Components of a functional cell. Boundary-membrane Cytoplasm: Cytosol (soluble components) & particulates DNA-information Ribosomes-protein synthesis

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1 Cell (Outline) - Components of a functional cell - Major Events in the History of Earth: abiotic and biotic phases; anaerobic and aerobic atmosphere - Prokaryotic cells impact on the biosphere - Origin of Eukaryotic cells - Emergent properties of eukaryotic cells: animal and plant cells - Role of cellular membranes: external and internal - Cytoskeleton: structure and functions - Flow of genetic information: DNA to protein - The endomembrane system - Other organelles: Fatty acid metabolism and Energy Processing - Cell surface and extracellular matrix

2 Components of a functional cell Boundary-membrane Cytoplasm: Cytosol (soluble components) & particulates DNA-information Ribosomes-protein synthesis

3 Major Events in the History of Earth Cenozoic Humans Land plants Animals Origin of solar system and Earth Multicellular eukaryotes 1 Proterozoic eon 2 Archaean eon 3 4 Anaerobic Single-celled eukaryotes Atmospheric oxygen Prokaryotes Aerobic

4 Prokaryotic Cell Structure Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

5 Eukaryotic Cell Structure

6 Cenozoic Humans Land plants Animals Multicellular eukaryotes Single-celled eukaryotes 1 Proterozoic eon 2 Archaean eon 3 Origin of solar system and Earth 4 Atmospheric oxygen Prokaryotes Evolution of larger Eukaryotic cells The Endo-symbiotic Theory

7 Size Limitations Single-celled organisms- - physical force of diffusion of material in and out of the cells. Multi-cellular organisms - Number of cells increases size. - Individual cells vary in size

8 The Endosymbiotic Theory: Origin of Eukaryotes

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10 Ancestral eukaryotic cells two or more prokaryotic cells in a state of endo-symbiosis: animal cell- 2 different prokaryotes plant cell- 3 different prokaryotes Mitochondrion Engulfing of aerobic prokaryote Host cell Some cells Engulfing of photosynthetic prokaryote Chloroplast Mitochondrion Host cell

11 Comparing Prokaryotic and Eukaryotic Differ in - size - complexity Cells - internal membrane, creating organelles (Sub-cellular compartments where different cell functions of eukaryotic cells are carried out)

12 Emergent Properties of Eukaryotic cells Functions Structural support, movement, and communication Manufacturing of molecules Breakdown of molecules Energy processing Eukaryotic cells structures and organelles specialize for functions

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14 Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

15 Role of Cell membranes in Compartmentalization of cellular functions

16 A. Plasma membrane - Boundary of the cell - Surrounds the cytoplasm - Selective barrier - Allows passage of oxygen, nutrients, and wastes.

17 B. Internal membranes of eukaryotes Partitioning the cell into compartments - Sites of metabolic biochemical reactions, enzymes - Local environments that facilitate specific metabolic biochemical functions

18 Cytoskeleton The cytoskeleton is a network of protein fibers that functions in cell structural support and motility Nucleus Nucleus Actin subunit Fibrous subunits Tubulin subunit 7 nm 10 nm 25 nm Microfilament Intermediate filament Microtubule

19 Cytoskeleton (Protein Fibers) Microtubules (hollow/tubulin): cell shape, movement of organelles Microfilaments (actin): three-dimensional network just inside the plasma membrane Intermediate filaments (keratin): reinforce cell shape and fix organelle location

20 Components of the cytoskeleton pull past each other Vesicles or organelles carried to various destinations along monorails of microtubules.

21 The Flow of Genetic Information: The Central Dogma of Molecular Biology The sequence of bases in DNA determines the sequence of amino acids in proteins - DNA codes for the production of messenger RNA. - Messenger RNA codes for the production of protein. - Proteins do not code for the production of protein, RNA or DNA

22 Cell organelles and structures involved with the flow of genetic information Nucleus Ribosomes

23 Nucleus Home of most genetic material (DNA) Double membrane with pores, nuclear envelope Shape maintained by nuclear lamina, a network of protein filaments

24 The Nucleus: Site of transcription of messenger RNA (mrna) The nucleolus Site of ribosomal RNA (rrna)synthesis and ribosome assembly

