Cell Structure and Function. Handout Prok vs Euk Table Handout Structure-Function Table. Prokaryotic Microbes

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PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 3 Cell Structure and Function CSLO 1: Describe distinctive

What are the features/structures present in prok and eukaryotes? What is their function? Which ones are uniques to each of them?

1 PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 3 Cell Structure and Function CSLO 1: Describe distinctive characteristics and diverse growth requirements of prokaryotic organisms compared to eukaryotic organisms. How are prokaryotes and eukaryotes similar and different? What are the features/structures present in prok and eukaryotes? What is their function? Which ones are uniques to each of them? Handout Prok vs Euk Table Handout Structure-Function Table Prokaryotic Microbes Common Features Unicellular cell walls contain peptidoglycan cell walls do not contain peptidoglycan but other polymers lack nuclei or nuclear around DNA Much smaller Most have cell walls simpler 1

2 Structure = specific Function Humming bird feeder Capsule enhances the ability of bacteria to cause disease Figure 3.2 Typical prokaryotic cell. Nucleoid Inclusions Ribosome Cytoplasm Glycocalyx Cell wall Flagellum 2

bacteria from being recognized by host Slime layer Loosely attached to cell surface Water soluble Sticky layer allows prokaryotes to attach to surfaces forms BIOFILMS e.g. Dental plaques (check page 63 for highlight) Figure 3.

3 External Structures of Bacterial Cells Glycocalyces Structure - Gelatinous, sticky substance surrounding the outside of the cell. Composed of polysaccharides, polypeptides, or both Function 1) avoid dessication, 2) adhesion, 3) protect from host defense Two Types of Glycocalyces Capsule Firmly attached to cell surface Prevent bacteria from being recognized by host Slime layer Loosely attached to cell surface Water soluble Sticky layer allows prokaryotes to attach to surfaces forms BIOFILMS e.g. Dental plaques (check page 63 for highlight) Figure 3.6 Proximal structure of bacterial flagella. Flagella Rod Filament Direction of rotation during run Peptidoglycan layer (cell wall) Composed of 3 units - filament, hook, and basal body Filament made of flagellin protein Protein rings Cytoplasmic responsible for movement Cytoplasm Filament Gram + Gram Outer protein rings Rod Integral Basal protein body Inner protein rings Integral protein Cytoplasm Outer Cell Peptidoglycan wall layer Cytoplasmic 3

Endoflagella Special form of flagella Axial filament Endoflagella rotate Axial filament rotates around cell Outer

4 Figure 3.7 Micrographs of basic arrangements of bacterial flagella. Different Arrangement of flagella Figure 3.8 Axial filament. Endoflagella Special form of flagella Axial filament Endoflagella rotate Axial filament rotates around cell Outer Cytoplasmic Spirochete corkscrews and moves forward Axial filament Figure 3.9 Motion of a peritrichous bacterium. 100,000 rpm = 670 miles per hour Positive/Negative taxis Chemo/Photo Movement in response to stimulus = taxis 4

Fimbriae Nonmotile, rodlike, sticky, bristlelike projections Shorter than flagella but more

important function in biofilms Pili or Pilus (singular) Pili - special type of fimbria hollow

conjugation transfer DNA from one cell to another also called conjugation pili Bacterial Cell

5 Fimbriae Nonmotile, rodlike, sticky, bristlelike projections Shorter than flagella but more numerous Used by bacteria to adhere to one another and to substances in environment - serve an important function in biofilms Pili or Pilus (singular) Pili - special type of fimbria hollow tubes Longer than fimbriae but shorter than flagella and only have 1 or 2 per cell Function in conjugation transfer DNA from one cell to another also called conjugation pili Bacterial Cell Walls Scientists describe two basic types of bacterial cell walls Gram-positive and Gram-negative 5

Figure 3.13 Possible structure of peptidoglycan.

acid) crossbridge Connecting chain of amino acids Bacterial Cell

of peptidoglycan Contain unique polyalcohols called teichoic

positive bacteria have up to 60% mycolic acid (waxy lipids)

6 Figure 3.13 Possible structure of peptidoglycan. Sugar backbone Composed of peptidoglycan Tetrapeptide (amino acid) crossbridge Connecting chain of amino acids Bacterial Cell Walls Gram-Positive Bacterial Cell Walls Relatively thick layer of peptidoglycan Contain unique polyalcohols called teichoic acids Appear purple following Gram staining procedure Some gram positive bacteria have up to 60% mycolic acid (waxy lipids) which helps cells survive desiccation called Acid Fast bacteria M. leprae and M. tuberculosis 6

