Plant Cellular Respiration Flashcards
In plant metabolism, sugar can be in the form of ___ and ___.
sucrose
starch
Disaccharide: _____
Polysaccharide: ______
sucrose
starch
Sucrose consists of ___;
Starch consists of ____.
glucose + fructose
many glucose units
Where does sucrose accumulate? Where is it transported after?
cytosol
heterotrophic sink tissues (roots, stems, tuber)
What happens to starch during daytime?
stored at the vacuole; called “transitory starch” which is insoluble and dense.
At night, what happens to the transitory starch?
subjected to degradation
A part of a plant that produces or releases sugars, such as a leaf is called ___.
source
A part of a plant that receives or stores sugars, such as seeds, fruits, flowers, roots, and storage organs are called ____.
sink
What are photosynthates?
sucrose and starch
What part of the plant transports photosynthates?
phloem
During photosynthesis, the amount of photosynthates increases, which drives increased cellular metabolism and growth and development.
true
What is the second most abundant polysaccharide next to cellulose?
starch
Two types of starch
amylose
amylopectin
Where is starch synthesized and stored?
synthesized in the chloroplast;
stored in the vacuole
A type of starch that is linear; glucose units are connected by alpha - 1,4 glycosidic bond; has less than 1% branching.
amylose
A type of starch that is branching; branching pattern is facilitated by alpha - 1,6 glycosidic bond; 5-6% branching.
amylopectin
It is the reverse chemical reaction of photosynthesis.
cellular respiration
What are the various substrates of plants to fuel cellular respiration?
- disaccharides
- organic acids: pyruvate, malate
- phosphorylated sugar like triose phosphate
- lipids and proteins
What are the three main phases of cellular respiration?
- glycolysis
- TCA cycle/citric-acid cycle
- oxidative phosphorylation
The oxidation of sucrose can be grouped into 4 major processes. What are these?
- glycolysis
- oxidative pentose phosphate pathway
- citric acid cycle
- oxidative phosphorylation
The process by which sugar is split to produce glucose is called ____.
glycolysis
Where does glycolysis occur?
cytosol
When O2 is unavailable for glycolysis, it is followed by ____.
fermentative pathway
How does glycolysis in plants differ from animals?
variations in:
1. regulatory features
2. alternative enzymatic routes
3. a parallel partial glycolytic pathway in plastid
What are the two pathways for splitting sucrose?
- invertase pathway
- sucrose synthase pathway
Invertase pathway and sucrose synthase pathway: irreversible or reversible?
- invertase pathway: irreversible
- sucrose synthase pathway: reversible
The existence of two different pathways that split sucrose and can replace each other without a clear loss in function is called ___.
metabolic redundancy
What are the two phases of glycolysis?
- initial phase
- energy conserving phase
What happens in the initial phase of glycolysis?
hexose is phosphorylated
twice and split, which produces 2 triose-P. this consumes 2 – 4 ATPs/ sucrose unit.
The initial phase of glycolysis includes 2/3 irreversible reactions, catalyzed by ___ and ___.
hexokinase, phosphofructokinase.
What happens in the energy conserving phase of glycolysis?
nad+ is reduced to nadh via 3-phosphate dehydrogenase.
Products of glycolysis
2 molecules of Pyruvate
2 molecules of CO2
2 molecules of NADH
An alternative pathway for the oxidation of
sugars.
oxidative pentose phosphate pathway
Oxidative pentose phosphate pathway is carried out by the enzymes in ___ and ___.
cytosol and plastids
Main idea of OPPP
glucose-p (hexose-p) is converted to ribulose-p (pentose-p); which is then converted to triose (g3p) to enter glycolytic pathway.
Products of OPPP
- CO2
- NADPH
- Pentose-p
Roles of oxidative pentose phosphate pathway in plant metabolism
- NADPH supply in the cytosol
- NADPH supply in plastids
- Supply of substrate for biosynthetic
pathways
Cytosolic reactions generate products that are transported into the mitochondria to feed the
citric acid cycle. True or False?
true
Fates of PEP:
* Pyruvate → transported directly to
mitochondrion via pyruvate dehydrogenase
* Oxaloacetate → transported directly to
mitochondrion; converted to malate via PEP carboxylase & malate dehydrogenase → OAA, pyr
true
Oxidizes organic acid → CO2, and transfer electrons to reduce NAD+ and FAD → NADH & FADH2 respectively.
citric acid / tca / krebs cycle
Where does citric acid cycle take place?
mitochondria
TCA can oxidize amino acid, but fatty acid oxidation occurs in peroxisome in plants (vs. animal mitochondrion). True or False?
true
What are the unique features in Plant TCA cycle?
- ATP; animals: GTP
- malic enzyme ; animals have none
What are the major events that take place in citric acid cycle?
- oxidation: OAA to citric acid
- reduction: NAD to NADH and FAD to FADH2
- phosphorylation (substrate-level): ATP
- decarboxylation: CO2 is released
Components of Mitochondrial ETC found in the inner mitochondrial membrane
- protein complexes
- mobile electron carriers
- ATP synthase (complex v)
The presence of __ and ___ are unique features of plant mitochondrial ETC.
- alternative oxidase
- NAD(P)H dehydrogenase
A feature of plant mitochondrial ETC that is tightly bound to the inner mitochondrial membrane.
alternative oxidase
Alternative oxidase transfers electrons from UQ → O2, which bypasses ___, generating ___ as a product.
cytochrome c oxidase; H2O
Alternative oxidase: No proton translocation. True or False?
true
A feature of plant mitochondrial ETC that is rotenone-insensitive and transfers electrons to UQ.
NAD(P)H dehydrogenase
Where is NAD(P)H dehydrogenase located?
matrix and external sides of the inner
membrane/ ~intermembrane
What kind of membrane protein is NAD(P)H dehydrogenase?
peripheral membrane protein
NAD(P)H dehydrogenase: No proton translocation. True or False?
true
The mitochondrial ATP synthase is almost the same as chloroplast ATP synthase. True or False?
true
Mitochondrial ATP synthase is also called as ___.
FOF1 – ATP synthase; Complex V
What kind of membrane protein is mitochondrial ATP synthase?
peripheral membrane protein
The F0 subunit of mitochondrial ATP synthase promotes ____; while
The F1 subunit is the ____.
proton translocation
catalytic portion
F0 subunit of mitochondrial ATP synthase: Peripheral membrane protein. True or False?
integral membrane protein
