Term
Describe the plasma membrane as a fluid mosaic. |
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Definition
The fluid mosaic model states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it. |
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Term
What are the 4 components of the plasma membrane? |
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Definition
a. Phospholipid bilayer
i. Flexible matrix, barrier to permeability
b. Transmembrane proteins
i. Integral membrane proteins
c. Interior protein network
i. Peripheral or Intracellular membrane proteins
d. Cell surface markers
i. Glycoproteins and glycolipids |
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Term
Describe the orientation of the phospholipids bilayer. |
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Definition
Structure consists of
i. 2 fatty acids attached to glycerol
1. Nonpolar and hydrophobic
ii. Phosphate group attached to the glycerol
1. Polar and hydrophilic |
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Term
| Describe the fluidity of the plasma membrane. |
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Definition
a.Saturated fatty acids make the membrane less fluid than unsaturated fatty acids
i.Double bonds keep them from packing tightly |
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Term
| What role does temperature play [w/ the fluidity of the plasma membrane]? |
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Definition
a.Warm temperatures make the membrane more fluid than cold temperatures
b.At cool temperatures it maintains fluidity by preventing tight packing |
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Term
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Definition
i.Only single bonds between neighboring carbons in the hydrocarbon chain
ii.Fatty acid is said to be saturated with hydrogen
1.In other words the number of hydrogen atoms attached to the carbon skeleton is maximized |
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Term
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Definition
| i.If the hydrocarbon chain contains a double bond the fatty acid is said to be unsaturated |
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Term
| What is the role of cholesterol? |
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Definition
| a.The steroid cholesterol has different effects on membrane fluidity at different temperatures |
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Term
| What are the 6 major functions of membrane proteins? |
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Definition
a.Transporters
b.Enzymes
c.Cell-surface receptors
d.Cell-surface identity markers
e.Cell-to-cell adhesion proteins
f.Attachments to the cytoskeleton |
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Term
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Definition
| i.Bound to the surface of the membrane |
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Term
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Definition
| i.Span the lipid bilayer (transmembrane proteins) |
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Term
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Definition
i.Extensive nonpolar regions within a transmembrane protein can create a pore through the membrane
1.Interior is polar and allows water and small polar molecules to pass through the membrane |
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Term
| Nonpolar Regions Of The Protein |
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Definition
| Embedded in the interior of the bilayer |
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Term
| Polar Regions Of The Protein |
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Definition
| Protrude From Both Sides Of The Bilayer |
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Term
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Definition
i.Movement of molecules through the membrane in which
1.No energy required
2.Down a concentration gradient |
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Term
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Definition
i.Movement of molecules through the membrane in which
1.No energy required
2.Down a concentration gradient |
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Term
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Definition
i.Movement of molecules from high concentration to low concentration
1.Until the concentration is the same in all regions |
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Term
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Definition
i.Molecules that cannot cross membrane easily may move through proteins
ii.Move from higher to lower concentration |
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Term
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Definition
i.Ion channels
1.Allow the passage of ions
ii.Gated channels
1.Open or close in response to stimulus (chemical or electrical)
iii.Hydrophilic channel when open |
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Term
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Definition
i.Bind specifically to molecules they assist
ii.Can help transport both ions and other solutes
1.Such as some sugars and amino acids
iii.Requires a concentration difference across the membrane |
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Term
| What molecules are permeable through the membrane? |
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Definition
a.Nonpolar molecules pass through
b.Limited permeability to small polar molecules
c.Very limited permeability to larger polar molecules and ions |
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Term
| What is responsible for selective permeability? |
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Definition
| a.The hydrophobic interior repels polar molecules but not nonpolar molecules |
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Term
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Definition
| i.Net diffusion of water across a semi-permeable membrane toward a higher solute concentration |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
i.Facilitate osmosis
ii.Channel proteins that move water |
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Term
| What happens to plant and animal cells in hypotonic solutions? |
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Definition
a.Cell in a hypotonic solution gains water causing cell to swell
i.Creates pressure
b.If membrane is not strong may burst
c.Animal cells must be in isotonic environments
