Exam 1 BIO 121

Characteristics of Living Organisms

Organization, metabolism, responsiveness, movement, growth, development/reproduction, and differentiation

Anatomy

The study of body structures and their physical relationships

Physiology

The study of how those body structures function.

Hierarchy of Complexity

Chemical level $\rightarrow$ Cellular level $\rightarrow$ Tissue level $\rightarrow$ Organ level $\rightarrow$ Organ system level $\rightarrow$ Organism level

Homeostasis

The body's ability to maintain a stable, relatively constant internal environment despite external changes.

Negative

Reverses a change to return the body to its set point (e.g., body temperature regulation).

Positive

Amplifies or reinforces a change away from the normal state (e.g., childbirth/oxytocin release, blood clotting)

Anatomical Position

Body standing erect, facing forward, feet flat on the floor pointing forward, with arms at the sides and palms facing forward.

Sagittal

Divides body into left and right.

Frontal

Divides body into front (anterior) and back (posterior).

Transverse

Divides body into top (superior) and bottom (inferior)

Dorsal Cavity:

Contains cranial (brain) and spinal (spinal cord) cavities.

Anterior/Ventral

Front

Posterior/Dorsal

Back

Superior

Towards Head

Inferior

Towards Feet

Distal

Away from trunk

Proximal

Towards trunk

Medial

Toward Midline

Supine

Facing up

Prone

facing down

Dorsal Cavity

Contains cranial (brain) and spinal (spinal cord) cavities.

Ventral Cavity

Contains thoracic (heart/lungs) and abdominopelvic (digestive/reproductive organs) cavities.

Atomic Structure Basics

Protons (+ charge) and neutrons (neutral) reside in the nucleus; electrons (- charge) orbit the nucleus in electron shells.

Ionic

Electrons are transferred from one atom to another.

Covalent

Electrons are shared between atoms (can be polar or nonpolar).

Hydrogen

Weak attraction between a partially positive hydrogen atom and a partially negative atom (like oxygen or nitrogen).

Anabolism

Synthesis reactions that build larger molecules from smaller ones (requires energy).

Catabolism

Decomposition reactions that break down large molecules into smaller ones (releases energy).

Dehydration Synthesis

Monomers join together to form polymers, releasing a water molecule.

Hydrolysis

Polymers are broken down into monomers by adding a water molecule.

pH

A measure of hydrogen ion ($H^+$) concentration (0–6 is acidic, 7 is neutral, 8–14 is basic).

Buffers

Chemical complexes that resist abrupt changes in pH by binding or releasing H+

Carbohydrate types

Monosaccharides (glucose), Disaccharides (sucrose), Polysaccharides (glycogen).

Carbohydrates function

Primary and immediate source of cellular energy.

Lipid Types

Triglycerides (energy storage), Phospholipids (cell membranes), Steroids/Cholesterol (hormones).

Saturated vs. Unsaturated

Saturated fats have single bonds and are solid at room temp; Unsaturated fats have one or more double bonds and are liquid at room temp.

Protein Structure

Built from amino acids linked by peptide bonds.

Protein Function

Enzymes, structural support, transport, defense.

Denaturation

The loss of a protein's 3D shape (and function) due to extreme heat or pH changes.

Enzymes function

Biological catalysts that speed up reactions by lowering activation energy.

Enzyme Mechanism

The substrate binds to the enzyme's active site perfectly ("lock and key" or "induced fit"), meaning an enzyme's specific shape dictates exactly which reaction it can catalyze.

ATP structure

Adenosine attached to three phosphate groups.

ATP Function

The primary "energy currency" of the cell; breaking the high-energy phosphate bond releases energy for cellular work.

DNA

Double-stranded helix, uses deoxyribose sugar, contains bases A, T, C, G; stores genetic information.

RNA

Single-stranded, uses ribose sugar, contains bases A, U, C, G; functions in protein synthesis.

Complementary

Base pairing rules (DNA: A-T, C-G; RNA: A-U, C-G).

Cell Theory Principles

All living things are composed of cells; the cell is the basic structural and functional unit of life; all cells arise from pre-existing cells.

Cellular Differentiation

The process by which an unspecialized cell becomes specialized in structure and function to perform specific tasks.

Intracellular Fluid (ICF)

Fluid found inside cells (about 2/3 of total body water).

Extracellular Fluid (ECF)

Fluid outside cells (includes interstitial fluid and blood plasma).

Fluid outside cells (includes interstitial fluid and blood plasma).

(creates a hydrophobic barrier) embedded with proteins (channels, receptors, markers) and cholesterol (stabilizes fluidity).

Mitochondria

ATP production (powerhouse)

Ribosomes

Protein synthesis.

Rough ER

Modifies proteins

Smooth ER

Lipid synthesis and detoxification

Golgi Apparatus

Sorts, modifies, and ships proteins.

Nucleus Structure

Enclosed by a double nuclear membrane with nuclear pores.

Nucleus Contents

Contains nucleolus (ribosome assembly) and chromatin (DNA).

Nucleus Function

The control center of the cell; directs all activities by hosting DNA.

Transcription

DNA is copied into mRNA inside the nucleus.

Translation

mRNA travels to a ribosome in the cytoplasm, where tRNA brings amino acids to build the protein chain.

Passive transport

Movement down the concentration gradient; requires no ATP (e.g., simple diffusion, facilitated diffusion, osmosis).

Active Transport

Movement against the concentration gradient; requires ATP (e.g., sodium-potassium pump, vesicular transport like endocytosis/exocytosis).

Isotonic

Equal solute concentration; cell stays the same.

Hypertonic

Higher solute outside; water leaves cell; cell shrinks (crenation).

Hypotonic

Lower solute outside; water enters cell; cell swells and may burst (lysis).

Interphase

The metabolic phase where the cell grows (G1, G2) and prepares for division.

DNA Replication

Occurs during the S phase of interphase, creating an exact copy of the cell's DNA.

Mitosis

Division of the nucleus into two identical daughter nuclei.

Prophase

Chromatin condenses into chromosomes; spindle fibers form

Metaphase

Chromosomes line up along the middle of the cell.

Anaphase

Sister chromatids are pulled apart to opposite poles.

Telophase

Nuclear membranes reform around the two new sets of chromosomes. (Followed by Cytokinesis: division of the cytoplasm).