BIOL 1111 Prokaryotes and Early Eukaryotes

Vocabulary-style flashcards covering key concepts about prokaryotes, archaea, bacteria, and early eukaryotes from the notes.

Prokaryote

A microorganism whose cells lack a membrane-bound nucleus and other membrane-bound organelles; includes Bacteria and Archaea; typically 1–10 μm and divide by binary fission.

Nucleoid

Region in prokaryotic cells where the circular chromosome is located; not enclosed by a membrane.

Capsule

Polysaccharide or protein layer outside the cell wall that protects the cell and aids adhesion; present in some bacteria.

Cytoplasm

Internal cellular region where metabolic processes occur; contains cytosol and ribosomes.

Ribosomes

Molecular machines for protein synthesis; in prokaryotes typically free in the cytoplasm and 70S in size.

Flagellum

Long, whip-like structure used for locomotion in many prokaryotes.

Peptidoglycan

Rigid polymer forming the bacterial cell wall; provides structural support; absent in Archaea.

Cell wall

Rigid layer outside the plasma membrane; in bacteria largely composed of peptidoglycan and helps determine cell shape.

Outer membrane

Additional membrane around the peptidoglycan layer in Gram-negative bacteria; absent in Gram-positive bacteria.

Pili

Hair-like projections on the bacterial surface used for adhesion to surfaces and other cells.

Sex pilus (donor pilus)

Pilus used to transfer DNA between bacteria during conjugation.

Conjugation

Direct transfer of DNA between bacterial cells through a sex pilus.

Cytoskeleton

System of protein filaments that maintains cell shape and assists in cell division in some prokaryotes.

Binary fission

Asexual if cell division in prokaryotes, producing two identical daughter cells.

Internal membranes

Infoldings of the plasma membrane that create internal membrane structures in some prokaryotes.

Gram stain

Differential staining method using violet and red dyes to categorize bacteria by cell wall structure.

Gram-positive

Bacteria with thick peptidoglycan layers that retain the violet dye, appearing purple.

Gram-negative

Bacteria with thin peptidoglycan and an outer membrane; retain the red dye, appearing pink/red.

Cocci

Spherical bacterial shape.

Bacilli

Rod-shaped bacterial shape.

Spirilla

Spiral-shaped bacterial form.

Bacteria

Domain of prokaryotes with peptidoglycan in cell walls and ester-linked membrane lipids; includes cocci, bacilli, spirilla.

Archaea

Domain of prokaryotes with ether-linked membrane lipids, often branched; lack peptidoglycan in cell walls.

Eukarya

Domain of organisms with nuclei and membrane-bound organelles; 80S ribosomes; ester-linked lipids.

70S ribosome

Prokaryotic ribosome (50S + 30S subunits); found in Bacteria and Archaea; sensitive to chloramphenicol and streptomycin.

80S ribosome

Eukaryotic ribosome (40S + 60S subunits); not susceptible to the same antibiotics as 70S ribosomes.

Initiator tRNA

tRNA that initiates translation; in bacteria it carries formylmethionine, in archaea/eukarya methionine.

Formylmethionine

Initiator amino acid used to start protein synthesis in bacteria.

Methionine

Initiator amino acid used to start protein synthesis in archaea and eukaryotes.

Operons

A cluster of genes transcribed under a single promoter; common in bacteria.

Plasmids

Small, circular DNA molecules separate from the chromosome; carry accessory genes and can be transferred between cells.

RNA polymerases (count)

Bacteria: one RNA polymerase; Archaea: one; Eukarya: three.

Membrane lipids

Bacteria and Eukarya: ester-linked; Archaea: ether-linked.

Unbranched vs branched lipids

Bacterial and Eukaryotic membrane lipids are typically unbranched; archaeal lipids are often branched.

Nucleoid region

Area within a prokaryotic cell where the single circular chromosome resides; not membrane-bound.

Nucleus

Membrane-bound organelle in eukaryotes that houses DNA; absent in prokaryotes.

Phylogenetic Tree of Life

Diagram showing evolutionary relationships among Bacteria, Archaea, and Eukarya.