7 Figure 3.14a Comparison of cell walls of Gram-positive and Gram-negative bacteria. Peptidoglycan layer (cell wall) Cytoplasmic Gram-positive cell wall Lipoteichoic acid Teichoic acid Integral protein Prokaryotic Cell Walls Gram-Negative Bacterial Cell Walls Have only a thin layer of peptidoglycan Bilayer outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS) Lipid A portion of LPS can cause fever, vasodilation, inflammation, shock, and blood clotting May impede the treatment of disease (OM is protective) Appear pink following Gram staining procedure Figure 3.14b Comparison of cell walls of Gram-positive and Gram-negative bacteria. Porin Outer of cell wall Peptidoglycan layer of cell wall Porin (sectioned) Periplasmic space Gram-negative cell wall Cytoplasmic Phospholipid layers Lipopolysaccharide (LPS) layer, containing lipid A Integral proteins 7

Bacterial Cell Walls Function: 1) provide structure and shape and 2) protect cell from osmotic forces 3) assist some cells in attaching to other cells 4) in resisting antimicrobial drugs Cell walls

8 Bacterial Cell Walls Function: 1) provide structure and shape and 2) protect cell from osmotic forces 3) assist some cells in attaching to other cells 4) in resisting antimicrobial drugs Cell walls provide structure and shape A few bacteria lack cell walls Mycoplasma pneumoniae Bacterial Cytoplasmic Membranes Structure Referred to as phospholipid bilayer Composed of lipids and associated proteins Integral proteins Peripheral proteins Fluid mosaic model describes current understanding of structure 8

9 Figure 3.15 The structure of a prokaryotic cytoplasmic : a phospholipid bilayer. phospholipid bilayer Head, which contains phosphate (hydrophilic) Phospholipid Tail (hydrophobic) Cytoplasm Integral proteins Phospholipid bilayer Integral protein Integral protein Peripheral protein Bacterial Cytoplasmic Membranes Function Energy storage Harvest light energy in photosynthetic bacteria Selectively permeable Naturally impermeable to most substances Proteins allow substances to cross Maintain concentration and electrical gradient Bacterial Cytoplasmic Membranes Function Passive processes Diffusion Facilitated diffusion Osmosis 9

Figure 3.17 Passive processes of movement across a cytoplasmic.

18 Osmosis, the diffusion of water across a semipermeable.

10 Figure 3.17 Passive processes of movement across a cytoplasmic. Semi-permeable Gases/alcohol permease Figure 3.18 Osmosis, the diffusion of water across a semipermeable. Water moves from high to low hypotonic cell Figure 3.19 Effects of isotonic, hypertonic, and hypotonic solutions on cells. Cells without a wall (e.g., mycoplasmas, animal cells) Cell wall Cell wall Cells with a wall (e.g., plants, fungal and bacterial cells) Cell Isotonic solution Cell Hypertonic solution Hypotonic solution 10

11 Figure 3.19 Effects of isotonic, hypertonic, and hypotonic solutions on cells. Cells without a wall (e.g., mycoplasmas, animal cells) Cell wall Cell wall Cells with a wall (e.g., plants, fungal and bacterial cells) Cell Isotonic solution Cell Hypertonic solution Hypotonic solution Figure 3.19 Effects of isotonic, hypertonic, and hypotonic solutions on cells. Cells without a wall (e.g., mycoplasmas, animal cells) Cell wall Cell wall Cells with a wall (e.g., plants, fungal and bacterial cells) Cell Isotonic solution Cell Hypertonic solution Hypotonic solution Figure 3.19 Effects of isotonic, hypertonic, and hypotonic solutions on cells. Cell wall Cell wall Cells with a wall (e.g., plants, fungal and bacterial cells) Cell Isotonic solution Cell Hypertonic solution Hypotonic solution 11

Against gradient Extracellular fluid Uniport Cytoplasmic ATP ATP ADP P ADP P Cytoplasm Uniport Antiport Gated Channels or Ports

