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CH. 7 – CELLS. I. CELLS A. What is a cell? 1. Cell – the smallest unit of matter that can carry on all the processes of life.

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Presentation on theme: "CH. 7 – CELLS. I. CELLS A. What is a cell? 1. Cell – the smallest unit of matter that can carry on all the processes of life."— Presentation transcript:

1 CH. 7 – CELLS

2 I. CELLS A. What is a cell? 1. Cell – the smallest unit of matter that can carry on all the processes of life

3 I. CELLS B. Who first discovered the cell? 1. Anton van Leeuwenhoek – first to observe cells 2. Robert Hooke – used the light microscope to observe cork a. First person to call the shapes inside of organisms “cells”

4 I. CELLS 3. Rudolph Virchow – studied cell reproduction and discovered that all cells come from other pre- existing cells.

5 I. CELLS 4. Mathias Schleiden – studied plants and discovered that all plants are made of cells 5. Theodor Schwann – studied animals and discovered that all animals are made of cells

6 I. CELLS C. What is the cell theory? 1. The cell theory was developed by theories of Hooke, Virchow, Schleiden, and Schwann. a. The cell is the basic unit of organization for organisms. b. All organisms are made of one or more cells. c. All cells come from other pre-existing cells.

7 I. CELLS 2. With better microscopes, scientists observed that cells contained specialized structures. a. Organelles – cells parts that perform a specific job or function for the cell

8 I. CELLS D. Cell Diversity! 1. Your body alone contains 200 different cell types! 2. Cells Organisms can be classified by the number of cells they are made up of. a. Unicellular Organism – single celled organism Example: bacteria, yeast b. Multicellular Organism – organism made up of many cells Example: plants, animals

9 I. CELLS E. How are cells classified based upon the presence/absence of organelles? 1. Eukaryotic Cells – cells with a membrane-bound nucleus and organelles a. Examples: plant and animal cells 4. Cell membrane 1. Nucleus 2. Nucleolus 3. Chromatin 5. Organelles

10 I. CELLS 2. Prokaryotic Cells – cells with no membrane-bound nucleus or organelles (except ribosomes) a. Examples: bacteria 1. Ribosomes 2. DNA 3. Cell membrane 4. Cell wall

11 I. CELLS Left: Colorized micrograph of a prokaryotic cell of the bacterium. Right: Colorized micrograph of a eukaryotic cell of the green algae.

12 I. CELLS Cell TypeNucleus?Organelles?Uni or Multicellular? Prokaryotic Eukaryotic 3. Review:

13 II. CELL BOUNDARIES Plasma (Cell) Membrane  Function:  Surrounds cell  Allows things in and out (homeostasis)  Fact:  Selectively permeable – allows water and nutrients in and waste out  Made of phospholipids  Found in:  Prokaryotes  Eukaryotes

14 Cell Wall  Function:  Surrounds cell membrane to provide extra support and protection  Fact:  Made of cellulose in plants  Found in:  Prokaryotes  Eukaryotes (plants) 1. Cell membrane 2. Cell wall II. CELL BOUNDARIES

15 Nucleus  Function:  Controls the organelles  Contains DNA  Fact:  “Command center” or “brain” of the cell  Most prominent structure  Found in:  Eukaryotes Nucleus III. CELL CONTROL

16 Chromatin  Function:  Condense to form chromosomes in nucleus  Fact:  Strands of DNA that look like spaghetti  Found in:  Eukaryotes

17 III. CELL CONTROL Nucleolus  Function:  Makes ribosomes  Fact:  Found inside the nucleus  Found in:  Eukaryotes Nucleolus

18 III. CELL CONTROL Ribosomes  Function:  Makes proteins  Fact:  Made of RNA  Can be free or attached to ER  Found in:  Eukaryotes  Prokaryotes Ribosomes

