Organic Molecules and Cells (Lecture Notes)

Vocabulary flashcards focusing on key terms and definitions from organic molecules and cell biology topics covered in the lecture.

Organic molecule

A carbon-containing molecule; in this lecture, the four basic categories are carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

A class of organic molecules including sugars; they can be monosaccharides, disaccharides, or polysaccharides.

Glucose

A C6H12O6 sugar; a major monosaccharide and building block for starch; hydrophilic.

Starch

A polysaccharide polymer of glucose used for energy storage in plants.

Monosaccharide

A single sugar unit; the basic building block of carbohydrates.

Disaccharide

Two monosaccharide units linked together (e.g., sucrose).

Polysaccharide

Many sugar units linked together; examples include starch and cellulose.

Hydrophilic

Water-loving; molecules that interact with water, often due to higher oxygen/nitrogen content.

Hydrophobic

Water-fearing; nonpolar molecules that do not mix with water and have a high carbon-to-oxygen ratio.

Amphipathic

A molecule that has both a hydrophilic head and a hydrophobic tail, such as a phospholipid.

Phospholipid

A lipid with a phosphate group; has a hydrophilic head and two hydrophobic tails, forming cell membranes.

Phospholipid bilayer

Two layers of phospholipids forming the cell membrane; heads face water, tails hide from water.

Head (phospholipid)

Hydrophilic part of a phospholipid that faces water.

Tail (phospholipid)

Hydrophobic part of a phospholipid that avoids water.

Cholesterol

A steroid lipid in membranes; stabilizes membranes and serves as a precursor for steroid hormones.

Steroids

A class of lipids, including cholesterol and steroid hormones.

Mer

Suffix meaning unit or piece; used in terms like monomer and polymer.

Monomer

A single building block that can join with others to form polymers (e.g., amino acids, nucleotides, glucose).

Polymer

A large molecule made of many repeating monomer units.

Amino Acid

The monomer of proteins; contains an amino group, carboxyl group, central carbon, hydrogen, and an R group.

R group

The side chain of an amino acid that determines its identity and properties.

Peptide Bond

Covalent bond linking amino acids in a protein chain.

Primary Structure

The linear sequence of amino acids in a protein, held together by peptide bonds.

Secondary Structure

Local folding patterns of a protein, mainly alpha helices and beta pleated sheets.

Alpha Helix

A coiled secondary structure of a protein formed by hydrogen bonds within the chain.

Beta Pleated Sheet

A sheet-like secondary structure formed by hydrogen bonds between segments of the chain.

Tertiary Structure

Three-dimensional folding of a single polypeptide, creating functional pockets.

Quaternary Structure

Assembly of two or more polypeptide chains into a functional protein.

Denature

Unfolding or loss of protein structure and function due to heat, salt, or acidity changes.

Enzyme

A protein that accelerates a chemical reaction at body temperature by lowering activation energy.

Active Site

The region of an enzyme where the substrate binds.

Substrate

The molecule that binds to and is acted upon by an enzyme.

Specificity

Enzymes catalyze one type of reaction or act on specific substrates.

Sucrase

An enzyme that breaks down sucrose; ends with -ase.

Sickle Cell Anemia

A disease caused by a single amino acid change in hemoglobin leading to improper folding.

Nucleic Acid

DNA and RNA; polymers made of nucleotides.

Nucleotide

Monomer of nucleic acids; consists of a nitrogenous base, a sugar (ribose or deoxyribose), and a phosphate group.

Nitrogenous Base

Adenine, guanine, cytosine, thymine (DNA), and uracil (RNA); determine RNA vs DNA.

Ribose

Five-carbon sugar in RNA (pentose).

Deoxyribose

Five-carbon sugar in DNA lacking one oxygen (at C2).

Uracil

Nitrogenous base found in RNA, not present in DNA.

Thymine

Nitrogenous base found in DNA, not in RNA.

DNA

Deoxyribonucleic acid; typically double-stranded; sugar is deoxyribose; bases A, C, G, T.

RNA

Ribonucleic acid; typically single-stranded; sugar is ribose; bases A, C, G, U.

Cytoplasm

Region inside the cell excluding the nucleus; contains cytosol and organelles.

Cytosol

The watery fluid portion of the cytoplasm in which organelles float.

Extracellular Fluid

Fluid outside cells surrounding tissues and cells.

Intracellular Fluid

Fluid inside cells; synonymous with cytosol.

Plasma Membrane

The phospholipid bilayer that encloses the cell and regulates movement and communication.

Nuclear Envelope

Membrane surrounding the nucleus.

Integral Protein

Membrane-spanning protein; can function as channels or receptors.

Peripheral Protein

Protein associated with one side of the membrane; does not span the membrane.

Channel Protein

Protein that forms a pore allowing specific molecules or ions to pass through the membrane.

Glycoprotein

Protein with carbohydrate groups attached; involved in cell identification.

Glycolipid

Lipid with carbohydrate groups attached; involved in cell recognition.

Pore/Water Channel

Channel that allows water to pass through the membrane; often a channel protein.

Ion Channel

Channel protein that selectively conducts ions (e.g., Na+, K+, Cl−) across the membrane.

Ligand gated Channel

An ion channel that opens when a ligand binds to its receptor.

Voltage gated Channel

An ion channel that opens in response to changes in electrical potential.

Mechanically gated Channel

An ion channel opened by mechanical force (pressure).