Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 1 Chapter 3: Cell Structure Section 2: Cell Features
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 2 Objectives 1.List the three parts of the cell theory. 2.Determine why cells must be relatively small. 3.Compare the structure of prokaryotic cells with that of eukaryotic cells. 4.Describe the structure of cell membranes.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 3 The Cell Theory
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 4 The Cell Theory Cell theory is an excellent example of how scientific concepts are developed by the accumulation of observations over time.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 5 The Cell Theory It also shows how scientific discovery is often dependent upon advances in technology; in this case, the microscope.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 6 The Cell Theory History of Cell Theory 1665—Robert Hooke discovers and names cells while observing thin slices of cork. 1675—Anton Van Leeuwenhoek discovers living microorganisms 1830s– Mattias Schleiden, after many observations, concludes that plants are made of cells and Theodor Schwann concludes that animals are made of cells.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 7 The Cell Theory 1858—Rudolf Virchow determines that cells come only from other cells. These observations form Cell Theory: 1.All organisms are made of one or more cells. 2.Cells are the basic units of structure and function in organisms. 3.All cells arise from pre-existing cells.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 8 Cell Size
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 9 Cell Size Cells are small. Cells must be small in order to maintain a high surface area to volume ratio.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 10 Cell Size Cells are small. High surface area to volume ratio allows for efficient exchange of materials into and out of cells.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 11 Cell Size Cells are small. Also, in multicellular organisms, many small cells are easier to support on a skeletal framework than a few large cells.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 12 The Cell Theory Here we see that as the size of a cell increases its surface area to volume ratio decreases.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 13 Cell Features Common Features of Cells
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 14 Common Features of Cells Cell membrane Cytoplasm (containing ribosomes) DNA (within nucleus in most eukaryotic cells) [movie] Cell Features
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 15 Cell Features Common Feature of Cells Cell (plasma) membrane –Outer boundary, separates cell contents from surroundings –Regulates the passage of materials into/out of the cell
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 16 Cell Features Common Feature of Cells Cytoplasm –Cell’s interior –Includes: cytosol—fluid portion ribosomes—sites where proteins are made organelles (in some types)
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 17 Cell Features Common Feature of Cells DNA (present in all cells at some point) –Provides genetic instructions for making proteins –Regulates cell functions and reproduction
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 18 Cell Features Cells are divided into two distinct types: PROKARYOTIC and EUKARYOTIC
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 19 Prokaryotes
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 20 Prokaryotes Are the smallest, simplest cells
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 21 Prokaryotes Single-celled organisms that lack a nucleus and other membrane bound compartments (organelles).
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 22 Prokaryotes The most familiar representatives are bacteria.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 23 Prokaryotes
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 24 Prokaryotes Are metabolically diverse –Some do not need oxygen –Some cannot survive when oxygen is present
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 25 Prokaryotes Are metabolically diverse –Some are autotrophic (able to make their own food by either photosynthesis or chemosynthesis)
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 26 Prokaryotes Are structurally similar –Genetic material is a single circular molecule of DNA. Located in nucleoid region
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 27 Prokaryotes Are structurally similar –Have outer cell wall Provides protection and support May be surrounded by a capsule composed of polysaccharides
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 28 Eukaryotes
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 29 Eukaryotic Cells Are much larger than prokaryotic cells. Have a nucleus, and other membrane-bound organelles.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 30 Eukaryotic Cells Organelle = a structure that carries out specific activities in the cell.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 31 Eukaryotic Cells The nucleus is an organelle that contains the cell’s DNA. Cells contain many organelles.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 32 Eukaryotic Cells * Chromatin Nucleus
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 33 Eukaryotic Cells
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 34 The Cell Membrane
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 35 The Cell Membrane Cell membranes are: Fluid –Fluidity caused by phospholipids Phospholipids form the foundation of the membrane.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 36 The Cell Membrane Cell membranes are: Selectively permeable –Determines which substances enter and leave the cell –Due to the way phospholipids interact with water
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 37 The Cell Membrane Phospholipids: Recall that –The phosphate head is polar and attracts water –The fatty acid tails are nonpolar and repelled by water
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 38 The Cell Membrane Phospholipids: Phospholipid bilayer –Lipids are arranged in a double layer with the nonpolar fatty acid tails on the interior
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 39 The Cell Membrane
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 40 The Cell Membrane Membrane Proteins: Various proteins are located in the lipid bilayer and have different functions: Markers Receptors Enzymes Transporters
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 41 The Cell Membrane Membrane Proteins: –Marker proteins—attached to surface carbohydrates, they serve to identify the cell
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 42 The Cell Membrane Membrane Proteins: –Receptor proteins—bind specific signal molecules outside the cell
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 43 The Cell Membrane Membrane Proteins (cont.): –Enzymes—involved in important biochemical reactions in the cell
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 44 The Cell Membrane Membrane Proteins (cont.): –Transport proteins—aid the movement of substances into/out of the cell.
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 45 The Cell Membrane
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 46 Guided Practice 1.What determines the maximum size of a cell? –The ratio of the cell’s surface area to its volume 2.In what way(s) do eukaryotic cells differ from prokaryotic cells? –Eukaryotic cells have a nucleus and other membrane bound organelles
Chapter 3: Cell Structure Section 2 & 3: Cell Features/Organelles 47 Guided Practice 3.Explain how the cell membrane contributes to a cell’s ability to maintain homeostasis. –The cell membrane regulates what substances enter and leave the cell. 4.In the cell membrane, the fatty acids of phospholipid molecules are located _____________________________. on the interior of the lipid bilayer