Cell Communication
Synaptic signaling of neurons is an example of what type of cellular communication.
Paracrine
What are the stages of interphase, and what happens during each?
G1 or gap 1 is a period of cell growth after the cell has finished dividing. The cell grows in size and synthesizes mRNA and proteins needed for DNA replication.
S or synthesis: DNA is replicated
G2 or gap 2 is a period of rapid cell growth to prepare for cell division (mitosis)
What are the phases of mitosis?
PMAT
A specialized condensed region of each chromosome that appears during mitosis where the chromatids are held together to form an X shape.
Centromere
Explain the importance of mitosis of cells in a skinned knee and during the growth of a plant.
New cells need to replace the damaged cells. New cells need to produce in order for the plant to grow in size.
Quorum sensing in bacteria is an example of what type of cellular communication?
Paracrine
On the board, draw an unduplicated chromosome vs. a duplicated chromosome.
See board.
What types of cells undergo mitosis?
Somatic cells or body cells
What is actually dividing during cytokinesis?
Cytoplasm
Consider the effect on a cell if the sister chromatids did not line up correctly during metaphase. For example, if some lined up side by side instead of a single file along the middle, how might this affect the resulting cells?
Aneuploidy
What are the 3 stages of cell signaling?
1. Reception
2. Transduction
3. Response
In between cell divisions, DNA in eukaryotic cells is uncoiled and spread out in the form of what?
Chromatin
The process in which prokaryotes (bacteria) reproduce.
Binary fission
In some cells, mitosis occurs without cytokinesis. What would the resulting cell look like?
Multinucleated (multiple nuclei)
Colchicine is a poison that acts to inhibit the development of spindle fibers. Describe the effects on mitosis in a cell that has been treated with colchicine.
Spindle fibers will not form during prophase resulting in an inability of chromosomes to separate.
What is the difference between a protein kinase and a second messenger? Can both operate in the same signal transduction pathway?
A protein kinase is an enzyme that adds a phosphate group to another protein. Protein kinases are often part of a phosphorylation cascade that transduces a signal. A second messenger is a small, nonprotein molecule or ion that rapidly diffuses and relays a signal throughout a cell. Both protein kinases and second messengers can operate in the same pathway. For example, the second messenger cAMP often activates protein kinase A, which then phosphorylates other proteins.
Cells that don't divide go into this step. Give an example.
G0, neurons, liver cells, muscle cells.
A chicken has 78 chromosomes in its somatic cells. How many chromosomes did the chicken inherit from each parent? How many chromosomes are in each of the chicken’s gametes? How many chromosomes will be in each somatic cell of the chicken’s offspring?
39; 39; 78
Differentiate between these terms: chromosome, chromatin, and chromatid.
The DNA of a eukaryotic cell is packaged into structures called chromosomes. Each chromosome is a long molecule of DNA, which carries hundreds to thousands of genes, with associated proteins that maintain chromosome structure and help control gene activity. This DNA-protein complex is called chromatin. The chromatin of each chromosome is long and thin when the cell is not dividing. Prior to cell division, each chromosome is duplicated, and the resulting sister chromatids are attached to each other by proteins at the centromeres and, for many species, all along their lengths (a phenomenon called sister chromatid cohesion).
Based on the figure (handed out by Ms. Klees), what role does the p53 protein play in cell division? Why might a cell need to stop dividing?
The p53 protein, referred to as the “Guardian of the Genome,” is a tumor suppressor that plays an important role in halting the division of cells (mitosis) that have sustained DNA damage.
How is ligand binding similar to the process of allosteric regulation of enzymes?
Binding of a ligand to a receptor changes the shape of the receptor, altering the ability of the receptor to transmit a signal. Binding of an allosteric regulator to an enzyme changes the shape of the enzyme, either promoting or inhibiting enzyme activity.
What is the resulting complex when mitotic cyclins bind to Cdks in G2 phase?
Mitosis-promoting factor/Maturation Promoting Factor (MPF)
The drug 55-fluorouracil inhibits thymine production in eukaryotic cells. Which of the following cell cycle stages will be most directly affected by 55-fluorouracil?
S phase
Give an example of apoptosis during embryonic development, and explain its function in the developing embryo.
In formation of the hand or paw in mammals, cells in the regions between the digits are programmed to undergo apoptosis. This serves to shape the digits of the hand or paw so that they are not webbed. (A lack of apoptosis in these regions in water birds results in webbed feet.)
Explain the significance of the G1, G2, and M checkpoints and the go-ahead signals involved in the cell cycle control system.
Checkpoints allow cellular surveillance mechanisms to determine whether the cell is prepared to go to the next stage. Internal and external signals move a cell past these checkpoints. The checkpoint determines whether a cell will proceed forward in the cell cycle or switch into the phase. The signals to pass this checkpoint often are external, such as growth factors. Passing the checkpoint requires sufficient numbers of active MPF complexes, which in turn orchestrate several mitotic events. MPF also initiates degradation of its cyclin component, terminating the M phase. The M phase will not begin again until sufficient cyclin is produced during the next S and phases. The signal to pass the M phase checkpoint is not activated until all chromosomes are attached to kinetochore fibers and are aligned at the metaphase plate. Only then will sister chromatid separation occur.