分子复习题
Section A
Differentiation: P3.
Complex macromolecules: P9
判断题：
1. Polysaccharides are polymers of simple sugars covalently linked by glycosidic bonds. T
2. Differential centrifugation is according to the value of sedimentation coefficients. T
3. In mitochondria the light-dependent assimilation of CO2 and water to form carbohydrates and oxygen. F
4. Oxidation of nutrients to generate energy in the form of adenosine 5’-triphosphate (ATP) occurs in mitochondria. T
5. Differential centrifugation is used to separate organelles of similar densities. F
6. In equilibrium centrifugation, the density gradient extends to a density higher than that of one or more components of the mixture so that these components come to equilibrium at a point equal to their own density and stop moving. T
选择题：
1. Which of the following is an example of a nuleoprotein?
A．keratin B．chromatin C．histone D．proteoglycan
填空题：
1. Like all other cellular processes, differentiation if controlled by genes .
2. The rough endoplasmic reticulum has attached ribosomes engaged in the synthesis of membrane-targeted and secreted proteins .
3. Proteins are polymers of amino acids , and the nucleic acids DNA and RNA are polymers of nucleotides .
4. Associations of nucleic acid and protein are known as nucleoproteins .
Section C
Hybridization: The renaturation of complementary sequences between different nucleic acid molecules. Nucleosides: P33
Hypochromicity：P44
判断题：
1. Denaturation of double stranded DNA involves hydrolysis of the DNA backbone. F
2. The double helices of DNA and RNA secondary structure are stabilized by the hydrogen bonding between base pairs. F
3. In strong acid and at elevated temperatures, nucleic acids are hydrolyzed completely to their constituents. T
4. Increased temperature can bring about the denaturation of DNA and RNA. T
选择题：
1. Which of the following correctly describes B-DNA? ( )
A. a right-handed antiparallel double helix with 10 bp/turn
B. a right-handed antiparallel double helix with 12 bp/turn
C. a left-handed antiparallel double helix with 10 bp/turn
D. a left-handed antiparallel double helix with 12 bp/turn
2. Denaturation of double stranded DNA involves ( )
A. breakage into short double-stranded fragment
B. separation into single strands
C. hydrolysis of the DNA backbone
D. cleavage of the bases from the sugar-phosphate backbone
3. The sequence 5’-AGTCTGACT-3’ in DNA is equivalent to which sequence in RNA?
A. 5’-AGUCUGACU-3’
B. 5’-UGTCTGUTC-3’
4. Which has the highest absorption per unit mass at a wavelength of 260 nm?
A. double-stranded DNA
B. mononucleotides
C. RNA
D. protein
填空题：
1. The A260/A280 ratio of a double-stranded DNA sample can be used to assess its purity. For pure DNA, the value is 1.8. Above this value suggest RNA contamination and below this value suggest protein contamination.
2. Base+sugar+phosphate= nucleotide .
3. Base+sugar = nucleoside .
4. In DNA, there are four heterocyclic bases: A and G are purines; C and T are pyrimidines.
5. The absorbance of isolated nucleotides is greater than that of RNA and single stranded DNA.
6. In nucleosides, the bond between the bases and the sugars is the glycosylic bond.
Section D
DNase I hypersensitivity: Active regions of chromatin or regions where the 30 nm fiber is interrupted by the binding of a specific protein to the DNA or by ongoing transcription are characterized by hypersensitivity to deoxyribonuclease Ⅰ.
判断题：
1. All histone proteins have a large positive charge. T
2. A large proportion of the DNA in eukaryotic cells does not code for protein. T
选择题：
1. Which of the following is common to li and eukaryotic chromosomes?
A. the DNA is circular
B. the DNA is packaged into nucleosomes
C. the DNA is contained in the nucleus
D. the DNA is negatively supercoiled
2. In what region of the interphase chromosome does transcription take place?
A. the telomere
B. the centromere
C. euchromatin
D. heterochromatin
3. A complex of 166 bp of DNA with the histone octamer plus histone H1 is known as a ( )
A. nucleosome core
B. solenoid
C. 30 nm fiber
D. chromatosome
4. Which statement about CpG islands and methylation is not true?
A. CpG islands are particularly resistant to DNase I
B. CpG methylation is responsible for the mutation of CpG to TpG in eukaryotesbacterium

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