BIO 105 Chapter Unit 2: Unit 2 Reading Notes

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10 Mar 2017

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7. 2 dna is a double helix of nucleotides. 1929, biochemists discovered the difference between rna and dna. Rna and dna are two types of nucleic acid. Nucleotides are the building blocks of nucleic acid. Erwin chargaff: discovered that the amount of base guanine=the amount of base cytosine and the amount of adenine=the amount of thymine. Maurice wilkins and rosalind franklin used x-ray diffraction to help reveal the geometric structure of dna. James watson and francis crick: built a ball-and-stick model of the dna double helix. Twin rails - units of deoxyribose and phosphate joined with covalent bonds. Rungs - a-t and g-c base pairs joined by hydrogen bonds. 7. 3 dna contains the recipes for a cell"s proteins. Genome: all the genetic material in an organism"s cells. Chromosome: package of dna and associated proteins. Gene: a sequence of dna nucleotides that codes for a specific protein or rna molecule. Human genome: 20,000-25,000 on 23 pairs of chromosomes.

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1. Characters that show a continuous range of variation, such as height and eye color, usually are controlled:

a.	by a single gene with two alleles that are codominant.

b.	by many genes with an additive effect.

c.	by epistatic interactions between two genes.

d.	mainly by the environment, with only a small genetic component.

2. In humans, red-green colorblindness is inherited as a sex-linked recessive trait. In order for a woman to be red-green colorblind, which of the following statements must be true.

a.	Her mother must be red-green colorblind.

b.	All of her brothers must be red-green colorblind.

c.	Her father must be red-green colorblind.

d.	All of the above statements must be true if a woman is red-green colorblind.

3. The x-ray crystallography data collected by Rosalind Franklin suggested to Watson and Crick that the:

a.	structure of DNA is a double helix.

b.	two strands of the DNA molecule are joined by hydrogen bonds between the bases.

c.	four bases within DNA pair in a specific way.

d.	two strands of the DNA molecule are joined by covalent bonds between the bases.

4. In the genetic code, _________ one amino acid.

a.	one nucleotide specifies

b.	two nucleotides specify

c.	three nucleotides specify

d.	four nucleotides specify

5. During Meiosis I, a homologous pair of chromosomes may not separate, resulting in daughter cells that have extra chromosomes or are missing chromosomes. This can lead to genetic disorders, including Down Syndrome. This phenomenon is called:

a.	independent assortment.

b.	nondisjunction.

c.	segregation.

d.	crossing over.

6. You are a human geneticist studying the incidence of retinitis pigmentosa in the residents of Tristan de Cunha, a group of small islands in the middle of the southern Atlantic Ocean. The allele for retinitis pigmentosa, which causes a form of blindness, is inherited as an autosomal recessive. You have determined that the frequency of this allele (r) in the population is 0.4 (40%). Using the principles of the Hardy-Weinberg rule, you would estimate the frequency of individuals who are heterozygous for this allele (Rr) in the population to be:

a.	0.16 (16%)

b.	0.24 (24%)

c.	0.36 (36%)

d.	0.48 (48%)

7. Natural selection acts at the level of the:

a.	phenotype.

gene.

c.	population.

d.	nucleotide.

8. You are working with pea plants, trying to recreate the experiments that Mendel performed. You are doing a dihybrid cross with a plant that is heterozygous for both seed shape and seed color, with the genotype RrYy. Which allelic combinations would you expect to find in the gametes produced by this plant?

a.	This plant would produce only RY and ry gametes.

b.	This plant would produce only RrYy gametes.

c.	This plant would produce RY, Ry, rY, and ry gametes.

d.	You cannot determine which gametes this plant can produce without knowing the genotypes of its parents.

9. Biochemist Erwin Chargaff found that in DNA there is a special relationship between the four bases that we now call Chargaff's rule. His observation was that, in an organism's genome the:

a.	percentage of A nucleotides = the percentage of T nucleotides, and the percentage of C nucleotides = the percentage of G nucleotides.

b.	four bases all occur in an equal frequency (25%) within each organism.

c.	percentage of A nucleotides = the percentage of G nucleotides, and the percentage of C nucleotides = the percentage of T nucleotides.

d.	genetic material is composed of proteins, not DNA.

10. During DNA replication:

a.	each strand of the double helix acts as a template for the synthesis of a new strand.

b.	the enzyme DNA polymerase adds nucleotides to the strand being synthesized.

c.	the bases A,C,G and T are required.

d.	All of the above are true of DNA replication.

