Photosynthesis and Cellular Respiration

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Questions and Answers

Which form of vitamin B6 is predominantly found in plant materials?

Vitamin B5

Pyridoxal

Pyridoxamine

Pyridoxine (correct)

What is one of the primary uses of vitamin B6?

Boosting muscle mass

Improving mood (correct)

Enhancing vision

Increasing bone density

Which of the following is a symptom of vitamin B6 deficiency?

Excessive sweating

Peripheral neuropathy (correct)

Weight gain

Vision impairment

Which of the following foods is not a good source of vitamin B6?

Rice Signup and view all the answers

What role does vitamin B6 play in the body?

Amino acid metabolism Signup and view all the answers

Which of the following foods is most likely to provide a high source of vitamin B7?

Eggs Signup and view all the answers

What is the primary metabolic role of vitamin B7?

Transference of carbon dioxide Signup and view all the answers

Which symptom is most likely associated with a deficiency of vitamin B7?

Hair loss Signup and view all the answers

Vitamin B9 is crucial for which aspect of health?

Brain development Signup and view all the answers

Which of the following is a rich source of vitamin B9?

Liver Signup and view all the answers

What is the primary function of folate in the body?

Brain development Signup and view all the answers

Which vegetables are mentioned as a source of vitamin B7?

Sweet potatoes Signup and view all the answers

What can be a result of vitamin B7 deficiency?

Fatigue and depression Signup and view all the answers

Which enzyme catalyzes the reaction between CO2 and ribulose-1,5-bisphosphate (RuBP)?

Rubisco Signup and view all the answers

What is the main product formed from the reduction of 3-phosphoglyceric acid (3-PGA)?

Glyceraldehyde-3-phosphate (G3P) Signup and view all the answers

During glycolysis, which of the following substances is produced?

Pyruvate Signup and view all the answers

What is required for the regeneration of ribulose-1,5-bisphosphate (RuBP)?

ATP Signup and view all the answers

Which building block is derived from L-methionine?

C1 Signup and view all the answers

What occurs during the Krebs cycle?

Acetyl-CoA is oxidized to form CO2 Signup and view all the answers

How many ATP molecules are generated from one molecule of glucose during glycolysis?

2 Signup and view all the answers

What are the substrates that drive the shikimic acid pathway?

Phosphoenol pyruvate and erythrose-4-phosphate Signup and view all the answers

Which of the following intermediates is crucial for biosynthesis from primary metabolites?

Acetyl-CoA Signup and view all the answers

What type of compounds does the shikimic acid pathway primarily biosynthesize?

Phenolic compounds and alkaloids Signup and view all the answers

Which aromatic amino acids are synthesized through the chorismate pathway?

Phenylalanine, tyrosine, and tryptophan Signup and view all the answers

Which of the following is NOT an environmental trigger for the expression of aromatic compounds?

Excess nitrogen availability Signup and view all the answers

What is one of the main consequences of vitamin B deficiency?

Megaloblastic anemia Signup and view all the answers

Which enzyme catalyzes the reaction to form 5-enolpyruvylshikimate-3-phosphate?

EPSP synthase Signup and view all the answers

What is the overall reaction formula for the metabolization of glucose in the presence of ADP and inorganic phosphate?

C6H12O6 + 6CO2 + 38 ADP + 38P → 6H2O + 6CO2 + 38 ATP Signup and view all the answers

Which of the following types of organisms utilizes the shikimate pathway?

Bacteria, archaea, fungi, algae, and some protozoans Signup and view all the answers

What is the end product of the shikimic acid pathway?

Chorismate Signup and view all the answers

Which vitamin is crucial for preventing scurvy?

Vitamin C Signup and view all the answers

Which of the following is a good dietary source of vitamin C?

Citrus fruits Signup and view all the answers

What effect does cooking have on the vitamin C content in foods?

It can cause a loss of up to 50% of vitamin C Signup and view all the answers

Which property of vitamin C is highlighted as one of its important functions?

Oxidant activity Signup and view all the answers

What role does vitamin C play related to iron?

Facilitates iron absorption Signup and view all the answers

What is an important function of vitamin C in the body?

Synthesis of collagen Signup and view all the answers

Which of the following symptoms is associated with vitamin B deficiency?

Numbness in arms and legs Signup and view all the answers

Study Notes

Carbon Dioxide Fixation

CO2 combines with RuBP (ribuose-1,5-bisphosphate) to form a six-carbon compound.
This compound is unstable and splits into two molecules of 3-phosphoglyceric acid (3-PGA).
This reaction is catalyzed by the enzyme RuBP carboxylase/oxygenase, or rubisco.

Reduction in Photosynthesis

ATP and NADPH are used to convert 3-PGA molecules into G3P (glyceraldehyde-3-phosphate)
NADPH donates electrons to a three-carbon intermediate to make G3P.

