Test 2 shit Flashcards
This is where photosynthesis takes place?
chloroplasts
these membranous structures in chloroplasts are stack, flattened disks.
Thylakoids
This is the principle photoreceptor in chloroplasts of green plants
chlorophyll A
chlorophyll a contains this ion in the center of the tetrapyrrole
magnesium
Plastocyanin requires this cofactor for activity
copper
what is the prosthetic group of ferredoxin-NADP+ reductase
FAD
This is one of the accessory pigments in plants
B-carotene
this electron carrier of photosystem I is an iron sulfur protein
ferredoxin b
Photosystems II responds to waves shorter than this value
680 nm
the inner membarne of a chloroplast surrounds a space called the
stroma
the process in which a positive charge forms on one molecule by the loss of a photo excited electron, and a negative charge forms on another by a gain of an electron is referred to as
photo induced charge seperation
P700 is the pigment reaction center for___
photosystem I
The manganese center of photosystem II converts __ to+___
H2O to O2
electrons flow from photosystem I to photosystem II through the
cytochrome bf
In the light reactions of photosynthesis, the cooperation between photosystem I and photosystem II creates a flow of electron from H2O to
NADP+
The light induced electron transfer in photosynthesis result in the transfer of __ into the thylakoid space
H+ or prtons
In ___, ATP is generated without the commitment of NADPH
cyclic phosphorylation
The transfer of excitation energy from one molecule to one nearby through electromagnetic interactions is called
resonance energy transfer
How is light used in photosynthesis?
The light is used to generate high energy electrons with great reducing potential
How many chloroplasts does a typical plant have?
1 to 100
Light absorbed by a chlorophyll a causes
an electron to move from ground state to an excited state
Bacterial reaction centers a analogous to
Photosystem I and II
The D1 and D2 subunits of photosystem II
span the thylakoid membrane
- are similar to each other
- are homologous to the L and Mchains of the bacterial center
Light absorption induces electron transfer from P680 to__
Pheophytin
What is the original source of electrons used to neutralize the special pair in photosystem II?
H2O
The pathway of electron flow from H2O to NADP+ in photosynthesis is referred to as
Z scheme of photosynthesis
How many protons are transferred into the thylakoid lumen after absorption of four photons?
12
What are the light harvesting molecules?
Carotenoids
Chlorophyll b
How is chloroplast similar to mitochondria?
both are site of ATP synthesis
- both have inner and outer membrane
- The thylakoids of chloroplast are analogous to membrane cristae structure
- both may have rise from symbiotic event
these organisms can synthesize glucose from CO2 and water
autotrophs
This is one of the products of photorespiration
phosphoglycolate
This is another name for ribulose 1,5-bisphosphate carboxylase/oxygense
rubisco
this is the pathway that ensures that sufficient amount of CO2 are available to minimize wasteful photorespiration
C4
the reduced form of this molecule is critical to reducing reactive oxygen species
glutathione
this enzyme is involved in both the Clavin cycle and the pentose phosphate pathway
transketolase
this metabolic adaptation is employed by plants living in hot dry climates
Crassulacean acid metabolism
This is a readily transportable and mobilizable sugar in plants
sucrose
these organisms obtain energy from chemical fuels
heterotrophs
This prosthetic group is tightly bound to the enzyme transketolase
TPP
The pentose phosphate pathway is also called
phosphogluconate pahtway
hexose monophosphate pathway
pentose shunt
the enzymes that catalyze the dark reaction of photosynthesis are located in the ___ of the chloroplast
stroma
The first of the Calvin cycle involves the addition of CO2 to ___to produce 2 molecules of 3-phosphoglycerate
ribulose 1,5-bisphosphate
The binding site of Mg2+ to rubisco involves the formation of a ___ group between lysine and Co2
carbamate
In photorespiration, the oxidation of glycol ate to glyoxylate occurs in the __
peroxisomes
The enzyme transketolase, transfers a ___ carbon fragment from a ketose to an aldose
2
In C4 plants, carbon dioxide is added to ____ to form oxaloacetate, which is reduced to malate, which carries CO2 to the bundle sheath cells
PEP
The oxidative phase of the pentose phosphate pathway produces ___which is required for lipid biosynthesis
NADPH
A ___ intermediate is formed between the carbonyl group of the ketose substrata and the 3-amino group of a lysine residue of transaldolase
Schiff base
Hemolytic anemia is caused by a deficiency of the enzyme
glucose 6-phosphate dehydrogenase
What is the source of carbons for the calvin cycle
Carbon dioxide
In the Calvin cycle, 3-phosphoglycerate is converted into which hexose phosphate?
