Campbell Biology in Focus
3rd Edition
ISBN: 9780134710679
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Rebecca Orr
Publisher: PEARSON
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Textbook Question
Chapter 18.3, Problem 1CC
The best estimate is that the human genome contains fewer than 21,000 genes. However, there is evidence that human cells produce many more than 21,000 different polypeptides. What processes might account for this discrepancy?
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You are studying a large eukaryotic gene that is 439,515 base pairs long. You find the polypeptide that this gene produces in liver cells is 46,771 amino acids long. Your colleague studies the function of this gene in brain cells, and finds the polypeptide produced in the brain is much larger – 61,438 amino acids long. How do you explain this difference?
Possible Answers:
A. The cell cycle of liver cells is much longer than that of brain cells.
B. This is due to alternative splicing. in the brain
C. There was a different complement of sequence-specific transcription factor binding sites in the CRM of the brain cells.
D. There is no 5' cap added to the gene product from the liver cells.
When the human genome sequence was finally completed, scientists were surprised to discover that the genome contains far fewer genes than expected. How many genes are present in the human genome? Scientists have also found that there are many more different kinds of proteins in the human cells that there are different genes in the genome. How can this be explained?
A 2500 bp region of the human genome encodes two genes. One of the genes encodes a protein of 600 amino acids and the other gene encodes a protein of 280 amino acids. The mRNA sequences of the two genes do not contain any of the same nucleotide sequences (i.e. they do not overlap). How is this possible? Fully explain your answer.
Chapter 18 Solutions
Campbell Biology in Focus
Ch. 18.1 - Prob. 1CCCh. 18.2 - Prob. 1CCCh. 18.2 - Explain the advantage of the systems biology...Ch. 18.2 - Prob. 3CCCh. 18.3 - The best estimate is that the human genome...Ch. 18.3 - Prob. 2CCCh. 18.3 - Prob. 3CCCh. 18.4 - Discuss the characteristics of mammalian genomes...Ch. 18.4 - Which of the three mechanisms described in Figures...Ch. 18.4 - Prob. 3CC
Ch. 18.5 - Describe three examples of errors in cellular...Ch. 18.5 - Prob. 2CCCh. 18.5 - Prob. 3CCCh. 18.6 - Would you expect the genome of the macaque (a...Ch. 18.6 - Prob. 2CCCh. 18 - Prob. 1TYUCh. 18 - Prob. 2TYUCh. 18 - Two eukaryotic proteins have one domain in common...Ch. 18 - DRAW IT Comparing amino acid sequences of similar...Ch. 18 - SCIENTIFIC INQUIRY The scientists mapping human...Ch. 18 - FOCUS ON EVOLUTION Genes important in the...Ch. 18 - FOCUS ON INFORMATION The continuity of life is...Ch. 18 - SYNTHESIZE YOUR KNOWLEDGE Insects have three...
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- E. How many nucleotides would be required to generate a polypeptide that is 15 amino acids long? This requires knowing how many nucleotides of DNA code for one amino acid. F. Assuming that there are between 20,000-25,000 genes in the human genome, do you think there are 1) fewer, 2) approximately the same number, or 3) more proteins in the human genome? Explain your answer.arrow_forwardOn the basis of current knowledge, the protein-encoding regions account for only about 3% of the human genome. What is the function of the rest of the DNA?arrow_forwardIn a study showing that approximately 10% of protein-coding genes are essential for Cell survival .This translates into which of the following number of essential genes in the human genome .a)100 b) 500 c)1000 d)2000arrow_forward
- The human genome contains thousands of sequences known as small open reading frames, some of which encode proteins of about 30 amino acids. What is the minimum number of nucleotides required to encode such a protein?arrow_forwardWhat percentage of the DNA in the genome actually corresponds to genes? How much is actually protein-coding exons? What makes up the rest?arrow_forwardwhat is the answer of (a)?arrow_forward
- Annotation of the human genome sequence reveals a discrepancy between the number of protein-coding genes and the number of predicted proteins actually expressed by the genome. Proteomic analysis indicates that human cells are capable of synthesizing more than 100,000 different proteins and perhaps three times this number. What is the discrepancy, and how can it be reconciled?arrow_forwardYour advisor, a brilliant bioinformatician, has high regard for your intellect and industry. she suggests that you write a computer program that will identify the exons of protein- coding genes directly from the sequence of the human genome. In preparation for that task, you decide to write down a list of the features that might distinguish protein- coding sequences from intronic DNA and from other sequences in the genome. What features would you list?arrow_forwardAll the cells of one organism share the same genome. However, during development, some cells develop into skin cells while others develop into muscle cells. Briefly explain how the same genetic instructions can result in two different cell types in the same organism.arrow_forward
- What is the central dogma of biology? Describe the molecular processes that accomplish the flow of genetic information as listed by the central dogma?arrow_forwardIt is possible to take the DNA of a gene from any source and place it on a chromosome in the nucleus of a yeast cell. When you take DNA of a human gene and put it into a yeast cell chromosome, the yeast cell can synthesize the human protein. However, when you remove the DNA for a gene normally present on yeast mitochondrial chromosomes and put it on a yeast chromosome in the nucleus, the yeast cell cannot synthesize the correct protein, even though the gene comes from the same organism. Explain. What would you need to do to ensure that such a yeast cell could make the correct protein?arrow_forwardYou have sequenced the genome of the bacterium Salmonella typhimurium and find a protein that is 100 percent identical to a protein in the bacterium Escherichia coli. When you compare nucleotide sequences of the S. typhimurium and E. coli genes, you find that their nucleotide sequences are only 87 percent identical. How would you interpret the observations? Please make sure to select ALL correct answer options. Because genetic code is redundant, changes in the DNA nucleotide sequence can occur without change to its encoded protein. Due to the flexibility in the third positions of most codons, the DNA sequence can accumulate changes without affecting protein structure. Natural selection will eliminate many deleterious amino acid changes. This will reduce the rate of change in the amino acid sequence and lead to sequence conservation of the proteins. Protein sequences are expected to evolve and diverge more slowly than the genes that encode them.arrow_forward
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