d.Plant cells use turgor pressure to push the cell membrane against the cell wall and keep the cell rigid |
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Term
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Definition
| a.The pressure of water pushing the plasma membrane against the cell wall of a plant cell |
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Term
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Definition
i.Requires energy
ii.ATP is used directly or indirectly to fuel active transport
iii.Moves substances from low to high concentration
iv.Requires the use of highly selective carrier proteins |
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Term
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Definition
a.Coupled Transport
i.Glucose-Na+
1.Captures the energy from Na+ diffusion to move glucose against a concentration gradient |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| i.Movement of substances into the cell |
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Term
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Definition
i.Cell takes in particulate matter
ii.“Cellular Eating” |
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Term
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Definition
i.Cell takes in only fluid
ii.“Cellular Drinking” |
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Term
| Receptor-mediated Endocytosis |
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Definition
i.Specific molecules are taken in after they bind to a receptor
ii.(Ex. hypercholesterolemia) |
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Term
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Definition
i.Discharge of materials out of the cell
ii.Requires energy
iii.Used in animals to secrete hormones, digestive enzymes |
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Term
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Definition
i.Able to produce their own food through photosynthesis
ii.(Ex. Algea and Plants) |
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Term
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Definition
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Term
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Definition
i.Live on organic compounds produced by other organisms
ii.(Ex. Dogs, Cats, and Birds) |
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Term
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Definition
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Term
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Definition
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Term
| During aerobic respiration, what is reduced, what is oxidized? |
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Definition
a. During aerobic respiration the fuel (such as glucose) is oxidized and O2 is reduced
b. Oxygen is necessary |
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Term
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Definition
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Term
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Definition
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Term
| What is NAD+ and what is its role? |
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Definition
a.NAD+
i.Nicotinamide adenosine dinucleotide
1.An electron carrier
2.Reaction is reversible |
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Term
| What is the final electron acceptor in Aerobic Respiration? |
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Definition
| a. Final electron receptor is Oxygen (O2) when present. |
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Term
| What is the final electron acceptor in Anaerobic Respiration? |
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Definition
| a. Final electron acceptor is an inorganic molecule (not O2) |
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Term
| What is the final electron acceptor in Fermentation? |
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Definition
| a. Final electron acceptor is an organic molecule |
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Term
| What is the equation for aerobic respiration? |
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Definition
| a. C6H12 + 6O2 --> 6CO2 + 6H2O |
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Term
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Definition
a. -686 kcal/mol of glucose
b. This large amount of energy must be released in small steps rather than all at once |
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Term
| What is the equation for aerobic respiration? Is free energy + or -? |
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Definition
a.C6H12 + 6O2 6CO2 + 6H2O
b.Free energy
i.-686 kcal/mol of glucose
ii.This large amount of energy must be released in small steps rather than all at once |
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Term
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Definition
| a. NAD+ acquires 2 electrons and a proton to become NADH |
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Term
| What are the 2 mechanisms for ATP synthesis in cellular respiration? |
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Definition
i.Substrate Level Phosphorylation
1.Transfer group directly to ADP
2.During glycolysis
ii.Oxidative Phosphorylation
1.ATP synthase uses energy from a . proton gradient |
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Term
| What are the 4 stages of aerobic respiration? |
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Definition
a. Glycolysis
b. Pyruvate Oxidation
c. Krebs Cycle (Citric Acid Cycle)
d. Electron Transport Chain and Chemiosmosis (Oxidative Phosphorylation) |
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Term
| Why is it important that NADH is recycled? |
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Definition
| a. For glycolysis to continue NADH must be recycled to NAD+ by either Aerobic Respiration or Fermentation. |
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Term
| What happens in glycolysis? Where does it take place? How many ATP, NADH are made? |
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Definition
i. Converts 1 glucose (6 carbons) to 2 pyruvate (3 carbons)
ii. 10 step biochemical pathways
iii. Occurs in the cytoplasm
iv. Net production of 2 ATP molecules by substrate level phosphorylation
v. 2 NADH produced by the reduction of NAD+ |
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Term
| What happens to pyruvate when oxygen is present? Absent? |
