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BIOL 240 Lecture Notes - Lecture 14: P680, Oxidative Phosphorylation, P700

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azuremole431
24 Oct 2018
School
University of San Diego
Department
Biology Courses
Course
BIOL 240
Professor
Lisa Baird

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Document Summary

A photon hits a pigment in a light-harvesting complex of ps ii, and its energy is passed among pigment molecules until it excites p680 (we"ll call it p680+) An excited electron from p680 is transferred to the primary electron acceptor. H2o is split by enzymes, and the electrons are transferred from the hydrogen atoms to p680+, thus reducing it to p680. P680+ is the strongest known biological oxidizing agent. The h+ are released into the thylakoid space. O2 is released as a by-product of this reaction. Each electron is transferred down an electron transport chain from the primary electron acceptor of psii to psi. Energy released by this process drives the creation of a proton gradient across the thylakoid membrane. Potential energy stored in the proton gradient drives production of atp by chemiosmosis. In psi, transferred light energy excites p700, which loses an electron to the primary electron acceptor.

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Related Questions

Which of the following best describes what happens next to the energy from a photon of light after it excites an electron in the pigment molecule of a plant?

a. The excited electron carries the energy to the primary electron acceptor in the reaction center complex

b. the energy is released as heat and the electron drops back down to its ground state

c. the energy is passed to the other electrons in the light-harvesting complex until it reaches the reaction center complex and reduces the primary electron acceptor

d. the energy is released as light and the electron drops back down to its ground state

e. the excited electron carries the energy to the reaction center complex and oxidizes the primary electron acceptor

2. chromosomes are replicated in the _______ of a cell and sister chromatids are separated in the ____

a. nucleus; cytosol

b. nuclear envelope; nucleus

c. nuclear lamina, nucleus

d. cytosol; cytosol

e. centriole; nucleus

3.which of the following accurately describes a difference between sister chromatids and a chromosome?

a. a pair of sister chromatids contain 2 double-stranded molecules of DNA and a chromosome has 4 double-stranded molecules of DNA

b. each sister chromatid has a single strand of DNA and chromosomes have 2

c. sister chromatids have centromeres and a chromosome does not

d. a pair of sister chromatids contain identical genes, and a chromosome does not

e. sister chromatids are produced during M phase and chromosomes are always present in the cell cycle

4. all of the following take place during mitosis except..

a. DNA is proofread for replication errors

b. chromosomes are replicated

c. the mitotic spindle is formed

d. the nuclear envelope breaks down

e. sister chromatids are separated

f. A and B only

g. B and C only

h. C and D only

i. D and E only

The complete set of reactions carried out by an organism is called:

a. anabolism

b. catabolism

c. metabolism

Value: 2

The breakdown of starch is broken down to glucose is an example of:

a. anabolism

b. catabolism

c. metabolism

Value: 3

For the following statement, determine which description best describes the process: DNA is synthesized from free nucleotides.

a. anabolism

b. catabolism

c. metabolism

Value: 4

Fill in the blank: Catabolic reactions result in the synthesis of molecules of .............via cellular respiration. This is then used to power anabolic reactions.

Value: 5

The energy in organic molecules is released in a series of steps because:

a. it is not possible to release it in a single step.

b. more total energy is released in multiple steps than would be released in a single step

c. less total energy is released in multiple steps than would be released in a single step.

d. more energy can be harvested for cellular use in multiple steps than from a single step.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

photosynthesis

1-The light reaction of photosynthesis does not include

a. chemiosmosis

b. oxygen liberation

c. glucose synthesis

d. electron transport

Value: 2

Photosynthesis takes place in the membranes of small sacs called

a. thylakoids

b. photosystems

c. stroma

d. photons

Value: 3

During what stage of photosynthesis is O2 produced?

a. the light-dependent reactions involving photosystems I and II

b. carbon fixation

c. the Krebs cycle

d. O2 is not produced during photosynthesis

Value: 4

The pigment molecules responsible for photosynthesis are located in the

a. mitochondria

b. cytoplasm of the cell

c. stroma of the chloroplast

d. thylakoid membrane of the chloroplast

Value: 5

During what stage of photosynthesis are ATP and NADPH converted to ADP + Pi and NADP+?

a. the light-dependent reactions

b. the light-independent reactions

c. both of the above

d. none of the above

Value: 6

What energy-rich organic compound is produced as a result of the Calvin cycle?

a. ATP

b. NADPH

c. glucose

d. H2O

Value: 7

During photosynthesis, photons raise electrons to higher energy levels. These excited electrons belong to what compound?

a. water

b. ATP

c. chlorophyll

d. electron transport chain

Value: 8

Which of the following statements accurately describes the relationship between photosynthesis and cellular respiration?

a. photosynthesis occurs only in autotrophs; cellular respiration occurs only in heterotrophs

b. photosynthesis uses solar energy to convert inorganics to energy-rich organics; respiration breaks down energy-rich organics to synthesize ATP

c. photosynthesis involves the oxidation of glucose; respiration involves the reduction of CO2

d. the primary function of photosynthesis is to use solar energy to synthesize ATP; the primary function of cellular respiration is to break down ATP and release energy


All True orFalse

6.___ During the process of human fermentation the pyruvatemolecule produced at the end of glycolysis is converted into athree carbon molecule called ethyl alcohol while NAD+ is reduced toNADH and a CO2 molecule is released to the atmosphere.

7.___ The proton pumps of the inner membrane of themitochondrion are examples of integral transmembrane,active-transport carrier proteins.

8.___ Photosynthetic pigment molecules of plants are able torelease electrons to an ETC that are utilized to power the eventsof chemiosmosis.

9.__ Photoautotrophs (plants) use inorganic CO2 molecules astheir carbon source for building organic molecules and they usepigment molecules as their proximate source of electrons for theprocess of chemiosmosis.

10.__ The overall process of the TCA/CAC is exergonic with theproduction of ATP molecules and NADH/FADH2 all having stored energyderived from the reactants.

11.__ If a chemical reaction is catalyzed by an enzyme then thereactants will be able to initiate a chemical reaction withslightly more activation energy and the reaction would beclassified as an endergonic process if the products have lessenergy than the reactants.

12.__ The chemical reactions of glycolysis, the Krebs Cycle (TCAcycle), and oxidative phosphorylation, are all processes that canonly be performed when O2 is present (aerobic conditions).

13.___ Photophosphorylation is a type of chemiosmotic processand it possesses a key component of electron transport a finalelectron acceptor and in this case an organic molecule (FEA).

14.___ The pigment molecules, that make up a component of thechloroplasts of a plant, absorb light best in the green wavelengthsand that is why the plants appear so green.

15.___ Features in common for oxidative phosphorylation andphotophosphorylation are an electron source from dinucleotideelectron carrier molecules and an inorganic final electronacceptor.

16.___ In the metabolic pathways we discussed one would expectto find a number of points where allosteric enzymes are associatedwith positive feedback and/or negative feedback systems, and insome systems the allosteric enzyme is affected by both types ofregulatory molecules.