Basic Unit of Life

Vocabulary

Archaea

domain encompassing unicellular organisms that lack nuclei or membrane-bound organelles that do not contain peptidoglycan in their cell walls

Bacteria

domain encompassing unicellular organisms that lack nuclei or membrane-bound organelles that contain peptidoglycan in their cell walls

cell wall

rigid carbohydrate structure that provides overall support and protection for the cell

chloroplast

membrane-bound organelle found in plants and some other organisms that captures energy from light and converts it into chemical energy

chromosome

structure that contains DNA, the genetic material that is passed from one generation to the next

cyanobacteria

group of phototrophic bacteria that are bluish-green in color and produce oxygen as a product of photosynthesis

cytoplasm

combination of cytosol—a jellylike fluid primarily made up of water and dissolved substances that fills the spaces around the internal cell structures—and organelles (excluding the nucleus)

deoxyribonucleic acid (DNA)

organic molecule containing coded instructions for the life processes of an organism; consists of nucleotides bonded together in the form of a double helix

domain

largest taxonomic grouping

endoplasmic reticulum (ER)

network of membranes that helps process molecules in a cell and transports cell materials; may be rough (ribosomes attached) or smooth (without ribosomes attached)

endosymbiosis

symbiotic relationship in which one organism lives inside another

eukaryote

organism characterized by membrane-bound organelles, such as the nucleus

evolution

when defined narrowly, a change in gene frequencies within a population from one generation to the next

fungus (plural, fungi)

eukaryotic organism that may be unicellular or multicellular and that produces spores and contains chitin (a polysaccharide used for structure) in its cell walls

gene

unit of heritable material that codes for a particular trait

Golgi apparatus

organelle that attaches chemical markers to molecules produced in the endoplasmic reticulum in order to transport the molecules to their places inside or outside a cell

lysosome

organelle that digests bacteria that enter a cell, eliminates toxins, and recycles worn cell materials

mitochondrion (plural, mitochondria)

organelle that changes energy from food into energy a cell can use

nucleus

membrane-bound organelle that contains most of the genetic material (DNA); this structure directs a cell's growth, division, and death

organelle

membrane-bound structure in a cell that has a specific task, such as a mitochondrion or Golgi apparatus

peroxisome

structure in eukaryotes that transforms fatty acids into sugars and aids chloroplasts in oxidizing plant sugars

plasma membrane

membrane that encloses a cell and is made of layers of lipids, organic molecules made of carbon and hydrogen

prokaryote

unicellular organism with no nucleus

ribosome

structure composed of RNA and protein that constructs proteins based on the instructions provided by DNA. It may be free-floating in cytoplasm or attached to form rough endoplasmic reticulum.