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Definition
a. When oxygen is present, pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle
i.Aerobic respiration
b. Without oxygen, pyruvate is reduced in order to oxidize NADH back to NAD+
i.Fermentation |
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Term
| What are the products of pyruvate oxidation? CO2? Per glucose? |
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Definition
a.For each 3-carbon pyruvate molecule:
i.1 CO2
1.Decarboxylation by pyruvate dehydrogenase
ii.1 NADH
iii.1 acetyl-CoA which consists of 2 carbons from pyruvate attached to coenzyme A
1.Acetyl-CoA proceeds to the Krebs cycle |
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Term
| What enters the Kreb Cycle? Where does it occur? What is the significance of oxaloacetate? Citrate? What is the yield of CO2, NADH, FADH2, ATP, per glucose? |
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Definition
i.Oxidizes the acetyl group from pyruvate
ii.Occurs in the matrix of the mitochondria
iii.Biochemical pathway of 9 steps in three segments
iv.Acetyl-CoA + oxaloacetate → citrate
v.Citrate rearrangement and decarboxylation
vi.Regeneration of oxaloacetate
vii.For each Acetyl-CoA entering:
1.Release 2 molecules of CO2
2.Reduce 3 NAD+ to 3 NADH
3.Reduce 1 FAD (electron carrier) to FADH2
4.Produce 1 ATP
5.Regenerate oxaloacetate |
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Term
| What is the total yield for first 3 stages/glucose? |
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Definition
a.6 CO2
b.4 ATP
c.10 NADH
d.2 FADH2 |
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Term
| Describe ETC, where is it located. What happens there? |
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Definition
i. ETC is a series of membrane-bound electron carriers
ii. Embedded in the inner mitochondrial membrane
iii. Electrons from NADH and FADH2 are transferred to complexes of the ETC
iv. Each complex
1.A proton pump creating proton gradient
2.Transfers electrons to next carrier |
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Term
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Definition
| i. Protein complexes that pump protons from the interior of the cell to the exterior |
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Term
| Describe chemiosmosis. What is made? |
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Definition
a.Accumulation of protons in the intermembrane space drives protons into the matrix via diffusion
b.Membrane relatively impermeable to ions
c.Most protons can only reenter matrix through ATP synthase
d.Uses energy of gradient to make ATP from ADP + Pi |
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Term
| What is the energy yield/ glucose? Theoretical vs Actual? |
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Definition
a.Theoretical energy yield
i. 38 ATP per glucose for bacteria
ii. 36 ATP per glucose for eukaryotes
b. Actual energy yield
i.30 ATP per glucose for eukaryotes
ii.Reduced yield is due to
1.“Leaky” inner membrane
2.Use of the proton gradient for purposes other than ATP synthesis |
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Term
| Define anaerobic respiration. |
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Definition
i. Use of inorganic molecules (other than O2) as final electron acceptor
ii. Many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals |
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Term
| What happens in fermentation? |
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Definition
| i. Use of organic molecules as final electron acceptor |
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Term
| What are the products of ethanol fermentation? What organism does this occur in? |
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Definition
a. Ethanol fermentation occurs in yeast
b. CO2, ethanol, and NAD+ are produced |
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Term
| What are the products of lactic acid fermentation? Where does it occur? |
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Definition
a. Occurs in animal cells (especially muscles)
b. Electrons are transferred from NADH to pyruvate to produce lactic acid |
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Term
| What is the significance of photosynthesis? |
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Definition
| a. Energy for all life on Earth ultimately comes from photosynthesis |
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Term
| Describe where photosynthesis takes place in a plant? |
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Definition
a. Leaf
i. Main organ of photosynthesis
b. Mesophyll
i. Middle of leaf where chloroplasts are found |
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Term
| What are stoma and what do they do? |
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Definition
| i. Pores in leaf that let CO2 in, O2 out |
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Term
| What are the 2 main stages of photosynthesis? What happens in each? |
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Definition
a. Light-dependent reactions
i. Require light to make ATP & NADPH
ii. Oxygen produced from water splitting
b. Light-independent reactions (Calvin Cycle)
i. Does not require light
ii. Use ATP and NADPH to “fix” CO2 into organic molecules (glucose) |
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Term
| What is the role of pigments? |
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Definition
| i. Absorb light energy in the visible range |
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Term
| Define absorption spectrum. |
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Definition
| i. Range and efficiency a photon molecule is capable of absorbing |
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Term
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Definition
a. Packets of light energy
i. Inversely proportional to the wavelength of the light |
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Term
| What are the 2 main types of pigments? |
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Definition
a. Only two general types of pigments
i. Chlorophylls
ii. Carotenoids |
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Term
| Differentiate chloropyll a from chlorophyll b. |
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Definition
a. Chlorophyll a
i. Main pigment in plants
ii. Absorbs violet-blue and red light
iii. Transmits blue-green
b. Chlorophyll b
