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Last Updated 8/29/05

Genetics Problem Set 1

General Essay Type Questions
1) Describe the structure of a dsDNA molecule. Include its parts, the forces that hold it together, and its shape.
2) Describe the events which occur at one replication fork of an E. coli chromosome.
3) Describe the basic events which occur during transcription in eukaryotes.
4) Describe the basic events which occur during translation in eukaryotes.

Multiple Choice Questions (Pick the best answer.)
1) Watson and Crick described... A) the trp operon. B) the structure of DNA. C) catabolite repression. D) the lac operon. E) the structure of tRNA. F) supercoiling.

2) A nucleic acid with the base composition 35% adenine, 35% cytosine, 15% thymine and 15% guanine is... A) ssDNA. B) ssRNA. C) a DNA-RNA hybrid. D) dsDNA. E) dsRNA. F) tRNA

3) Wobble is... A) eukaryotic. B) neither prokaryotic nor eukaryotic. C) prokaryotic. D) both prokaryotic and eukaryotic.

4) Lambda genes ... A) are eukaryotic. B) can be either prokaryotic or eukaryotic. C) are prokaryotic. D) are neither prokaryotic nor eukaryotic.

5) The most common form of DNA in living things is... A) A-DNA. B) C-DNA. C) CACA box. D) B-DNA. E) X-DNA. F) Z-DNA.

6) Denaturing a section of DNA... A) breaks ionic bonds between purines and pyrimidines. B) causes point mutations. C) causes nondisjunction. D) introduces negative supercoiling in the double stranded section.

7) Virus genes... A) are prokaryotic. B) can be either prokaryotic or eukaryotic. C) are eukaryotic. D) are neither prokaryotic nor eukaryotic.

8) Cotranslational transcription... A) is nuclear. B) is neither prokaryotic nor nuclear. C) is prokaryotic. D) can be either prokaryotic or nuclear.

9) Polycistronic messenger RNAs... A) can be either prokaryotic or eukaryotic. B) are prokaryotic. C) are neither prokaryotic nor eukaryotic. D) are eukaryotic.

10) 80s ribosomes are... A) both prokaryotic and eukaryotic. B) prokaryotic. C) neither prokaryotic nor eukaryotic. D) eukaryotic.

11) Bidirectional DNA replication can occur in... A) only eukaryotes. B) both prokaryotes and eukaryotes. C) only prokaryotes. D) neither prokaryotes nor eukaryotes.

12) Which of the following statements is NOT true about DNA? A) Adenine and guanine are purines. B) There are 2 hydrogen bonds between guanine and cytosine. C) "Melted" DNA is single stranded. D) DNA is composed of two antiparallel strands. E) B-DNA is the most abundant form of DNA in living things.

True/False Questions
A) Transcription of RNA occurs in the 3' to 5' direction. B) Denaturing a section of DNA breaks ionic bonds between purines and pyrimidines. C) The energy for transcription comes from the rNTPs. D) The 3'->5' exonuclease activity of DNA pol I is the proof reading activity. E) The 5'-> 3' exonuclease activity of DNA pol I removes bases from one strand of a dsDNA molecule. F) Generalized transduction packages random chromosomal DNA from bacteria into phage particles. G) Hfr E. coli cells conjugate with F+ E. coli cells. H) DNA is usually a double helix. I) A nucleotide in a DNA molecule has one nitrogenous base, one sugar molecule, and three phosphates. J) Linear dsDNA is found in the nucleus. K) A pairs with U and G pairs with C in DNA molecules. L) The sugar in DNA is deoxyribose. M) The arrangement of bases in a DNA molecule is its sequence. N) tRNA's are part of ribosomes. O) rRNA's are needed for translation to occur. P) Three base sequences on mRNA's which specify an amino acid are called anticodons. Q) RNA polymerase makes DNA. R) When a ribosome reaches a stop codon translation stops. S) DNA pol I has a 5'-> 3' polymerase activity. T) DNA pol II is the major enzyme for filling in gaps in the lagging strand. U) Polypeptides are synthesized from their amino to their carboxyl ends. V) The growing polypeptide chain is attached to the tRNA in the P site of the ribosome. W) Translation requires more ATP than GTP. X) Charged tRNAs have amino acids attached to their 3' ends. Y) DNA pol III has a 5'-> 3' polymerase activity. Z) Phosphodiester bonds link ribose to phosphate in DNA strands. a') The template strand of DNA is the transcribed strand. b') A-DNA has one major and one minor groove. c') T pairs with A through 2 hydrogen bonds. d') Cotranslational transcription occurs for eukaryotic nuclear genes. e') Pyrimidines are one ring molecules. f') Uracil is a purine. g') Transcription of RNA occurs in the 3' to 5' direction. h') 80s ribosomes are prokaryotic. i') Z-DNA has a zigzag sugar-phosphate backbone. j') Most DNA has 3' phosphates and 5' hydroxyl groups. k') Z-DNA is a right handed dsDNA. l') It is easier to melt a dsDNA sequence rich in AT than one rich in GC. m') tRNA forms from 3 to four hairpin loops. n') Ribosomes move down mRNA three bases at a time by hydrolyzing ATP. o') In B-DNA the base pairs stack one on top of another like coins. p') Phosphodiester bonds form between amino acids in the A and P sites of a ribosome. q') Eukaryotic ribosomes have a 40s subunit.

