Photosynthesis
What is the general equation for photosynthesis?
6CO2 + 12H2O -> C6H12O6 + 6O2
What is a G-protein?
it is an ON-OFF molecular switch that gets activated by the membrane-bound receptor
What is the major difference between a kinase and a second messenger?
A kinase is an enzyme that directly transfers a phosphate group from ATP to another molecule (phosphorylation), while a second messenger is a small molecule that relays a signal received by a cell surface receptor to intracellular components.
Often by activating a kinase; essentially, a kinase is the "active" enzyme that performs the phosphorylation, while a second messenger is the signal molecule that triggers the kinase activation.
Apoptosis can occur in a cell under what conditions?
when a cell is infected by a virus
when a cell is damaged
when a cell is no longer needed
all of the above
d. all of the above
Which type of molecule acts as a signaling molecule in yeasts?
autoinducer
mating factor
second messenger
steroid
b. mating factor
21.
What is the product of the Calvin cycle?
glucose
glyceraldehyde-3-phosphate
phosphoglycerate (PGA)
sucrose
b. glyceraldehyde-3-phosphate
which one of the following would not normally diffuse through the lipid bilayer of a plasma membrane and gives the reason for your answer?
a. CO2; because it is small and polar
b. amino acid; because it is acidic and large
c. starch; because it is too large
d. water; because it is strongly polar
c. starch; because it is too large
What property enables the residues of the amino acids serine, threonine, and tyrosine to be phosphorylated?
They are polar.
They are nonpolar.
They contain a hydroxyl group. R -O-H
They occur more frequently in the amino acid sequence of signaling proteins.
They contain a hydroxyl group.
Epinephrine mediates the fight-or-flight response of the body. One of the effects is to increase the amount of glucose available to muscles. What does the signaling pathway triggered by epinephrine cause to occur in liver cells?
activation of metabolism
cell division
inhibition of glucose metabolism by liver cells
synthesis of enzymes
a. activation of metabolism
Dopamine is a neurotransmitter in the brain that causes long-term responses in neurons and binds to a G-protein-linked receptor. Which of the following chemicals would you expect to increase in concentration immediately after dopamine binds its receptor?
ATP
cAMP
calcium ions
sodium ions
b. cAMP
Only certain organisms, called __________________, can perform photosynthesis; they require the presence of ________________ a specialized pigment that absorbs certain portions of the visible spectrum and can capture energy from sunlight.
photoautotrophs
chlorophyll
The secretion of hormones by the pituitary gland is an example of which type of signaling?
autocrine signaling
direct signaling across gap junctions
endocrine signaling
paracrine signaling
c. endocrine signaling
which of the following correctly describes the role of cyclic AMP?
a. it acts as a second messenger for signaling molecules that cannot pass through the cell membrane
b. it assists in the activation of the tyrosine kinase receptor
c. it activates the g-protein coupled receptor
d. it is an allosteric receptor in an ion-channel receptor
a. it acts as a second messenger for signaling molecules that cannot pass through the cell membrane
DOUBLE JEOPARDY
You need to remember 5 things about signal transduction pathways. What are they?
1. they are characterized by a signal, transduction, and a response.
2. they are highly specific and regulated.
3. one signal molecule can cause a cascade effect, releasing thousands of molecules inside a cell.
4. they regulate cellular activity, altering gene expression, protein activity, or protein synthesis
5. these pathways evolved millions of years ago in a common ancestor
5.
Describe the role of a programmed cell death in development and the maintenance of homeostasis.
during embryonic development when cells are no longer needed, they die and are engulfed by neighboring cells. a familiar example is provided by the cells in the tadpole; which undergo apoptosis during frog metamorphosis
what is carbon fixation? When does it occur in photosynthesis?
Carbon fixation is a reduction of CO2. It occurs during the Calvin Cycle.
Which of the following properties prevents the ligands of cell-surface receptors from entering the cell?
The molecules bind to the extracellular domain.
The molecules are hydrophilic and cannot penetrate the hydrophobic interior of the plasma membrane.
The molecules are attached to transport proteins that deliver them through the bloodstream to target cells.
