Chapter 3 Cells: Agriculture’s Building Blocks

1. Chapter 3Cells: Agriculture’s Building Blocks

2. Introduction • Most important was the invention of the microscope in the 1600s. • Robert Hook termed the tiny spaces “cells” • Cells vary greatly in size and shape • Largest is ostrich egg • Smallest is bacteria • Round, square, long, thin plate • Amoebas change shape constantly • All of agriculture is built around cells. • Plants and animals grow from cells • Reproduction begins with cells • One-celled bacteria digest food in certain animals

3. Types of Cells • Prokaryotic Cells

4. Types of Cells • Eukaryotic Cells

5. Cell Components • Cell wall – cellulose provides rigidity for the walls of the cell and provides some support for the entire plant • Lumber and paper are manufactured from the cellulose • Pectin is found in softer plant tissues such as leaves ad fruit. • Pectin gives jelly its thick consistency

6. Cell Membrane • Inside the cell wall is the cell membrane • Semi permeable which means that it allows only certain material to pass through • Diffusion –molecules in a solution pass through the membrane from a region of higher concentration to a region of lower concentration • Osmosis – diffusion of water • Homeostasis- the ability of an organism to remain stable when conditions around it change • Turgid – when cells are filled with the proper amount of water, cells are filled out and taut • In a drought plants are limp and wilted, but as soon as water is made available, they return to their normal healthy apperance

7. The Nucleus • Eukaryotic cells have a nucleus • Prokaryotic cells do not have a true nucleus • Composed primarily of nucleic acids, protein, and enzymes and serves as the control center for all of the activities of the cell

8. Cytoplasm • Is a thick, clear fluid that surrounds the nucleus and it contains all of the material needed by the cell to conduct life processes. • Mitochondria – break down food nutrients and supply the cell with energy • Vacuoles are organelles that serve as storage compartments for the cell • Microtubules act as the bones of the cell • Microfilaments are fine fiberlike structures composed of protein • Ribosomes are the sites where protein molecules are assembled. • Golgi apparatus remove water from proteins and prepare them for export from the cell • Endoplasmic reticulum is a large webbing or network of double membranes that transport material within the cell • Lysosomes are the digestive units of the cell

9. Plastids • Plant cells have organelles called plastids that are present in animal cells. Three types of plastids exist: chloroplasts, leucoplasts and chromoplasts.

10. Cell Reproduction • Eukaryotic cells divide by a process called mitosis. • Activity on mitosis