Bio Exam 2: Photosynthesis & Cellular Respiration

What does the plant produce from photosynthesis?

sugar and oxygen

What is the outcome of glycolysis

the breakdown of glucose molecule into two smaller pyruvate molecules

Fermentation reactions generally occur under conditions of:

low oxygen concentrations

Potential energy

stored energy; the capacity to work that results from an object’s location, position, or composition

Which molecule is used as the primary source of chemical energy for tasks within a cell?

ATPI

Which stage of cellular respiration generates the greatest amount of ATp molecule per metabolized glucose molecule?

electron transport chain (ETC)

Inputs of cellular respiration

oxygen and sugar

Outputs of cellular respiration

carbon dioxide, energy (ATP), water

During the citric acid cycle, the products of glycolysis are further broken down, generating ….

additional ATP and the high-energy electron carrier NADH

In harvesting the chemical energy of the molecules in food, organsism can use ________

sugars, lipids, and proteins

Only energy-generating process that occurs in ALL living organisms

glycolysis

T/F: Oxygen is required in glycolysis

false

Why does the passage of one glucose through glycolysis ahve a payoff of only two ATP molecules (instead of 4)?

two ATP molecules are used in the initial phase of glycolysis, reducing the net gain to two ATP

Product of glycolysis that can be modified to enter the citric acid cycle under aerobic conditions:

pyruvate

Alcohol and lactic acid fermentation are examples of _______ respiration

anaerobic

The capacity to cause change or do “work”

energy

the energy of motion

Kinetic energy

stored energy

potential energy

energy cannot be created or destroyed, only transformed or transferred

1st Laws of Thermodynamics

no energy transformation process is 100% efficient

2nd Law of Thermodynamics

the measure of disorder or randomness

entropy

(exothermic) gives off energy, products have less energy than reactants

• example would be cellular respiration

Exergonic Reaction

(endothermic) consumes energy, products have more energy than reactants

• example would be photosynthesis

Endergonic Reaction

the sum total of an organism’s reactions

metabolism

builds up molecules

anabolism

breaks down molecules

catabolism

biological catalysts, help speed up reactions by subsequently reducing the activation energy required per reaction

enzymes

• substrate concentration

• pH

• temperature

• co-enzymes

• presence of inhibitors

factors that affect rate of enzyme reactions

inhibitor has a similar shape as the substrate, binding to the active site and preventing the binding of the actual substrate

competitive inhibitor

inhibitor has a different shape than substrate, binds to an allosteric (“other”) site

non-competitive inhibitor

the process where green plants (including algae and some prokaryotes) convert light energy and carbon dioxide into the chemical energy of sugars

photosynthesis

"self-feeders”, make their own food

autotrophs

organisms that make their own food via phtosynthesis (plants, algae, some bacteria)

photoautotrophs

prokaryotic self-feeders that make their own food using inorganic chemicals as their source of energy

chemoautotrophs

“different feeders”, feed on plants, animals or decompose organic matter as a source food, includes herbivores & carnivores

heterotrophs

specificially consume non-living organic matter (decayign plants/animals), includes fungi, most bacteria, and earthworms

saprotrophs

waxy cuticle that helps prevent water loss in the leaf

trichome

the leaf vein, contains the xylem and phloem

Bundle Sheath Cell

tiny pores in the leaves, has guard cells around them

• When guard cells are FULL, it is Turgit

• When guard cells are EMPTY, they are closed

Stoma

where the dark reactions/Calvin Cycle occurs

Stroma

the source of oxygen that is given off during photosynthesis

oxidation is loss, reduction is gain (of electrons)

Redox Reaction

sunlight moves into the chloroplasts, hitting the photosystems, water comes into the light reactions (in the thylakoids) and oxygen gass is produced

• NADP+ and ADP + P_i are reduced into NADPH and ATP

Stage 1 of Photosynthesis

moves into the dark reactions in the Calvin Cycle, located in the stroma of the chloroplast. ATP, NADPH, and CO₂ are consumed and transformed into sugar, regenerating it back into

• NADP+ and ADP + P_i, feeding back into the light reactions

Stage 2 of Photosynthesis

6 CO₂ + 12 H₂O —→ C₆H₁₂O₆ + 6H₂O + 6 O₂

Photosynthesis Equation

• Light energy is absorbed by chlorophyll

• Water molecules are split (2 H₂O → 2 e- + 2 H⁺ + O₂)

• Electrons are transferred (NADP+ + 2e- +H⁺ → NADPH)

• A transmembrane H⁺ gradient is created

→ ATP is synthesized (ADP + P_i → ATP)