i.Accessory pigment
ii. Absorbs light wavelengths that chlorophyll a does not absorb
iii. Transmits yellow-green |
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Term
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Definition
i. Transmit yellow, orange, red
ii. Accessory pigments
iii. Absorbs others
iv. Protect chlorophyll from uv radiation |
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Term
| Where are photosystems located? What are they made up of? |
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Definition
a. Embedded in thylakoid membrane
b. Contain
i. Antenna complex
ii. Reaction center |
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Term
| Describe the antenna complex. What does it do? |
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Definition
a. Light-harvesting complex
b. Captures photons from sunlight and channels them to the reaction center |
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Term
| Describe the reaction center. What does it do? |
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Definition
a. Protein–pigment complex
b. When reaction center chlorophyll absorbs a photon of light, an electron is excited to a higher energy level
c. Light-energized electron can be transferred to the primary electron acceptor
d. Chlorophyll then fills its electron “hole” by oxidizing a donor molecule |
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Term
| What are the 4 parts of the light-dependent reactions? |
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Definition
a. Photon of light is captured by a pigment molecule
b. Energy is transferred to the reaction center; an excited electron is transferred to an acceptor molecule
c. Electron transport
i. Electrons move through carriers to reduce NADP+
d. Chemiosmosis
i. Produces ATP |
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Term
| What is cyclic photophosphorylation? What is generated? |
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Definition
a. In sulfur bacteria, only one photosystem is used
b. Generates ATP via electron transport
c. Anoxygenic photosynthesis
d. Excited electron passed to electron transport chain
e. Generates a proton gradient for ATP synthesis |
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Term
| What happens between electrons from PSI? PSII? |
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Definition
a. Photosystem I transfers electrons ultimately to NADP+ producing NADPH
b. Electrons lost from photosystem I are replaced by electrons from photosystem II
c. Photosystem II oxidizes water to replace the electrons transferred to photosystem I
d. 2 photosystems connected by an ETC |
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Term
| What is the role of water in PSII? |
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Definition
| a. Photosystem II oxidizes water to replace the electrons transferred to photosystem I |
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Term
| How is PSII different from PSI? |
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Definition
a. The main difference between Photosystem I and Photosystem II is the absorption peak
b. Photosystem I has an absorption peak of 700 nanometers, while Photosystem II has an absorption peak of 680 nanometers |
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Term
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Definition
i. P700 chlorophyll
ii. PS I accepts an electron from PSII
iii. Passes electrons to NADP+ to form NADPH |
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Term
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Definition
i. - P680 chlorophyll molecules
ii. Proton pump embedded in thylakoid membrane |
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Term
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Definition
| a. Used to synthesize ATP |
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Term
| Where is ATP synthase located? (chemiosmosis) |
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Definition
b. ATP synthase enzymes in the thylakoid membrane
i. Allows protons back into stroma |
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Term
| What happens in the Calvin Cycle? Where are the enzymes found? |
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Definition
a. Enzymes found in stroma
b. Uses ATP and NADPH from light reactions
c. Key step is attachment of CO2 to RuBP to form PGA (carbon fixation)
d. Uses enzyme RUBISCO |
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Term
| What is RUBISCO? What does it do? |
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Definition
a. Helps initiate the light-independent reactions of photosynthesis
b. Enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) |
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Term
| What are the 3 phases of the Calvin Cycle? What is directly made? |
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Definition
a. Carbon fixation
i. RuBP + CO2 → PGA
b. Reduction
i. PGA is reduced to G3P
c. Regeneration of RuBP
i. PGA is used to regenerate RuBP
d. 3 turns incorporate enough carbon to produce a new G3P
e. 6 turns incorporate enough carbon for 1 glucose |
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Term
| How many turns of the cycle are required to make glucose? |
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Definition
| e. 6 turns incorporate enough carbon for 1 glucose |
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Term
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Definition
a. G3P is a 3 carbon sugar
i. Used to form sucrose
ii. Used to make starch |
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Term
| When does photorespiration occur? What does it create? |
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Definition
a. CO2 and O2 compete for the active site on RuBP when stoma are closed in hot conditions
b. Creates low-CO2 and high-O2 |
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Term
| What do C3 and CAM adaptations minimize? |
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Definition
a. C4 and CAM adaptations
i. Minimize photorespiration |
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Term
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Definition
a. C4 plants
i. Spatial solution
ii. Ex. corn, sugarcane |
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Term
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Definition
i. Temporal solution
ii. Stomata open at nightand closed during the day
iii. Ex. cacti, pineapple |
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