Chapter 5: Cell Structure and Function

Cell

The basic unit of structure and function in life.

Surface Area-to-Volume Ratio

The ratio of the surface area of an object to its volume. In cells, as the ratio decreases, the exchange of materials becomes less efficient.

Geometry Formulas

Mathematical formulas used to calculate the surface area and volume of cells.

Organisms

Living things made up of cells that can be affected by the surface area-to-volume ratio concept.

Heat-Exchange

The transfer of heat between an organism and its surroundings.

Small Organisms

Organisms with a high surface area-to-volume ratio, resulting in more efficient heat-exchange with their surroundings.

Larger Organisms

Organisms with a lower surface area-to-volume ratio, resulting in less efficient heat-exchange with their surroundings.

Light Microscopes

Used to study stained or living cells and can magnify the size of an organism up to 1,000 times.

Electron Microscopes

Used to study detailed structures of a cell that cannot be easily seen or observed by light microscopy.

Prokaryotic Cells

A type of cell that lacks a nucleus and other membrane-bound organelles.

Eukaryotic Cells

A type of cell that contains a nucleus and other membrane-bound organelles.

Prokaryotic Cell

A type of cell that is smaller and simpler than eukaryotic cells. Examples include bacteria and archaea. The genetic material is one, circular DNA molecule found in the nucleoid. They have a cell wall made of peptidoglycans and a plasma membrane. Prokaryotes lack membrane-bound organelles.

Eukaryotic cells

Cells that are more complex and have many smaller structures called organelles.

Organelles

Small structures within eukaryotic cells that perform specific functions.

Fungi, protists, plants, and animals

Examples of eukaryotes - organisms made up of eukaryotic cells.

Prokaryotic cells

Cells that lack a nucleus and organelles, and are generally smaller and simpler than eukaryotic cells.

Plasma membrane

The outer envelope of the cell, made up of mostly phospholipids and proteins, that regulates the movement of substances into and out of the cell.

Semipermeable

A characteristic of the plasma membrane that allows certain substances to pass through while blocking others.

Peripheral proteins

Proteins associated with the cell membrane that are loosely bound to the lipid bilayer and located on the inner or outer surface of the membrane.

Integral proteins

Proteins firmly bound to the plasma membrane that are amphipathic, meaning they have both hydrophobic and hydrophilic regions.

Transmembrane proteins

Integral proteins that extend all the way through the membrane, allowing them to transport substances across the membrane.

Fluid-mosaic model

The arrangement of phospholipids and proteins in the plasma membrane, which is constantly in motion and resembles a mosaic.

Nucleus

The largest organelle in the cell that directs cell activities and is responsible for the cell's ability to reproduce.

DNA

The hereditary information that is organized into large structures called chromosomes and located in the nucleus.

Chromosomes

The structures that organize DNA in the nucleus.

Nucleolus

The visible structure within the nucleus where rRNA is made and ribosomes are assembled.

Ribosomes

Sites of protein synthesis in the cell that manufacture all proteins required by the cell or secreted by the cell.

Large Subunit

One of the two subunits that make up a ribosome, composed of ribosomal RNA (rRNA) and proteins.

Small Subunit

One of the two subunits that make up a ribosome, composed of ribosomal RNA (rRNA) and proteins.

Free Floating Ribosomes

Ribosomes that are not attached to the endoplasmic reticulum (ER) and are found in the cytoplasm of the cell.

Attached Ribosomes

Ribosomes that are attached to the endoplasmic reticulum (ER) and are involved in protein synthesis for export out of the cell.

Endoplasmic Reticulum (ER)

A continuous channel in the cytoplasm that provides mechanical support and transportation.

Rough ER

The region of ER that compartmentalizes the cell and has ribosomes attached to it.

Smooth ER

The region of ER that lacks ribosomes and makes lipids, hormones, and steroids, and breaks down toxic chemicals.

Rough ER

An organelle involved in protein synthesis that has ribosomes attached to its surface.

Golgi complex

An organelle that modifies, processes, and sorts proteins synthesized by the rough ER and packages them into vesicles.

Vesicles

Little sacs that are used for packaging and transporting materials within the cell or to the plasma membrane.

Plasma membrane

The outer layer of a cell that separates it from its environment and regulates the movement of materials in and out of the cell.

Mitochondria

Organelles responsible for converting energy from organic molecules into ATP for the cell

ATP

The most common energy molecule in the cell, produced by mitochondria through the conversion of organic molecules

Lysosomes

Organelles containing digestive enzymes used to break down old organelles, debris, and large ingested particles.

Apoptosis

Programmed cell death that involves the use of lysosomes.

Vacuoles

Fluid-filled sacs that store water, food, wastes, salts, or pigments in plant cells.

Peroxisomes

Organelles that detoxify various substances, producing hydrogen peroxide (H2O2) as a byproduct.

Cytoskeleton

A network of protein fibers that determines the shape of a cell, including microtubules and microfilaments.

Microtubules

Protein fibers that participate in cellular division and movement, made up of the protein tubulin.

Microfilaments

Thin, rodlike structures composed of the protein actin, important for cell movement.

Cilia and Flagella

Locomotive structures in single-celled organisms, with a beating motion that allows movement.

Transport

Traffic of molecules across the cell membrane.

Semipermeability

Property of the plasma membrane that allows only certain molecules to pass through.

Facilitated transport

Assistance required for hydrophilic substances to pass through the hydrophobic central zone of the bilayer.

Aquaporins

Channels that allow specific transport of water molecules across the membrane.

Membrane proteins

Proteins that transport glucose and ions such as Na+ and K+ across the plasma membrane.

Polarisation

Condition of the membrane as ions move across it.

Passive Transport

The movement of substances across a cell membrane without the need for energy.

Simple Diffusion

The movement of small non-polar molecules across a cell membrane without the need for assistance.

Facilitated Diffusion

The movement of molecules across a cell membrane with the help of channel-type proteins.

Osmosis

The movement of water across a cell membrane from an area of high water potential to an area of low water potential.

Tonicity

The measure of osmotic gradients between a cell and its environment.

Isotonic Solution

A solution with the same solute concentration as the cell.

Hypertonic Solution

A solution with a higher solute concentration than the cell.

Hypotonic Solution

A solution with a lower solute concentration than the cell.

Water Potential

The measure of potential energy in water that describes the eagerness of water to flow from an area of high water potential to an area of low water potential.

Pressure Potential

The component of water potential that measures the impact of pressure on water movement.

Solute Potential

The component of water potential that measures the impact of solutes on water movement.

Active Transport

Movement of molecules against the natural flow, powered by ATP, to maintain a concentration gradient.

Sodium-Potassium Pump

A special protein that uses ATP to transport three sodium ions out of the cell and two potassium ions into the cell.

Primary Active Transport

The direct use of ATP to transport molecules across the cell membrane.

Secondary Active Transport

The use of energy captured from the movement of another substance flowing down its concentration gradient to actively transport something.

Endocytosis

The process by which a portion of the cell membrane engulfs a substance to form a vacuole or vesicle.

Pinocytosis

The type of endocytosis where the cell ingests liquids.

Phagocytosis

The type of endocytosis where the cell takes in solids.

Receptor-Mediated Endocytosis

The type of endocytosis that involves cell surface receptors that work in tandem with endocytic pits lined with clathrin.

Bulk Flow

The one-way movement of fluids brought about by pressure, for example, the movement of blood through a blood vessel and the movement of fluids in xylem and phloem of plants.

Dialysis

Diffusion of solutes across a selectively permeable membrane, used for blood filtration in kidney dialysis.