University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2022
Views:

338

Pages:

6
Author:

Ruben Owens

Section 2.2: Structure of Prokaryotic Cells §Prokaryotes – immense/heterogeneous group §Structure: Bacillus-cylindrical/rod-like; Cocci-spheroidal §Two types: Bacteria and Archaea §Common features: cell wall, plasma membranes, circular DNA, and no membrane-bound organelles Figure 2.7 Typical Bacterial Cell Section 2.2: Structure of Prokaryotic Cells Bacterial Cell Section 2.2: Structure of Prokaryotic Cells §Cell Wall Bacterial Cell §Complex semi-rigid structure primarily for support and protection •Primarily composed of peptidoglycan •Covalent complexes of short peptide chains linking long carbohydrate chains •Cell differentiation -retaining crystal violet stain •Gram positive – carbohydrates take up stain •Gram negative – no carbohydrates Section 2.2: Structure of Prokaryotic Cells Figure 2.8 Bacterial Plasma Membrane §Plasma Membrane §Phospholipidbilayer held together by weak noncovalent forces ü Covalent bonds would provide more stability but less flexibility & movement in and out §Integral proteins - selectively permeable for nutrient uptake and waste disposal §Photosynthesis – light energy to chemical energy §Respiration – oxidation of fuel molecules to generate energy Section 2.2: Structure of Prokaryotic Cells §Cytoplasm §Functional compartments §Nucleoid – centrally located and contains the circular DNA (chromosome) §Contains small DNA plasmids §Exist outside nucleoid; replicates independent of chromosome §Ribosomes give uniform, grainy appearance §RNA & proteins – synthesize polypeptides, macromolecules, smaller metabolites §Inclusion bodies - large granules contain organic or inorganic compounds Figure 2.9 Bacterial Cytoplasm Section 2.2: Structure of Prokaryotic Cells Figure 2.7 Typical Bacterial Cell §Pili and Flagella §Many bacteria have external appendages §Pili (pilus) are for attachment and sex §Flagella (flagellum) are used for locomotion