Lecture Notes: Nucleic Acids, ATP, Proteins, and the Cell Membrane

Vocabulary flashcards covering key terms from Pages 1–5 of the notes.

Nucleic acids

Biomolecules (DNA and RNA) that store and transmit genetic information; built from nucleotides.

Nucleotide

Monomer of nucleic acids; consists of a nitrogenous base, a five‑carbon sugar (pentose), and a phosphate group.

Nitrogen base

Organic molecule in nucleotides; purines (adenine, guanine) and pyrimidines (cytosine, thymine in DNA; uracil in RNA).

Pentose sugar

Five‑carbon sugar in nucleotides; deoxyribose in DNA and ribose in RNA.

Phosphate group

Phosphate moiety linking nucleotides to form nucleic acids; can be hydrolyzed to release energy (as in ATP).

DNA

Deoxyribonucleic acid; double‑stranded molecule in the nucleus that stores genetic information; forms chromosomes; uses thymine.

RNA

Ribonucleic acid; single‑stranded nucleic acid; involved in transcription and translation; synthesized in the nucleolus.

Gene

Segment of DNA that codes for a specific protein.

Double helix

The twisted ladder structure of DNA; two antiparallel strands wound into a helix.

Chromosome

Condensed form of DNA that becomes visible during cell division; carries genes.

Transcription

Process of copying a DNA sequence into RNA.

Translation

Process of synthesizing proteins from an mRNA template.

Nucleus

Membrane‑bound organelle containing the cell's DNA.

Nucleolus

Nuclear region where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins.

ATP

Adenosine triphosphate; the cell’s energy currency; consists of adenine, ribose, and three phosphate groups.

Adenosine

Nucleoside formed from adenine and ribose; component of ATP.

Adenine

Purine nitrogenous base found in DNA, RNA, and ATP.

Ribose

Five‑carbon sugar in RNA and in ATP; in DNA the sugar is deoxyribose.

Phosphate groups

Three phosphate groups in ATP; cleavage releases energy for cellular work.

ATP hydrolysis

Process of removing the terminal phosphate from ATP, releasing energy to power cellular processes.

Phosphorylation

Transfer of a phosphate group to another molecule, often altering its activity.

Energy release from ATP

Energy released when the terminal phosphate is cleaved from ATP, used to power cellular work.

Fibrous proteins

Proteins with long, threadlike chains; usually insoluble in water; provide structural support.

Globular proteins

Spherical, water‑soluble proteins; include many enzymes and regulatory proteins.

Denaturation

Unfolding of a protein due to disruption of bonds, leading to loss of function.

Enzymes

Catalytic proteins that speed up chemical reactions by lowering activation energy.

Protein

Macromolecule made of amino acids; includes enzymes and structural proteins; diverse functions.

Plasma membrane

Cell membrane composed of a phospholipid bilayer with embedded proteins and carbohydrates; regulates movement of substances into and out of the cell.

Cytoplasm

The cellular interior outside the nucleus; contains cytosol and organelles.

Nucleus (cell)

Control center of the cell; houses genetic material.

Phospholipid bilayer

Two‑layer arrangement of phospholipids forming the core of the plasma membrane; hydrophilic heads face outward, hydrophobic tails inward.

Phospholipid head

Polar, hydrophilic part of a phospholipid that faces water.

Lipid tail

Nonpolar, hydrophobic part of a phospholipid.

Fluid mosaic model

Model describing the plasma membrane as a dynamic mosaic of lipids, proteins, and carbohydrates.

Selective permeability

Property of the plasma membrane that allows some substances to cross more easily than others.

Hydrophilic

Water‑loving; polar.

Hydrophobic

Water‑fearing; nonpolar.

Amino acids

Building blocks of proteins; linked by peptide bonds to form polypeptides.