Biology Chapter 2 Quiz

Biology 1 - Cells, Molecular Biology and Genetics (BIOL 1000)

• This is a course on cells, molecular biology, and genetics, taught by Dr. Michael Cardinal-Aucoin during Winter 2025 at York University.
• Students are expected to know about proteins, carbohydrates, lipids, and nucleic acids consumed as breakfast.
• The course will cover the building blocks of life including chemistry of life, biological macromolecules, polymers, carbohydrates, lipids, proteins, and nucleic acids.

Review Chapter 2

• Building Blocks: Matter, element, atom, neutron, proton, electron, nucleus, atomic mass, atomic number, isotope, valence electron, ion (cation, anion)
• Bonds: Ionic, covalent (non-polar, polar), electronegativity, hydrogen, van der Waals forces
• Chemical Reactions: Reactants, products, reversible, equilibrium, specificity, properties of water (polarity, cohesion, adhesion, high specific heat), functional groups

The Molecules of Life

• All cells are made of four classes of biological macromolecules: carbohydrates, lipids, nucleic acids, and proteins.
• All these macromolecules have a carbon skeleton.
• The macromolecules have a wide variety of ways to be built and combined.

The Chemistry of Life

• 20-25% of 92 elements are crucial for life.
• Approximately 96% of living material is made up of carbon, hydrogen, oxygen, and nitrogen.
• Other elements like calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium make up the remaining 4%.

Table 2.1 Elements in the Human Body (Summary)

• Oxygen is the most abundant element in the human body (65%).
• Other percentages of elements listed for the human body, including water.

Water and Life

• Water is the biological medium on Earth, crucial for life's evolution.
• All living things need water more than any other substance.
• Most cells are surrounded by water, making up 70-95% of a cell's composition.
• Cells are essentially bags of molecules dissolved in water, and the availability of liquid water makes Earth habitable.

Summary

• The four emergent properties of water (expansion upon freezing, cohesion/adhesion, moderation of temperature, and versatility as a solvent) are mainly due to its polarity and formation of hydrogen bonds; important for life on Earth.
• The pH of water is tightly regulated in living systems.

The Backbone of Life

• Living things are mainly composed of carbon-based compounds.
• Carbon's ability to form complex and diverse molecules makes it a key component of life and abundant in the cosmos.
• Proteins, DNA, carbohydrates, and other molecules that differentiate living matter are all built from carbon compounds.

A Note about Formulae

• Aspartic acid is an amino acid, a building block of proteins.
• Chemical formula (C₄H₇NO₄)
• Condensed structural formula (NH₂CH(CH₂COOH)COOH)
• A visual representation of its structure showing the bonds and atoms.

Diversity of chemical functional groups constructed with carbon.

• Various chemical groups commonly connected to carbon atoms are mentioned, along with their properties.

The Molecules of Life (Summary)

• Carbohydrates: provide energy and support structural components.
• Lipids: make up cell membranes, store energy, and serve as signaling molecules.
• Nucleic acids: store and transmit genetic information.
• Proteins: provide structural support and act as catalysts (enzymes) in chemical reactions.

Polymers (Summary)

• Most biological macromolecules are polymers, made from repeating units called monomers.
• Proteins, for instance, are made of monomers, amino acids.
• Polymers are assembled and disassembled through dehydration and hydrolysis reactions respectively.

Carbohydrates

• Simple sugars have a 1:2:1 C:H:O ratio (CH₂O), making them essential energy sources for many life forms.
• Examples: glucose, fructose, ribose, etc.
• Monosaccharides differ based on carbon number (triose, tetrose, pentose, hexose) and C=O position (aldose, ketose).
• Numerous structural variations exist in carbohydrate polymers formed from these monomers.
• Glycosidic bonds link monosaccharides to create disaccharides and polysaccharides such as starch, glycogen, and cellulose.

Disaccharides

• Disaccharides comprise two monosaccharides linked together via glycosidic bonds.
• Important examples include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).
• Disaccharides have crucial roles in the transport and storage of sugars within organisms.

Polysaccharides

• Polysaccharides consist of long linked monosaccharide chains.
• Common examples are starch, glycogen, and cellulose.
• Starch (amylose and amylopectin) in plants along with glycogen in animals and fungi, serve as energy storage molecules.
• Cellulose in plants provides structural support, while chitin plays a similar role in fungi.

Lipids

• Lipids differ from proteins, nucleic acids, and carbohydrates since the units aren't repeating monomers.
• Lipids are hydrophobic.
• Important lipid types include neutral fats (or triglycerides), phospholipids (crucial membrane constituents), and steroids (for hormones and membranes).
• Neutral fats are for energy storage, insulation, protection of internal organs.
• Phospholipids form cell membranes.
• Steroids are hormones and components of membranes

Nucleic Acids

• Nucleic acids are made of nucleotides composed of a nitrogenous base, a pentose (5-carbon sugar), and a phosphate group.
• Nucleotides are linked together by phosphodiester bonds during dehydration synthesis creating a chain.
• DNA stores hereditary information in a double helix.
• RNA carries information from DNA and plays a role in protein synthesis.
• The Central Dogma describes DNA instructions being transformed into proteins with the aid of mRNA

Proteins

• Proteins are polypeptides or polymers formed by amino acid subunits.
• Important protein functions include catalysis (enzymes), defense (antibodies), transport (hemoglobin), storage (ovalbumin) and movement.
• Protein functions are related to their structures.
• Different protein structures include (Primary, Secondary, Tertiary, and Quaternary).

Denaturation

• The tertiary structure of a protein determines its function.
• Proteins can be denatured or disrupted through high temperatures or chemical treatments, causing a loss of function.

Quaternary Structure

• Some proteins consist of multiple polypeptide chains, forming a quaternary structure.

• Hemoglobin in red blood cells, a good example, is composed of four subunits (2α and 2β).

Proteins

• Some amino acids are essential, meaning they must be obtained from diet.

Summary

• The course will touch on the various aspects of the chemistry of life, covering polymers (carbohydrates, lipids, nucleic acids, and proteins), summarizing each class's structure, function, and importance.