12 Prokaryotic Cytoplasmic Membranes Function Active processes Active transport Group translocation Substance is chemically modified during transport Figure 3.20 Mechanisms of active transport. Against gradient Extracellular fluid Uniport Cytoplasmic ATP ATP ADP P ADP P Cytoplasm Uniport Antiport Gated Channels or Ports Symport Coupled transport: uniport and symport Figure 3.21 Group translocation. Glucose Extracellular fluid Very efficient 1 ppm Substance chemically changed PO 4 Cytoplasm Glucose 6-PO 4 12

Cytoplasm of Bacteria Cytosol Liquid portion of cytoplasm Mostly water Contains cell's DNA in region called the nucleoid Inclusions May include reserve deposits of chemicals Magnetospirillum

13 Cytoplasm of Bacteria Cytosol Liquid portion of cytoplasm Mostly water Contains cell's DNA in region called the nucleoid Inclusions May include reserve deposits of chemicals Magnetospirillum magnetotacticum Cytoplasm of Bacteria Endospores Unique structures produced by some bacteria Defensive strategy against unfavorable conditions Vegetative cells transform into endospores when multiple nutrients are limited Resistant to extreme conditions such as heat, radiation, chemicals 13

Cytoskeleton Composed of three or four types of protein fibers Can play different roles in the cell Cell

14 Also make endotoxins present in bacteria which cause anthrax, tetanus, gangrene Cytoplasm of Prokaryotes Nonmembranous Organelles Ribosomes Sites of protein synthesis Composed of polypeptides and ribosomal RNA Cytoskeleton Composed of three or four types of protein fibers Can play different roles in the cell Cell division Cell shape Segregate DNA molecules Move through the environment Figure 3.26 Representative shapes of archaea. Archae 14

External Structures of Archaea Glycocalyces Function in the formation of biofilms Adhere cells to one another and inanimate objects Flagella Consist of basal body, hook, and filament Numerous

15 External Structures of Archaea Glycocalyces Function in the formation of biofilms Adhere cells to one another and inanimate objects Flagella Consist of basal body, hook, and filament Numerous differences with bacterial flagella analogous structures Fimbriae and hami Many archaea have fimbriae Some make fimbria-like structures called hami Function to attach archaea to surfaces Figure 3.25 Archaeal hami. Hamus Grappling hook Prickles Archaeal Cell Walls and Cytoplasmic Membranes Most archaea have cell walls Do not have peptidoglycan Contain variety of specialized polysaccharides and proteins All archaea have cytoplasmic s Maintain electrical and chemical gradients Control import and export of substances from the cell 15

Cytoplasm of Archaea similar and different compared to bacterial Archaeal cytoplasm similar to bacterial cytoplasm 70S ribosomes Fibrous cytoskeleton Circular DNA Archaeal cytoplasm also differs from

16 Cytoplasm of Archaea similar and different compared to bacterial Archaeal cytoplasm similar to bacterial cytoplasm 70S ribosomes Fibrous cytoskeleton Circular DNA Archaeal cytoplasm also differs from bacterial cytoplasm Different ribosomal proteins Different metabolic enzymes to make RNA Genetic code more similar to eukaryotes Clear-cut differences? Eukaryotic Microbes (-bound nucleus) Protozoa Similar to animal cells Algae Similar to plant cells Fungi Decomposers, obtain food from others Common Features Uni/Multicellular Nuclei present (internal -bound Organelles) Relatively bigger some have cell walls Relatively complex 16

Protozoa (Animals) Single-celled eukaryotes Similar to animals in nutrient needs and cellular structure Live freely in water; some live in animal hosts Most

environment Flagella extensions of a cell that are fewer, longer, and more whiplike than cilia Pseudopods Cilia Flagellum Figure 1.

17 Protozoa (Animals) Single-celled eukaryotes Similar to animals in nutrient needs and cellular structure Live freely in water; some live in animal hosts Most are capable of locomotion by Pseudopods cell extensions that flow in direction of travel Cilia numerous short protrusions that propel organisms through environment Flagella extensions of a cell that are fewer, longer, and more whiplike than cilia Pseudopods Cilia Flagellum Figure 1.6 Locomotive structures of protozoa. Eukaryotic Microbes Algae (Plants) Unicellular or multicellular Photosynthetic Categorized on the basis of pigmentation and composition of cell wall 17