Matching
I) Match the term on the left with the BEST term on the right (You may use each answer more than once).

___1) Denatures DNA sequences ................................ A) DNA pol I
___2) Can remove supercoiling .................................... B) DNA pol II
___3) Makes SHORT RNA sequences ........................ C) Helicase
___4) Makes leading strand DNA in prokaryotes ........ D) Primase
___5) Keeps ssDNA strands apart ............................... E) Polysome
___6) Made on the lagging strand ................................ F) mRNA
___7) Start codon ......................................................... G) rRNA
___8) Initiation sequence for translation ....................... H) tRNA
___9) This RNA has a cloverleaf structure .................... I) Okazaki fragments
___10) Shows active translation..................................... J) UGA
___11) RNA polymerase lacking its s factor................. K) AUG
___12) Origin of replication ......................................... L) Topoisomerase
....................................................................................... M) SSBP
....................................................................................... N) Ori
....................................................................................... O) DNA pol III
....................................................................................... P) Holoenzyme
....................................................................................... Q) Core enzyme

II) Match the term on the left with the BEST description on the right.

___1) Generalized transduction ........................ A) Tube to transport DNA
___2) Specialized transduction ......................... B) Bacterial DNA randomly packaged into phage heads.
___3) Transformation ....................................... C) Genes next to the prophage are given to another bacterium.
___4) Conjugation ............................................ D) Plasmid which can integrate into a chromosome
___5) Episome .................................................. E) Protein covering of a virus
___6) Pillus ....................................................... F) Makes RNA from RNA template
___7) Bionary fission ....................................... G) DNA is given to one bacterium directly from another bacterium
___8) Capsid ..................................................... H) Cell division in bacteria
___9) Code for more than one polypeptide ......I) DNA is taken up by a cell from the environment.
........................................................................... J) Polycistronic
........................................................................... K) Monocistronic

Other Questions
1) Use a genetic code table to determine the polypeptide sequence synthesized from the mRNA below. Assume that translation begins at the first nucleotide at the 5' end.
5' AUGAAGUGUUAACCC 3'

2) What RNA sequence is transcribed by the gene with the template strand below? Answer in the space below with the 5' end of the RNA sequence on the left.
template strand of dsDNA 5' TTGAGCGCGTA 3'

3) Use a genetic code table to write one possible mRNA sequence for the amino acid sequence below? Answer in the space below with the 5' end of the RNA sequence on the left.
amino acid sequence Amino End Leu Pro Met His

4) What RNA sequence is transcribed by the gene with the non template strand below? Answer with the 5' end of the RNA sequence on the left.
non template strand of dsDNA 5' GCTATTCCGAC 3'

5) What sugar is found in DNA? ______________________________________.

6) RNA attached to Protein is called a ______________________________________.

7) Use a genetic code table to write one possible mRNA sequence for the amino acid sequence below? Answer with the 5' end of the RNA sequence on the left.
amino acid sequence Amino End ...Ser Val Asp Lys...

8) mRNA attached to ribosomes is called a ______________________________________.

9) An Hfr strain of E. coli is mixed with an F- strain of E. coli and "mating" is interrupted every two minutes. The F- bacteria are A- B- C- D- E- and the Hfr bacteria are A+ B+ C+ D+ E+. After "mating", the bacteria are plated on media Hfr bacteria can not grow on. The phenotypes are named for the genotypes and the following table was produced.

Phenotype Time of first appearance of the phenotype (min.)
 A+ ............................................ 82
B+ ............................................ 32
C+ ............................................ 54
D+ ............................................ 62
E+ ............................................ 48

Draw a genetic map of the chromosome showing the distance between adjacent genes.

10) An Hfr strain of E. coli is mixed with an F- strain of E. coli and "mating" is interrupted every two minutes. The F- bacteria are a- Adh- Sod- D- Q- and the Hfr bacteria are a+ Adh+ Sod+ D+ Q+. After "mating", the bacteria are plated on media Hfr bacteria can not grow on. The phenotypes are named for the genotypes and the following table was produced.

