affected male would pass it on to all his sons  If the trait were autosomal and sex-limited, affected heterozygous males would pass it on to only half of their sons on average.      For single crossovers, the frequency of recombinant gametes is half the frequency of crossing over because  a. each crossover takes place between only two of the four chromatids of a homologous pair.    A DNA molecule 300 bp long has 20 complete rotations. This DNA molecule is  a. negatively supercoiled.        Neutralizing their positive charges would have which effect on the histone proteins?  a. They would bind less tightly to the DNA.    How many bands of DNA would be expected in Meselson and Stahl’s experiment after two rounds of conservative replication?  Two bands    Discontinuous replication is a result of which property of DNA?  a. antiparallel nucleotide strands      Which of the following phrases does NOT describe a function of the promoter?  a. signals where transcription ends      Why is it that pre-mRNAs are capped, but tRNAs and rRNAs are not?  A protein that adds the 5' cap is associated with RNA polymerase II, which transcribes pre- mRNAs, but is absent from RNA polymerases I and III, which transcribe rRNAs and tRNAs, respectively.        Alternative 3′ cleavage sites result in  a. multiple mRNAs of different lengths.      Through wobble, a single _____ can pair with more than one _____.   a. anticodon; codon    Amino acids bind to which part of the tRNA?  a. 3′ end    In elongation, the creation of peptide bonds between amino acids is catalyzed by  a. rRNA.        How do amino acids in DNA-binding proteins interact with DNA?  a. by forming hydrogen bonds with DNA bases      What is the difference between a structural gene and a regulator gene?  a. Structural genes encode proteins; regulator genes control the transcription of structural genes.      In the presence of allolactose, the lac repressor  a. cannot bind to the operator.      In a negative repressible operon, the regulator protein is synthesized as an  a. inactive repressor.    In RNA silencing, siRNAs and miRNAs usually bind to which part of the mRNA molecules that they control?    a. 3′ UTR          If all possible base mutations are equally likely, what would be the ratio of Transitions to Transversions?                  Which of the following changes is a transition base substitution?  a. Guanine is replaced by adenine.     Base analogs are mutagenic because of which characteristic?  a. They are similar in structure to the normal bases.    Mismatch repair in bacteria distinguishes between old and new strands of DNA on the   basis of  a. methyl groups on the old strand.    How does direct repair differ from mismatch repair and base-excision repair?  Direct-repair mechanisms return an altered base to its correct structure without removing and replacing nucleotides. Mismatch repair and base-excision repair remove and replace nucleotides.    Why are defects in DNA repair often associated with increases in cancer?