Unit 2A The Cell & Cell Parts

What is a cell? A cell is the smallest part of an organism that is still considered to be alive.

Is a cell alive? Yes a cell is alive.

Can a cell live on its own? Some cells can live on their own. It depends on whether the organisms is unicellular or multicelluar.

Unicellular vs Multicellular What does multi mean? More than one. What does Uni mean? One So what is the difference between multicellular and unicellular organisms? Multicellular organsims are made up of more than one cell, while unicellular organisms are made up of only one cell. Unicellular organisms, obviously, have the ability to live on their own. BUT, Cells from multicellular organisms can’t live on their own. Exceptions: A sperm cell can live for a few days on its own. Cells harvested from a multicellular organism can be encouraged to grow alone if scientists make the conditions appropriate for it to grow.

What are cell organelles? Organelles are the “little organs” within a cell. The organelles “run” the cell like workers run a factory. Organelles

Organelle #1 The Nucleus

What is the nucleus? The nucleus is the “control center” of the cell. The nucleus contains the genetic material (DNA or RNA) and ribosomes.

What types of organisms contain a nucleus? There are two main groups of organisms: The Eukaryotes – they contain a nucleus Ex: Plants, Animals, Fungi, Protists The Prokaryotes – they do not contain a nucleus Ex: Bacteria No Nucleus Nucleus is Present

What is a prokaryote? Prokaryotes do NOT have a nucleus. Their genetic material floats around the inside of their cell unprotected. Prokaryotes ARE BACTERIA!!!! Strep. E. Coli Bacteria in the Nose.

No Nucleus!!

What is a eukaryote? A eukaryote is ANY organism that contains a nucleus. The four groups of eukaryotes are: The Animals Slide 13 The Plants Slide 14 The Fungi (Mushrooms & Yeasts) Slide 15 The Protists (Unicelled or Very Small Multicellular Organisms that act like Animals) Slide 16

Describe the structure of the nucleus. The nucleus is surrounded by a membrane. The Nuclear Membrane has Nuclear Pores that control what materials enter and leave the Nucleus. The nucleus contains the genetic material (DNA) and the Nucleolus. The nucleolus makes ribosomes (we will learn about these later).

What is the function of the nucleus? What does it contain? The nucleus is the “Central Processing Unit” the “Main Office” that holds the instruction manual (the DNA). The nucleus’s main job is to house and protect the genetic material in the cell.

Organelle #2 The Plasma Membrane… Also called the Cell Membrane The Plasma Membrane and the Cell Membrane are the SAME THING!!

Where is the plasma membrane located? The plasma membrane is the outermost layer of the cell, which holds all of the cell parts in. Plasma Membrane

What is the purpose of the Plasma Membrane? The plasma membrane controls what enters and leaves the cell. What can enter? Nutrients, Water, Important molecules, such as oxygen What can leave? Waste products, chemicals to signal other cells to do something (ex: insulin)

What types of cells have a plasma membrane? ALL cells have a plasma membrane!!!

So, how do things enter and leave through the cell membrane? The Cell Membrane is made up of: Phospholoipids Carbohydrates, Proteins, A few other random molecules. All of these things together control what is allowed to enter and leave the cell.

Describe the structure of the plasma membrane. The plasma membrane is often referred to as a Fluid Mosaic… …because the many molecules (Carbohydrates, Phospholipids, and Proteins) can float freely around one another. See Here

So, What about the Parts of the Cell Membrane? Phospholipids… What are lipids? Fats Phospholipids are these same fats…made up of glycerol and fatty acids. BUT, instead of 3 fatty acids, there are two fatty acids and 1 phosphate group. Glycerol Glycerol Fatty Acid Fatty Acid Phosphate Group

Phospholipids Continued Because Phospholipids are lipids with phosphates, they are special: They have a hydrophobic end That end is scared of water And they have a hydrophilic end That end loves water. Hydro means Water Phobic means Scared Philic means Loves Hydrophilic Head Hydrophobic Tails

Phospholipids in the Plasma Membrane Because one end is scared of water, the lipids form “Lipid Bilayer”. Now, the ends that are scared of water will only touch each other and not face toward any water Hydrophilic Heads Hydrophobic Tails

Proteins in the Plasma Membrane Floating around with the phospholipids are proteins. Proteins help let things in & out of the cell that the phospholipids won’t.

Carbohydrates in the Plasma Membrane Carbohydrate also float in the plasma membrane on the OUTER surface of the cells. Carbohydrates are used in communicating with other cells. Carbohydrate Phospholipid Lipid Bilayer Protein