Glucose 1-phosphate
Glucose 6-phosphate
Fructose 6-phoshate
Which sugars are converted into ribulose 5-phosphate by a single enzyme step
ribose 5-phosphate
xylose 5-phosphate
Which form of thioredoxin activates certain Calvin cycle enzymes
reduced
Which coenzyme is required by glyceraldehyde 3-phosphate dehydrogenase in chloroplasts to convert 3-phosphoglycerate into glyceraldehyde 3-phosphte
NADPH
The C4 pathway is necessary in tropical plants because
at high temperatures, the oxygenate activity of rubisco is high
What is the energy cost of the C4 pathway
30 molecules of ATP are used per hexose molecule made
the purpose of the pentose phosphate pathway is to
generate NADPH
synthesize 5-carbon sugars
Which of the following tissues does not contain the enzymes for an active pentose phosphate pathway
Skeletal muscle
Which cofactor is required in glutathione reductase to aid in the reduction of oxidized glutathione by NADPH
FAD
Why are components of the Calvin cycle called the “dark reactions”
unlike photosynthetic reactions the reactions of Calvin cycle do not depend on light to proceed
Describe the stages of the Calvin cycle
1) fixation of CO2 by reaction with ribulose 1,5-bisphosphate to form 2 molecules of 3-PG
2) the formation of hexose sugars from 3-PG
3) the regeneration of ribulose 1,5-Bisphosphate
most of the glucose residues in glycogen are linked by this type of bond
a-1,4 glycosidic bond
This is the activated form of glucose that is required for glycogen synthesis
UDP-glucose
This is the process by which a bond is cleaved by the addition of orthophosphate
phosphorylysis
This type of bond is located at the branch points in glycogen
a-1,6 glycosidic bonds
This is the liver enzyme that cleaves the phosphate from glucose 6-phosphate
glucose 6-phosphatase
this enzyme catalyzes the phosphorylation of glycogen phosphorylase
phosphorylase kinase
this enzyme is the 8 subunit of phosphorylase kinase
Calmodulin
This hormone signifies the starved state
glucagon
This protein serves as the primer used by glycogen synthase
glycogenin
this enzyme serves as the glucose “sensor” enzyme in liver cells
phosphorylase a
Phosphorylase requires the coenzyme ___ for activity
pyridoxal phosphate
phosphoglucomutase requires the intermediate ___ for the interconversion of glucose 1-phosphate and glucose 6-phosphate
glucose 1,6-bisphosphate
In skeletal muscle, the binding of ___converts phosphorylating b into the active form
AMP
Phosphorylase kinase becomes fully active by being phosphorylated and binding
calcium ions
____ stimulates glycogen breakdown in muscle by initiating a cAMP signal-transduction pathway
epinephrine
Glycogen synthase catalyzes the transfer of a glucose residue from UDP-glucose to one of the ____ ends of glycogen
non reducing
the glycogen branching enzyme moves a block of ___ or so glucose residues to form a branch point at least four residues from a preexisting branch
7
glycogen synthase is converted into the active form by the action of ___
protein phosphatase 1, PP1
The complete oxidation of glucose residues from glycogen produces ___ ATP
31
Insulin stimulates glycogen synthase by inactivating ___
glycogen synthase kinase
the major sites of glycogen storage is
Liver
skeletal muscle
The key enzyme I glycogen degradation is
glycogen phosphorylasae
Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme
phosphoglucomutase
what molecule must be excluded from the active site of glycogen phosphorylase
water
how is phosphorylase b converted into phosphorylase A
addition of a phosphate to a serine residue
Why is the T state of glycogen phosphorylase less active
the active site is partially blocked
what physiological conditions render phosphorylase b less active?
