Exam 3
In a diploid cell with four chromosome pairs (2n=8), how many sister chromatids will be found in a nucleus at pro phase of mitosis?
16
Which of the sequences below best describes the sequential steps (numbered 1-5) in a signal transduction pathway that utilizes a G protein-coupled receptor?
3. A signal molecule 1. the signal-receptor complex activated a G protein 5. cAMP is produced 2. protein jumases are activated 4. target proteins are phosphorylated
If a cell has 15 chromosomes, how many sister chromatids will be present at the start of mitosis?
30
How many chromosomes are found in a human somatic cell?
46
Signaling molecules that bind to receptors are called?
???????
Which of these is a G-protein-linked receptor?
A
Which of these is a signal molecule?
A
Which of these is responsible for initiating a signal transduction pathway?
A
Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?
A Cdk is an enzyme that attaches phosphate groups to other properties
Which of the following statements best describes a key aspect of a G protein signaling pathway?
A G protein bound is active when bound to GTP
Which of the following statements best describes a key aspect of a G protein signaling pathway?
A G protein is active when bound to GTP
Which of the following statements best describes a key aspect of a G protein signaling pathway?
A G protein is inactivated by hydrolysis of bound GTP
The region of a duplicated chromosome in which the sister chromatids are held together is called
A centromere
Which of the following statements best describes a cleave furrow?
A groove in the plasma membrane between daughter nuclei
Which of the following is responsible for cytokinesis?
Actin filaments
Which of the following statements describes a characteristic feature of metaphase?
Alignment of chromosomes on the equator of the cell
A protein kinase activating many other protein kinases is an example of
Amplification
In which phase of mitosis do the sister chromatids become daughter chromosomes?
Anaphase
To what does the term ligand refer in cel biology?
Any small molecule that can bind in a specific manner to a larger one
Which of the following statements best describes density-dependent inhibition?
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing
Which of these is a membrane receptor?
B
Which of these is a receptor molecule?
B
A protein kinase is an enzyme that functions in which of the following ways?
By adding a phosphate group to activate or inactivate other proteins
What role does a transcription factor play in a signal transduction pathway?
By binding to DNA it triggers the transcription of a specific gene
The binding of signal molecules to ____ results in the phosphorylation of tyrosines
C
Which of these is a receptor tyrosine kinase?
C
Which of the following are amount the most common second messengers?
Calcium ions and cAMP
Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cyclin to become catalytically active?
Cdk
Which of the following is NOT a property of cancer cell?
Cell arrest at the S phase of the cell cycle
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
Cells with more than one nucleus
What is the name of the microtuble-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?
Centrosome
One difference between cancer cells and normal cells is that cancer cells
Continue to divide even when they are tightly packed together
Which of these is NOT correct?
Cyclic AMP binds to calmodulin
Which of the following is a protein that is synthesized only at specific times during the cell cycle, and that associate with a kinase to form a catalytically active complex?
Cyclin
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex worth a kinase?
Cyclin
Maturation promoting factor (MPF) triggers the cell's passage past the G2 checkpoint into mitosis. MPF is a dimer consisting of ____
Cylin and a cyclin-dependent kinase
Which of these acts as a second messenger?
D
Which of these is an ion-channel receptor?
D
_____ is a signal molecule that binds to an intracellular receptor
D
Which of these receptor molecules would allow Na+ to flow into the cell?
D (this is an ion-channel receptor)
Mutations in the BRCA1 and BRCA2 genes causes a very high risk in breast cancer development because these genes are responsible for
DNA damage repair
Which of these phases encompasses all of the stages of mitosis but no other events?
E
Which of these receptors is NOT a membrane receptor?
E
Which of the following is a type of signaling in which a cell secretes a signal into the bloodstream, which then affects cells long distances away?
Endocrine signaling
Which type of signaling is also considered hormonal signaling because it signals through long distances?
Endocrine signaling
Calcium ions that act as second messengers are stored in ____
Endoplasmic reticula
Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?
Estrogen
A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors.
G-protein-linked
Epinephrine acts as a signal molecule that attaches to _____ proteins.
G-protein-linked receptor
Which of the following correctly matches a phase of the cell cycle with its description?
G1, follows cell division
A G-protein is active when
GTP is bound to it
The cleavage of glycogen by glycogen phosphorylase releases _____.
Glucose-1-phosphate
Which of the following is a substance that acts at a long distance from the site at which it is secreted?
