Biology Chapter on Lipids and Carbohydrates

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What key feature distinguishes lipids from other major biological molecules?

Lipids are the only class of biological molecules that do not contain nitrogen.

Lipids are the only class of biological molecules that form polymers.

Lipids are the only class of biological molecules that contain carbon.

Lipids are the only class of biological molecules that are hydrophobic. (correct)

Which of the following statements accurately describes the relationship between cellulose and starch?

Both cellulose and starch are composed of glucose monomers, but they differ in the type of linkage between monomers. (correct)

Cellulose is a more complex polysaccharide than starch, with multiple branching chains.

Cellulose is a precursor to starch in plants, and it is converted to starch during energy storage.

Cellulose and starch are both structural polysaccharides, but cellulose is more commonly found in animal cells.

Why are fats hydrophobic?

Fats have a complex three-dimensional structure that prevents water molecules from interacting with them.

Fats contain a high proportion of hydrophilic glycerol molecules.

Fats contain a high proportion of ionic bonds, which repel water.

Fats contain a high proportion of nonpolar hydrocarbon chains, which repel water. (correct)

What is the significance of the double bonds in unsaturated fatty acids?

Double bonds cause kinks in the fatty acid chain, making it less dense and more fluid at room temperature. (B) Signup and view all the answers

How does the structure of cellulose contribute to its function as a structural component in plant cell walls?

The linear structure of cellulose allows for the formation of strong, parallel microfibrils. (D) Signup and view all the answers

How do herbivores, lacking the necessary enzymes to digest cellulose, obtain energy from plant material?

By harboring symbiotic microbes that digest cellulose for them. (C) Signup and view all the answers

What is the primary function of chitin in arthropods?

To provide structural support for the exoskeleton. (C) Signup and view all the answers

Which of the following is NOT a key component of a fat molecule?

Amino acids (B) Signup and view all the answers

What is the main difference between saturated and unsaturated fatty acids?

Saturated fatty acids have double bonds between carbon atoms, while unsaturated fatty acids do not. (C) Signup and view all the answers

What is the role of dehydration reactions in the formation of fats?

Dehydration reactions remove water molecules from glycerol and fatty acids to form an ester linkage. (A) Signup and view all the answers

What is true regarding hydrogenated vegetable oil?

It will solidify at room temperature. (A) Signup and view all the answers

What are the components of a triglyceride molecule?

One glycerol and three fatty acids. (A) Signup and view all the answers

Which category encompasses all others listed?

Carbohydrate. (B) Signup and view all the answers

Which of the following can the enzyme amylase break down?

Starch and glycogen. (A) Signup and view all the answers

What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?

C54H90O45. (D) Signup and view all the answers

Why is butter solid at room temperature, while vegetable oil is a liquid?

Butter is a saturated fat and vegetable oil is an unsaturated fat (B) Signup and view all the answers

What type of carbohydrate is sucrose?

Disaccharide (C) Signup and view all the answers

Which of the following statements is true of the carbohydrate glucose?

Glucose is a structural isomer of galactose (B), Glucose contains carbon, hydrogen and oxygen atoms (C) Signup and view all the answers

How are triglycerides formed?

Triglycerides are formed through dehydration synthesis, which results in the loss of H2O molecules (C) Signup and view all the answers

Which of the following is a characteristic of lipids?

They are not soluble in water (C), They are either fats or oils (D) Signup and view all the answers

Which of the following occurs when hydrogen is reacted with vegetable oil?

Trans fats are produced (B) Signup and view all the answers

What type of bond is primarily found in saturated fats?

Single bonds (C) Signup and view all the answers

Which carbohydrate is commonly known as blood sugar?

Glucose (D) Signup and view all the answers

Study Notes

Bioprocess Fundamentals - CENV 2200

Course instructor: Dr. Ali Al Jibouri, P.Eng.
Office: SW01-1580
Email: [email protected]

The Molecules of Life

Organic molecules are the most important large molecules found in living things.
These include carbohydrates, proteins, nucleic acids, and lipids.

Macromolecules

Macromolecules are large molecules composed of thousands of covalently connected atoms.
Most macromolecules are polymers.
Polymers are long molecules consisting of many similar building blocks (monomers).

Polymers

Monomers form larger molecules through condensation reactions called dehydration reactions.
One molecule loses hydrogen, the other loses OH.
Polymers are disassembled to monomers by hydrolysis.
Hydrolysis is the reverse of dehydration reaction.

Polymers (continued)

Each cell has thousands of different kinds of macromolecules.
Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species.
An immense variety of polymers can be built from a small set of monomers.

Carbohydrates

Carbohydrates include sugars and the polymers of sugars.
Simple carbohydrates are monosaccharides.
Monosaccharides are single sugars.
Carbohydrate macromolecules are polysaccharides.
Polysaccharides are polymers composed of many sugar building blocks.

Monosaccharides

Monosaccharides have molecular formulas that are usually multiples of CH2O.
Glucose is the most common monosaccharide.
Monosaccharides are classified by the location of the carbonyl group and by the number of carbons in the carbon skeleton.
Monosaccharides serve as a major fuel for cells and as raw material for building molecules.
In aqueous solutions, monosaccharides form rings, the most stable form.

