Key Concepts in Biology and Chemistry

Atomic number

The number of protons in the nucleus of an atom.

Atomic mass (mass number)

The total number of protons and neutrons in an atom's nucleus.

Atom

The smallest unit of matter that retains the properties of an element.

Sub-atomic particles

Proton (+), Neutron (0), Electron (−)

Ion

An atom or molecule with a net electric charge due to loss or gain of electrons.

Cation

A positively charged ion (loss of electrons).

Anion

A negatively charged ion (gain of electrons).

Enzyme

A biological catalyst that speeds up chemical reactions.

Base pairings in DNA and RNA

DNA: A-T, C-G | RNA: A-U, C-G

Proteins

Chains of amino acids.

Carbohydrates

Chains of monosaccharides (e.g., glucose).

Triglycerides

Glycerol + 3 fatty acids.

Nucleic acids

Nucleotides (sugar + phosphate + base).

pH scale

The concentration of hydrogen ions (H⁺); ranges from 0 (acidic) to 14 (basic); 7 is neutral.

Mitosis

The process of cell division that results in two identical daughter cells.

Mitochondria

Produces ATP (cell energy).

Ribosomes

Synthesize proteins.

Lysosomes

Digest cellular waste and foreign material.

Golgi bodies

Modify, sort, and package proteins.

Rough ER

Synthesizes proteins (has ribosomes on surface).

Replication

Copying DNA.

Transcription

Making RNA from DNA.

Translation

Making protein from RNA.

Long bone parts

Diaphysis: Shaft of the bone; Epiphysis: Ends of the bone; Periosteum: Membrane covering the bone.

Muscle fiber structures

Sarcolemma: Cell membrane of the muscle fiber; Sarcoplasm: Cytoplasm of the muscle fiber; Myofibrils: Contractile units containing actin and myosin; Sarcoplasmic reticulum: Stores and releases calcium; T-tubules: Invaginations of the sarcolemma for signal transmission.

Neuron anatomy

Cell body (soma): Contains nucleus; Dendrites: Receive signals; Axon: Sends signals; Axon terminal: Releases neurotransmitters; Myelin sheath: Insulates axon (increases signal speed); Nodes of Ranvier: Gaps in myelin for signal jumping (saltatory conduction).

Action potential phases

Depolarization: Na⁺ enters cell, making inside positive; Repolarization: K⁺ exits cell, restoring negative charge; Hyperpolarization: K⁺ channels stay open too long; cell becomes overly negative.

Neuroglial cells

Support cells in the nervous system (e.g., astrocytes, oligodendrocytes, Schwann cells, microglia).

Pituitary hormones

Anterior pituitary: ACTH, TSH, GH, LH, FSH, PRL; Posterior pituitary: ADH, Oxytocin.

Nervous system functions

Sympathetic: 'Fight or flight' - increases heart rate, dilates pupils, inhibits digestion; Parasympathetic: 'Rest and digest' - slows heart rate, promotes digestion.

DNA vs RNA

Similar: Made of nucleotides; carry genetic information; DNA: Double-stranded, deoxyribose sugar, bases A-T-C-G; RNA: Single-stranded, ribose sugar, bases A-U-C-G.

Parasympathetic vs Sympathetic

Opposing effects on target organs; Sympathetic uses norepinephrine; Parasympathetic uses acetylcholine.

Cephalic

Toward the head

Posterior

Toward the back

Dorsal

Also toward the back (used in animals/humans)

Contralateral

Opposite side

Cranial

Brain

Thoracic

Heart/lungs

Abdominal

Digestive organs

Pelvic

Bladder, reproductive organs

Intracellular fluid

High in K⁺, low in Na⁺

Interstitial fluid

High in Na⁺, low in K⁺

Dura mater

Outermost, tough layer

Arachnoid mater

Middle, web-like layer

Pia mater

Innermost, adheres to brain/spinal cord

Heart valves

Control blood flow direction (tricuspid, bicuspid, semilunar)

Heart chambers

Right/left atria and ventricles

Aorta

Largest artery; carries blood from left ventricle to body

Pulmonary trunk

Carries blood from right ventricle to lungs

Artery

Carries blood away from heart

Vein

Carries blood to the heart

Capillary

Site of gas and nutrient exchange

Hematocrit

~42-52% (men), 37-47% (women)

Hemoglobin

~13-18 g/dL (men), 12-16 g/dL (women)

Cardiac Output

~4-8 L/min

ADH

Posterior pituitary → Kidneys (water reabsorption)

Epinephrine/Norepinephrine

Adrenal medulla → Heart, lungs, liver, muscles (fight or flight)

Acetylcholine

Released by neurons → Skeletal muscles, glands, etc. (parasympathetic effects)

Total blood volume

About 5 liters (or 8% of body weight)

Hemoglobin's role in circulation

Binds and transports oxygen (and some CO₂) in red blood cells

Endocardium

Inner lining of the heart chambers

Myocardium

Thick middle muscle layer (responsible for contraction)

Epicardium

Outer layer (also part of the pericardium)

Mole in chemistry

A unit of measurement for amount of substance; 1 mole = 6.022 × 10²³ particles (Avogadro's number)

Osmolarity

The concentration of solute particles per liter of solution; affects water movement across membranes

Deci

10⁻¹ (0.1)

Milli

10⁻³ (0.001)

Micro

10⁻⁶ (0.000001)

pH

Measures acidity or alkalinity; < 7 = acidic, = 7 = neutral, > 7 = basic (alkaline)

Function of enzymes

Speed up (catalyze) biochemical reactions without being consumed

Pulmonary circulation

Right ventricle → lungs → left atrium (oxygenates blood)

Systemic circulation

Left ventricle → body → right atrium (delivers oxygen)

Four heart chambers and their valves

Right atrium → Tricuspid valve → Right ventricle; Right ventricle → Pulmonary valve → lungs; Left atrium → Bicuspid (mitral) valve → Left ventricle; Left ventricle → Aortic valve → body

Three divisions of the pharynx

Nasopharynx: Upper (behind nose); Oropharynx: Middle (behind mouth); Laryngopharynx: Lower (leads to larynx/esophagus)

Functions of the following organs; Esophagus, Stomach, small and large intestine, pancreas, liver, gallbladder, trachea and bronchi, alveoli, kidneys

Esophagus: Moves food to stomach via peristalsis; Stomach: Digests proteins; stores and churns food; Small intestine: Main site of nutrient absorption; Large intestine: Absorbs water and forms feces; Pancreas: Produces digestive enzymes and insulin; Liver: Detoxifies, produces bile, stores nutrients; Gallbladder: Stores and releases bile; Trachea and Bronchi: Conduct air to lungs; Alveoli: Gas exchange (O₂/CO₂) in the lungs; Kidney: Filters blood, produces urine, regulates fluid/electrolytes; Lymphatic system: Returns interstitial fluid to blood, immune defense