Indietro
Problema 1
Name the nucleoside shown here. Copy the structure, and number the C and N atoms (refer to Table 26.1).
Problema 5a
Write the full name of:
a. dUMP
Problema 6
Name the bases in the pentanucleotide with the sequence G-A-U-C-A. Does this come from RNA or DNA? Explain.
Problema 8a
Write the complementary sequence of bases for each DNA strand shown next.
a. 5′T-A-T-A-C-T-G 3′
Problema 9
Draw the structures of adenine and uracil (which replaces thymine in RNA), and show the hydrogen bonding that occurs between them.
Problema 10
Is a DNA molecule neutral, negatively charged, or positively charged? Explain.
Problema 11a
DNA and RNA, like proteins, can be denatured to produce unfolded or uncoiled strands. Heating DNA to what is referred to as its “melting temperature” denatures it (the two strands of the double helix become separated). Why does a longer strand of DNA have a higher melting temperature than a shorter one?
Problema 12
What are Okazaki fragments? What role do they serve in DNA metabolism?
Problema 13
What is the difference between DNA polymerase and DNA ligase?
Problema 14
What is the function of the spliceosome in hnRNA?
Problema 15a
What mRNA base sequences are complementary to the following DNA template sequences? Be sure to label the 5′ and 3′ ends of the complementary sequences.
a. 5′ CAT GCT CTA CAG 3′
Problema 16a
List possible codon sequences for the following amino acids.
a. Val
Problema 17
Identify the amino acid for which the codon GAG codes, and what other codon could encode for this same amino acid?
Problema 18a
What amino acids do the following sequences code for?
a. AUC
Problema 20
What amino acid sequence is coded for by the mRNA base sequence CUC-AUU-CCA-UGC-GAC-GUA?
Problema 23
Copy the diagram and use dotted lines to indicate where hydrogen bonding occurs between the complementary strands of DNA. What is the sequence of each strand of DNA drawn (remember that the sequence is written from the 5′ to 3′ end)?
Problema 24a
Copy the following simplified drawing of a DNA replication fork:
a. On the drawing, indicate the direction of synthesis of the new strand labeled A and the location of DNA polymerase on the strand.
Problema 27a
Gln-His-Pro-Gly is the sequence of a molecule known as progenitor thyrotropin-releasing hormone (pro-TRH). If we were searching for pro-TRH genes, we would need to know what sequence of bases in DNA we should be looking for. Use the following boxes to indicate answers to parts (a)–(d).
a. What RNA sequence could code for these four amino acids?
Problema 28
What is the difference between a gene and a chromosome?
Problema 29
What are the two major components of chromatin?
Problema 30
What genetic information does a single gene contain?
Problema 31
How many chromosomes are present in a human cell?
Problema 32a
For the following molecule:
a. Label the three nucleic acid building blocks it contains.
Problema 33
What are the sugars in DNA and RNA, and how do they differ?
Problema 34a
What are the four major heterocyclic bases in DNA?
Problema 35
What are the two structural types of bases in DNA and RNA? Which bases correspond to each type?
Problema 38
What is the difference between the 3′ end and the 5′ end of a polynucleotide?
Problema 39
Are polynucleotides synthesized 3′ to 5′ or 5′ to 3′?
Problema 40
Draw the complete structure of uridine 5′- phosphate, one of the four major ribonucleotides.
Problema 41
Draw the complete structure of the RNA dinucleotide U-C. Identify the 5′ and 3′ ends of the dinucleotide.
