Under the Microscope: A Tour of the Living Cell. Chapter 4:

Transcription

1 Under the Microscope: A Tour of the Living Cell Chapter 4:

2 The Cell Theory (p. 56): All organisms composed of 1 or more cells. All cells reproduce from other cells. Cell is the smallest living unit. This conclusion was reached in the 1800 s Basis for modern Biology. Stimulated by advances in microscope technology.

3 Components of All Cells (p. 58) Plasma Membrane cell boundary DNA-containing region Cytoplasm (everything else)

4 2 Types of Cells (P.58, 60) Prokaryotic cells Small, lack nucleus. Earliest cells were prokaryotes. No membrane-bound compartments (= organelles). Eukaryotic cells: Larger, evolved later. DNA contained in nucleus. membrane-bound internal organelles.

5 Components of Eukaryotic Cells: Plasma membrane (p. 60) Composition: Double layer of phospholipids. proteins. Function: cell outer boundary. Regulates movement of materials. - via transport Proteins (p. 83).

6 The Nucleus (62) Contains DNA (chromosomes). Two membrane layers with pores.

7 Ribosomes (p. 63): Micro-Granules of RNA and protein. Responsible for protein synthesis using instructions from DNA.

8 Endoplasmic Reticulum (= ER) (p ) Internal membrane tubes & channels. Connects to membrane of nucleus. Functions: Assembly of lipids. Routing, modification & transport of new proteins. 2 Types: Smooth ER (no ribosomes) Rough ER (with ribosomes) Nucleus

9 Golgi Bodies (p. 65) Stacked, flattened membrane-sacs. Vesicles Function: Modification, mixing, sorting & packaging of proteins, lipids, etc. Vesicles (=Membrane sacs) Golgi originate from ER, migrate, to Golgi. Other vesicles released from Golgi; Nucleus contents secreted or used inside cell. ER Golgi

10 Central Vacuole of plant Cells (P. 67): Large watery vesicle in plant cells. Storage of: water, ions, sugars, amino acids, pigments, waste products, defensive poisons, etc % of cell volume.

11 Mitochondria (p. 68) Energy Release, Power Generator Aerobic respiration: Food (Sugar, etc.) + Oxygen ----> Carbon Dioxide + Water + Energy (for ATP) Folded inner membrane: Site of most ATP generation. Matrix (interior): site of organic molecule breakdown. Outer membrane DNA (???)

12 Chloroplasts: Energy Capture (P. 68). Photosynthesis Captures energy to produce sugars & food: Carbon Dioxide + Water + Energy (Sunlight) ----> Food (Sugar) + Oxygen internal membranes: Sunlight energy capture Chloroplast stroma: (interior): site of CO2 capture & food synthesis Chloroplast membrane DNA (!!!) (2 layers)

13 Chlorplasts & Mitochondria Evolved From Bacteria (p. 307 in ch. 15) Bacteria entered pre-eukaryotic cells. Evolved symbiotic relationship: Pre-plastid/ mitochondrion: protection, raw materials. host cell: photosynthesis. efficient way to release energy. Process is called endsymbiosis. Mitochondria entered anscestor of all Eukaryotic cells about 2 billion Years ago. Chloroplasts came later in ancestors of plants, green algae & red algae.

14 Evidence for Endosymbiosis (p. 307) Existence of mitochondrial & chloroplast DNA. Still code & synthesize some of their own proteins. Bacteria-like features of mitochondria & chloroplasts: Features of both their ribosomes & DNA. Documentation of more recent (less complete thus easier to recognize) endosymbioses: Lichens Corals Amoeba / bacteria interactions & experiments.

15 The Cytoskeleton (p ) Protein microfilaments & microtubules: Functions: Contributs to cell shape. Anchors/ organizes organelles. Movement: Cilia & flagella muscle contractions. Chromosome movement during cell division.