high ATP and low calcium ion levels
what is the function of liver glycogen degradation
for glucose export to other tissues when glucose levels are low
Phosphorylase kinase is regulated by
calcium ions
cAMP activated PKA
two critical hormones that signal for glycogen breakdown are?
glucagon and epinephrine
the key regulatory enzyme in glycogen synthesis is
glycogen synthase
Why is glycogen branching important
branching increases the solubility of glycogen
branching increases glycogen synthesis and degradation by increasing potential sites of action
Which of the following occur after a carbohydrate rich meal
blood glucose levels increase leading to glycogen storage in the liver
what is the normal glucose concentration in the blood?
80-120mg/100mL(4.4-6.7mM)
what are the 3 steps in glycogen degradation
1) release of glucose 1-phosphate from glycogen
2) remodeling of glycogen substrate
3) formation of glucose 6-phospahte from glucose1-Phosphate
Why can’t glucose 1-phosphate diffuse out of the cell?
there is no membrane transporter
-negative charge traps it
Triacylglycerols are stored in these cells in animals
adipose
the approximate energy yield from complete oxidation of fatty acids
9kcal/g
these amphipathic molecules facilitate the digestion of fats by incorporating dietary triacylglycerols into micelles in the intestine
bile salts
This molecule is the form in which triacylglycerols are transported rom the intestine to the rest of the body
chylomicrons
This molecule is required to translocate long chain fatty acyl groups in the mitochondria
carnitine
This is the pathway by which an acyl CoA is degraded into acetyl CoA
B oxidation (Fatty acid degradatino)
This is another name for vitamin B12
Cobalamin
The availability of this metabolite determines whether acetyl CoA, made from fatty acids can enter the citric acid cycle
Oxaloacetate
This compound is considered as one of the ketone bodies
D3-hydroxybutyrate
Acetoacetate
Acetone
this molecule is the form in which acetyl groups are carried across the mitochondrial membrane from the matrix to the cytoplasm
citrate
In eukaryotes the degradation of fatty acids occur in the
matrix of the mitochondria
The first step of B-oxidation is a ___ -linked oxidation of the fatty acyl chain
flavin
What stimulates the breakdown of triacylglycerols by activation of a hormone-sensitive lipase
Epinephrine
glucagon
B-oxidation of odd numbered fatty acids produce
Acetyl CoA
Propionyl CoA
The synthesis of fatty acids take place in ___ of the cell
cytoplasm
The coenzyme required for fatty acid synthesis is
NADPH
the commited step of fatty acid synthesis is the formation of
malonyl-CoA
What are the ketone bodies that are a major fuel source of the heart muscle
Acetoacetate and B-hydroxybutyrate
Prostaglandins and Thromboxanes are synthesized from __, a 20 carbon fatty acid
arachidonate
Fatty acids are the building blocks of
phospholipids
glycolipids
Why are triacylglycerols an excellent design for energy storage
anhydrous and reduced
enzymes that digest the triacylglycerol into free fatty acids and monoacylglycerol are called
lipases
The hormone ___ induces lipolysis, where as the hormone ___ inhibits the process
Glucagon
Insulin
The function of the enzyme acyl CoA synthetase is
ATP-dependent activation of fatty acids using CoA
What are the coenzyme(s) involved in the degradation of saturated fatty acyl CoA
FAD
NAD+
How many round of B-oxidation would be required for a 16-C fatty acyl chain to be degraded to Acetyl CoA
7
What types of reactions do cobalamin enzymes catalyze
Intramolecular rearrangements
methylations
reduction of ribonucleotides to deoxyribonucleotides
How does the B-oxidation differ In peroxisomes
the initial dehydrogenation reaction is different in that electrons are transferred to O2 to yeild H2O2
What organs or tissues prefer to use ketone bodies such as acetoacetate as a fuel energy source instead of glucose
Heart muscle
renal cortex
what is the commited step in fatty acid synthesis
synthesis of malonyl CoA
How is acetyl carboxylase globally regulated
Phosphorylation-off
Dephosphorylation-on
How are fatty acid larger than 16 carbons formed
by elongation reactions catalyzed by the enzymes on the endoplasmic reticulum