19 III. CELL CONTROL Nuclear Envelope/Membrane  Function:  Controls what enters/exits the nucleus  Fact:  Surrounds the nucleus  Found in:  Eukaryotes

20 IV. CELL ASSEMBLY Cytoplasm  Function:  Suspends/holds organelles  Site of chemical reactions  Fact:  Contains clear gel-like fluid called cytosol  Found in:  Eukaryotes  Prokaryotes

21 IV. CELL ASSEMBLY Rough Endoplasmic Reticulum (ER)  Function:  Produces proteins  Fact:  Helps move molecules throughout the cell  Found in:  Eukaryotes

22 IV. CELL ASSEMBLY Smooth Endoplasmic Reticulum (ER)  Function:  Produces lipids (steroids)  Detoxifies poisons  Fact:  Helps move molecules throughout the cell  Found in:  Eukaryotes

23 IV. CELL ASSEMBLY Golgi Apparatus  Function:  Processes, packs, and secretes proteins and lipids  Fact:  Works closely with ER  Flattened stack of membranes  Found in:  Eukaryotes Golgi

24 IV. CELL ASSEMBLY Vacuole  Function:  Stores food, water, waste, proteins, carbs  Fact:  Helps maintain homeostasis  Found in:  Eukaryotes (plants have a LARGE vacuole) Vacuole

25 IV. CELL ASSEMBLY Lysosomes  Function:  Uses enzymes to digest old organelles and foreign objects (bacteria, viruses)  Fact:  “Suicide sacs”  Found in:  Eukaryotes Lysosome

26 IV. CELL ASSEMBLY Ever wonder how a tadpole gets rid of its tail and grows legs???? It’s lysosomes digest the cells in the tail, and these molecules are released to build different cells, like legs!

27 V. ENERGY TRANSFORMERS Chloroplast  Function:  Capture light (solar energy) and convert it to chemical energy during photosynthesis  Fact:  Glucose is the sugar made  Found in:  Eukaryotes (plants) Chloroplast

28 Mitochondria V. ENERGY TRANSFORMERS Mitochondria  Function:  Breaks down food into ATP energy during cellular respiration  Fact:  “Powerhouse” of the cell  Found in:  Eukaryotes

29 VI. SUPPORT & LOCOMOTION Cytoskeleton  Function:  Maintains the shape & supports the cell  Fact:  Made of microfilaments & microtubules  Found throughout the cytoplasm  Found in:  Eukaryotes  Prokaryotes

30 VI. SUPPORT & LOCOMOTION Cilia  Function:  Movement of cells or fluids  Fact:  Short hair-like fibers  Found in:  Eukaryotes  Prokaryotes

31 VI. SUPPORT & LOCOMOTION Flagella  Function:  Movement of cells  Fact:  Long hair-like fibers  Found in:  Eukaryotes  Prokaryotes Flagella Cilia

32 VII. LEVELS OF ORGANIZATION A. Organization: Organelles  Cells  Tissues  Organs  Organ systems  Organisms

33 VIII. THE CELL MEMBRANE A. A cell’s survival depends on the cell’s ability to maintain the necessary conditions inside itself. 1. Maintaining these constant internal conditions is called homeostasis.

34 VIII. THE CELL MEMBRANE B. Cell Membrane – flexible boundary between the cell and its outside environment 1. Allows water and nutrients to enter the cell and wastes to leave the cell. Water Cell Membrane

35 VIII. THE CELL MEMBRANE 2. Selectively Permeable – allowing some materials to pass while keeping others out a. Example: A spaghetti strainer allows water, but not spaghetti to pass through

36 VIII. THE CELL MEMBRANE C. What is the cell membrane made up of? 1. Phospholipids – diglyceride with a phosphate group attached

37 VIII. THE CELL MEMBRANE a. Phospholipid Bilayer – the cell membrane is TWO layers thick

38 VIII. THE CELL MEMBRANE b. Phospholipids have a polar “head” and non polar “tail”. - Polar “heads” are attracted to water, sugars, and proteins.

