A researcher examines genes for several proteins that are quite similar in both structure and function. He is interested in determining whether the genes form a multigene family and in working out which of the proteins arose first evolutionarily. What would be the BEST approach to take to address this question? Be careful to look for the best approach; some other approaches could also provide useful information while being less definitive. A. The researcher should sequence the genes and compare their sequences. The most similar genes are likely the most closely related, while those that have more base differences probably diverged earlier. B. The researcher should examine the functions of the proteins. Those with the most similar functions are the most closely related. C. The researcher should induce mutations in the genes to see how these affect the function. The most mutations needed to cause changes in the function of the protein, the older the gene. D. The researcher should examine the functions of the proteins. Whichever protein has the most critical function is probably the oldest protein. A researcher sequences the genome of a variety of bacterial and eukaryotic cells. She finds that the bacterial genome is smaller, but that there are more genes for a given number of base pairs in the eukaryotic cells. In other words, there are fewer genes per unit of length of DNA in the eukaryotic cells. What do you predict she will find if she examines the DNA more closely? A. All of the bacterial DNA consists of coding sequences, but this is not true of the eukaryotic DNA. B. There are more repetitive sequences in the eukaryotic DNA than in the bacterial DNA. C. There are densely packed genes in the eukaryotic DNA that were not immediately distinguishable during the first analysis. D. The bacteria have larger quantities of noncoding DNA than the eukaryotic cells. Which of the following is true regarding the presence of a multigene family? A. Multigene families are produced by any sort of chromosomal rearrangement. B. Multigene families are produced whenever a transposon is inserted into a gene. C. Multigene families are produced by all types of mutation, including single base substitutions. D. Multigene families are produced by some mutations that involve duplication. Developmental genes are often highly conserved. However, organisms with very similar genes can appear quite different. How is this possible? A. The genes may usually undergo mutation during development, resulting in the production of varied proteins in individual cells. B. If an identical gene is turned on at different stages in development, it can have very different effects. C. Even if genes are quite similar, they always produce proteins with different functions. D. If the genes are very similar, they must always be expressed similarly (at similar times in development) but may sometimes still have varying effects. Analyses of genomes have allowed researchers to determine that some cells have very small genomes. If you were asked to predict which organisms are likely to have smaller genomes than others, which option below would be MOST likely? A. Bacteria that live in plant hosts are likely to have smaller genomes than those that live in animal hosts as it takes a smaller variety of metabolic processes to survive in an animal host. B. Although less is known about Archaea than about Bacteria as fewer species have been studied, it is likely that Archaea have smaller genomes on average than Bacteria as they have fewer metabolic needs. C. Bacteria that are endosymbionts, living within a host, can survive with smaller genomes than free-living Bacteria because they can rely on their host for many of their needs. D. Protists generally have had smaller genomes than Bacteria because Bacteria have such large amounts of noncoding DNA.
A researcher examines genes for several proteins that are quite similar in both structure and function. He is interested in determining whether the genes form a multigene family and in working out which of the proteins arose first evolutionarily. What would be the BEST approach to take to address this question? Be careful to look for the best approach; some other approaches could also provide useful information while being less definitive.
-
A.
The researcher should sequence the genes and compare their sequences. The most similar genes are likely the most closely related, while those that have more base differences probably diverged earlier.
-
B.
The researcher should examine the functions of the proteins. Those with the most similar functions are the most closely related.
-
C.
The researcher should induce mutations in the genes to see how these affect the function. The most mutations needed to cause changes in the function of the protein, the older the gene.
-
D.
The researcher should examine the functions of the proteins. Whichever protein has the most critical function is probably the oldest protein.
-
A researcher sequences the genome of a variety of bacterial and eukaryotic cells. She finds that the bacterial genome is smaller, but that there are more genes for a given number of base pairs in the eukaryotic cells. In other words, there are fewer genes per unit of length of DNA in the eukaryotic cells. What do you predict she will find if she examines the DNA more closely?
-
A.
All of the bacterial DNA consists of coding sequences, but this is not true of the eukaryotic DNA.
-
B.
There are more repetitive sequences in the eukaryotic DNA than in the bacterial DNA.
-
C.
There are densely packed genes in the eukaryotic DNA that were not immediately distinguishable during the first analysis.
-
D.
The bacteria have larger quantities of noncoding DNA than the eukaryotic cells.
Which of the following is true regarding the presence of a multigene family?
-
A.
Multigene families are produced by any sort of chromosomal rearrangement.
-
B.
Multigene families are produced whenever a transposon is inserted into a gene.
-
C.
Multigene families are produced by all types of mutation, including single base substitutions.
-
D.
Multigene families are produced by some mutations that involve duplication.
Developmental genes are often highly conserved. However, organisms with very similar genes can appear quite different. How is this possible?
-
A.
The genes may usually undergo mutation during development, resulting in the production of varied proteins in individual cells.
-
B.
If an identical gene is turned on at different stages in development, it can have very different effects.
-
C.
Even if genes are quite similar, they always produce proteins with different functions.
-
D.
If the genes are very similar, they must always be expressed similarly (at similar times in development) but may sometimes still have varying effects.
Analyses of genomes have allowed researchers to determine that some cells have very small genomes. If you were asked to predict which organisms are likely to have smaller genomes than others, which option below would be MOST likely?
-
A.
Bacteria that live in plant hosts are likely to have smaller genomes than those that live in animal hosts as it takes a smaller variety of
metabolic processes to survive in an animal host. -
B.
Although less is known about Archaea than about Bacteria as fewer species have been studied, it is likely that Archaea have smaller genomes on average than Bacteria as they have fewer metabolic needs.
-
C.
Bacteria that are endosymbionts, living within a host, can survive with smaller genomes than free-living Bacteria because they can rely on their host for many of their needs.
-
D.
Protists generally have had smaller genomes than Bacteria because Bacteria have such large amounts of noncoding DNA.
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