Disaccharides

Disaccharides are formed when a dehydration reaction joins two monosaccharides.
The covalent bond formed is called a glycosidic bond.
Examples include: Lactose (glucose and galactose), Maltose (glucose and glucose), Sucrose (glucose and fructose).

Polysaccharides

Polysaccharides, the polymers of sugars, have storage and structural roles.
The structure and function of a polysaccharide are determined by its sugar monomers and the positions of the glycosidic linkages.

Storage Polysaccharides

Starch is a storage polysaccharide of plants, consisting entirely of glucose monomers.
Two types of starch are amylose and amylopectin.
Plants store surplus starch as granules within chloroplasts and other plastids.
Glycogen is a storage polysaccharide in animals.
Humans and other vertebrates store glycogen in liver and muscle cells.

Structural Polysaccharides

Cellulose is a major component of the tough wall of plant cells.
Cellulose is a polymer of glucose, but the glycosidic linkages differ.
The difference is based on two ring forms for glucose: alpha (a) and beta (β).
Polymers with a-glucose are helical, while polymers with β-glucose are straight.
In straight structures H atoms on one strand can bond with OH groups on other strands.
Parallel cellulose molecules are grouped into microfibrils, strong building material for plants.
Chitin is another structural polysaccharide found in the exoskeleton of arthropods and cell walls of many fungi.

Lipids

Lipids are the only class of large biological molecules that do not form polymers.
The unifying feature of lipids is having little or no affinity for water.
Lipids are hydrophobic because they consist mostly of hydrocarbons which form nonpolar covalent bonds.
The most biologically important lipids are fats, phospholipids, and steroids.

Fats

Fats are constructed from glycerol and fatty acids.
Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon.
A fatty acid consists of a carboxyl group attached to a long carbon skeleton.
In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride.
Fatty acids vary in length (number of carbons) and in the number and locations of double bonds.
Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds.
Unsaturated fatty acids have one or more double bonds.
The major function of fats is energy storage.

Phospholipids

In a phospholipid, two fatty acids and a phosphate group are attached to glycerol.
The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head.
When phospholipids are added to water, they self-assemble into a bilayer.
The structure of phospholipids results in a bilayer arrangement found in cell membranes.
Phospholipids are the major component of all cell membranes.

Steroids

Steroids are lipids characterized by a carbon skeleton consisting of four fused rings.
Cholesterol, an important steroid, is a component in animal cell membranes.

Proteins

Proteins account for more than 50% of the dry mass of most cells.
Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances.
Proteins consist of a backbone of an amino group (-NH2) and a carboxyl group (-C(=O)OH).
Twenty different amino acids are involved in the structure of a variety of proteins which have various functions.

Polypeptides

Polypeptides are polymers of amino acids.
A protein is a biologically functional molecule composed of one or more polypeptides.
Amino acids are linked by peptide bonds.

Amino Acid Monomers

An amino acid is an organic molecule with both an amino group and a carboxyl group.
Amino acids differ in their properties due to differing side chains (R groups).
Proteins are constructed from the same set of 20 amino acids, linked in unbranched polymers.

Protein Structure and Function

A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape.
The sequence of amino acids determines a protein's three-dimensional conformation.
A protein's conformation determines its function.
Ribbon models and space-filling models can depict a protein's conformation.

Protein Structure - Primary

The amino acid sequence in a protein.
Determined by inherited genetic information

Protein Structure - Secondary

Coils and folds found in most proteins
Result from hydrogen bonds between repeating constituents of polypeptide backbone.
Include a-helix and ẞ pleated sheet.

Protein Structure - Tertiary

Overall shape of a polypeptide, resulting from interactions between side chains (R groups) of various amino acids.
Includes hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide linkages.

Protein Structure - Quaternary

Results when a protein consists of multiple polypeptide chains.

Protein Folding

It is hard to predict a protein's conformation from its primary structure.
Most proteins probably go through several states on their way to a stable conformation.
Chaperonins are protein molecules that assist the proper folding of other proteins.

Protein Denaturation

Denaturation is loss of conformation which occurs in protein structure due to physical or chemical conditions (pH, salt concentration, temperature).
Denatured proteins are biologically inactive.

Nucleic Acids

Nucleic acids are polymers called polynucleotides.
Each polynucleotide is made of monomers called nucleotides.
Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group.
DNA provides directions for its own replication.
DNA directs synthesis of messenger RNA (mRNA) in which mRNA controls protein synthesis.
Protein synthesis occurs in ribosomes.

DNA double helix

A DNA molecule has two polynucleotides spiralling around an imaginary axis, forming a double helix.
In the DNA double helix, the two backbones run in opposite 5' to 3' directions, antiparallel.
One DNA molecule includes many genes.
The nitrogenous bases in DNA form hydrogen bonds in a complementary fashion. A always with T, and G always with C

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the characteristics and functions of lipids and carbohydrates in biological systems. It covers key concepts such as the structure of fats, the differences between saturated and unsaturated fatty acids, and the significance of polysaccharides like cellulose and chitin. Test your understanding of these essential biomolecules and their roles in organisms.