Biology - physiology - Plant Chemistry

Return to: Biology of Horticulture

Physiology - Plant Chemistry

How do plants differ from other organisms?

They contain a lot less nitrogen than animals, bacteria and fungi.

What kinds of molecules go to make up a plant?

carbohydrates

lipids

proteins

nucleic acids

Which of these molecules are polymers?

some of the carbohydrates (polysaccharides), proteins, nucleic acids
most lipds are not polymers except for cutin

How do the polymers differ in terms of complexity and regularity?

polysaccharides, are simplest containing only one or two kinds of sugar with simple pattern or sequence

nucleic acids only contain 4 kinds of monomer (nucleotide) but in a very complex sdquence

proteins have 20 kinds of monomer (amino acids) and sequence is complex

How do plants transport and store energy?

Energy is usually transported as the disaccharide (sucrose) and stored as monosaccharide (glucose, fructose).

What is the most important structural component?

cellulose

What are the three main kinds of lipids in plants?

fats/oils (triglycerides)

cuticular lipids (cutin and waxes)

membrane lipids (phospholipids and glycolipids)

What do the lipid molecules have in common?

long hydrocarbon chains, usually as fatty acids

How might oil storage be advantageous for a seed?

Oil contains more energy for its weight than starch. This helps in seed dispersal and germination.

How do the properties of lipids relate to their structural roles?

Hydrocarbon chains are hydrophobic, making a water impermeable barrier at plant surface and a semi-permeable barrier in cell membranes. Polar head groups of membrane lipids stabilize membrane in an aqueous environment.

What is the primary structure of a protein?

a specific sequence of amino acids

What do enzymes do?

catalyze chemical changes

If nucleic acids are made of bases, why are they acids?

The bases are weak (and concealed by hydrogen bonding in DNA) whereas the phosphate groups in the backbone of DNA and RNA are strongly acidic.

In what molecular form is genetic information stored and processed?

stored in DNA, processed as RNA

In what other forms do nucleotides occur?

in NAD(P) and ATP (and a number of other molecules)

Where do the building blocks (atoms) come from and what are the implications for plant nutrition?

The carbon in all organic molecules comes from CO2 in the air. Hydrogen comes from water and oxygen could come from air or water. The nitrogen in proteins and nucleic acids comes from the soil, usually as nitrate. Phosphorus are in nucleic acids and lipids come from the soil as phosphate.

Return to: Biology of Horticulture

	How do plants differ from other organisms?
	They contain a lot less nitrogen than animals, bacteria and fungi.

	What kinds of molecules go to make up a plant?
	carbohydrates lipids proteins nucleic acids

	How do the polymers differ in terms of complexity and regularity?
	polysaccharides, are simplest containing only one or two kinds of sugar with simple pattern or sequence nucleic acids only contain 4 kinds of monomer (nucleotide) but in a very complex sdquence proteins have 20 kinds of monomer (amino acids) and sequence is complex

	How do plants transport and store energy?
	Energy is usually transported as the disaccharide (sucrose) and stored as monosaccharide (glucose, fructose).

	What is the most important structural component?
	cellulose

	What are the three main kinds of lipids in plants?
	fats/oils (triglycerides) cuticular lipids (cutin and waxes) membrane lipids (phospholipids and glycolipids)

	What do the lipid molecules have in common?
	long hydrocarbon chains, usually as fatty acids

	How might oil storage be advantageous for a seed?
	Oil contains more energy for its weight than starch. This helps in seed dispersal and germination.

	How do the properties of lipids relate to their structural roles?
	Hydrocarbon chains are hydrophobic, making a water impermeable barrier at plant surface and a semi-permeable barrier in cell membranes. Polar head groups of membrane lipids stabilize membrane in an aqueous environment.

	What is the primary structure of a protein?
	a specific sequence of amino acids

	If nucleic acids are made of bases, why are they acids?
	The bases are weak (and concealed by hydrogen bonding in DNA) whereas the phosphate groups in the backbone of DNA and RNA are strongly acidic.

	In what molecular form is genetic information stored and processed?
	stored in DNA, processed as RNA

	In what other forms do nucleotides occur?
	in NAD(P) and ATP (and a number of other molecules)

	Where do the building blocks (atoms) come from and what are the implications for plant nutrition?
	The carbon in all organic molecules comes from CO2 in the air. Hydrogen comes from water and oxygen could come from air or water. The nitrogen in proteins and nucleic acids comes from the soil, usually as nitrate. Phosphorus are in nucleic acids and lipids come from the soil as phosphate.