BIOL 150: lecture 4 (40-81)

Questions and Answers

What condition is associated with heart diseases, strokes, and high blood pressure?

Atherosclerosis (correct)

Hypertension

Diabetes

Heart failure

What hormone is primarily responsible for the development of male genital organs?

Testosterone (correct)

Lutenizing hormone

Estrogen

Progesterone

How is estrogen synthesized in the body?

From testosterone (correct)

From progesterone

From cholesterol

From fatty acids

What is a characteristic of anabolic steroids?

Mimic testosterone effects Signup and view all the answers

What type of molecule is a wax considered to be?

Simple lipid Signup and view all the answers

Which of the following is NOT a type of protein mentioned?

Alkaline Signup and view all the answers

What are proteins composed of?

Amino acids Signup and view all the answers

Which protein type is responsible for catalyzing biochemical reactions?

Enzymatic proteins Signup and view all the answers

What is the primary structure of cell membranes in most organisms?

Lipid bilayer Signup and view all the answers

What characteristic defines saturated fats?

Contain the maximum possible amount of hydrogens Signup and view all the answers

What property of the lipid bilayer makes it an effective barrier for cells?

It is impermeable to most hydrophilic molecules. Signup and view all the answers

From which precursor are all steroids derived in animals?

Lanosterol Signup and view all the answers

How do unsaturated fats differ structurally from saturated fats?

They contain double bonds causing bends in the chain. Signup and view all the answers

What forms the structure of a phospholipid?

Glycerol, fatty acids, and a phosphate group Signup and view all the answers

What structural feature is characteristic of steroids?

Fused ring system of cyclohexanes and cyclopentane Signup and view all the answers

What is the arrangement of a phospholipid bilayer in cell membranes?

Hydrophobic ends facing inward Signup and view all the answers

Which of the following is NOT a function associated with steroids?

Storing genetic information Signup and view all the answers

What is a known consequence of cholesterol in the bloodstream?

It can deposit on blood vessel walls. Signup and view all the answers

Which statement about triglycerides is true?

They are primarily composed of saturated fats. Signup and view all the answers

Which steroid is known to help in fat transport and excretion from the liver?

Cholic acid Signup and view all the answers

What is a significant advantage of the phospholipid bilayer structure?

It creates a selective barrier around the cell. Signup and view all the answers

Which fatty acid structure can be described as 'saturated with hydrogen'?

Fatty acids without double bonds Signup and view all the answers

How do lipid bilayers affect the regulation of ion concentrations in cells?

They help maintain steady ion concentrations. Signup and view all the answers

What is the primary function of cell membranes formed by phospholipids?

To protect the cell and regulate transport Signup and view all the answers

What is a characteristic feature of all amino acids?

They have an alpha carbon and a side chain. Signup and view all the answers

What is the primary structure of a protein?

The sequence of amino acids in a peptide chain. Signup and view all the answers

Which statement describes the secondary structure of proteins?

It involves hydrogen bonds forming alpha helices and beta sheets. Signup and view all the answers

What is true about denaturation of proteins?

It disrupts both secondary and tertiary structures without breaking peptide bonds. Signup and view all the answers

How does an enzyme function in a living system?

By increasing the rate of a reaction without being consumed. Signup and view all the answers

What defines the quaternary structure of a protein?

The arrangement of subunits in a protein with multiple polypeptide chains. Signup and view all the answers

Enzymes are specific to their substrates. This means that:

Each enzyme acts specifically with only one substrate. Signup and view all the answers

What role do R groups (side chains) play in amino acids?

They determine the unique characteristics and interactions of each amino acid. Signup and view all the answers

What type of bond links two monosaccharides to form disaccharides?

Glycosidic bond Signup and view all the answers

Which of the following is a disaccharide formed from glucose and fructose?

Sucrose Signup and view all the answers

Which statement accurately describes glycogen?

