Cell Structure and Function

Transcription

1 Cell Structure and Function Many Scientists Contributed to the Cell Theory! Hooke discovered cells while looking at cork under the microscope! Leewenhoek was the first to observe bacteria! Schleiden discovered that plants are composed of cells! Shwann discovered that animals are composed of cells! Virchow discovered that cells come from other cells What technological advancement enabled these scientists to learn more about cells? 1&

2 The Cell Theory The cell theory is a unifying concept of biology and states that: 1. All organisms are made of cells 2. All existing cells are produced by other living cells 3. The cell is the most basic unit of life! What is the largest cell? Eukaryotic vs. Prokaryotic Cells Cells can be separated into two broad categories based on their internal structures! Prokaryotic Cells: do not have a nucleus or other membrane-bound organelles. Instead the DNA is suspended in the cytoplasm. All Prokaryotes are microscopic singlecelled organisms! What is an example? 2&

3 Eukaryotic vs. Prokaryotic Cells Cells can be separated into two broad categories based on their internal structures! Eukaryotic Cells: have a nucleus and other membrane bound organelles. The nucleus, the larges organelle, encloses the genetic information. Eukaryotes may be multicellular or single-celled organisms! What are some examples? What structures are found in all cells? 3&

4 Cell Organelles! There are two types of Eukaryotic Cells: Plant Cells and Animals Cells! Organelle is a membrane-bound structure that is specialized to perform a distinct process within a cell 1. Plasma (cell) membrane: Found in ALL cells. Provides protection. Gatekeeper. Outer membrane on animal cells and on the inside of the cell wall in plant cell. Pores (holes) shown. 4&

5 2. Cell Wall: Found in plants, fungi, bacteria. Provides strength, support. Plant cell walls are made of cellulose (a complex carbohydrate. 3. Cytoplasm: Fluid inside cells in which cell parts (organelles) are suspended. White (or in between) space in plant and animal diagrams. Found in ALL cells. 5&

6 5. Ribosome: Cell part that makes protein (Smallest dot in diagrams). Found floating in cytoplasm and on E.R. Found in ALL cells. 5. Endoplasmic Reticulum (E.R.): Transports cellular products (lipids, carbs and proteins) within cells. Ribbon looking structure in cells with ribosomes attached. Smooth: No ribosomes Rough: With ribosomes 6&

7 6. Golgi Apparatus (Body): Mail deliverer an packager of cells. Packages and delivers cell products often via vesicles that pinch off, move and get exported. Typically shown with vesicles budding off of it. 7. Vesicle: Packages of cell material that move within and sometimes exported out of cells. 7&

8 8. Mitochondria: Powerhouse of the cells that convert food to energy (ATP). Found in higher amounts in active animal and plant cells (ie: muscle cells). Bean shaped with several folded membranes within. 9. Chloroplast: Structures in plant cells that convert sunlight, carbon dioxide, and water into glucose (carbohydrate/energy) and oxygen. (CO2+H2O+light"C6H12O6 + O2) 8&

9 10. Nucleus: Control Center of cells. Stores genetic information (DNA). Big round structure usually depicted in center of cell. 11. Nuclear Membrane (envelope): Protect nucleus. Allows things to move in and out of the nucleus. 9&

10 12. Chromosomes: Genetic material in nucleus made of coiled DNA and Protein. 13. Lysosome: Round vesicles that is garbage disposal of cell. Engulfs (surrounds) cell waste and exports it out of the cell. 10&

11 14. Vacuole: Specialized vesicles in both plant and animal cells that stores water and nutrients for the cell. Central Vacuole: Only present in plant cells. Can take up a majority of the cell. 15. Cilia: Hair-like threads on the surface of cells that move stuff across or between cells. Can also help in cell movement. 11&

12 16. Flagella: Whip or Tail-like that enables cell movement (ie: sperm cells). Cell Membrane KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment. 12&

13 Cell Membrane The cell membrane has two major functions. 1. Forms a boundary between inside and outside of the cell 2. Controls passage of materials cell membrane outside cell inside cell Cell Membrane! Cell membranes are composed of two phospholipid layers.! Phospholipids consist of three components: 1. Phosphate head: Polar molecule (hydrophilic: waterloving ) 2. Glycerol: part of phosphate head 3. 2 Fatty acid/lipid tails: non-polar (hydrophobic: waterfearing ) 13&

14 Cell Membrane! There are other molecules embedded in the membrane! These include (but are not limited to): cholesterol, protein channels and receptors! The fluid mosaic model describes the membrane. cell membrane carbohydrate chain protein cholesterol protein channel Cell Membrane! Cell membranes are composed of two phospholipid layers.! The cell membrane is selectively permeable. Selectively permeable: Some molecules can cross the membrane while others cannot. 14&

15 Cell Membrane Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape to allow passage of molecules. Receptor: Protein that detects a signal molecule and performs an action in response. Recognizes and bonds only to certain molecules called ligands. Ligand: The molecule that binds to the receptor. Cell Membrane Chemical signals are transmitted across the cell membrane. There are two types of receptors: 1. intracellular receptor: receptor found inside the cell 15&

16 Cell Membrane Chemical signals are transmitted across the cell membrane. There are two types of receptors. 1. intracellular receptor: receptor found inside the cell. 2. membrane receptor: receptors that are embedded within the cell membrane. 16&