Concepts of Biology chapter 9 Answers

2. which of the following does cytosine pair with? A. guanine B. thymine C. adenine D. a pyrimidine

A

6. A promoter is ___ A. a specific sequence of DNA nucleotides B. a specific sequence of RNA nucleotides C. a protein that binds to DNA D. an enzyme that synthesizes RNA

A

9. how long would the peptide be that is translated from this MRNA sequence: 5'-AUGGGGCUACCGA-3" A. 0 B. 2 C. 3 D. 4

A

13. describe the structure and complementary base paring of DNA

A single strand of DNA is a polymer of nucleic acids joined covalently between the phosphate group of one and the deoxyribose sugar of the next to for a "backbone" from which the nitrogenous bases stick out. In its natural state, DNA has two strands wound around each other in a double helix. The bases on each strand are bonded to each other with hydrogen bonds. Only specific bases bond with each other; adenine bonds with thymine, and cytosine bonds with guanine.

11. post-translational control refers to: A. regulation of gene expression after transcription B. regulation of gene expression after translation C. control of epigenetic activation D. period between transcription an translation

B

4. DNA replicates by which of the following models? A. conservative B. semiconservative C. dispersive D. none of the above

B

3. prokaryotes contain a ___ chromosome, and eukaryotes contain ___ chromosomes. A. single-stranded circular; a single-stranded linear B. single-stranded linear; a single-stranded circular C. double-stranded circular; double-stranded linear D. double-stranded linear; double-stranded circular

C

7. portions of eukaryotic mRNA sequence that are removed during RNA processing are ___ A. exons B. caps C. poly-A tails D. introns

C

8. The RNA components of ribosomes are synthesized in the ___ A. a cytoplasm B. nucleus C. nucleolus D. endoplasmic reticulum

C

10. Control of gene expression in eukaryotic cells occurs at which level(s)? A. only the transcriptional level B. epigenetic and transcriptional levels C. epigenetic, transcriptional, translational levels D. epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels

D

5. the initial mechanism for repairing nucleotide errors in DNA is ___ A. mismatch repair B. DNA polymerase proofreading C. nucleotide excision repair D. thymine dimers

D

12. Describe the organization of the eukaryotic chromosome

The DNA is wound around proteins called histones. The histones then stack together in a compact form that creates a fiber that is 30-nm thick. The fiber is further coiled for greater compactness. During metaphase of mitosis, the chromosome is at its most compact to facilitate chromosome movement. During interphase, there are denser areas of chromatin, called heterochromatin, that contain DNA that is not expressed, and less dense euchromatin that contains DNA that is expressed.