16 Cell Surface Specializations (p. 61) Peptidoglycan wall of bacteria. Eukaryotic cell walls Cellulose-based wall of Plants. Chitin-based wall of fungi. Matrices between animal cells A Plant Cell Wall Hardened matrix surrounding a bone cell

17 Single-cell vs.multicellular Organisms According to Cell Theory organisms may consist one or many cells: Whole individual = 1 cell: Bacteria, yeasts, many algae, others: Exist singly or as colonies of identical cells. Whole individual = many cells: Several Eukaryote groups: plants, animals, fungi, some brown algae, red algae, etc. Body composed of many cell types: Genetically identical but different genes expressed.

18 Multicellular organisms Begin as a fertilized egg; divides... Young immature cells form: potential to become any type of cell type in the body. = Stem cells (animal). = Meristem cells (plant). As growth & development progresses: formerly identical cells become The beginning: A different from each other: young animal just a Differentiation: the process by few cell divisions after a fertilized egg. which genetically-identical cells become different from those of other cell types & the (meri) stem cells they originated from. Cutting edge stem cell research: stem cells to regenerate damaged organs.

19 Organization of Multicellular Organisms Cells organize into tissues. Organs. Array of cells interacting for a task. 2 or more tissues forming a functional unit. Multiple organs & organ systems make up the individual. Various Cells of a plant tissue

20 Plants are Multicellular (Ch. 28) Basic Plant Body Plan (p. 607): Root: Anchorage, absorb water & minerals. Shoot: Stem, leaves, buds, flowers & fruits. Growth regions: Meristems = areas of juvenile (meristem) cells capable of division; p Primary meristems (Apical: root & shoot tips), length growth, etc.; all plants; p Secondary meristems; Thicken older woody stems & roots; only trees, shrubs, etc.; p Plant organs are composed of 3 tissue types.

21 Organs & Meristems of the Plant Body Shoot apical meristem: Produces stem, leaves, buds, flowers, etc. Flower Leaf bud Vascular cambium (secondary meristem): thickens older stem, roots. Root apical meristem: Produces roots Root

22 Plant Tissues: Ground Tissue (p. 610) Composed of parenchyma, collenchyma, or fiber cells. Interior matrix of root, stem, leaf, flower parts, fruit wall, etc. Basic metabolism (photosynthesis, respiration, etc.), support & storage.

23 Vascular Tissues: Xylem (p. 610): Conducts water from soil into & throughout plant. Vessel members & tracheids: thick-walled, strong tube-like conducting cells. Parenchyma cells. Fibers (strengthen).

24 Vascular Tissues: Phloem (p. 610): Food transport (sugars, sucrose). Sieve tube members (conducting). Companion cells (helpers). Parenchyma cells. Fibers (strengthen).

25 Dermal Tissues (p. 610) Epidermis: Protective covering of all soft or young plant parts & leaves. Periderm: Outer bark of woody plant parts. Replaces epidermis during secondary growth. Hair Guard cell Ground cell Leaf epidermis Periderm (outer bark)

26 Tissues of Plant Roots p. 610 Epidermis Ground tissue Vascular tissues Buttercup root Corn root

27 Cells and Tissues of Stems P. 610 Epidermis Vascular tissues Ground tissue Corn root Alfalfa root

28 Inside a Leaf (p. 611) Upper epidermis Photosynthetic cells (ground tissue) Vascular tissues Lower epidermis Cuticle (wax layer)

29 Secondary Growth in Woody Stems & Roots (p.614) Only trees & shrubs--woody plants: Older stems & roots Increase in width each season. Begins with formation of vascular cambium. Produces ring of secondary xylem = wood (inside) and secondary phloem (outside). Epidermis destroyed during 1st season & Replaced by periderm.

30 Many Years of Secondary Growth

31 Animal Cells & Tissues Multicellularity at highest level of complexity; Numerous cell types Four main tissue types: Connective tissue. Muscle tissue. Nervous tissue. Epithelial tissue. All organs: GI tract, heart, brain, others, etc. composed of these tissues.

32 Animal Tissues: Stomach

33 Animal Tissues: Arm

34 Beyond Plants & Animals: Other Multicellular Organisms Most Fungi Some Brown algae (kelps) Some red algae A few green algae Fungus Kelp Red alga

35 The End Version 13.01