Cell Bio Chapter 20
Which type of junction involves a connection to the actin cytoskeleton
adherens junctions
proteoglycans in the extracellular matrix of animal tissues______
allow cartilage to resist compression
induced pluripotent stem cells____
are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types
tight junctions_____
are formed from claudins and occludins
Hemidesmosomes are important for____
attaching epithelial cells to the extracellular matrix
Which of the following statements about gap junctions is false
because gap junctions do not allow ions to pass through they are not used for electrically coupling cells
Which of the following statements about cancer is false?
a mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell
Which of the following types of mutation would convert a proto-oncogene into an oncogene?
a mutation that greatly increases the amount of the proto-oncogene protein
Which of the following genetic changes cannot convert a proton-oncogene into an oncogene
a mutation that introduces a stop codon immediately after the codon for the initiator methionine
from this description the normal RAS gene is_______
a proto-oncogene
a metastasis is______
a secondary tumor in a different part of the body that arises from a cell from the primary tumor
adherens junctions_____
can be used to bend epithelial sheets into tubes
a pluripotent cell___-
can give rise to all tissues and cell types in the body
cells that are terminally differentiated_______
can no longer undergo cell division
an adult hemopoietic stem cell found in the bone marrow______
can undergo self-renewing divisions for the lifetime of a healthy animal
which of the following statements about tumor suppressor genes is false
cells with one functional cope of a tumor suppressor gene will usually proliferate faster than normal cells
Which of the following molecules is NOT found in plants?
collagen
Which of the following statements about collagen is false?
collagen synthase organizes the mature collagen molecules into ordered collagen fibrils
A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?
colorectal only
Mouse embryonic stem cells _____
come from the inner cell mass of early embryos
how do reproductive cloning and therapeutic cloning differ
embryos are placed into foster mothers during reproductive cloning but not during therapeutic cloning
Forms of the Ras protein found in tumors usually cause which of the following events to occur?
excessive cell division
Forms of the Ras protein found in tumors usually cause which of the following?
excessive cell division
All the various cell types in a typical carcinoma, including fibroblasts, inflammatory cells, and blood vessels, evolve from the cancer cell population.
false
Cancer cells consume glucose more rapidly than their normal neighbors because they need much more energy (ATP) to drive their high rates of proliferation
false
Genetic instability in the form of point mutations, chromosome rearrangements, and epigenetic changes needs to be maximal to allow the development of cancer.
false
Viruses and other infectious agents play no role in human cancers.
false
the plasmodesmata in plants are functionally most similar to which animal cell junction
gap junction
In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated?
genes involved in control of the cell cycle
A cell can crawl through a tissue because of the transmembrane ____ proteins that can bind fibronectin outside of the cell
integrin
Which of the following statements about interns is false?
integrins use adaptor proteins to interact with the microtubules cytoskeleton
at desmosomes, cadherin molecules are connected to _____
intermediate filaments
a basal lamina_____
is a thin layer of extracellular matrix underlying an epithelium
A malignant tumor is more dangerous than a benign tumor because
its cells invade other tissues
CANCER a malignant tumor is more dangerous than a benign tumor because______
its cells invade other tissues
cadherins_____
mediate cell-cell attachments through hemophiliac interactions
What do you think will happen in the mice that lack APC gene?
mice lacking the APC gene will have inappropriate proliferation of gut stem cells
Which of the following statements about cellulose is false?
microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers
plasmodesmata____
permit small molecules to pass from one cell to another
when terminally differentiated cell in an adult body dies it can typically be replaced in the body by a stock of_____
proliferating precuror cells
Which of the following statements is false?
proteoglycans are major component of compact connective tissues but are relatively unimportant in watery tissues such as the jelly like substance in the interior of the eye
Which of the following statements about connective tissues is true?
proteoglycans can resist compression in the extracellular matrix
Fibroblasts organize the collagen of the extracellular matrix____
pulling the collagen into sheets or cables after it has been secreted
Which type of junction contributes the most to the polarization of epithelium cells
right junctions
an individual that arises by reproductive cloning has a nuclear genome that is identical to_____
the adult who donated the cell for nuclear transplantation
a major distinction between the connective tissues in an animal and other main tissue types such as epithelium nervous tissue or muscle is______
the amount of extracellular matrix in connective tissues
Which of the following is NOT an example of a connective tissue?
the layer of go photoreceptors in the eye
Which of the following statements about plant cell walls is true?
the microtuble cytoskeleton directs the orientation in which cellulose is deposited in the cell wall
Which of the following processes do normal proto-oncogenes typically exhibit?
they stimulate cell growth and division
Both multicellular plants and animals have____
tissues composed of multiple different cell types
the artificial introduction of three key____ into an adult cell can convert the adult cell into a cell with the properties of es cells
transcription factors
Anticancer therapies take advantage of some molecular abnormality of cancer cells that distinguishes them from normal cells.
true
In the cellular regulatory pathways that control cell growth and proliferation, the products of oncogenes are stimulatory components and the products of tumor suppressor genes are inhibitory components.
true
The loss of p53 protein makes some cancer cells much less sensitive to irradiation and to many anticancer drugs, which would otherwise destroy tumors by inducing proliferating cells to either stop dividing or undergo apoptosis.
true
Oncogenes and tumor suppressor genes can both be detected by intro- ducing fragmented DNA from cancer cells into suitable cell lines and isolating colonies that display cancerous properties
False
When cancer cells from individual patients are analyzed, they are often found to have mutations in multiple components of the Rb pathway (Rb itself, along with genes that directly regulate Rb), which governs initiation of the cell-division cycle
False
Which of the following functions does the product of the normal p53 gene carry out?
It inhibits the cell cycle.
Papillomavirus (HPV) can cause human warts, but is not a causative factor in carcinomas of the uterine cervix.
The hypermutable nature of tumor cells means that treatments with single anticancer drugs or even combinations of such drugs are unlikely to eradicate all the cancer cells.
Why are BRCA1 and BRCA2 considered to be tumor-suppressor genes?
Their normal products participate in repair of DNA damage.
Which of the following statements correctly describes a characteristic of tumor-suppressor gene?
They encode proteins that help prevent uncontrolled cell growth.
