Biology: Key Concepts in Life Sciences

Kingdoms of Life

Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia

Archaebacteria Example

Methanogens

Eubacteria Example

E. coli

Protista Example

amoebas

Fungi Example

mushrooms

Plantae Example

trees

Animalia Example

humans

Prokaryotes

Organisms with no nucleus/membrane organelles, including Archaebacteria and Eubacteria

Eukaryotes

Organisms with a nucleus/membrane organelles, including Protista, Fungi, Plantae, and Animalia

Cellular Organization

All living things are made of one or more cells; the cell is the basic unit of structure/function for all living organisms.

Metabolism

Living organisms obtain and use energy to fuel their life processes, including growth, movement, and reproduction.

Response to Stimuli

Living things can detect and respond to changes in their internal/external environment.

Growth and Development

Living organisms increase in size and mature over time, following patterns determined by their genetic information.

Reproduction

Living things have the ability to produce offspring, either through sexual reproduction (combining genetic material from two parents) or asexual reproduction (producing exact copies from a single parent).

Levels of Organization of Life

Atoms, Molecules, Organelles, Cells, Tissues, Organs, Organ systems, Organisms, Populations, Communities, Ecosystems, Biomes, Biosphere.

Theory of Evolution

Charles Darwin's theory that every group of organisms descended from a common ancestor, ultimately tracing back to a 'Single origin of life on earth.'

Homeostasis

The process where the human body maintains a stable internal environment, even when external conditions change.

Body Temperature Regulation

Normal: ~98.6°F (37°C), maintained by sweating (cool down) or shivering (warm up).

Blood Glucose Levels Regulation

Maintained by insulin (lowers blood sugar) and glucagon (raises blood sugar) produced by the pancreas.

Water Balance (Osmoregulation)

Controlled by the kidneys and hormones like ADH (antidiuretic hormone) to balance water intake and loss.

pH of Blood and Body Fluids

Normal blood pH: ~7.35-7.45, maintained by buffers, respiration (CO₂ removal), and kidney function.

Oxygen and Carbon Dioxide Levels Regulation

Controlled by the respiratory system and blood circulation to ensure proper gas exchange in the lungs.

Blood Pressure Regulation

Regulated by the heart, blood vessels, and hormones like adrenaline and angiotensin.

Electrolyte Balance

Sodium, potassium, calcium, and other ions are balanced by the kidneys and hormones like aldosterone.

Scientific Method Steps

List the 4 steps, in order.

Observation

Identify a problem/ask a question based on something you notice.

Hypothesis

Form a testable explanation or educated guess to answer the question.

Experiment

Test the hypothesis → controlled investigation and data collection.

Conclusion

Analyze the results to determine if they support or refute the hypothesis.

Cell Theory

A fundamental principle in biology that explains the structure and function of all living things, developed in the 1800s by scientists like Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.

First part of Cell Theory

All living things are made of one or more cells.

Second part of Cell Theory

The cell is the basic unit of life.

Third part of Cell Theory

All cells come from pre-existing cells.

Gene Theory

Genes are the basic units of heredity and are made of DNA, located on chromosomes and carry instructions for building proteins.

Theory of Heredity

Explains how traits are passed from parents to offspring through genes.

Parts of an Atom

Proton - Positive charge (+), found in the nucleus; Neutron - No charge (neutral), found in the nucleus; Electron - Negative charge (−), orbits the nucleus.

Ions

Atoms that have gained or lost electrons → they have a charge.

Isotopes

Atoms of the same element with different numbers of neutrons → they have different masses.

Difference between Atom and Ion

Atom: Has an equal number of protons and electrons (neutral charge); Ion: Has more or fewer electrons than protons (charged).

Hydrogen Ion

A hydrogen ion (H⁺) is a hydrogen atom that has lost its only electron, leaving just a proton, giving it a positive charge.

Uses of Isotopes

Carbon-14: Dating fossils; Iodine-131: Thyroid scans in medicine; Cobalt-60: Cancer radiation treatment; Tracers: Follow pathways in metabolism or photosynthesis.

Molecular Bonds

Molecules are held together by chemical bonds, which are interactions between electrons of atoms.

Ionic Bond

One atom transfers electrons to another; forms between metals and nonmetals (e.g., NaCl).

Covalent Bond

Atoms share electrons; very strong; forms most biological molecules (e.g., H₂O).

Hydrogen Bond

Weak attraction between polar molecules; important in water and DNA structures.

Polar Molecule

A molecule is polar if it has an uneven distribution of electrons, creating a positive end and a negative end.

Unique Properties of Water

Cohesion - Water sticks to itself; Adhesion - Water sticks to other substances; High Specific Heat - Water resists temperature changes; Universal Solvent - Dissolves many substances; Ice Floats - Solid water is less dense than liquid.

pH

pH is a measure of the concentration of hydrogen ions (H⁺) in a solution, showing how acidic or basic a substance is.

pH Scale

Ranges from 0 to 14

Acidic

0-6.9 = Acidic (more H⁺ ions). Example: Lemon juice (~2), vinegar (~3)

Neutral

7 = Neutral. Example: Pure water

Basic

7.1-14 = Basic (more OH⁻ ions). Example: Baking soda (~9), bleach (~13)

Macromolecules of Life

Carbohydrates, Proteins, Lipids, Nucleic Acids

Monomer

A single building block

Polymer

A chain of monomers bonded together

Proteins Composition

Proteins are made of chains of amino acids

Number of Amino Acids

20

Enzymes

Enzymes are proteins that speed up chemical reactions by lowering activation energy. They are specific to the reactions they catalyze.