Hormone
At what stage of the cell cycle is the cyclin component of MPF destroyed?
In late M
During ___ the cell grows and replicates both its organelles and its chromosomes
Interphase
Which of the following characteristics would be most important for a chemotherapeutic drug designed to treat cancer cells?
It specifically inhibits the cell division cycle in rapidly dividing cells
If an animal cell suddenly loses the ability to produce GTP, what will most likely happen to its signaling system?
It will not be able to activate G proteins on the cytoplasmic side of the plasma membrane
A signal molecule is also know as
Ligand
Progression beyond the G2 checkpoint into mitosis is triggered by which of the following molecules?
MPF
Testosterone does NOT affect all cells of the body because
Not all cells in the body have receptors for testosterone
A type of localized signaling in which a cell secretes a signal molecule that affects neighboring cells is best described as which of the following?
Paracrine signaling
_____ catalysts the production of ____, which then opens an ion channel that releases ___ into the cell's cytoplasm
Phospholipase C... IP3... Ca2+
____ is an enzyme that transfers phosphate groups from ATP to a protein
Protein kinase
In the epinephrine pathway, the molecule cAMP directly activates ____ in order to stimulate glycogen conversion to glucose
Protein kinase A
Which of the following statements best describes an aspect of signal transduction?
Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors
Which of the following events would be most likely to produce cells with several nuclei?
Repeated mitosis without cytokinesis
Which of the following occurs during S phase?
Replication of the DNA
In which phase of the cell cycle are the chromosomes duplicated?
S
The mitotic spindle plays a critical role in which of the following processes?
Separation of sister chromatids
Movement of the chromosomes during anaphase would be most affected by a drug that prevents
Shortening of microtubules
A signal transduction pathway is initiated when a _____ binds to a receptor
Signal molecule
A signal transduction pathway is initiated when a _____ binds to a receptor.
Signal molecule
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
Sister chromatids
Tissues culture experiments demonstrate that without PDGF
Skin cells fail to divide
A(n) ____ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off
Steroid
Which type of signaling would be found mainly between neurons
Synaptic signaling
DNA replication occurs in
The S phase of interphase
Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?
The cells show characteristics of tumors
Which of the following statements best describes what would happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells would enter mitosis
What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?
The centromere
When a cell in M phase is fused with a cell in G1, ___
The chromosomes of the original G1 nucleus condense in preparation for mitosis
The decline of MPF activity at the end of mitosis is due to
The degradation of cyclin
During _____ both the contents of the nucleus and the cytoplasm are divided.
The mitotic phase
In liver cells, epinephrine stimulates the breakdown of glycogen. As the signal transduction pathway progresses, __________.
The signal is amplified
Which of the following conditions is required for a target organ to respond to a particular hormone?
The target organ must have receptors that recognize and bind the hormone molecule
Which of the following statements describes why a signaling molecule can cause different responses in different cells?
The transduction process is unique to each cell type; to respond...
Which of the following could account for the different cellular responses to histamine? Select all that apply
The types of relay The cell type the enzyme that is activated the type of second messengers
Which of the following statements best describes why phosphorylation cascades are useful in cellular signal transduction?
They amplify the original signal many times
Which of the following statements describing kinetochores is correct?
They are sites at which microtubules attach to chromosomes
What is a primary function of transcription factors?
They control gene expression
What role do phosphatases play in signal transduction pathways?
They inactivate protein kinases to turn off signal transduction
Which of these is the second of the three stages of cell signaling?
Transduction
Metaphase is characterized by _____.
aligning of chromosomes on the cell equator
Which of the following molecules serves as a second messenger in the signaling pathway below: epinephrine >>> G protein-coupled >> G protein >>> adenylyn cyclase >>> cAMP
cAMP
Which of the following molecules serves as a second messenger in this pathway?
cAMP
Which of these is activated by calcium ions?
calmodulin
Which of the following is a second messenger?
cyclic AMP
Which of these acts as a second messenger?
cyclic AMP
Which of the following pairs of molecules make up an active MPF
cyclin and a cyclin-dependent kinase
What is the final result of mitosis in a human?
genetically identical somatic cells containing 46 chromosomes
In signal transduction, phosphates ___
inactivate protein kinases and turn off the signal transduction
Thyroid hormones bind to ____ receptors
intracellular
Which of these is a karyotype?
organized images of a cell's chromosomes