Fungi Obtain food from other organisms possess cell walls Yeasts

9 A colorized electron microscope image of viruses infecting a

Virus Viruses (acellular) Bacterium Viruses assembling inside

18 Fungi Obtain food from other organisms possess cell walls Yeasts unicellular Molds multicellular grow as long filaments Figure 1.9 A colorized electron microscope image of viruses infecting a bacterium. Virus Viruses (acellular) Bacterium Viruses assembling inside cell Figure 1.8 An immature stage of a parasitic worm in blood. Why Parasites? Red blood cell Immature stages are microscopic 18

19 Figure 3.3 Typical eukaryotic cell. Nuclear envelope Nuclear pore Nucleolus Cilium Lysosome Mitochondrion Centriole Secretory vesicle Golgi body Transport vesicles Ribosomes Rough endoplasmic reticulum Smooth endoplasmic reticulum Cytoskeleton Cytoplasmic Eukaryotic Cell Walls and Cytoplasmic Membranes Fungi, algae, plants, and some protozoa have cell walls But no glycocalyx and cell walls do not contain peptidoglycan Composed of various polysaccharides Plant cell walls contain cellulose Fungal cell walls composed of cellulose, chitin, and/or glucomannan Algal cell walls composed of a variety of polysaccharides Eukaryotic Cell Walls and Cytoplasmic Membranes All eukaryotic cells have cytoplasmic Are a fluid mosaic of phospholipids and proteins Contain steroid lipids to help maintain fluidity Contain regions of lipids and proteins called rafts 19

20 Eukaryotic Cell Walls and Cytoplasmic Membranes Do not perform group translocation but endocytosis unique to eukaryotes Figure 3.29 Endocytosis. Pseudopodium LJYr_JA9Jjd6zhzlkN4OOldkc7gCft9Pa Phagocytosis? Pinocytosis? 20

21 Eukaryotic flagella and cilia. Flagellum Cilia Figure 3.6 Proximal structure of bacterial flagella. Filament Direction of rotation during run Rod Peptidoglycan layer (cell wall) Protein rings Cytoplasm Cytoplasmic Filament Gram + Gram Outer protein rings Rod Integral Basal protein body Inner protein rings Integral protein Cytoplasm Outer Cell Peptidoglycan wall layer Cytoplasmic Figure 3.30c Eukaryotic flagella and cilia. Cytoplasmic Cytosol Central pair microtubules Microtubules arrangement (doublet) Cytoplasmic Basal body Portion cut away to show transition area from doublets to triplets and the end of central microtubules Microtubules (triplet) arrangement 21

Flagella of Eukaryotes Structure and arrangement different from prokaryotic flagella composed of tubulin protein Filaments and basal body; but no hook May be single or

flagella Function: 1) move cells - coordinated beating propels cells through their environment 2) move substances past the surface of the cell eukaryote Flagellum

22 Flagella of Eukaryotes Structure and arrangement different from prokaryotic flagella composed of tubulin protein Filaments and basal body; but no hook May be single or multiple; found at one pole of cell Function - move cell - but flagella do not rotate - undulate rhythmically Cilia of Eukaryotes Structure: Shorter and more numerous than flagella Function: 1) move cells - coordinated beating propels cells through their environment 2) move substances past the surface of the cell eukaryote Flagellum Prokaryotic and eukaryotic flagella are different Flagellin/tubulin bacteria Cilia Rotatory/Side-to-Side movement Basal body structure Membrane bound or not Only eukaryotes have cilia 22

prokaryotic cells Internal s (nuclear, golgi,

23 Eukaryotic ribosome (80S) larger than prokaryotic ribosomes (70S) Present in eukaryotic cells but in prokaryotic cells Internal s (nuclear, golgi, endoplasmic reticulum etc) Internal membranous organelles centrosomes 23

Endosymbiotic Theory from 1406 Aerobic prokaryotes photosynthetic evolved prokaryotes evolved into mitochondria into chloroplast Eukaryotes formed from union of small aerobic prokaryotes with larger

24 Endosymbiotic Theory from 1406 Aerobic prokaryotes photosynthetic evolved prokaryotes evolved into mitochondria into chloroplast Eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes prokaryotes became internal parasites Cytoplasm of Eukaryotes Endosymbiotic Theory Eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes Smaller prokaryotes became internal parasites Parasites lost ability to exist independently Larger cell became dependent on parasites for aerobic ATP production Aerobic prokaryotes evolved into mitochondria Similar scenario for origin of chloroplasts Theory is not universally accepted 24

Cell Structure and Function

PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 3 Cell Structure and Function Handout Structure-Function Table Handout Prok vs Euk Table