11. During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:

12. If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

a.	RR and rr.

RR and Rr

Rr and rr

d.	Each of the three possible genotypes will have a different phenotype.

mauvefox570

Which of the following did Erwin Chargaff observe?

A)	Base composition changes as the organism ages.

B)	Base composition of DNA does not vary from one species toanother.

C)	In all species the number of adenines equals the number ofguanines.

D)	In all species A + T = G + C.

E)	DNAs isolated from different tissues of the same species havethe same base composition.

The melting temperature (Tm) of a DNA duplex is:

A)	the temperature at which double-stranded nucleic acids degradeinto free nucleotides.

B)	the temperature at which double-stranded DNA is toosingle-stranded to ever renature back to double strands.

C)	the temperature at which double-stranded DNA is completelymelted.

D)	the temperature at which double-stranded DNA has become 50%single-stranded.

E)	the temperature at which double-stranded DNA begins to melt.

Given your knowledge and the descriptions of each of thesemethods, which of the following does NOT rely on the ability ofnucleic acids to hybridize with each other?

A)	Southern blotting for the detection of specific DNA fragmentsthat have been separated by gel electrophoresis.

B)	Colony blot hybridization to identify a specific sequence from acollection of sequences that have been inserted into bacteria.

C)	Northern blotting for the detection of specific RNA fragmentsthat have been separated by gel electrophoresis.

D)	A DNA oligonucleotide microarray incubated with probes made fromcDNA.

E)	Western blotting for the detection of specific proteins thathave been separated by gel electrophoresis.

Which of the following is a possible reason why DNA uses thymineinstead of uracil?

A)	Cytidine is deaminated to uracil so it would be difficult forany repair mechanism to differentiate between uracil that belongsin the sequence and uracil that resulted from deamination.

B)	Adenine is deaminated to uracil so it would be difficult for anyrepair mechanism to differentiate between uracil that belongs inthe sequence and uracil that resulted from deamination.

C)	When uracil is bound to a deoxyribose it will become morereactive, forming covalent bonds with other bases.

D)	None of the above.

Which of the following is an enzyme used in cloning to breakcovalent bonds?

A)	DNA ligase

B)	Restriction endonuclease

C)	Reverse transcriptase

D)	DNA polymerase I

E)	Alkaline phosphatase

Which of the following could you use to remove the 5' phosphatesafter cleavage of a plasmid with a single type of restrictionenzyme to ensure that the plasmid would not simply fuse backtogether upon addition of ligase?

A)	Reverse transcriptase

B)	Alkaline phosphatase

C)	DNA ligase

D)	DNA polymerase I

E)	Restriction endonuclease

Which of the following would you use to create a cDNA librarythat you would not use for a genomic library?

A)	Alkaline phosphatase

B)	Reverse transcriptase

C)	Restriction endonuclease

D)	DNA ligase

E)	DNA polymerase I

A plasmid vector typically has which of the followingfeatures?

A)	An origin of replication

B)	A selectable marker to ensure that the only bacteria growingcontain the intact or recombinant vector.

C)	Unique restriction sites for insertion of DNA.

D)	Small size to facilitate entry into the cell and biochemicalmanipulation of the DNA.

E)	All of the above are features of plasmid vectors.

Which of the following is FALSE of genomic or cDNAlibraries?

A)	Genes represented in cDNA libraries include control sequencesthat direct transcription.

B)	cDNA libraries contain cDNAs made from mRNA.

C)	Genomic libraries contain fragments of genomic DNA that aregenerated by partial digests with restriction enzymes.

D)	Genomic libraries usually contain large fragments and are likelyto be constructed in YAC or BAC vectors.

E)	cDNA libraries contain sequences from expressed genes only.

Which of the following is NOT a typical component of apolymerase chain reaction (PCR)?

dNTPs

B)	DNA containing the sequences to be amplified

C)	DNA ligase to connect the fragments together

D)	Primers complementary to each end of the sequence to beamplified

E)	Heat stable Taq polymerase

How can a fusion protein be formed?

A)	Site-directed mutagenesis where a fragment is replaced with asynthetic sequence containing the altered DNA sequence.

B)	Two proteins can recombine in the bacterial cell to form a newhybrid protein.

C)	Portions of two different genes are ligated together to create anew hybrid gene. When expressed the gene product is a fusion of thetwo gene products.

