The Cell Structures and Functions Chapter 7 Sections 1, 2, and 3

Cell Discovery and Theory Section 1 Main Idea: The invention of the microscope led to the discovery of cells.

1665 Robert Hooke Observes cork through a microscope Names the tiny structures cells.

1683 Anton van Leeuwenhoek Discovered single- celled, animal-like organisms. Now we call them protozoans.

1830 to 1855 Scientists discover the cell nucleus – scientists propose that both plants and animals are made of cells.

1880 to 1890 Louis Pasteur and Robert Koch pioneer the study of bacteria.

Lynn Margulis 1970 Proposed that organelles in Eukaryote cells were once free- living Prokaryotes cells.

Cell Theory 1.All living organisms are composed of one or more cells.

2. Cells are the basic unit of structure and organization of all living things.

3. Cells arise only from previously existing cells. Cells pass on copies of their genetic material on to their daughter cells.

Basic Cell Types Prokaryotic CellEukaryotic Cell

Prokaryote Cells  Simple structure  Contains a plasma membrane  Does not contain membrane-bound organelles Genetic material Small

Eukaryotic Cells More complex structure Contains a plasma membrane Contains membrane-bound organelles Large

The Plasma Membrane Section 2 Main Idea: The plasma membrane helps to maintain a cell’s homeostasis.

Thin, flexible boundary between the cell and its environment Allows nutrients into the cell Allows waste to leave the cell

Selective Permeability The plasma membrane controls the movement of substances into and out of the cell. Controls the amount of a substance entering the cell. Controls the amount of a substance leaving the cell

The plasma membrane is composed of the phospholipid bilayer. A phospholipid molecule is composed of a glycerol backbone, two fatty acid chains, and a phosphate group.

Fluid Mosaic Model The phospholipid bilayer allows other molecules to “float” in the membrane. Other Components Proteins Cholesterol Carbohydrates

Proteins in the plasma membrane PROTEINS: Transmit signals inside the cell Act as a support Structure Provide pathways for substances to enter and leave

Cholesterol in the plasma membrane Cholesterol Prevents fatty acid tails from sticking together

Carbohydrates in the plasma membrane Carbohydrates Identify chemical signals

Which Is Which and How Do You Know? Cell A Cell B

Structures and Organelles Section 3 Main Idea: Eukaryotic cells contain organelles that allow the specialization and the separation of functions within the cell.

Eukaryotic Cells contain organelles that allow the specialization and functions within a cell. Organelles = little organs in Greek Each organelle has a unique structure and function The following slides will explore all the organelles that make up the structure and functions in a normal cell. We will start with organelles that are in both plant and animal cells.

Organelles carry out essential cell process such as: 1. Protein synthesis (makes protein) 2. Energy transformation 3. Digestion of food 4. Excretion of waste 5. Cell division

Cytoplasm Semi fluid material found inside the plasma membrane. Cytoskeleton is the fiber in the cytoplasm that support the organelles in cells. This is made up of microtubules and microfilaments.

Nucleus is the director of all cell processes. Most of the cell’s DNA is in the nucleus. DNA stores the information on how to make proteins for cell growth, functions and reproduction.

Nucleus Nuclear envelope is a double membrane around the nucleus. Nuclear pores allow substances to move in and out of the nucleus.

Nucleus Chromatin is DNA that is spread throughout the nucleus. The Nucleolus is the site of ribosome production.

Ribosome The function of a ribosome is to help produce proteins. Ribosomes are made in the nucleolus in the nucleus.

Endoplasmic Reticulum membrane system of folded sacs and connected channels for protein and lipid production. Rough ER is where ribosomes are attached. These ribosomes produce proteins to export to other cells. Smooth ER is where lipids, carbohydrates and phospholipids are produced.

Golgi Apparatus is a flattened stack of membranes that modifies, sorts and packages proteins into sacs called vesicles. After proteins are made in the Rough ER they are sent to the Golgi apparatus. Proteins are packaged in Vesicles to be sent outside the cell’s plasma membrane.

Mitochondria produce energy for the cell by converting fuel particles (mainly sugars) into usable energy. The powerhouse of the cell. The folded membranes provide large surface area for breaking the bonds in sugar molecules. The energy produced by breaking bonds is stored in the bonds of other molecules in the cell to use later.

Lysosomes (animal cells) Lysosomes are vesicles that contain digestive enzymes that break down the worn-out organelles and food particles. Lysosomes digest bacteria and viruses that may enter the cell. Lysosomes are the cleanup crew in the cell.

Centrioles (animal cells) Centrioles are found in the cytoplasm of animals near the nucleus. Centrioles are made of Microtubules. Centrioles play a role in cell division.

Vacuoles (plant cells) Vacuoles are sacs used to temporarily store food, enzymes, and other materials needed by the cell. Some vacuoles may store waste produces.

Chloroplasts Chloroplasts belong to a group plant organelles called Plastids. Chloroplasts capture light energy and convert it to chemical energy in the process called Photosynthesis.

Cell Wall (plant cells) The cell wall is thick, rigid fibers that surrounds the outside of the plasma membrane. The cell wall protects the cell and gives it support. The cell wall is made of a carbohydrate called cellulose.

Cilia are many short projections that look like hairs. Cilia are made of microtubules that extend outside the plasma membrane. The movement of cilia propels cells and organisms in their environment.

Flagella are longer and few projections outside the plasma membrane. Flagella move in a whip- like motion to power a cell or organism through the environment.