The ligands are able to penetrate the membrane, directly influencing gene expression upon receptor binding.
b. The molecules are hydrophilic and cannot penetrate the hydrophobic interior of the plasma membrane.
Connect what you have learned about signaling pathways to provide a hypothesis for why signaling differs between types of organisms. Specifically, why is signaling in multicellular organisms more complicated than signaling in single-celled organisms?
Multicellular organisms coordinate between distantly located cells; single-celled organisms communicate only with nearby cells.
Multicellular organisms involve receptors for signaling; single-celled organisms communicate by fusion of plasma membrane with the nearby cells.
Multicellular organisms require more time for signal transduction than single-celled organisms, as they show compartmentalization.
Multicellular organisms require more time for signal transduction than single-celled organisms, as they lack compartmentalization.
a. Multicellular organisms coordinate between distantly located cells; single-celled organisms communicate only with nearby cells.
What condition or event triggers quorum sensing to begin? Provide a real-world example
a sufficient density of bacteria are present
antibiotic resistance or plaque buildup
What is EGF and why would it bind to EGFR?
epidermal growth factor binds to the epidermal growth factor receptor in the case of healing, repairing and/or growing skin cells
Briefly describe the process of photosynthesis. Be sure to name specific parts and steps. Such as light-dependent, light-independent, photosystem I and II, chloroplast, NADPH etc.
OR Draw a picture
1. the light-dependent reactions, absorb energy from sunlight.
2. A photon strikes the antenna pigments of photosystem II to initiate photosynthesis.
3. energy travels to the reaction center that contains chlorophyll a and then to the electron transport chain, which pumps hydrogen ions into the thylakoid interior.
4. action builds up a high concentration of ions.
5. ions flow through ATP synthase via chemiosmosis to form molecules of ATP, which are used for the formation of sugar molecules in the second stage of photosynthesis.
6. Photosystem I absorbs a second photon, which results in the formation of an NADPH molecule, another energy and reducing power carrier for the light-independent reactions.
The gas nitric oxide has been identified as a signaling molecule. Which of the following mechanisms of action would you expect from a gaseous molecule?
It binds to a G-protein-linked receptor.
It binds to a receptor tyrosine kinase.
It binds to a gated ion channel.
It binds to an intracellular receptor.
d. It binds to an intracellular receptor.
The same second messengers are used in many different cells, but the response to those second messengers differs in each cell. How is this possible? Compare explanations below and select the one that supports this claim of varying responses.
Different cells produce the same receptors, which bind to the same ligands but have differing responses in each cell type.
Cells produce variants of a particular receptor for a particular ligand through alternative splicing, resulting in a different response in each cell.
Cells contain different genes, which produce different receptors that bind to the same ligand, activating different responses in each cell.
Cells produce different receptors that bind to the same ligand, or the same receptor that binds to the same ligand with different signaling components, activating different responses in each cell.
d. Cells produce different receptors that bind to the same ligand, or the same receptor that binds to the same ligand with different signaling components, activating different responses in each cell.
Using the yeast mating factor as an example, support the hypothesis that signaling pathways appeared early in evolution and are well-conserved. Evaluate the explanations provided to select the one that best supports the hypothesis.
Signaling in yeast uses the RTK pathway and is evolutionarily conserved, like insulin signaling in humans.
Signaling in yeast uses G-protein coupled receptors for signaling and is evolutionarily conserved, like insulin signaling in humans.
Signaling in yeast uses an endocrine pathway and is evolutionarily conserved, like insulin signaling in humans.
Mating factor in yeast uses an autocrine signaling pathway and is evolutionarily conserved.
b. Signaling in yeast uses G-protein coupled receptors for signaling and is evolutionarily conserved, like insulin signaling in humans.
Bisphenol A is a chemical agent found in many plastics. Its presence in the environment is concerning many scientists. What is the danger of this substance?
a. it is a greenhouse gas and is, in part, responsible for the rise in global temperatures.
b. it blocks a common plasma membrane receptor and prevents normal neuron function.
c. it lowers the water potential and makes it difficult for large fish to diffuse oxygen through their gills.
d. it mimics the hormone estrogen and causes problems in fetal development even when estrogen is not present in excess.
d. it mimics the hormone estrogen and causes problems in fetal development even when estrogen is not present in excess.