Biology 101: Key Concepts in Life Sciences

Homeostasis

Humans perspire to prevent body temperature from rising too high.

Evaporation of sweat

Has a cooling effect, hence in hot weather, or when the individual's muscles heat up due to exertion, more sweat is produced.

Biotic factors

Living factors that influence an ecosystem.

Abiotic factors

Non-living factors that influence an ecosystem and an organism's life.

Levels of Organization

Living things may be studied on many different levels ranging from simple to complex.

Unicellular organisms

Single-celled organisms where the single cell performs all life functions independently.

Multicellular organisms

Organisms with various levels of organization where individual cells perform specific functions and work together.

Cells

The basic unit of life.

Tissues

Groups of cells that perform a specific function.

Organs

Structures made of different tissues that perform specific functions.

Organ Systems

Groups of organs that work together to perform complex functions.

Organisms

Individual living entities.

Population

A group of organisms of the same species living in a specific area.

Community

Different populations that live together in a defined area.

Ecosystem

A community of living organisms and their interactions with their environment.

Biosphere

The global sum of all ecosystems.

Covalent bonds

Bonds formed when two elements share one or more electrons.

Ionic bonds

Bonds formed when an electron is transferred from one atom to another.

Hydrogen bonds

The electromagnetic interaction of a hydrogen atom and an electronegative atom, classified as weak bonds.

Chemical equation

Includes reactants and products, an arrow showing the direction of the process, and the ratio and number of molecules involved.

Essential Elements for Life

The six elements necessary for life.

Organic compounds

Compounds that contain Carbon atoms that are covalently bonded to other elements.

Lipids

Organic molecules that are insoluble in water, serving as building blocks of the cell membrane and energy storage.

Carbohydrates

Key source of energy, made of monosaccharides bonded together in long chains.

Proteins

Made of amino acids, some act as enzymes, structural components, or antibodies.

Nucleic Acids

Long chains of nucleotides that store hereditary information (DNA) and aid in building proteins (RNA).

Enzymes

Proteins that act as catalysts and help complex reactions occur everywhere in life.

Activation Energy

The energy needed to start a chemical reaction.

Factors affecting enzyme function

pH and temperature, with enzymes in the body working best at 98.6°F.

Eukaryote

What is a eukaryote?

Eukaryote

Any organism consisting of one or more cells that contain DNA in a membrane-bound nucleus, separate from the cytoplasm.

Prokaryote

Any organism - usually single-celled - whose DNA is suspended freely in the cytoplasm.

Extremophiles

Prokaryotes, particularly archaea, that are capable of surviving in extreme conditions due to their simple cell structure.

Organelles

Specialized, membrane-bound structures within eukaryotic cells that compartmentalize functions.

Nucleus

Control center of the cell that separates the genetic material (DNA) from the rest of the cell.

Cytoplasm

The matrix that supports organelles and metabolic reactions, located between the nuclear membrane and cell membrane.

Cell Membrane

A selectively permeable membrane that controls what goes in and out of the cell.

Ribosome

The protein factory of the cell that makes proteins, found alone in the cytoplasm or attached to the rough endoplasmic reticulum.

Mitochondria

The powerhouse of the cell that breaks down food to make ATP, the major fuel for all cell activities that require energy.

Chloroplasts

Organelles found only in plant cells that contain chlorophyll and are involved in photosynthesis.

Photosynthesis

The process that converts sunlight, water, and carbon dioxide into glucose and oxygen.

Endoplasmic Reticulum

The internal production and delivery system of the cell, consisting of membranous channels.

Rough ER

A type of endoplasmic reticulum studded with ribosomes that modifies and transports proteins.

Smooth ER

A type of endoplasmic reticulum that lacks ribosomes and makes lipids and breaks down toxins.

Golgi Apparatus

The shippers of the cell that package, modify, and transport proteins to different locations inside or outside of the cell.

Lysosomes

The clean-up crew of the cell that breaks down food and destroys old cells, containing enzymes for intracellular digestion.

Vacuoles

Storage structures within the cell that can store a variety of substances.

Vesicles

Small membrane-bound sacs that transport materials within the cell.

Nuclear membrane

The double membrane structure that separates the nucleus from the cytoplasm.

Nucleoplasm

The semifluid medium inside the nucleus.

Nucleolus

The part of the nucleus that makes ribosomes.

