Unit 4 Flashcards
What are two ways cells communicate with each other?
Through direct contact and chemical signaling
What is plasmodesmata?
Microscopic channels that traverse the [lant cell walls, enabling transport and communication between them.
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How do immune cells interact?
Through cell-to-cell contact
what are some defects of cell signaling?
Cancer, autoimmunity, and diabetes.
what are some examples of cell-to-cell contact?
A flu shot or plasmodesmata
What are some examples of short distance communication?
paracine signaling, synaptic signaling, quorum sensing, or morphogens
What are some examples of long-distance communication?
Endocrine signaling, insulin, growth hormone, thyroid hormone, testosterone
What are the stages of sending and receiving cell messages?
Reception: when ligand binds itself to its receptor
Transduction: signal is internalized
Response: Initiate cascade of reactions
Where is the signal transduction pathway and what does it include?
It’s in the cytoplasm and it includes protein modification and phosphorylation cascades.
How does signaling begin?
Begins with the recognition of a chemical messenger (ligand) by a receptor protein in a target cell
What do signaling cascades do?
relay signals from receptors to cell targets, often amplifying the incoming signals, resulting in the appropriate actions taking place such as cell growth, secretion of molecules, and gene expression
What do the signal transduction pathways do?
influence how cells respond to the environment
What is quorum sensing?
The use of chemical messengers by microbes to communicate with other nearby cells and to regulate specific pathways in response to population density.
What changes can signal transduction cause?
may result in changes in gene expression and cell function, which may alter phenotypes or result in programed cell death (apoptosis)
What so cytokines do?
Regulate gene expression to allow for cell replication and division
What does the SRY gene do?
Expression may trigger mating gene expression
What does Ethylene do?
Cause changes in the production, of different enzymes allowing fruits to ripen
What does change in the signal transduction pathway cause?
Causes alteration in cellular response
What do mutations affect?
mutations in any domain of the receptor protein or in an component of the signaling pathway may affect the downstream components by altering the subsequent transduction of the signal
What are feedback mechanisms used for?
To maintain their internal environments and respond to internal and external environmental changes.
What is negative feedback?
a mechanism that returns a system back to its target set point if perturbed. It maintains homeostasis for a particular condition regulating physiological processes.
What are examples of negative feedback?
Body temp, heart rate, breathing rate, etc.
What is positive feedback?
A mechanism that moves the variable farther away from the initial set point. It amplifies responses and processes in biological organisms
What are examples of positive feedback?
Blood clotting, childbirth, fruit ripening, etc.
When does amplification occur?
When the stimulus is further activated, which, in turn, initiates an additional response that produces system change.
What is Mitosis?
a process that ensures the transfer of a complete genome from a parent cell to two genetically identical daughter cells
what does mitosis do?
Plays a role in growth, tissue repair, and asexual reproduction
What are the stages in mitosis?
Prophase, metaphase, anaphase, and telophase
what happens during prophase?
what happens during metaphase?
what happens during anaphase?
what happens during telophase?
What are the sequential stages of the cell cycle?
Interphase, mitosis, and cytokinesis
What are the stages in interphase?
G1, S, G2
What happens during the G1 stage?
Cell increases in size by duplicating cell structures and divide mitochondria and chloroplasts by binary fission
What happens during the S stage?
DNA is duplicated, creating sister chromatids
What happens during the G2 stage?
Cell is checked for integrity. Errors are corrected and repairs are made
What is cytokinesis
The division of the cytoplasm (all other parts of the cell)
What happens during cytokinesis?
Separates the cell into two daughter cells, each containing identical genomes
What is the G0 stage?
When a cell can no longer divide and exits cell cycle or is held in a particular stage. Upon appropriate cues, it can renter the cell cycle.
How is the cell cycle controlled?
It is controlled with the help of enzymes called cyclin-dependent kinases (CDKs) and cyclins
What is Mitosis-promoting factor (MPF)?
A complex that contains cyclin A or B and CDK, which allows cells to proceed from G2 to mitosis
What are the three checkpoints a cell must pass through to progress through the cycle
Cell growth (G1) checkpoint, G2 checkpoint, and M-spindle checkpoint
What happens in the cell growth (G1) checkpoint?
when cells are stimulated by appropriate external growth factors; for example, platelet-derived growth factor (PDGF) stimulates cells near a wound to divide so that they can repair the injury.
What happens in the G2 checkpoint?
checks for damage after DNA is replicated, and if there is damage, it prevents the cell from going into mitosis.
What happens in the M-spindle checkpoint?
assures that the mitotic spindles or microtubules are properly attached to the kinetochores (anchor sites on the chromosomes). If the spindles are not anchored properly, the cell does not continue on through mitosis.
What is the DNA synthesis checkpoint?
determines if the cell is ready for mitosis. DNA repair enzymes check the replicated DNA at this point.
What is carcinogenesis?
the process by which normal cells are transformed into cancer cells. The process depends on both the activation of oncogenes and deactivation of tumor suppressor genes.
How do cancer or tumors occur?
they occur due to mutations. When the receptor does not need a growth factor to function, transduction occurs continuously, leading to uncontrolled cell growth, which turn into tumors.
What is p53?
The guardian of the cell. If this is mutated, it becomes a cancer chromosome
What happens when the chromosome has a mutation?
It is treated with restriction enzymes (DNA scissors) and turned into small and medium strands of DNA
what activates the adenylyl cyclase?
It’s activated by the alpha subunit and catalyzes the reaction to produce cAMP
What does cAMP do?
Activates protein kinases
True or False: G-protein coupled receptors can pass through the membrane without binding to a receptor
True
What is meiosis?
Process in eukaryotic, sexually reproducing animals that reduces the number of chromosomes in a cell before reproduction
