Unit 01: Molecules, Cells and Proteins - Structure & Function

Comprehensive vocabulary flashcards covering macromolecule structures, DNA replication, transcription, translation, protein functions, cell theory, organ systems, immune responses, and homeostatic feedback mechanisms.

Nutrients

Substances produced when the digestive system breaks down food so the body can absorb and utilize them for energy, growth, and maintenance.

Monosaccharides

The simplest carbohydrate molecules consisting of a single sugar unit, such as glucose, which provide quick energy.

Disaccharides

Carbohydrates composed of two monosaccharide sugar units linked together, such as sucrose and maltose.

Polysaccharides

Complex carbohydrates made of long chains of many sugar units, with examples including starch and cellulose.

Nucleotide

The repeating monomer unit of nucleic acids, consisting of three parts: a phosphate group, a five-carbon pentose sugar, and a nitrogenous base.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid molecule located in the cell nucleus that carries genetic blueprints and instructions for life.

Gene

A specific segment of DNA that codes for the sequence of amino acids to produce a particular protein.

Helicase

The replication enzyme responsible for unzipping and separating the two complementary strands of DNA.

Primase

An enzyme that attaches to the unzipped DNA strand and begins laying down the initial nucleotides during DNA replication.

DNA Polymerase

The enzyme that synthesizes new DNA strands by laying down complementary nucleotides along the template strand.

Ligase

An enzyme that binds the newly laid complementary nucleotides together to complete the DNA strand backbone.

Semi-Conservative Replication

The method of DNA replication that yields two identical sets of DNA, each composed of one original parent strand and one newly synthesized strand.

Transcription

The first step of protein synthesis occurring in the nucleus, where RNA polymerase transcribes a DNA sequence into a complementary strand of messenger RNA (mRNA).

Codon

A three-base nitrogenous sequence on an mRNA molecule that codes for a specific amino acid.

RNA Polymerase

The enzyme that unzips the DNA double helix, reads the template strand, and copies the sequence into an mRNA molecule substituting uracil for thymine.

Translation

The process occurring at ribosomes where mRNA codons are decoded with the assistance of tRNA and rRNA to assemble amino acids into a polypeptide chain.

Transfer RNA (tRNA)

An RNA molecule carrying a specific amino acid and a complementary anticodon that matches a corresponding codon on mRNA during translation.

Ribosomal RNA (rRNA)

The structural RNA component of ribosomes that attaches amino acids together in the proper order to form a growing protein chain.

Hormones

Protein chemical messengers secreted into the body that help regulate various physiological processes, such as insulin and adrenaline.

Enzymes

Proteins that act as biological catalysts to speed up chemical reactions, whose activity is sensitive to shape, temperature, pH, and concentration.

Cell Receptors

Membrane-bound proteins that receive and transmit chemical signals across cell membranes to mediate cellular communication.

Structural Proteins

Proteins that provide physical support, rigidity, and shape to cells and tissues, such as collagen and keratin.

Antibodies

Proteins produced by white blood cells that bind to, identify, and attack foreign invaders or pathogens as part of the immune system.

Mutation

A change in the nucleotide base sequence of DNA that can alter corresponding mRNA codons and result in the insertion of different amino acids in a protein.

Sickle Cell Anemia

A genetic condition caused by a single DNA base change ($\text{CTT} \rightarrow \text{CAT}$), leading to an mRNA change ($\text{GAA} \rightarrow \text{GUA}$) that replaces glutamic acid (Glu) with valine (Val), altering the shape of hemoglobin and red blood cells.

Cell

The basic microscopic unit of structure and function in all living organisms.

Cell Theory

A foundational biological principle stating that all living things are composed of cells, cells are the basic structural and functional units of life, and all cells arise from pre-existing cells.

Cell Membrane

A selectively permeable boundary that separates a cell\'s interior from the outside environment, regulates transport, and facilitates cellular communication through receptor molecules.

Mitochondria

Membrane-bound organelles known as the powerhouses of the cell, where cellular respiration occurs to produce ATP energy.

Ribosomes

Small cellular structures that serve as the site of protein synthesis in both prokaryotic and eukaryotic cells.

Vacuoles

Membrane-bound storage organelles that hold water and waste products, appearing large in plant cells and small in animal cells.

Chloroplasts

Plant-specific organelles containing chlorophyll where the process of photosynthesis takes place.

Tissue

A group of interconnected cells with similar structures that work together to perform a shared or specific function.

Organ

A discrete bodily structure composed of multiple different tissue types that collaborate to perform a specific physiological task.

Organ System

A coordinated group of organs that interact cooperatively to carry out complex, integrated bodily functions.

System Handoffs

Complex, coordinated physiological transitions where one biological system completes an action or supplies a resource to another system that manages the subsequent phase.

Innate Immunity

The rapid, non-specific branch of the immune system that provides immediate defense against pathogens.

Adaptive Immunity

The targeted branch of the immune system that takes longer to respond but creates pathogen-specific defenses and immunological memory.

Antigens

Unique protein markers found on the outer surface of pathogens that are recognized as non-self by immune receptors.

Vaccination

The medical introduction of a weakened or dead pathogen to trigger a protective immune response without causing illness.

Homeostasis

The continuous maintenance of a stable internal environment within an organism despite fluctuations in the external environment.

Negative Feedback Mechanism

A primary homeostatic regulatory loop where a detected deviation triggers responses by an effector to counteract the stimulus and restore balance, such as temperature regulation around $37^\circ\text{C}$.

Positive Feedback Mechanism

A physiological control mechanism that magnifies and accelerates an initial stimulus until an endpoint is reached, such as oxytocin-induced contractions during childbirth.

Osmoregulation

The physiological process wherein the kidneys filter blood, reabsorbing water and essential ions like sodium while eliminating waste products.

Nephrons

The functional microscopic units of the kidneys responsible for filtering blood and balancing water and dissolved solute levels.