39 VIII. THE CELL MEMBRANE - Non-polar “tails” repel water, sugars, and proteins. - Resulting in a selectively permeable membrane.

40 VIII. THE CELL MEMBRANE 2. Proteins are embedded in the cell membrane to recognize substances that can enter and exit the cell.

41 VIII. THE CELL MEMBRANE 3. Cholesterol stabilizes the membrane by preventing lipids from sticking together.

42 VIII. THE CELL MEMBRANE D. Fluid Mosaic Model - describes how phospholipids can move around like a fluid and the proteins make a pattern

43 VIIII. CELL TRANSPORT A. What types of materials need to cross the cells membrane? Water, nutrients, oxygen, waste B. In cells, particles always move to reach equal concentrations. 1. Concentration Gradient – unequal distribution of particles

44 VIIII. CELL TRANSPORT C. Types of Transport 1. Passive Transport – movement of any substance across a membrane WITHOUT the use of chemical energy. a. Occurs from high to low concentration, with the concentration gradient.

45 VIIII. CELL TRANSPORT b. Types of Passive Transport - Diffusion – movement of molecules across a selectively permeable membrane; occurs from high to low concentration, with the concentration gradient.

46 VIIII. CELL TRANSPORT - Example: Oxygen diffuses into the bloodstream because of a high pressure in the lungs.

47 VIIII. CELL TRANSPORT - Osmosis – movement of water across a selectively permeable membrane; occurs from high to low concentration, with the concentration gradient.

48 VIIII. CELL TRANSPORT c. How are larger and strongly charged molecules, such as glucose, able to pass through the cell membrane more quickly than they should? - Facilitated diffusion – passive transport of large particles across a membrane with the help of proteins; occurs from a high to low concentration, with the concentration gradient - Example: Sugars, Amino Acids Glucose molecules Low Concentration Cell Membrane High Concentration Protein channel


50 2. Types of Solution – How does the water “know” which way to move? a. Hypertonic Solution – (high solute concentration) more water on the inside of the cell than the outside of the cell. - Water moves OUT of the cell. - Size of the cell = shrinks (plasmolysis) H 2 O + NaCl Solution

51 VIIII. CELL TRANSPORT b. Hypotonic Solution – (low solute concentration) more water on the outside of the cell than the inside of the cell. - Water moves INTO the cell. - Size of the cell = swells - Cytolysis = animal cells burst - Turgor Pressure = water pushes against cell wall in plants H2O + NaCl Solution

52 VIIII. CELL TRANSPORT c. Isotonic Solution – equal concentration of water and solute inside and outside the cell - Water moves in and out of cell equally. - Size of cell = stays the same H2O + NaCl Solution

53 VIIII. CELL TRANSPORT CriteriaInside CellOutside Cell Where is there more solvent (water)? hypertonichypotonic Where is there more solute (salts, dissolved substances)? hypotonichypertonic


55 VIIII. CELL TRANSPORT 3. Diffusion is a powerful process, however, sometimes cells need to move materials in the opposite direction. a. Active Transport – proteins are used to move ions or molecules against the concentration gradient, using ATP energy. - Occurs from areas of low to high concentrations. - Examples: minerals, nutrients

56 VIIII. CELL TRANSPORT 4. Types of Active Transport a. Endocytosis – process when a cell surrounds and takes in materials from the environment - Example: White blood cell engulfing a bacterium.

57 VIIII. CELL TRANSPORT - Two types of Endocytosis - Pinocytosis – movement of liquids into a cell - Phagocytosis – movement of solids in a cell

58 VIIII. CELL TRANSPORT b. Exocytosis – the explusion (exit) or secretion of material out a cell - Example: Cell getting rid of waste.

59 VIIII. CELL TRANSPORT c. Although endocytosis and exocytosis are different, the two processes often work TOGETHER.

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