Chapter 21 Flashcards
Antigen
Substances that stimulate antibody production by the immune system.
Bioremediation
Applications of chemical and biological knowledge to decontaminate polluted environments.
Archaea aka Archaebacteria
One of two domains of prokaryotes; archaeans have some unique molecular and biochemical traits, but they also share some traits with Bacteria and other traits with Eukarya.
Bacteria
One of the two domains of prokaryotes; collectively, bacteria are the most metabolically diverse organisms.
Eukarya
The domain that includes all eukaryotes, organisms that contain a membrane-bound nucleus within each of their cells; all protists, plants, fungi, and animals.
What are the three domains of living organisms?
- Archaea (Archaebacteria) - prokaryotes
- Bacteria - prokaryotes
- Eukarya - eukaryotes
Biomass
The dry weight of biological material per unit area or volume of habitat.
Eukaryote
Organism in which the DNA is enclosed in a nucleus.
Prokaryote
Organism in which the DNA is suspended in the cell interior without separation from other cellular components by a discrete membrane.
Identify the structural features of organelles and cell walls that distinguish prokaryotes from eukaryotes.
- Prokaryotes have a nucoleoid rather than a nucleus.
- Prokaryotes do not have anything equivalent to the mitochondria, endoplasmic reticulum, or Golgi complex found in eukaryotes. With few exceptions, the reactions carried out by these organelles in eukaryotes are distributed between the cytoplasmic solution and the plasma membrane in prokaryotes.
- Both have flagella but they are different in structure and pattern of movement.
Nucleoid
The central region of a prokaryotic cell with no boundary membrane separating it from the cytoplasm, where DNA replication and RNA transcription occur.
What are the common shapes of prokaryotes?
- Spiral (spirilla)
- Spherical (cocci; coccoid)
- Cylindrical (rods; bacilli)
- Square
Draw a Bacterial Cell

Describe the general structure of prokaryotic cells.
- Cell Wall
- Plasma Membrane
- Cytoplasm
- Most consist of a single, circular DNA molecule.
- Plasmids
- Ribosomes
- Capsule
- Flagella
- Pili
Plasmid
A DNA molecule in the cytoplasm of certain prokaryotes, which often contains genes with functions that supplement those in the nucleoid and which can replicate independently of the nucleoid DNA and be passed along during cell division.
Generally contain genes for nonessential but beneficial functions such as antibiotic resistance.
Cell Wall
A rigid external layer of material surrounding the plasma membrane of cells in plants, fungi, bacteria, and some protists, providing cell protection and support.
Cytoplasm
All parts of the cell that surround the central nuclear or nucleoid region.
Plasma Membrane
The outer limit of the cytoplasm responsible for the regulation of substances moving into and out of cells.
Ribosome
A ribonucleoprotein particle that carries out protein synthesis by translating mRNA into chains of amino acids.
Messenger RNA (mRNA)
An RNA molecule that serves as a template for protein synthesis.
Amino Acid
A molecule that contains both an amino and a carboxyl group.
Ribonucleic Acid (RNA)
A polymer assembled from repeating nucleotide monomers in which the five-carbon sugar is ribose. Cellular RNAs are mRNA (which is translated to produce a polypeptide), tRNA (which brings an amino acid to the ribosome for assembly into a polypeptide during translation), and rRNA (which is a structural component of ribosomes). The genetic material of some viruses is RNA.
Amino Group
Group that acts as an organic base, consisting of a nitrogen atom bonded on one side to two hydrogen atoms and on the other side to a carbon chain.
Peptidoglycan
A polymeric substance formed from a polysaccharide backbone tied together by short polypeptides, which is the primary structural molecule of bacterial cell walls.
