bio 110 chapter 11
Terms
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- The term gene expression refers to the:
- process by which genetic information flows from genes to proteins
- The cells that make up the various tissues of an animal are so different because:
- only certain genes in each cell type are expressed
- The lac operon is found:
- in E. coli
- The lac operon:
-
both A and B are correct
A. prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment
B. coordinates the production of lactose-utilizing enzymes when lactose is present in the environment - RNA polymerase binds to which of the following?
- the promoter
- In the lac operon, a regulatory gene outside of the operon is always producing ___, which (in the absence of lactose) binds to the ___.
- a repressor, operator
- The lac operon is ___ when the repressor is bound to lactose.
- active
- Specialization in the structure and function of cells that occurs during the development of a multicellular organism is called:
- cellular differentiation
- The basis of cellular differentiation is:
- selective gene expression
- The production of an organism that is genetically identical to another organism is called:
- cloning
- The result of cloning is an offspring who is always genetically identical to the organism that supplied:
- the nucleus
- Cells from a differentiated part of a plant can be removed, placed into nutrient medium, and the cells may grow into a complete plant. This shows that:
- differentiation does not involve irreversible changes in DNA
- Which of the following types of cells has the greatest potential for differentiation?
- embryonic stem cells
- If the DNA in a human cell was stretched out straight, how long would it be?
- 3 meters long
- In the eukaryotic nucleus, the unit that consists of DNA wound around a core of eight histone proteins is called a:
- nucleosome
- Dense packing of DNA in chromosomes:
- prevents gene expression
- X-chromosome inactivation
- can lead to a tortoiseshell pattern in cats
- In eukaryotic cells, enhancers and activators regulate:
- transcription
- In eukaryotic cells, transcription factors can bind to:
-
all of the above
A. enhancers
B. the promoter
C. RNA polymerase - Regions of noncoding DNA within a gene are called:
- introns
- The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called:
- exons
- RNA splicing involves the:
- removal of introns from the molecule
- Which of the following is an explanation of why a single gene may code for more than one polypeptide?
- alternative RNA splicing
- After a polypeptide is produced, it may need further processing before it becomes an active protein. This activation of the protein in a eukaryotic cell:
- occurs in the cytoplasm
- Which of the following is a eukaryotic mechanism that regulates the amount of the active protein in a cell?
-
all of the above
A. breakdown of mRNA
B. regulation of translation initiation
C. activation of the protein
D. breakdown of the protein - In egg development or early embryonic development of animals, proteins are carried back and forth between cells to help guide development. This is called:
- cell-to-cell signaling
- A master control gene that regulates many other genes, and determines the identity of a body structure of a developing organism is called:
- a homeotic gene
- A signal molecule from one cell will bind to:
- a receptor protein in the membrane of the target cell
- A signal molecule from one cell can activate transcription factors in a target cell by:
- triggering a signal-transduction pathway
- Developmental similarities observed in most vertebrates are probably due to:
- nucleotide sequences called homeoboxes that have changed very little over time
- Homeoboxes of very similar sequences are found in:
- virtually all eukaryotic organisms
- Homeoboxes function as control mechanisms by:
- switching homeotic genes on and off
- Why can organisms be so different, yet still have very similar homeoboxes?
- Homeoboxes simply function as switches to turn homeotic genes on and off. Homeotic genes can still vary considerable among different organisms.
- A gene that causes cancer is called a:
- oncogene
- A normal gene with the potential to become an oncogene is called a:
- proto-oncogene
- The normal role of most proto-oncogenes is to:
- regulate the cell cycle
- The role of a tumor-suppressor gene it to:
- inhibit cell division and uncontrolled cell growth
- A mutant tumor-suppressor gene:
- produces a defective protein unable to function in a pathway that normally inhibits cell division
- Many cancers, such as colon cancer, can take a long time to develop because:
- it does not arise until several mutations have accumulated
- Why is cancer always a "genetic disease?"
- it is always the consequence of changes in DNA
- Why are most breast cancer cases considered to be "nonhereditary?"
- most breast cancers are due to somatic cell mutations, not inherited mutations
- The carcinogen known to cause the most cases of cancer is:
- tobacco