Which of these cell junctions form a barrier to the passage of materials?
tight junctions
The primary role of _____ is to bind animal cells together.
aid in the coordination of the activities of adjacent animal cells.
Gap junctions
What role does a transcription factor play in a signal transduction pathway?
By binding to DNA it triggers the transcription of a specific gene.
A signal transduction pathway is initiated when a _____ binds to a receptor.
signal molecule
Which of these acts as a second messenger?
cyclic amp
Calcium ions that act as second messengers are stored in _____
endoplasmic reticulum
A protein kinase activating many other protein kinases is an example of _____
_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell’s cytoplasm.
Phospholipase C … IP3 …. Ca2+
Nucleoli are present during _____.
During prophase a homologous pair of chromosomes consists of _____.
two chormosomes and four chromatids
Cytokinesis often, but not always, accompanies ___
Spindle fibers attach to kinetochores during _____.
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
Chromosomes become visible during _____.
Cytokinesis often, but not always, accompanies _____.
Which event does not take place before the start of mitosis?
nuclear envelope disintegrates
Which term describes two recently replicated DNA strands that are joined together just before cell division?
sister chromatids
True or false? Mitosis takes place during M phase, which is the longest phase of the cell cycle.
Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?
During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?
To which part of the centromere do mitotic spindle fibers attach during prometaphase?
Which of these is NOT a carcinogen?
all of the above,
fat, smoking, testerone, viruses, uv light
which causes colon cancer?
Treating dissociated cells with certain antibodies makes the cells unable to reaggregate. Why?
the antibodies bind to cell adhesion proteins called cadherins.
Why are tight junctions found in only certain types of tissues, while desmosomes are found in a wide array of cells?
water-tight epthilia
If cancer cells detach from neighboring cells, what is a likely outcome of this event?
Loss of desmosomes
All of the following can be proteins found in the extracellular matrix of animal cells except ________.
What is a major difference in the extracellular matrix (ECM) between plant and animal cells?
Plant ECM is primarily carbohydrate in nature, whereas animal ECM is largely protein based.
For a tissue or an organ to function as a unit, ________.
cell-cell communication
Integrins are integral membrane proteins. They are often attached to ________.
cytoskeletal proteins and molecules of the extracellular matrix.
Hormones function as ________.
signal molecules
DNA is composed of four nucleosides: adenosine, cytidine, thymidine, and guanosine. If scientists introduced radioactive thymidine into the growth medium of the cells, it would be incorporated into the DNA molecule ________.
during dna replication
The microtubular organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as which of the following?
A parent cell divides to form two genetically identical daughter cells in the process of mitosis. For mitosis to take place ________.
the parent cell must replicate its entire genome prior to mitosis.
Regulatory proteins that serve to prevent a cell from entering the S phase under conditions of DNA damage are also known as ________.
Regulatory proteins that serve to prevent a cell from entering the S phase under conditions of DNA damage are also known as ________.
What determines the primary structure of an RNA molecule?
What determines the primary structure of an RNA molecule?
Pemphigus vulgaris is an autoimmune disorder in humans in which antibodies are produced against the cadherins of desmosomes. The blistering of the skin and mucous membranes characteristic of this disorder is probably a result of _____.
loss in cell-cell adhesion
Plasmodesmata are cell-cell junctions that are found between _____.
adjacent plant cells
Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor-signal complex brings about a series of events that result in contraction of skeletal muscle. Venom from black widow spiders causes an explosive release of acetylcholine. What would that do to its victims?
muscles wouldn’t relax

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