Light Reaction

• CO₂ is fixed and reduced; sugars are synthesized (glucose)

• ATP and NAPH are consumed

ADP + P_i → ATP

NADPH → NADP⁺

Calvin Cycle

main form of energy emitted by the sun

→ travels in diferent wavelengths (lamda) and units of energy are “photons”

Electromagnetic Radiation

chlorophyll a, chlorophyll b, and caratenoids

Photosynthetic pigments

“accessory pigments”, helps photosynthesis in two ways:

I. extends the useful range of light into the blues ( = more absorption)

II. works as an antioxidant to protect the chloroplast from reactive oxygen species (ROS), right where oxyen is produced

carotenoid

a collection of “light-harvestign complexes” comprised of pigment molecules boudn to proteins, all embedded in the thylakoid membranes

Photosystem

recieve the radiation from the sunlight, collectively both the photosystems (II) & (I) help to collect the sunlight

Pigment Receptor

aborption of light energy and the initiation of electron transport

Photosytem’s function

absorb PAR and become energized; the energized state is transferred to reaction center chlorophyll (P680 & P700)

Chlorophylls a & b

makr first net redox electron transfer to primary acceptors

Reaction Centers

relay electrons via redox reactions to other electron carriers

Primary Acceptors

stands for “photosynthetically active radiation”, is the light of wavelengths (400-700nm)

PAR

1. Light (photon) absorption raises an electron to a higher energy orbital

2. Return to ground state, releasing light energy

Mechanism of Light Absorption

readily observed in the absence of light-harvesting complexes & always red

Fluorescence

_______ provides energy for synthesis of ATp by chemiosmosis

ETC

_______ reactions take place within the Thylakoid Membranes

Light

the final electron acceptor during the light reactions is ______

NADP+

1. Carbon Fixation

2. Carbon Reduction

3. Synthesis and release of 1 G3P

4. Regeneration of RuBP

Steps of Calvin Cycle

ATP synthesis in photosynthesis is called…

photophosphorylation

the “dark reactions” or Calvin Cycle occurs in the _____ of the chloroplast

Stroma

1. RuBisCo starts the Calvin Cycle, it gets an input of 3 CO₂, 6 ATP, & 6 ADP + P

• RuBisCo catalyzes the carboxylation of RuBP

Carbon Fixation

most abundant enzyme in the world

RuBisCo

2. Molecules of 3-PGA (3-phosphoglyceric acid) get converted into G3P (glycrealdehyde-3P) by using ATP and electrons from NADPH

Carbon Reduction

3. molecule of G3P is then released, leaving 5 G3P molecules

Release of 1 G3P

4. the remaining 5 G3P molecules are rearranged using ATP to create RuBP

Regeneration of RuBP

_____ is the starting molecule that RuBisCo (an enzyme) uses in the 1st step of the Calvin Cycle

RuBP

a regenerative cycle/pathway, makes the product that is needed to restart the pathway

Anapleurotic Pathway

a chemical compound formed when an acid donates a rpton (H+) to a base

Conjugate Acid

what is left over after a conjugate acid has donated a proton during a chemical reaction

Conjugate Base

sometimes, RuBisCo reacts with ______ instead of carbon dioxide (this becomes an issues)

oxygen

oxygen fixation leads to a salvaging process

• occurs int he light, ocnsuming oxygen and release carbon dioxide

• uses ATP instead of making it, doesn’t produce sugar

• major inefficiency in photosynthesis

photorespiration

these kinds of plants do not grow quickly or very tall because of the inefficiency with RuBisCo, about 20-40% of the time something gets messed up

C3

causes stomatal closure, reduces the entry of CO₂ into and escape of O₂ out of leaves

Water Stress

Was discovered in tropical, hot environment dwelling plants

• Has distinct leaf anatomy

• very high photosynthetic efficiency

C4 plants

example of C4 plant

sugar cane

Found in desert environments, stands for “cressaulacean acid metabolism”, adapted to live in hot and dry environments, very high water use efficiency

• CO₂ is fixed at night by PEP carboxylase (stomata is open)

• Next day, stomata’s close, malate is retrieved from the vacuole and decarboxylated to reduce CO₂

CAM photosynthesis

example of a CAM plant

cactus

____ plants are specifically structured and tightly organized to allow for maximum efficiency, therefore doesn’t have the isseus associated with RuBisCo b/c of the tightly organized mesophyll cells

C4

_________ cells are super efficient in C₄ plants

bundle sheath

C4 plants have no ________, so they grow much faster than C3 plants

photorespiration