Cell Structure and Function: Prokaryotes vs. Eukaryotes
Explore the differences between prokaryotic and eukaryotic cells, including their structures, functions, and external features. Learn about cell walls, cytoplasmic membranes, diffusion, and osmosis in this insightful chapter on cell biology.
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Presentation Transcript
Cell Structure and Function Chapter 3
There are 2 types of cells 1. Prokaryotes 2. Eukaryotes
Prokaryotes Do NOT have a membrane surrounding genetic material, therefore, can make proteins simultaneously when reading genetic code. Lack some structures found in Eukaryotic cells
Eukaryotes Have a membrane surrounding their DNA, forming a NUCLEUS Contain numerous internal membranes that have specific functions, called ORGANELLES
External Structures Bacteria Glycocalyces Sugar based external surrounding firmly attached to cell s surface. Flagella Tail like structure that propels bacteria (also found on sperm cells). Flow of hydrogen and sodium ions allows movement. Fimbriae and Pili Hair like structures that adhere to surfaces to move bacterium.
Cell Walls Found in most prokaryotes allows attachment to other cells and resistance to antimicrobial drugs. Eg. Penicillin attacks cell walls of microbes Peptidoglycan Polysaccharide, divides cells into two types: 1. Gram-Positive (Thick layer of peptidoglycan) 2. Gram-Negative (Thin layer of peptidoglycan)
Cytoplasmic Membrane Made up of a PHOSPHOLIPID BILAYER: outside is hydrophilic and inside is hydrophobic Selectively Permeable, but naturally impermeable to large objects Concentration Gradient Concentration of sodium ions can attract and repel charged substances into and out of cells.
Diffusion Simple Diffusion - When a small, non- polar molecule passes through a lipid bilayer. Channel Diffusion - Channel proteins where material moves through an open, aqueous pore. Facilitated diffusion - Type of passive transport that is dependent on single transport protein carriers.
Osmosis Movement of water across a selectively permeable membrane driven by a difference in solute concentrations on the two sides of the membrane.
Cytoplasm Gelatinous material inside of a cell Liquid portion is called CYTOSOL Contains INCLUSIONS Deposits of small compounds within the cytoplasm
Endospores Produced by Bacillus and Clostridium NOT FOR REPRODUCTION Constitute a defensive strategy for hostile or unfavourable conditions
Nonmembranous Organelles Ribosomes Sites of protein synthesis Cytoskeleton Structure of proteins which gives cells structure and movement: 1. Microfilaments: Fine, thread-like protein fibers, 3-6 nm in diameter 2. Microtubules: Cylindrical tubes, 20-25 nm in diameter 3. Intermediate filaments are about 10 nm diameter and provide tensile strength for the cell.
Archaea Glycocalyces Same characteristics as bacterial glycocalyces
Archaea Flagella Similar to bacterial flagella About half the thickness (10-14 nm)
Fimbriae and Hami Fimbriae nonmotile, rodlike, sticky projections Hami Fimbria of archaea. Filament frays into 3 hooks. Used for attachment
Eukaryotic Glycocalyces Most animal and protozoan cells lack cell walls Glycocalyces are anchored through covalent bonds
Eukaryotic Cell Walls and Membranes Cell walls of plants are made of cellulose Cell walls of fungi are made of chitin or glucomannan Cell walls of algae are made of cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate, or a combination of the aforementioned ALL have cytoplasmic membrane