25 Ribosomes Made of rrna and protein. two subunits that combine to carry out protein synthesis Number of ribosomes vary between cells Free and bound ribosomes (to endoplasmic reticulum)

26 The Endomembrane System Sub-cellular components Nuclear envelope Endoplasmic reticulum Golgi apparatus Vesicles Lysosomes Vacuoles Plasma membrane Function - Sites of certain metabolic functions in the cell (Synthesis, modification, & breakdown of macromolecules) - Regulation of protein traffic within the cell

27 Two connected regions of ER that differ in structure and function. Smooth ER (No ribosomes) Rough ER (bound ribosomes) are attached to the outside

28 Smooth ER Contains enzymes for synthesis of lipids, phospholipid, steroids Metabolism of carbohydrates Detoxification of poison Storage of Ca +2 for in muscle cells (necessary for contraction)

29 Rough ER (membrane factory) - Produces proteins and membranes for transport by vesicles, destined for secretion - Membrane-embedded and secretory proteins - Site of protein glycosylation (glycoproteins)

30 Transport vesicle buds off 4 Ribosome Secretory protein inside transport vesicle 1 3 Sugar chain Polypeptide 2 Glycoprotein Rough ER

31 The Golgi Apparatus Finishing, sorting, and shipping cell products Transport vesicles from the ER travel to the Golgi apparatus for modification of their contents Extensive in cells specialized for secretion.

32 Lysosomes Digestive compartment within the cells. Membranebounded sacs of hydrolytic enzymes that digests macromolecules: proteins, fats, polysaccharides, and nucleic acids.

33 The lysosomal enzymes and membrane are synthesized by rough ER and then transferred to the Golgi.

34 Vacuoles Larger versions of vesicles Many functions in cell maintenance Food vacuoles Contractile vacuoles, found in freshwater protists, pump excess water out of the cell. Central vacuoles- mature plant cells storage of some pigments.

35 Other Membranous Organelles not part of the endomembrane system Peroxisomes generate and degrade H 2 O 2 in performing various metabolic functions Fatty Acid metabolism Mitochondria and chloroplasts- sites of energy transformation from one form to another and of recycling of matter - Mitochondria (respiration) are present in animal & plant cells - Chloroplasts (photosynthesis) only in plant cells

36 Peroxisomes A single membrane Abundant in liver and kidney - breakdown of fatty acids for transport to mitochondria for fuel - detoxify alcohol and other harmful compounds. - Conversion of fatty acids in seeds to sugars.

37 Mitochondria and Chloroplasts Contain their own ribosomes and cytosol Contain small quantities of DNA that direct the synthesis of the polypeptides produced by these internal ribosomes. Grow and reproduce as semi-autonomous organelles Not part of the endomembrane system

38 Mitochondria Video (4) Matrix-contains DNA and ribosomes Cristae-contains enzymes for ATP generation during cellular respiration

39 Chloroplasts Present in plants and eukaryotic algae are the Sites of photosynthesis-production of sugar from CO 2 and water (high levels of the green pigment chlorophyll)

40 Mitochondria and chloroplasts - dynamic structures. - mobile and move around the cell along tracks in the cytoskeleton. - have double membranes. Cytoplasmic Streaming Video Campbell

41 Review of Functional Compartments of Eukaryotic cells Structural support, movement, and communication: cytoskeleton, plasma membrane, and cell wall Manufacturing: nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus Breakdown of molecules: lysosomes, vacuoles, and peroxisomes Energy processing: chloroplasts & mitochondria

42 Cell wall in some organisms proteins and polysaccharides, in plant cells The extracellular matrix (ECM) proteins and polysaccharides, in animal cells Extracellular components and connections between cells help coordinate cellular activities Cell Surfaces

43 Glycoprotein complex with long polysaccharide Collagen fiber EXTRACELLULAR FLUID Connecting glycoprotein Integrin Plasma membrane Microfilaments Functions of the ECM include Support Adhesion Movement Regulation CYTOPLASM A proteoglycan complex Polysaccharide molecule Carbohydrates Core protein Proteoglycan molecule

44 Intercellular junctions Plants- Plasmodesmata Animals- Tight junctions Desmosomes Gap junctions Activity: Cell Junctions