It is a branched polysaccharide. Signup and view all the answers

What distinguishes α and β glycosidic bonds?

They occur between alpha or beta sugars. Signup and view all the answers

Which polysaccharide is the most abundant organic compound on Earth?

Cellulose Signup and view all the answers

What characteristic makes polysaccharides ideal storage molecules for energy?

They are large and insoluble in water. Signup and view all the answers

What is the primary location for glycogen storage in humans?

Liver and muscles Signup and view all the answers

Which of the following best describes the structure of polysaccharides?

Chains of monosaccharides linked together Signup and view all the answers

Study Notes

Carbohydrates: Disaccharides

Disaccharides consist of two monosaccharides joined by a glycosidic bond, a type of covalent bond linking sugar molecules.
Sucrose, or table sugar, is formed from one glucose molecule and one fructose molecule through glycosidic linkage.
Maltose, known as beer sugar, is comprised of two glucose molecules.
Lactose, the milk sugar, consists of one galactose molecule and one glucose molecule.
Glycosidic linkages can be classified as α (between two alpha sugars) and β (between two beta sugars).

Polysaccharides

Polysaccharides are complex carbohydrates consisting of chains of monosaccharides linked by glycosidic bonds.
Ideal for energy storage, polysaccharides are large, insoluble in water, and can fold into compact shapes for easy conversion to sugars when needed.
Glycogen is a branched polysaccharide found in animal cells, primarily stored in the liver and muscles, serving as the main carbohydrate reservoir for glucose.
Cellulose, the most abundant organic compound on Earth, allows for permeability of water and solutes, crucial for cellular function.

Lipids

Lipids characterize several classes, including triglycerides, phospholipids, and steroids.
Saturated fats are triglycerides with fatty acids containing the maximum number of hydrogens, making them solid at room temperature and closely packed.
Unsaturated fats contain double bonds in fatty acids, resulting in kinks that prevent tight packing, leading to liquid forms like oils.
Phospholipids form the foundation of cell membranes, creating a bilayer with hydrophobic lipid ends facing inward and hydrophilic phosphate ends outward.

Steroids

Steroids have a unique structure, comprising a fused ring system of three cyclohexanes and one cyclopentane.
Steroids, including cholesterol and sex hormones, have numerous carbon-hydrogen bonds, rendering them non-polar.
Cholesterol, a key component in cell membranes, can lead to health issues such as atherosclerosis when deposited in the blood vessel walls.

Hormones

Testosterone, the primary male hormone, is synthesized from cholesterol and drives the development of male reproductive organs and secondary sexual characteristics.
Estrogen and progesterone, primary female hormones, regulate functions in the uterus and ovaries, impacting the menstrual cycle.

Proteins

Proteins are polymers made of amino acids and are crucial for structural components in tissues.
Amino acids consist of an alpha carbon, an amine group, a carboxyl group, a hydrogen atom, and a variable side chain (R group).
Out of hundreds of amino acids, only 20 are typically used to construct proteins, linked through peptide bonds into polypeptides.
Protein structure is classified into four levels:
- Primary structure (amino acid sequence),
- Secondary structure (hydrogen bond formations),
- Tertiary structure (3D arrangement, stabilized by disulfide bonds),
- Quaternary structure (arrangement of multiple polypeptide chains).
Denaturation disrupts secondary and tertiary structures, uncoiling proteins without breaking the primary peptide bonds.

Enzymes

Enzymes are proteins that act as catalysts, facilitating reactions and increasing their rates significantly.
Each enzyme is highly specific, acting on particular substrates to produce specific products.
Enzymes can catalyze reactions in both forward and reverse directions, showcasing their versatility in metabolic processes.

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Description

Explore the world of disaccharides in this quiz, focusing on their formation from monosaccharides through glycosidic bonds. You'll learn about common examples like sucrose, containing glucose and fructose. Test your knowledge and understanding of these essential carbohydrate compounds.