1 Cellular Structure

2 Cell Theory The cell theory is the unifying theme in biology because it emphasizes the similarity of all living things. All organisms are composed of one or more cells. Cells are the smallest living units of all living organisms. Cells arise only by division of a previously existing cell.

3 Cell Characteristics The basic processes necessary for living things to survive are the same for a single cell as they are for a more complex organism. A single-celled organism has to conduct all life processes by itself. A multi-cellular organism has groups of cells that specialize to perform specific functions. Small cells function more efficiently than large cells because they have a higher surface-area-to- volume ratio and therefore shorter diffusion time.

4 Examples of Cells Amoeba Proteus Plant Stem Red Blood Cell Nerve Cell Bacteria

5 Cells and Cell Size

6 All cells contain Genetic material single circular molecule of DNA in prokaryotes double helix located in nucleus in eukaryotes Cytoplasm jelly-like substance that fills the cells interior Plasma membrane encloses the cell Separates the cell interior phospholipid bilayer

7 Cell Types Cell structure is one of the ways in which organisms differ from each other. 2 Types of Cells Prokaryote – Greek words for pre- nucleus Eukaryote – Greek words for true- nucleus

8 Prokaryotic Cells Earth’s first cells were prokaryotes. The simplest life forms are the prokaryotes. Prokaryotic cells exist in two major forms: eubacteria and archaebacteria. ALL are UNICELLULAR

9 Prokaryotic Cells Prokaryotes are the Earth’s most abundant inhabitants. They can survive in a wide range of environments and obtain energy in a variety of ways.

10 Prokaryotic Cells Prokaryotes are cells that lack a nucleus and membrane bound organelles. cause disease and infection grow and divide very rapidly

11 Prokaryotic Cells Flagella Thread like structures used for locomotion Flagellum - singular Bacterial cell wall Flagellum Rotary motor Sheath

12 Eukaryotic Cells Contain organelles surrounded by membranes Most living organisms PlantAnimal

13 Eukaryote Eukaryotes arose from prokaryotes and developed into larger more complex organisms. Eukaryotes are cells that contain a nucleus and organelles surrounded by a membrane

14 Two Theories of Origin Autogenic vs. Endosymbiotic

15 Eukaryote Can be both unicellular or multi-cellular Examples of eukaryotes are: All fungi, plant, and animal cells

16 Typical Animal Cell /~ acarpi/NSC/images/cell.gif

17 Typical Plant Cell

18 Summary of differences! Prokaryotic CellsEukaryotic cells small cells 1um-10um)larger cells (10 um-100um) always unicellularoften multicellular no nucleus or any membrane-bound organelles in cytosol always have nucleus and other membrane-bound organelles in cytosol DNA is circular, without proteins Called a nucleoid DNA is linear and associated with proteins to form chromatin ribosomes are small (70S)ribosomes are large (80S) no cytoskeletonalways has a cytoskeleton cell division is by binary fissioncell division is by mitosis or meiosis reproduction is always asexualreproduction is asexual or sexual

19 Nucleus The Control Center Stores genetic material (DNA) Double membrane with pores Largest organelle Nucleolus – dark center where ribrosomes are made Chromatin – complex of DNA and protein that makes up chromosomes

20 Cytoskeleton Long slender protein tubes and fibers that extend from the nucleus to the plasma membrane. Provide the interior framework of an animal cell. The cytoskeleton contains three types of elements responsible for cell shape, movement within the cell, and movement of the cell: Actin filaments Microtubules Intermediate filaments

21 Cytoskeleton Actin filaments Muscle fibers used in locomotion Actin/myosin Shape – expand and contract

22 Microtubules Tubulin hollow Transportation system – railroad tracks that move Protein complexes RNA Cytoskeleton

23 Cytoskeleton Microtubules Flagellum Spindle fibres

24 Cytoskeleton Intermediate filaments Frame for confinement Anchors proteins together so they can work as a complex Solid

25 Cytoskeleton

26 o Found in ALL cells o Membrane that encloses the cytoplasm. Cell Membrane o Called plasma membrane o Controls what enters and leaves the cell

27 Cell Membrane Fluid Mosaic Model

28 Ribosomes Ribosomes are RNA-protein complexes composed of two subunits that join and attach to messenger RNA. site of protein synthesis Alone in cytoplasm makes proteins for use within the cell Attached to ER makes proteins for export out of the cell

29 Endoplasmic Reticulum ER –Made up of a lipid bilayer with embedded proteins Rough ER - studded with ribosomes Site of protein synthesis and processing Smooth ER - lacks ribosomes Site of synthesis of phospholipids and the packaging of proteins into vesicles

30 Endoplasmic reticulum

31 Golgi apparatus Golgi bodies Stacked flattened sacks Site where cell products are packaged for export Proteins are modified by being combined with fats or carbohydrates

32 Golgi apparatus Vesicle budding from rough endoplasmic reticulum Fusion of vesicle with Golgi apparatus Migrating transport vesicle Protein Proteins Transport vesicle Golgi apparatus Ribosome Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

33 Lysosomes Vesicles produced by the Golgi apparatus. Lysosomes contain digestive enzymes and are involved in intracellular digestion of food particles, disease causing bacteria and worn out cell parts

34 Organelles With DNA Mitochondria site of cell respiration Chloroplasts site of photosynthesis

35 Mitochondria Very active cells have more mitochondria Has its own DNA Found in both plants and animals

36 Chloroplasts Chloroplasts are larger and more complex than mitochondria Contain green pigment called chlorophyll that absorbs sunlight in the first step of photosynthesis Found ONLY in PLANTS

37 Chloroplasts Thylakoids are the site of photosynthesis Grana – stacked thylakoids Stroma – fluid around the grana

38 Cell Wall provides support Found in PLANT cells only Made from cellulose

39 Vacuoles Found in PLANT and ANiMAL cells The vacuole acts a container, storing water and dissolved particles Plants have a large central vacuole for water storage Turgor Pressure Unicellular animals can use contractile vacuoles for movement

40 Plant vs. Animal Cells PLANT CELL ANIMAL CELL Cell membrane Mitochondria Golgi apparatus Nucleus Cytoskeleton Ribosomes Endoplasmic reticulum Lysosomes HAVE: Cell Wall LARGE vacuoles Chloroplasts DO NOT HAVE: Cell Wall LARGE vacuoles Chloroplasts

41 Eukaryotic Plant Cell

42 Eukaryotic Animal Cell

43 Endosymbiosis Endosymbiosis theory suggests that eukaryotes arose from a symbiotic relationship between various prokaryotes. Heterotrophic bacteria became mitochondria. Cyanobacteria became chloroplasts. Host cell was a large eukaryotic cell.

44 Cell Differentiation Cell specialization occurs during the development of a multi-cellular organism. The genetic information necessary for all cellular functions remains in each cell but may not be used.

45 Cell Humor