Ch. 11-12 Quiz Flashcards
What is local signaling?
Local signaling is communicating with an adjacent or nearby cell
What are examples of local signaling?
Paracrine, synaptic
What is long-distance signaling?
Long-distance signaling is communicating with cells that may be further away
What are examples of long distance signaling?
Endocrine (hormonal)
What is paracrine signaling?
Numerous cells simultaneously receive and respond to molecules of growth factor
Occurs between cells very close by
Signal only lasts a short amount of time because the signaling molecules degrade quickly or cannot travel far
What is reception?
The target cell’s detection of a signal molecule coming from outside the cell. A chemical signal is detected when it binds to a receptor protein located at the cell’s surface or inside cell.
What is transduction?
Membrane protein may have a binding site w/specific shape that fits chemical messenger
Binding of the signal molecule changes the receptor protein in some way
External messenger may cause conformational change in protein that relays message to inside of cell
Converts signal to a form that can bring a specific response
Sometimes occurs in single step but more often requires a sequence of changes
What is response?
Transduced signal triggers a specific cellular response. The response may be almost any cellular activity, such as catalysis by an enzyme, rearrangement of cytoskeleton, or activation of specific genes in nucleus.
What is a ligand?
Ligands are molecules that specifically and reversibly bind to another molecule or receptor
What is testosterone?
Testosterone is a hormone secreted by testis and travels through the blood to enter cells throughout the body
Describe testosterone’s reception, transduction, and response.
Cytosol of target cells contains receptor molecules that bind testosterone, activating receptor.
These activated proteins enter the nucleus and turn on specific genes that control male sex characteristics.
What is a phosphorylation cascade?
Basically, an enzyme phosphorylates (adds a phosphate to) a protein, which causes a reaction to have another protein phosphorylated and so on and so on.
How are kinases involved in phosphorylation cascades?
A protein kinase is the enzyme that transfers phosphate groups from ATP to the protein while the protein phosphatase is the enzyme that removes phosphate groups.
Name the events of the cell cycle in order.
Interphase (G1, S, G2) and mitosis (prophase, prometaphase, metaphase, anaphase, telophase) cytokinesis
Describe the chromosome structure.
The DNA is wrapped around proteins called histones to create chromatin
The chromatin is tightly coiled to form a chromosome
What are the phases of cell division and what happens in each?
Interphase - cell prepares to divide
Mitosis - the nucleus divides
Cytokinesis - A cleavage furrow forms and pinches the cell in two
What are the stages of mitosis?
Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis
What happens in prophase?
Chromatin condenses into chromosomes Nucleoli disappear Each duplicated chromosome appears as two identical sister chromatids Mitotic spindle forms Centromeres move away from each other
What happens in prometaphase?`
The nucleus envelope fragments
Chromosomes are condensed
Microtubules extend to the middle of the cell
Kinetochores (protein structure attached to the centromere of the chromosome) attach to the microtubules to move them around
What happens in metaphase?
Centromeres at the opposite end of the cell Chromosomes convene (line up) on the metaphase plate The kinetochores of the sister chromatids are attached to kinetochore microtubules (protein structure attached to the centromere of the chromosome) coming from opposite poles (The sister chromatids are attatched to the microtubules, AKA the spindle)
What happens in anaphase?
Chromatid pairs are pulled apart by microtubules to each end of the cell
By the end of anaphase, the ends have complete collections of chromosomes
What happens in telophase?
Two daughter nuclei form
nuclear envelopes begin to form
chromosomes become less dense
What is the primary difference between animal and plant cells?
Animal Cells:
- pinching inward of cell membrane - center of cell - ”cleavage furrow”
Plant cells:
- no pinching inward - cell plate form in center of cell - cell membranes and cell walls form on each side of the cell plate
What is the mitotic spindle?
-the mitotic spindle separates the two sister chromatids during mitosis
What are the three checkpoints?
G1, G2, and S
What is G1 checkpoint?
Cyclically operating set of molecules in the cell that trigger and coordinate events of the cell cycle
What is the Mitosis checkpoint?
Internal signal (between metaphase and anaphase) sent by kinetochores, signals that it is okay to begin anaphase once all chromosomes are properly attached
