Online book study practice test for Ch. 18.
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| 382378027 | Why do both bacteria and humans need tryptophan to survive? | It is one of the 20 amino acids used by all organisms to synthesize proteins. | |
| 382378028 | What are some properties of feedback inhibition? | It is commonly found in anabolic pathways, it allows a cell to adapt quickly to fluctuations in the availability of important substances, and if the end product accumulates in the cell--the whole pathway is shut down. | |
| 382378029 | In prokaryotic genomes, where can we find groups of functionally related genes along with their promoters and operators? | In an operon. | |
| 382378030 | In general, operons that encode the enzymes of an anabolic pathway are what? | Repressible. | |
| 382378031 | Operons that encode the enzymes of a catabolic pathway are what? | Inducible. | |
| 382378032 | In an inducible operon, the inducer is often the _____ in the pathway being regulated. The inducer binds to the _____, rendering it ______. | Substrate, repressor, inactive. | |
| 382378033 | Both repressible and inducible operons control gene expression at what level? | Transcription level. | |
| 382378034 | What is gene expression bacteria primarily regulated by? | Control of the transcription of genes into mRNA. | |
| 382378035 | Why is the control of gene expression in multicellular eukaryotes more complex than in prokaryotes? | In a multicellular environment, different cells are specialized for different functions. | |
| 382378036 | In some cases, what can happen when DNA methylation and histone deacetylation combine? | Certain genes can be silenced. | |
| 382378037 | In eukaryotes, how does DNA packing primarily affect gene expression? | By controlling access to DNA. | |
| 382378038 | Are operons found in eukaryotes? | No, only in prokaryotes. | |
| 382378039 | In a eukaryote, activating transcription factors may stimulate gene expression by binding to a DNA site called what? | An enhancer. | |
| 382378040 | What do enhancers do and where are they located? | Increase the rate of transcription. May be upstream or downstream from the genes they regulate, possibly thousands of base pairs away from the promoter. | |
| 382378041 | What is the significance of post-transcriptional controls? | They can affect mRNA stability, regulate the rate at which a molecule is translated, and can regulate mRNA splicing. They may also include controls. | |
| 382378042 | What are some means of controlling eukaryotic gene expression? | Transcriptional regulation, methylation of DNA, mRNA processing, and DNA packing. | |
| 382378043 | What is the evolutionary significance of alternative RNA splicing? | It expands the number of proteins that can be coded for by one gene, increasing an organisms ability to produce novel proteins. | |
| 382378044 | What is the role of proteasomes? | They are giant protein complexes that recognize ubiquitin and degrade the tagged proteins. | |
| 382378045 | What determines how long a particular mRNA molecule will persist in a eukaryotic cell? | The nucleotide sequences in the poly-A tail. | |
| 382378046 | The expression of a gene located in a tightly coiled region of DNA can be promoted by what? | Histone acetylation. | |
| 382378047 | Do chemical mutagens play a role in epigenetic inheritance? | No. | |
| 382378048 | What is a high rate of transcription in eukaryotes usually dependent on? | Binding of general transcription factors to the TATA box, the coordinated control of genes in operons, specific binding of activator molecules to enhancers, and protein-protein interactions promoted by the activation domains. | |
| 382378049 | Although the number of genes in the human genome is low compared to less complex organisms, the number of possible products from those genes is greatly amplified. By what? | Alternate arrangements of exons from a primary transcript. | |
| 382378050 | What is a good general description for the makeup of the human genome? | Genes for noncoding RNA make up the majority of meaningful genetic information. | |
| 382378051 | MicroRNA's and small interfering RNAs both function to silence genes. What are two ways they may act? | They may either degrade mRNA, or bind to complementary mRNA sequences to prevent translation. | |
| 382378052 | Specific cells that appear undifferentiated under the microscope but are already set to become muscle cells are called what? | Myoblasts. | |
| 382378053 | How does MyoD promote muscle cell development? | By turning on the expression of multiple muscle-related genes. | |
| 382378054 | What codes cytoplasmic determinants? | Maternal genes. | |
| 382378055 | What is the process in which cells influence each other's development? | Induction. | |
| 382378056 | Instead of developing a head and a tail, an abnormal Drosophila develops two tails. What is the most likely cause of this? | A mutation in a maternal effect gene. | |
| 382378057 | When is cell differentiation first observable? | When mRNA's for tissue-specific proteins appear in a cell. | |
| 382378058 | What makes a cancer cell different from a regular organismal cell? | It does not respond to chemical signals that control cell division. | |
| 382378059 | What do oncogenes do in the human genome? | Stimulate cell division. | |
| 382378060 | How are most human cancers caused? | By the accumulation of somatic mutations. | |
| 382378061 | What gene has been called the guardian angel of the genome? | p53. | |
| 382378062 | What two genes are often mutated in colon cancer? | ras and p53. | |
| 382378063 | Why is cancer more prevalent in older people? | It involves an accumulation of mutations, and with more time to accumulate the mutations, the chances of it increase. | |
| 382378064 | How can cancer be hereditary? | One or two of several mutations necessary for development can be inherited, giving the person in question a higher chance of developing the issue. | |
| 382378065 | What are the BRCA1 and BRCA2 genes known as? | Tumor-suppressors. | |
| 382378066 | How can we accurately characterize our current understanding of cancer development? | In order for a cell to become fully changed, it typically must have at least one active oncogene and the mutation or loss of several tumor-suppresor genes. |
