1. Biology by Simon Kim, Ph.D., O.M.D.

2. What is biology?

11. The Cell

12. The cell is the basic unit of life. Some organisms are made up of a single cell, like bacteria, while others are made up of trillions of cells. Human beings are made up of cells, too.

26. Different Types of Cells There are lots of different types of cells. Each type of cell is different and performs a different function.

28. Different Types of Cells In the human body, we have nerve cells which can be as long as from our feet to our spinal cord. Nerve cells help to transport messages around the body.

29. Nerve cell

33. Different Types of Cells We also have billions of tiny little brain cells which help us think and muscle cells which help us move around. There are many more cells in our body that help us to function and stay alive.

39. Different Types of Cells Although there are lots of different kinds of cells, they are often divided into two main categories: prokaryotic and eukaryotic.

40. Prokaryotic Cells The prokaryotic cell is a simple, small cell with no nucleus. Organisms made from prokaryotic cells are very small, such as bacteria.

44. Prokaryotic Cells There are three main regions of the prokaryotic cell: 1.The outside protection or "envelope" of the cell. This is made up of the cell wall, membrane, and capsule.

46. Prokaryotic Cells 2. The flagella, which are a whip-like appendages that can help the cell to move. Note: not all prokaryotic cells have flagella.

48. Prokaryotic Cells 3. The inside of the cell called the cytoplasmic region. This region includes the nucleoid, cytoplasm, and ribosomes.

50. Eukaryotic Cells These cells are typically a lot bigger and more complex than prokaryotic cells.

51. Eukaryotic Cells They have a defined cell nucleus which houses the cell's DNA. These are the types of cells we find in plants and animals.

53. Parts of the Cell There are a lot of parts and functions to some cells. Here are some of the main components many cells have:

54. Parts of the Cell Membrane - This is the outer boundary of the cell. Sort of like the skin. It allows some substances in and keeps others out.

58. Parts of the Cell Mitochondria - This is where the cell gets its energy. In the human body, food we have digested reacts with oxygen in the mitochondria to make energy for the cell.

63. Parts of the Cell Ribosomes - Ribosomes are like tiny factories that make different things the cell needs to function, like proteins.

67. Parts of the Cell Nucleus - The nucleus is the brains of the cell. It uses chromosomes to instruct the rest of the cell what to do next.

72. Parts of the Cell Cytoplasm - This is the stuff that fills up the rest of the cell. The other components of the cell float around in the cytoplasm. It's mostly water.

74. Parts of the Cell Lysosomes - These guys clean up the place getting rid of waste and other unwanted substances that may get into the cell.

78. Parts of the Cell The machines inside the cell like the nucleus, ribosomes, and lysosomes are called organelles.

80. Fun Facts About Cells They were discovered by the scientist Robert Hooke.

86. Fun Facts About Cells One of the largest known cells is the ostrich egg which can weigh over three pounds(1.5 Kilograms).

88. Fun Facts About Cells When many cells of the same kind are together in a group, it's call tissue.

90. Fun Facts About Cells The word cell comes from the Latin word cellula, which means small room.

91. Fun Facts About Cells Humans actually carry more bacteria cells than human cells. Yuck!

92. Test Quiz

93. 1) Which of the following is a function of a nerve cell? 1.To help us think 2.To produce energy 3.To transport messages around the body 4.To fight off bacteria 5.To help us move

94. 2) The nucleus is to the cell as the ______ is too the human body. 1.Stomach 2.Lungs 3.Eyes 4.Brain 5.Ears

95. 3) What is the name of the whip-like appendages that can help most prokaryotic cells move? 1.Nucleus 2.Flagella 3.Mitochondria 4.Ribosomes 5.Lysosomes

96. 4) Which of the following is NOT made up of eukaryotic cells? 1.Animals 2.Bacteria 3.Humans 4.Plants 5.None of the Above

97. 5) Eukaryotic cells are typically a lot bigger and more complex than prokaryotic cells. 1.TRUE 2.FALSE

98. 6) The skin is to the human body as the ______ is to the cell. 1.Membrane 2.Lysosomes 3.Ribosomes 4.Nucleus 5.Mitochondria

99. 7) Ribosomes make what type of organic substances? 1.Carbohydrates 2.Proteins 3.Fats 4.Nucleic Acids 5.Simple Sugars

100. 8) The cell membrane allows ALL substances into the cell. 1.TRUE 2.FALSE

101. 9) Which of the following is where the cell gets its energy? 1.Membrane 2.Lysosomes 3.Ribosomes 4.Nucleus 5.Mitochondria

102. 10) The nucleus, ribosomes, and lysosomes can be classified as: 1.Bacteria 2.The envelope of the cell 3.Organelles 4.The cytoplasmic region 5.DNA