D)	Using oligonucleotide-directed mutagenesis to introduce specificmutations that cause the expressed protein to fuse to otherproteins.

E)	A portion of the gene can be removed to form a shorter gene andtherefore a shorter protein.

Why is green fluorescent protein (GFP) so useful in visualizingfusion proteins in eukaryotes?

A)	The GFP protein recognizes and binds to fusion proteins allowingthe location of the fusion protein to be determined.

B)	The reaction is only dependent on the presence of GFP and oneother cofactor.

C)	It is easily cloned and expressed in bacterial cells.

D)	The presence of just a few molecules of GFP fusion proteins canbe sufficient for observing the proteins microscopically allowingthe study of its location and movements in the cell.

E)	It is derived from fire flies, which are easy to cultivate inthe lab.

You wish to determine the cellular location of a protein butunfortunately it is not particularly antigenic (can t develop astrong antibody response). How could you solve this problem?

A)	Create a fusion protein with an epitope tag that can bevisualized by incubation with fluorescently tagged antibody to theepitope.

B)	Create a fusion with green fluorescent protein (GFP).

C)	Express the protein as a fusion with biotin. The addition of GFPwill cause fluorescence.

D)	A and B might work.

E)	A, B, and C might work.

F)	None of the above will work.

A positive result for the yeast two-hybrid analysis means thefollowing:

A)	The proteins that you are studying can be made into fusionproteins, but do NOT interact with each other within the nucleus ofyeast.

B)	A fusion protein containing the Gal4p activation domain, hasbound to RNA polymerase resulting increase transcription ofnumerous genes, including the reporter gene, and formation ofcolonies.

C)	Two fusion proteins, one containing the Gal4p binding sitedomain and one containing the Gal4p activation domain, haveinteracted through their Gal4p domains resulting in transcriptionof the reporter gene.

D)	Two fusion proteins interact with each other and because of theGal4p binding site domain and the Gal4p activation domain containedin each fusion protein, the reporter genes are activated and thecells die resulting in no colonies.

E)	The colonies growing are expressing the two fusion proteins, butthe two proteins have not interacted with each other.

Which of the following is the approximate size of the humangenome?

3 Gm

300 Kb

3 Mb

3 Gb

3 Mm

Which of the following is correct about the structure orlocation of genes?

Question 22 options:

A)	Prokaryotic genes typically possess their own regulatorysequences that only control expression of a single gene.

B)	Eukaryotic genes often encode introns that are spliced outbefore translation.

C)	Eukaryotic genes are mostly located at the telomeres and thecentromeres of chromosomes.

D)	Eukaryotic genes are typically arranged in operons.

E)	Prokaryotic genes often encode exons that are spliced out beforetranslation

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Match each term with its definition. Each term or definition is used only once

- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	right-spiraling common DNA form
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	referencing the opposite orientation of hydrogen-bonded DNA strands
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	viral particle whose natural host is a prokaryote
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	universal holding that the number of purines always equals the number of pyrimidines
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	nucleic acid base sequences able to form a double-stranded structure by virtue of matching base pairs
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	5ââ 3â or 3ââ 5â
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	nuclease able to cleave phosphodiester linkages in the DNA backbone
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	the structure formed by two DNA strands twisted around a common axis in a spiral
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	bacterial cycle of phage- infected cells resulting in cell destruction and viral release
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	main access site for proteins that recognize specific DNA sequences
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	a cytosine modification favoring Z DNA formation
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	nucleic acid monomer consisting of a sugar, a phosphate group, and a nitrogenous base
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	connects two nucleic acid sugar molecules via an ester bond
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	hydrolyzes peptide bonds linking amino acids
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	U or C in RNA
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	a pentose sugar
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	an enzyme that breaks down RNA
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	either of the two nucleotide chains of a double helix
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	a pyrimidine able to hydrogen bond with adenine
- A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T.	a DNA configuration favored by high ionic strength and GC repeats

A.	protease
B.	lysis
C.	double helix
D.	bacteriophage
E.	complementary
F.	Chargaffâs rule
G.	B DNA
H.	major groove
I.	nucelotide
J.	antiparallel
K.	RNAse
L.	directionality
M.	phosphodiester linkage
N.	ribose
O.	Z DNA
P.	pyrimidine
Q.	methylation
R.	DNAse
S.	uracil
T.	strand

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BIO 105 Chapter Unit 2: Unit 2 Reading Notes

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