Molecules of Life: Dehydration, Carbohydrates, Lipids

Molecules of Life

Dehydration & Hydration Reactions

• Dehydration synthesis removes water to form bonds between molecules like proteins, carbohydrates, and nucleic acids.
• Hydrolysis adds water to break bonds, such as in the digestion of biomolecules.

Carbohydrates

• Monosaccharides include simple sugars like glucose, fructose, and galactose.
• Disaccharides consist of two monosaccharides bonded together, such as sucrose, lactose, and maltose.
• Polysaccharides are complex carbohydrates like starch, glycogen, and cellulose.

Lipids

• Saturated fatty acids have no double bonds and are solid at room temperature, like butter and animal fat.
• Unsaturated fatty acids have one or more double bonds and are liquid at room temperature, like olive oil and fish oil.
• Phospholipids are major components of cell membranes, featuring a hydrophilic head and hydrophobic tails.
• Steroids include cholesterol and hormones like testosterone and estrogen.

Proteins

• Proteins function as enzymes, provide structural support, facilitate transport, defend, and signal.
• Primary protein organization is the sequence of amino acids.
• Secondary protein organization includes alpha helixes and beta-pleated sheets.
• Tertiary protein organization is the 3D structure formed by interactions between R-groups.
• Quaternary protein organization involves multiple polypeptides combined.

Nucleic Acids

• DNA stores genetic information.
• RNA helps in protein synthesis.

Periodic Table of Elements

• Atomic number indicates the number of protons in an atom.
• Atomic symbol is the abbreviation of the element's name.
• Atomic mass is the total mass of protons and neutrons in an atom.
• Hydrogen (H) has an atomic number of 1 and a mass of 1.008.
• Carbon (C) has an atomic number of 6 and a mass of 12.01.
• Oxygen (O) has an atomic number of 8 and a mass of 16.00.
• Nitrogen (N) has an atomic number of 7 and a mass of 14.01.
• Sodium (Na) has an atomic number of 11 and a mass of 22.99, essential for nerve function.
• Potassium (K) has an atomic number of 19 and a mass of 39.10, essential for muscle contractions.
• Calcium (Ca) has an atomic number of 20 and a mass of 40.08, important for bone strength and muscle function.

Cell Theory

• All living organisms consist of one or more cells.
• The cell represents the basic unit of life.
• All cells originate from pre-existing cells.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells lack a nucleus and have a simple structure, such as bacteria.
• Eukaryotic cells possess a nucleus and complex organelles, like plants, animals, and fungi.

Eukaryotic Cell Structure

• The plasma membrane regulates the entrance and exit of molecules.
• The cytoskeleton maintains cell shape and assists movement.
• Microtubules are cylinders of protein found in cilia and flagella.
• Intermediate filaments provide support and strength.
• Actin filaments aid in the movement of the cell and organelles.
• The nucleus is enclosed by a double membrane with pores called the nuclear envelope.
• Chromatin consists of DNA and proteins.
• The nucleolus produces ribosome subunits.
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• Rough ER has ribosomes and participates in protein synthesis.
• Smooth ER lacks ribosomes and synthesizes lipids.
• Ribosomes carry out protein synthesis.
• The Golgi apparatus processes, packages, and secretes proteins.
• Mitochondria produce ATP (cell energy).
• Lysosomes contain digestive enzymes.
• Centrioles are short cylinders that help in cell division.

Cell Membrane & Transport

Plasma Membrane Functions

• The plasma membrane is selectively permeable, controlling what enters and exits the cell.
• It consists of phospholipids, proteins, and cholesterol.
• Hydrophilic heads of phospholipids are attracted to water.
• Hydrophobic tails of phospholipids repel water.

Cellular Transport Mechanisms

• Passive transport doesn't require energy.
• Diffusion is the movement of molecules from high to low concentration.
• Osmosis is the movement of water across membranes.
• Facilitated transport uses protein channels.
• Active transport requires energy (ATP) to move substances against a concentration gradient.
• The sodium-potassium pump is an example of active transport.
• Endocytosis includes phagocytosis (cell eating) and receptor-mediated endocytosis.
• Exocytosis expels materials out of the cell.

Tonicity Effects on Red Blood Cells

• Isotonic solutions have equal solute concentration, maintaining normal cell shape.
• Hypotonic solutions have lower solute concentration outside the cell, causing water to move in and the cell to swell.
• Hypertonic solutions have higher solute concentration outside the cell, causing water to move out and the cell to shrivel.

Review Notes

• Phospholipid's hydrophilic heads interact with water, while hydrophobic tails repel water, making them ideal for cell membranes.
• Passive transport doesn't require ATP and moves substances from high to low concentration, including diffusion, osmosis, and facilitated diffusion.
• Active transport requires ATP and moves substances from low to high concentration, including phagocytosis and bulk transport.
• Sugar dissolves faster in hot tea due to increased molecular movement.
• Osmotic pressure, concentration gradients, gravity, and cholesterol maintain lipid bilayer integrity.
• Receptor-mediated endocytosis involves selective intake of molecules using receptors, unlike phagocytosis that engulfs large particles.
• Paramecium maintains osmotic balance using vacuoles to regulate water intake and expulsion.
• Coupled transport moves glucose and sodium simultaneously.
• Sodium (Na+), steroids, and complex molecules use active transport.
• DNA is found in the nucleus of animal cells.
• Mitochondria produce ATP (energy).