Photosynthesis
What organelle does photosynthesis occur in?
Chloroplast
What is the formula for water potential?
Y = YS + YP
Bile is produced by the liver and stored in the gallbladder.
What organelle does cellular respiration take place in?
mitochondria
Where is water absorbed?
What product of the light reaction provides the energy
required by the Calvin cycle?
ATP
What molecule does phloem generally transport?
sugar
Which macromolecules are ONLY digested in the small intestine?
lipids and nucleic acids
What is the final electron acceptor?
Which type of plant transport is bidirectional and which is unidirectional?
Phloem- bidirectional
Xylem- unidirectional
What product of the light reaction provides the electrons
required by the Calvin cycle?
NADPH
A plant cell with a Ys of -0.65 MPa maintains a constant volume (no net water movement) when bathed in a solution that has a Ys of -.30 Mpa and no pressure. The cell has a YP of what?
Ψp=0.35 MPa
What two enzymes are used for the digestion of proteins? Where are each of these enzymes produced?
1. Pepsin- epithelial cells of the stomach
2. Trypsin- pancreas
True or False: During cellular respiration, the NADH produced in glycolysis directly donates its electrons to the electron transport chain in the inner mitochondrial membrane without any shuttle system
Explain why.
False: the NADH from glycolysis remains in the cytoplasm and does not cross the mitochondrial membrane
Describe the role of transport proteins in the apical and basal surfaces of the small
intestine epithelial cells during the absorption of glucose. (e.g., Na+/glucose symporter,
GLUT2, Na+/K+ pump)
1. Na+/K+ ATPase: located in the basal membrane, pumps Na+ out and K+ in, creates the concentration gradient for Na+/glucose symporter
2. Na+/glucose symporter: located on the apical side, pumps Na+ and glucose into the cell
3. GLUT 2: a transport protein that allows glucose to flow out of the cell
What molecule is the source of the Oxygen that is produced
during the light reactions?
Water
What is the role of proton pumps in phloem and xylem transport?
Phloem: Create H⁺ gradient used to actively load sucrose via H⁺/sucrose symporters, think about the sieve-tube, companion cell, and root cell structure
Xylem: helps actively transport minerals into root cells, indirectly supporting water movement
What two hormones are used to maintain blood glucose homeostasis, and where are they produced? Briefly note the role of both hormones.
insulin and glucagon
both produced in the pancreas
insulin- reduces blood/glucose
glucagon- increase blood/glucose
Explain why ATP regulates phosphofructokinase.
High ATP → binds allosteric site → PFK slows → glycolysis slows.
Low ATP → doesn’t bind → PFK active → glycolysis runs faster.
What is the cohesion-tension theory?
A theory describing how water is pulled
through the xylem by negative
pressure. When tension pulls water
molecules into the air spaces, all the
water molecules below are pulled up
the xylem
Remember:
Tension: surface tension due to
Evaporation creates negative water
potential drawing water out
Cohesion: Water molecules in the leaf
and xylem are bound together in a
continuous chain by hydrogen
bonds
Describe the role of chemiosmosis in photosynthesis. What initially results in a high H+ concentration within the lumen? What molecule does H+ flow out of?
As electrons move through the electron transport chain, they move down their energy gradient and release energy, which is used to pump H+ ions into the lumen. H+ then diffuses out of ATP synthase and allows for the conversion of ADP into ATP.
The role of positive and negative pressure in phloem and xylem transport? i.e., which transport goes with what type of pressure and why.
In xylem, transpiration from leaves creates tension. This negative pressure pulls water upward from the roots.
Phloem transport is driven by positive pressure pushing sap through sieve tubes. (always moving from sources to sink)
Explain the cellular signaling events that occur when GLP-1 binds to its GPCR on
pancreatic beta cells and how the downstream effects are beneficial to individuals with
diabetes Type II.
1. GLP-1 binds GPCR
2. activates the G-protein
3. alpha subunit (GTP-bound), interacts with AC and produces cAMP
4. cAMP activates PKA
5. Pka closes K+ channels
6. Closed K+ channels change membrane voltage
7. Voltage-gated Ca2+ channels open
8. Ca2+ causes insulin vesicles to undergo exocytosis, secreting insulin
GLP-1 signaling increases insulin secretion from pancreatic β-cells, which lowers blood glucose and improves glucose regulation in people with Type II diabetes.
Describe what occurs at the active site of Phosphofructokinase and compare this to
what occurs at the regulatory/allosteric site of Phosphofructokinase (only mentioned on 1-2 slides, but part of C.R. study guide objectives)
Active site: a high-affinity binding site for
ATP and Fructose-6-phosphate
Regulatory site: low-affinity binding site
of ATP leads to the inhibition of the enzyme
What are the three pathways for water to reach the xylem? Briefly explain each.
Symplastic route: Crosses 1 membrane, then uses plasmodesmata
to vascular tissue
Transmembrane route: Repeated membrane crossing to the vascular space issue [Use of Aquaporins]
Apoplastic route: Travels along cell walls, never crossing a membrane (CANNOT enter vascular tissue by this route alone)