Regeneration in Photosynthesis

Some G3P molecules are used to make glucose.
Other G3P molecules are recycled to regenerate RuBP.
This requires ATP and a complex network of reactions.

Glycolysis

Converts glucose into pyruvate
Occurs in the cytosol, independent of oxygen
Generates a net gain of two ATP molecules

Citric Acid Cycle

Occurs in the mitochondrial matrix under aerobic conditions.
Oxidizes acetyl-CoA into CO2.
Reduces coenzymes which generate ATP via the electron transport chain.
Consists of eight enzymatic steps in the citric acid cycle.
Overall reaction equation: C6H12O6 + 6CO2 + 38 ADP + 38P (inorganic) → 6H2O + 6CO2 + 38 ATP

Biosynthesis Pathway of Secondary Metabolites

A multi-step, enzyme-catalyzed process that converts substrates into more complex products.
Simple compounds are modified, converted, or joined to form macromolecules.
Often consists of metabolic pathways with building blocks from primary metabolites like acetyl CoA, shikimic acid, mevalonic acid, and malonic acid.

Building Blocks in Biosynthesis

C1 derived from S-methyl of L-methionine
C derived from acetyl-CoA
C5 derived from isoprene units
C6-C3 units (phenyl propyl units) are derived from phenylalanine or tyrosine through the shikimic acid pathway.

Shikimic-acid Pathway

Basic process for biosynthesis of phenolic compounds, alkaloids, and others.
Occurs in plant chloroplasts.
Triggered by environmental stresses like pathogens, herbivores, pH, temperature, UV radiation, salinity, and heavy metals.
Used by bacteria, archaea, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (phenylalanine, tyrosine, and tryptophan).

Chorismate Pathway

Starts with phosphoenol pyruvate and erythrose-4-phosphate and ends with chorismate.
Enzyme DAHP synthase catalyzes the reaction between phosphoenol pyruvate and erythrose-4-phosphate to form 3-deoxy-D-arabino- heptulosonate 7-phosphate.
Shikimate kinase catalyzes the phosphorylation of shikimate to form shikimate 3-phosphate.
5-enolpyruvylshikimate-3-phosphate synthase (EPSP) synthase catalyzes the coupling of shikimate-3-phosphate with phosphoenol pyruvate to give 5-enolpyruvylshikimate-3-phosphate.
Chorismate synthase transforms 5-enolpyruvylshikimate-3-phosphate into chorismate.

Vitamin B6 Sources

Beef liver, tuna, salmon, fortified cereals, chickpeas, poultry, dark leafy greens, pineapple, papaya, oranges, and cantaloupe.

Vitamin B6 Uses

Improves mood.
Required for biological reactions like amino acid metabolism, neurotransmitter synthesis, and red blood cell formation.
A co-factor for biochemical reactions regulating cellular metabolism.

Vitamin B6 Deficiency

Can cause peripheral neuropathy, neurology abnormalities, skin lesions, and hypochromic microcytic anemia.

Vitamin B7 (Biotin) Sources

Eggs, fish, meat, seeds, nuts, and vegetables like sweet potatoes.

Vitamin B7 (Biotin) Uses

Plays a crucial role in metabolism as a coenzyme that transfers carbon dioxide.
Involved in the breakdown of carbohydrates, fats, and proteins into energy.
Involved in many cellular reactions, particularly in fat and protein metabolism of hair roots, fingernails, and skin.
Used in fatty acid synthesis.

Vitamin B7 (Biotin) Deficiency

Can cause fatigue, depression, and dermatitis.

Vitamin B9 (Folate) Sources

Beans, peanuts, sunflower seeds, fresh fruits, fruit juices, whole grains, and liver.

Vitamin B9 (Folate) Uses

Essential for brain development and function.
Helps in brain function and synthesis of red blood cells.

Vitamin B9 (Folate) Deficiency

Can involve rapidly dividing cells of the hematopoietic system (e.g., megaloblastic anemia) and irreversible neurologic damage (e.g., defective myelin nerve sheaths).
Symptoms include irritability, weakness, memory loss, mood swings, and tingling/numbness of limbs.

Vitamin C Sources

Citrus fruits, tomatoes, strawberries, and other fresh fruits and vegetables.

Vitamin C Uses

Antioxidant activity.
Functions in enzyme activation and oxidative stress reduction.
Roles in collagen synthesis and iron absorption.
Defense against infections and inflammation.

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Description

This quiz covers key processes in photosynthesis, including carbon dioxide fixation, reduction phase, and regeneration, as well as glycolysis and the citric acid cycle. Test your understanding of how these metabolic pathways function and their roles in energy production. Perfect for biology students!