Phenotype ............. Time of first appearance of the phenotype (min.)
 a+ .......................................................... 21
Adh+ ...................................................... 93
Sod+ ...................................................... 48
D+ ......................................................... 56
Q+ ......................................................... 70

Draw a genetic map of the chromosomeshowing the distance between adjacent genes.
=========================================================

ANSWERS for Genetics Problem Set 1

General Essay Type ANSWERS
1 through 4) There are many different ways these could be answered. The answers should be accurate, and show that you understand the concept.

Multiple Choice ANSWERS
1) Watson and Crick described... B) the structure of DNA.
2) A nucleic acid with the base composition 35% adenine, 35% cytosine, 15% thymine and 15% guanine is... A) ssDNA.
3) Wobble is... D) both prokaryotic and eukaryotic.
4) Lambda genes... C) are prokaryotic.
5) The most common form of DNA in living things is... D) B-DNA.
6) Denaturing a section of DNA... D) introduces negative supercoiling in the double stranded section.
7) Virus genes... B) can be either prokaryotic or eukaryotic.
8) Cotranslational transcription... C) is prokaryotic.
9) Polycistronic messages... B) are prokaryotic.
10) 80s ribosomes are... D) eukaryotic.
11) Bidirectional DNA replication is found in... B) both prokaryotes and eukaryotes.
12) The ONE False statement is... B) There are 2 hydrogen bonds between guanine and cytosine.

True/False ANSWERS [Only the true statements are written below]
C) The energy for transcription comes from the rNTPs. D) The 3'->5' exonuclease activity of DNA pol I is the proof reading activity. E) The 5'-> 3' exonuclease activity of DNA pol I removes bases from one strand of a dsDNA molecule. F) Generalized transduction packages random chromosomal DNA from bacteria into phage particles. H) DNA is usually a double helix. J) Linear dsDNA is found in the nucleus. L) The sugar in DNA is deoxyribose. M) The arrangement of bases in a DNA molecule is its sequence. O) rRNA's are needed for translation to occur. R) When a ribosome reaches a stop codon translation stops. S) DNA pol I has a 5'-> 3' polymerase activity. U) Polypeptides are synthesized from their amino to their carboxyl ends. V) The growing polypeptide chain is attached to the tRNA in the P site. X) Charged tRNAs have amino acids attached to their 3' ends. Y) DNA pol III has a 5'-> 3' polymerase activity. a') The template strand of DNA is the transcribed strand. b') A-DNA has one major and one minor groove. c') T pairs with A through 2 hydrogen bonds. e') Pyrimidines are one ring molecules. i') Z-DNA has a zigzag sugar-phosphate backbone. l') It is easier to melt a dsDNA sequence rich in AT than one rich in GC. m') tRNA forms from 3 to four hairpin loops. o') In B-DNA the base pairs stack one on top of another like coins. q') Eukaryotic ribosomes have a 40s subunit.

Matching ANSWERS
I -- 1) C) Helicase 2) L) Topoisomerase 3) D) Primase 4) O) DNA pol III 5) M) SSBP 6) I) Okazaki fragments 7) K) AUG 8) K) AUG 9) H) tRNA 10) E) Polysome 11) Q) Core enzyme 12) N) Ori

II -- 1) B) Bacterial DNA randomly packaged into phage heads 2) C) Genes next to the prophage are given to another bacterium 3) I) DNA is taken up by a cell from the environment 4) G) DNA is given to one bacterium directly from another bacterium 5) D) Plasmid which can integrate into a chromosome 6) A) Tube to transport DNA 7) H) Cell division in bacteria 8) E) Protein covering of a virus 9) J) Polycistronic

Other Questions ANSWERS
1) Use the genetic code table in your book to determine the polypeptide sequence synthesized from the mRNA below. Assume that translation begins at the first nucleotide at the 5' end. 5' AUGAAGUGUUAACCC 3' Answer: Met - Lys - Cys

2) What RNA sequence is transcribed by the gene with the template strand below? Answer in the space below with the 5' end of the RNA sequence on the left. Template strand of dsDNA 5' TTGAGCGCGTA 3' Answer: UACGCGCUCAA

3) MULTIPLE CORRECT Answers including: UUACCAAUGCAC & CUUCCUAUGCAU

4) non template strand of dsDNA 5' GCTATTCCGAC 3' Answer: GCUAUUCCGAC

5) What sugar is found in DNA? Deoxyribose.

6) RNA attached to Protein is called a Ribonucleoprotein.

7) amino acid sequence Amino End ...Ser Val Asp Lys... MULTIPLE CORRECT Answers including: AGCGUAGACAAA & UCUGUUGAUAAG

8) mRNA attached to ribosomes is called a Polysome (or Polyribosome, or Polysomal RNA).

9) A genetic map of the chromosome showing the distance between adjacent genes.

10) A genetic map of the chromosome showing the distance between adjacent genes.