SBI4U - Unit One - Biochemistry

Grade 12 University Biology, Unit One - Biochemistry

Ionic Bonds

Bonds formed by the transfer of one or more electrons between atoms with an electronegativity greater than 1.7, resulting in cations and anions.

Covalent Bonds

Bonds formed by the sharing of electrons between atoms.

Polar Covalent Bonds

Bonds where electrons are shared unequally, resulting in partial charges; electronegativity between 0.41 and 1.7 (e.g., H2O).

Nonpolar Covalent Bonds

Bonds where electrons are shared equally, with electronegativity less than 0.4 (e.g., H2, O2).

Amphiphilic

Molecules that have both polar and nonpolar parts (e.g., fatty acids).

Electronegativity

A measure of an atom's ability to attract electrons, influencing bond strength.

Hydrogen Bonds

Attractive forces between a partially positively charged hydrogen atom and a partially negative charge in another molecule (e.g., between water molecules).

Dehydration Reaction

A chemical reaction that removes an OH and H to join smaller molecules, producing water.

Hydrolysis Reaction

A reaction that adds water to split a larger molecule into smaller units.

Neutralization Reaction

A reaction between acids and bases that produces water and salt.

Redox Reaction

A reaction involving the transfer of electrons, where one atom loses electrons (oxidation) and another gains them (reduction).

Cohesion

The attraction between water molecules, contributing to surface tension.

Adhesion

The attraction of water molecules to other polar molecules.

Capillary Action

The ability of water to climb inside tubules due to adhesion and cohesion.

Surface Tension

The result of water molecules bonding more at the surface than below, creating a "skin" effect.

Lower Density Solid

Water expands when frozen, making ice less dense than liquid water, allowing it to float.

High Heat of Vaporization

The amount of heat required to convert water from liquid to vapor, aiding in cooling through sweat evaporation.

High Heat Capacity

The large amount of heat needed to raise the temperature of water, affecting climate and ecosystems.

Universal Solvent

Water's ability to dissolve ionic and polar substances.

Carbon Chains

The backbone of biochemistry, allowing for complex molecules due to carbon's ability to form four bonds.

Functional Groups

Specific groups of atoms within molecules that determine their chemical properties and reactions.

Macromolecules

Large biological molecules, including carbohydrates, lipids, nucleic acids, and proteins.

Monosaccharides

Simple sugars with a chemical formula of CHO in a 1:2:1 ratio (e.g., glucose).

Disaccharides

Formed from two monosaccharides through a dehydration reaction (e.g., sucrose).

Polysaccharides

Long chains of monosaccharides, serving as energy storage or structural support (e.g., cellulose).

Lipids

Nonpolar molecules that include fats, oils, and phospholipids, with functions in energy storage and membrane formation.

Nucleic Acids

Macromolecules (DNA and RNA) made of nucleotides, essential for genetic information storage and transfer.

Proteins

Polymers made of amino acids, serving various functions such as enzymes, hormones, and structural support.

Protein Denaturation

The process where proteins lose their functional shape due to changes in temperature, pH, or salt concentration.

Properties of Water

Key properties of water include low density solid, universal solvent, high heat capacity, heat of vaporization, adhesion/cohesion, capillarity, and surface tension.

Monosaccharide example

Glucose, Fructose

Disaccharide example

Sucrose, Lactose

Polysaccharide example

Starch, Glycogen, Cellulose

Saturated fatty acid

Straight chain fatty acid - no double bonds

Unsaturated fatty acid

“Kinked” chain fatty acid - at least one double bond

Eukaryotic Cell

Plant and animal cells.

Have organelles, the amount of which varies by cell type

Prokaryotic Cell

Bacteria Cell

No organelles

Cell Membrane Functions

• Maintains cell shape

• Semi-permeable

• Between-cell communication

• Show cell identity

Fluid Mosaic Model

flexible and made with many different parts; molecules are attracted to each other but float freely

Phospholipids

form a bilayer spontaneously; hydrophilic heads and hydrophobic tails line up with heads facing out and tails facing in

Primary Protein Stage

sequence of amino acids coded by DNA (peptide bonds)

Secondary Protein Stage

alpha helix and beta sheet (H- bonds between polar R’s)

Tertiary Protein Stage

3D shape is globular or fibrous and defined by various bonds

Quaternary Protein Stage

2 or more polypeptides join, making it a functional protein

Cell Carbohydrates

markers that identify the cell

Glycoprotein

“person specific” marker; lets immune system recognize invaders

Glycolipids

“tissue specific” marker; tells cells to stop multiplying and stay put

Cholesterol

contributes to the fluidity of the membrane; in moderate temperatures, reduces fluidity, but at low temperatures hinders solidification

Globular Proteins

• receptors for communication

• transport substances in and out

• speed up reactions

• anchors cells and their parts

Types of globular proteins

Integral and Peripheral

Integral

embedded in protein

Peripheral

attached to surface

Fibrous Proteins

form a cytoskeleton to maintain cell shape

Shape of Fibrous Proteins

shape is closely tied to function

osmosis

the diffusion of water across a membrane

simple diffusion

movement of molecules from [high] to [low] across a membrane (small, nonpolar molecules only)

Facilitated Diffusion

requires a specific protein channel, moving down concentration gradient.

It requires no energy and works for large, polar molecules

Ions require channel proteins

Hypotonic

Lower concentration of solute than inside the cell

Hypotonic Effects on Animal Cells

highly dangerous - can cause cell to burst

Hypotonic Effects on Plant Cells

beneficial - causes cell membrane to push against the cell wall, increasing pressure to make cell turgid (firm, healthy)

Hypertonic

higher concentration of solute than inside the cell

Hypertonic Effects on Animal Cells

cell shrinks and becomes flaccid

Hypertonic Effects on Plant Cells

highly dangerous - cell membrane tears away from cell wall, causing plasmolysis

Plasmolysis

Occurs only in plant cells; cell membrane ruptures after tearing away from the cell wall, killing the cell

Active Transport

The movement of particles from low concentration to high concentration, requiring ATP

Carrier Proteins

certain membrane proteins use ATP to change their shape, allowing particles to be taken in or out against natural diffusion

Endocytosis

the cell membrane folds around a substance, bringing it into the cell

Phagocytosis

cell “eating” - taking in solids

Pinocytosis

cell “drinking” - taking in liquids

Receptor-mediated Endocytosis

substances attach to membrane receptors, causing the membrane to fold inward and create a coated vessicle

Exocytosis

vacuoles containing wastes, to be removed or cell products for export. The vacuole approaches the cell membrane, fuses with it, and expels its contents.

Enzyme

biological catalyst that speeds up a chemical reaction without being consumed

Active Site

a pocket or groove in an enzyme that binds to a substrate

Substrate

a substance that is recognized by and binds to an enzyme

Anabolic Enzyme

pulls molecules together

Catabolic Enzyme

pulls molecules apart

Induced-Fit Hypothesis

enzymes are somewhat flexible and can change shape to better accommodate a substrate

Activation Energy…

is lower when enzymes are present

Cofactors and coenzymes

bind to an enzyme in order to make space for the correct substrate

Temperature

enzymes @ low temperatures - inactive

enzymes @ high temperatures - denatured

pH

different enzymes have different ideal pH

Substrate Concentration

enzymes can only do so much - as substrate concentration increases, reaction rate increases, until it reaches a maximum

Enzyme Concentration

As enzyme concentration increases, the reaction rate increases. these are directly proportional

Competitive Inhibitors

interference by a molecule (inhibitor) binding to the active site

Non-Competitive Inhibitor

a molecule binds to another place on the enzyme, causing a change in the shape of the active site