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The Cell Chapter 4.

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Presentation on theme: "The Cell Chapter 4."— Presentation transcript:

1 The Cell Chapter 4

2 Cells Marks the boundary between the “living and the dead”
Structural and functional unit of an organism Smallest structure capable of performing all of the functions necessary for life

3 What is a cell? Why do we care? We have TRILLIONS of them!! (@65)
Every organism is composed of one or more cells Basic unit of structure and function in organisms All come from pre-existing cells Cell Theory

4 Why are Cells so Small???? Large cells have far less surface for each unit of volume than do small cells

5 All cells……. Have an outer plasma membrane Contain DNA
Enclosed within the cell somewhere Contain cytoplasm

6 Plasma Membrane All cells surrounded by a plasma membrane
Phospholipid bilayer forms spontaneously whenever a collection of phospholipids is placed in water

7 Cytoplasm material inside a cell is the cytoplasm
Everything between the plasma membrane and the region of DNA Gives cells their shape Assist in movement of cell and organelles

8 Microscopes Compound light microscope
Multiple lenses increase magnifying power

9 Two basic kinds of cells
Prokaryotic Nothing separates the DNA from internal cell parts Eukaryotic Contain organelle sacs Nucleus – contains the DNA

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11 Eukaryotic Cells

12 Examples of Eukaryotic Cells:
Animal Plant Fungi Protozoa

13 Organelles Organelles act as their own separate “organs”
They physically isolate chemical reactions inside cells Animals and plants will differ in their organelles

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16 Nucleus Encloses the DNA of a eukaryotic cell Contains chromosomes
Functions: Prevents DNA from getting entangled with structures in the cytoplasm Outer membranes act as a boundary

17 Components of the nucleus
Nuclear pores Nuclear envelope Nucleolus Nucleoplasm DNA Chromosomes Chromatin

18 Nuclear envelope Double-membrane system composed of lipid bilayer (with pores) Bilayers surround the fluid part of nucleus (nucleoplasm) Continuous with the endoplasmic reticulum

19 Nucleolus Dense mass located within the nucleus Produces ribosomes

20 Ribosomes Site of protein synthesis
Occurs in the cytoplasm Attached to the endoplasmic reticulum Differ between prokaryotes and eukaryotes Why is this important from a health aspect?

21 Endomembrane System Helps modify proteins into final form
Lipids are assembled Compartmentalizes the cell Main components: 1. Nuclear envelope 2. Endoplasmic reticulum (ER) 3. Golgi body 4. Various vesicles (transport)

22 1. Nuclear envelope Merges with the membrane of the ER
Consists of membranous channels and saccules

23 2. Endoplasmic Reticulum
Channel that snakes through the cytoplasm Lipids assembled and polypeptide chains modified into final proteins Can be rough or smooth Dependant on the attachments of ribosomes Rough ER Processing and modification of proteins Smooth ER Synthesizes phospholipids

24 3. Golgi Body (Apparatus)
Series of flattened sacs Collects, sorts, packages, and distributes materials such as proteins and lipids Contain enzymes that put the finishing touches on proteins and lipids

25 4. Vesicles Enzymes from golgi apparatus sort and package the molecules into vesicles Tiny sac that moves through cytoplasm Function in transport, storage, or digestion of substances Two main types: Lysosomes Peroxisomes

26 Lysosome A lysosome is a membrane-enclosed sac
contains digestive enzymes to break down: Macromolecules damaged organelles

27 Put it all together……

28 Organelles That Contain DNA
Eukaryotic cells contain cell-like organelles that, besides the nucleus, also contain DNA these organelles appear to have been derived from ancient bacteria that were then assimilated by the eukaryotic cell they include the following organelles: Mitochondria Chloroplasts

29 Energy-Related Organelles
organelles specialize in converting energy to a form that can be used by the cell Requires solar energy Dissipates as heat Chloroplasts Use solar energy to synthesize carbohydrates Carbohydrates then broken down in the….. Mitochondria Produce ATP molecules

30 Energy-Related Organelles
Photosynthesis Cellular Respiration The chemical energy of carbohydrates is converted at ATP

31 DNA in mitochondria?? mtDNA Inherited solely from mother
First set of DNA to be sequenced Endosymbiotic theory Helps in evolutionary inheritance

32 Organelles That Contain DNA
The theory of “endosymbiosis” states that some organelles evolved from a symbiosis one cell of a prokaryotic species was engulfed by and lived inside of a cell of another species of prokaryote

33 Organelles That Contain DNA
Other evidence supporting endosymbiotic theory: Mitochondria are about the same size as modern bacteria The cristae in mitochondria resemble folded membranes in modern bacteria Mitochondrial ribosomes are similar to modern, bacterial ribosomes in size and structure Mitochondria divide by fission, just like modern bacteria

34 Cytoskeleton – Cytoplasm
System of interconnected fibers, threads, and lattices in the cytosol Extend from nucleus to the plasma membrane Gives cells their shape Assists in movement of cell and organelles Assemble and disassemble as needed

35 The three protein fibers of the cytoskeleton

36 The Cytoskeleton: Interior Framework of the Cell
Centrioles complex structures that assemble microtubules in animal cells and the cells of most protists anchor locomotory structures such as flagella or cilia

37 The Cytoskeleton: Interior Framework of the Cell
vacuoles membrane-bound storage centers central vacuole filled with water and dissolved substances

38 Outside the Plasma Membrane
Cell walls found in plants, fungi, and many protists comprised of different components than prokaryotic cell walls function in providing protection, maintaining cell shape, and preventing excessive water loss/uptake

39 Outside the Plasma Membrane
Extracellular matrix (ECM) takes the place of the cell wall in animal cells and is comprised by a mixture of proteins secreted by the cell collagen and elastin proteins Form a protective layer over the cell surface fibronectin protein Connects the ECM to the plasma membrane integrins Connected to fibronectin Proteins that extend into the cytoplasm of the cell

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41 Plant Cells Cell wall Central vacuole Chloroplasts

42 Fungal Cells Mold or yeast Spores Cell wall
Unicellular or multicellular

43 Protozoa Cells No cell wall Unicellular Motility

44 Prokaryotes Archae Bacteria

45 “Micro”organisms

46 Characteristics of Cells
Prokaryotic cells ~1.0 µm in diameter All are microorganisms Unicellular Bacteria and Archaea no nucleus no membrane-bound organelles

47 Prokaryotes – General cell structure
Nucleoid Pili Fimbriae Flagella Cell wall Glycocalyx Ribosomes


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