Denature

Denature means the enzyme's shape changes, so it can no longer function.

Factors that Denature Enzymes

High temperature and extreme pH levels

Polysaccharide

A polysaccharide is a long chain of sugar molecules. Example: Starch, cellulose, glycogen

Simple Sugar

One or two sugar units (fast energy). Example: Glucose, sucrose

Complex Sugar

Many sugar units (slower energy release). Example: Starch, fiber

Covalent Bonds in Macromolecules

Monomers of macromolecules are held together by covalent bonds, formed through dehydration synthesis (removal of water).

Nucleic Acids Composition

Nucleic Acids are made of chains of nucleotides

DNA

Deoxyribonucleic acid

RNA

Ribonucleic acid

Parts of a Nucleotide

Sugar (deoxyribose in DNA, ribose in RNA), phosphate group, nitrogen base

DNA Nucleotides

Adenine (A), Thymine (T), Cytosine (C), Guanine (G)

RNA Nucleotides

Adenine (A), Uracil (U) (replaces thymine), Cytosine (C), Guanine (G)

Differences between RNA and DNA

DNA: Deoxyribose, A,T,C,G, double-stranded, Nucleus, Stores genetic info; RNA: Ribose, A,U,C,G, Single-stranded, Nucleus & cytoplasm, Helps make proteins

Lipids Composition

Lipids are made of chains of fatty acids and glycerol

Types of Lipids

Fats and Oils (found in body fat, plant oils), Phospholipids (found in cell membranes), Steroids (found in hormones like estrogen/testosterone and cholesterol)

Prokaryotic Cell Parts

1.) Cell membrane - Controls what enters and exits the cell; maintains internal environment. 2.) Cell wall - Provides structural support and protection; made of peptidoglycan in bacteria. 3.) Cytoplasm - Jelly-like fluid where all cellular processes occur. 4.) Ribosomes - Small structures that build proteins by linking amino acids. 5.) Nucleoid region - Areas where the single circular DNA molecule is located; not enclosed by a membrane.

Plant Cell Parts

1.) Cell membrane - Regulates movements of substances into and out of the cell. 2.) Cell wall - Provides rigid support and shape; made of cellulose. 3.) Cytoplasm & cytoskeleton - Cytoplasm: Fluid that fills the cell and holds organelles; Cytoskeleton: Protein fibers that support cell shape and help with transport inside the cell. 4.) Ribosomes - Synthesize proteins from amino acids. 5.) Chloroplasts - Perform photosynthesis (convert sunlight into chemical energy); contain chlorophyll. 6.) Mitochondria - Powerhouse of the cell; convert glucose into ATP (energy) through cellular respiration. 7.) Central vacuole - Large, fluid-filled sac that stores water, nutrients, and waste; also maintains turgor pressure. 8.) Peroxisomes - Break down fatty acids and toxins; produce hydrogen peroxide, then break it down safely. 9.) Lysosomes - Contain digestive enzymes to break down old cell parts and invading pathogens (less common but can be present). 10.) Rough endoplasmic reticulum - Has ribosomes; modifies and packages proteins for export.

smooth endoplasmic reticulum

Makes lipids and detoxifies harmful substances

golgi body

Sorts, modifies, and ships proteins and lipids made by the ER

nucleus

Control center; contains the cell's DNA

nucleolus

Found inside the nucleus; makes ribosomes.

cell membrane

Controls what enters and leaves the cell; provides protection and communication.

Centrioles

Help organize cell division (mitosis and meiosis); form spindle fibers

cytoplasm

Jelly-like substance where organelles float

cytoskeleton

Gives the cell structure and helps move materials.

ribosomes

Build proteins from amino acids

mitochondria

Generate ATP from glucose; site of cellular respiration

small vacuoles

Store water, food, or waste (much smaller than in plant cells)

peroxisomes

Break down harmful substances; manage oxidative reactions

lysosomes

Contain enzymes to digest waste, old organelles, and invaders

Rough endoplasmic reticulum

Covered in ribosomes; helps fold and transport proteins.

reduction

Gain of electrons.

oxidation

Loss of electrons.

redox reaction

A reaction where one molecule is oxidized (loses electrons) and another is reduced (gains electrons).

ATP

Adenosine Triphosphate

3 main parts of ATP

Adenine (nitrogenous base), Ribose (sugar), 3 phosphate groups

purpose of ATP

Main energy currency of the cell

enzyme breakdown

ATPase

ATP breakdown equation

ATP → ADP + Pi + energy

enzymes to make ATP

ATP synthase

ATP formation equation

ADP + Pi + energy → ATP

macromolecule an enzyme is made of

Protein