Cells & cell transport

Cell

The smallest unit of life.

Cytology

The study of cells.

Prokaryote

A cell that does not have a nucleus or membrane-bound organelles.

Eukaryote

A cell that does have a nucleus and membrane-bound organelles.

Bacteria

Single-celled prokaryotic organisms.

Cytoplasm

Jelly-like substance inside the cell where organelles are found.

Nucleus

Controls cell activities and contains DNA.

Mitochondria

Produces energy (ATP) for the cell.

Chloroplast

Organelle where photosynthesis occurs.

Ribosome

Makes proteins.

Tissue

A group of similar cells working together.

Organ

A structure made of different tissues that performs a function.

Organ System

A group of organs working together.

Cell Wall

Rigid outer layer that provides support (plants, bacteria).

Cell Membrane

Thin, flexible barrier controlling what enters and leaves the cell.

Phospholipid Bilayer

Double layer of phospholipids forming the cell membrane.

Hydrophilic

Attracted to water.

Hydrophobic

Repelled by water.

Protein

Large molecules that perform cell functions.

Carbohydrate

Sugars used for energy or structure.

Cholesterol

Lipid that helps maintain membrane flexibility.

Fluid Mosaic Model

Model describing the flexible cell membrane with moving proteins.

Selective Permeability

Allows some substances to pass but not others.

Solute

Substance being dissolved.

Solvent

Substance that dissolves the solute.

Solution

Mixture of solute and solvent.

Concentration

Amount of solute in a solution.

Simple Diffusion

Movement of molecules from high to low concentration without energy.

Facilitated Diffusion

Diffusion using transport proteins.

Osmosis

Diffusion of water across a membrane.

Homeostasis

Maintaining stable internal conditions.

Hypertonic

Solution with higher solute concentration than the cell.

Hypotonic

Solution with lower solute concentration than the cell.

Isotonic

Equal solute concentration inside and outside the cell.

Active Transport

Movement against concentration gradient using energy.

Endocytosis

Cell takes material in by forming a vesicle.

Exocytosis

Cell releases material out.

Endosymbiotic Theory

Mitochondria and chloroplasts evolved from bacteria.

Positive Feedback Loop

Process that increases the original change.

Negative Feedback Loop

Process that reverses a change.