Chapter 2 Section 4: Looking Inside Cells Key Concepts: Cell wall Cell membrane What role do the cell wall and cell membrane play in the cell? Cytoplasm Mitochondria What are the functions of cell organelles? Endoplasmic Reticulum Ribosome How are cells organized in many-celled organisms? Golgi body Key Terms: Chloroplast CELL THEORY Vacuole Lysosome Organelle

Cell theory All living things are composed of cells Cells are the basic units of structure and function in living things All cells are produced from other cells

How to Enter the Cell Cell wall Cell Membrane Rigid layer of nonliving material (cellulose) that surrounds the cells of plants and some other organisms Helps protect and support plant cells Some materials, like water and oxygen, pass through easily Cell Membrane All cells have cell membranes In cells with cell walls (plant cells), the membrane is located just inside It controls what substances come into and out of a cell

Hmm! Why does a cell with a cell wall need a cell membrane? The cell wall separates the cell from the outside environment, but it cannot control all substances that come into and out of the cell. What are the differences and similarities between ceell walls and cell membranes?

Nucleus Think of it as the cell’s control center, directing all of the cell’s activities Nuclear Envelope A membrane that surrounds the nucleus (keeps nucleus material from spilling out into the cell) Chromatin Thin strands floating in the nucleus which contain genetic material (these are the instructions for direction the cell’s functions) Nucleolus Where ribosomes are made (ribosomes are organelles that make proteins)

Hmm! How is the nucleus like the manager of a company? What other analogies might we use for the nucleus?

Organelles Cytoplasm – the area/region between the cell membrane and the nucleus. Mitochondria – “powerhouses” – convert energy in food to energy the cell can use to carry out functions Endoplasmic Reticulum – carry proteins and other materials from one part of the cell to another Ribosomes – small, grainlike bodies produced in the nucleolus – work like factories to produce proteins

Organelles continued… Golgi Bodies – receive proteins and other newly formed materials from the endoplasmic reticulum, package them, and distribute them to other parts of the cell Chloroplasts (plants) – capture energy from sunlight and use it to produce food for the cell Vacuoles – storage areas of the cells Lysosomes – small, round structures containing chemicals that break down certain materials in the cell

Plants and photosynthesis Photosynthesis: the process by which a cell captures energy and uses it to make food. Plants capture the energy using chloroplasts. The captured energy combines H2O and CO2 into O2 and sugars.

Diagrams:

More diagrams

Why are cells small? It would take a long time for stuff to move around in the cell, so waste would take longer to remove, nutrients would take longer to absorb, and it would take more energy 

“Do I have to know all of the organelles?” Yes! “How am I going to be able to remember all of these things?” Review! Let’s come up with some other ways to absorb this information

Analogies for cells: “organelles” – named for being similar to the body organs How is a cell like a city? How is a cell like a house? How is a cell like an amusement park? What analogies can you come up with?

Specialized cells In many-celled organisms, cells are often organized into tissues, organs, and organ-systems.