Centrioles

Organelles present only in animal cells that play a role in cell division.

Chlorophyll

A green pigment in chloroplasts that absorbs solar energy for photosynthesis.

ATP

The major fuel for all cell activities that require energy.

Facilitated Diffusion

Proteins assist in diffusion of molecules across plasma membrane. From high to low concentration - requires no energy from cell.

Osmosis

Diffusion of water across the plasma membrane (partially permeable) in order to equalize the solute concentrations on the two sides.

Tonicity

A measure of the osmotic pressure gradient of two solutions separated by a semipermeable membrane.

Isotonic

No net movement of water between cell and environment.

Hypertonic

A cell in a hypertonic solution has a lower concentration of solutes than its surroundings, leading to a decrease of water in the cell.

Hypotonic

A cell in a hypotonic solution has a higher concentration of solutes than the surrounding solution, causing water to flow into the cell.

Active Transport

How most molecules move across the plasma membrane, analogous to a pump moving water uphill. Uses energy from low to high.

ATP

Drives substances across the plasma membrane with the aid of carrier molecules.

Vacuole

Stores water in plant cells, making lettuce crisp; when there is no water, the plant wilts.

Cell Wall

Provides support and protection to the cell membrane, found outside the cell membrane in plant cells.

Eukaryote

A type of cell that contains a nucleus and organelles, such as an animal cell.

Homeostasis

The internal balance maintained by controlling what enters and exits the cell.

Lipid Bilayer

Two layers of phospholipids that make up the cell membrane, with polar heads and non-polar tails.

Phospholipid

A molecule that makes up the lipid bilayer, with a polar head that loves water and non-polar tails that hide from water.

Fluid Mosaic Model

Describes the structure of the cell membrane, where proteins are embedded in a flexible lipid bilayer.

Passive Transport

Cell transport that does not use energy, including diffusion, facilitated diffusion, and osmosis.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Protein Pumps

A type of active transport where proteins move substances across the plasma membrane using energy.

Endocytosis

A process where cells engulf substances from the outside environment.

Exocytosis

A process where cells expel substances to the outside environment.

Cell Membrane

Controls what enters and exits the cell, providing protection and support.

Cytoplasm

The inside of the cell, where the lipid bilayer separates the outside environment from the cell's contents.

Passive Transport

Movement of molecules across a cell membrane without the use of energy.

Diffusion

The process by which molecules spread from areas of high concentration to areas of low concentration.

Facilitative Diffusion

Diffusion with the help of transport proteins.

Osmosis

Diffusion of water across a selectively permeable membrane.

Active Transport

The process by which cells use energy (ATP) to move molecules against their concentration gradient.

Carrier Proteins

Proteins in the cell membrane that transport substances across the membrane.

Protein Pumps

Transport proteins that require energy to move molecules, such as Sodium/Potassium Pumps.

Endocytosis

The process of taking bulky material into a cell by the cell membrane in-folding around the material.

Exocytosis

The process of forcing material out of the cell in bulk by the fusion of a membrane surrounding the material with the cell membrane.

ATP

Adenosine triphosphate, the usable form of energy produced by respiration.

ADP

Adenosine diphosphate, a molecule that can bond with another phosphate to form ATP.

Cellular Respiration

The process that releases energy by breaking down food molecules in the presence of oxygen.

Turgid

A state of a plant cell when water enters the cell by osmosis, pushing against the cell wall.

Plasmolysed

A state of a plant cell when water leaves the cell by osmosis, causing the cell membrane to pull away from the cell wall.

Lysis

The process in which an animal cell expands and can burst due to excessive water intake.

Autotrophs

Organisms that use energy from the sun or chemicals to make organic food molecules.

Heterotrophs

Organisms that consume other organisms for energy.

Bioluminescence

The production and emission of light by living organisms.

Sodium/Potassium Pumps

Active transport proteins essential for nerve responses.

Energy from ATP

Released by breaking the high-energy bonds between the last two phosphates in ATP.

Making ATP

ATP is formed by ADP bonding with another phosphate, storing energy.

ATPase

An enzyme that helps in the conversion of ADP to ATP.

Cellular Respiration

The process of breaking down glucose in the presence of oxygen to produce carbon dioxide, water, and energy.

Aerobic

A type of respiration that requires oxygen and produces up to 38 ATP molecules.