Unit 3 Lesson 1 What Are Cells? Copyright © Houghton Mifflin Harcourt Publishing Company.

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Transcript of Unit 3 Lesson 1 What Are Cells? Copyright © Houghton Mifflin Harcourt Publishing Company.

Unit 3 Lesson 1 What Are Cells?

Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 1 What Are Cells?

Copyright © Houghton Mifflin Harcourt Publishing Company

Vocabulary• cell• organism• cell membrane• nucleus• inherited trait• dominant trait• recessive trait

Unit 3 Lesson 1 What Are Cells?

Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 1 What Are Cells?

All Made of Cells

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• Cells are the basic units of structure and function in a living thing. The bodies of all living things are made up of cells, including nerve and skin cells.

• Living things are also called organisms and can be made up of one cell or trillions of cells.

All Made of Cells

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• People did not know cells existed because cells were microscopic, or not visible without a microscope.

• Robert Hooke was the first person to study cells using a microscope.

Unit 3 Lesson 1 What Are Cells?

All Made of Cells

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• Scientists developed the cell theory that states:

• All living things are made of cells.

• All life processes take place in cells.

• New cells come from existing cells.

Unit 3 Lesson 1 What Are Cells?

Unit 3 Lesson 1 What Are Cells?

All Made of Cells

Copyright © Houghton Mifflin Harcourt Publishing CompanyText book p. 104

Unit 3 Lesson 1 What Are Cells?

All Made of Cells Exit Slip

Copyright © Houghton Mifflin Harcourt Publishing CompanyBrain check p.118

Unit 3 Lesson 1 What Are Cells?

All Made of Cells H.W

Copyright © Houghton Mifflin Harcourt Publishing CompanyText book p.103

• Plants and animals are made of cells, but they need different cell parts to stay alive.

• The nucleus • Makes more cells. • produces energy. • Takes in materials. • Gets rid of wastes.

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

• Cell membranes control what enters and leaves the cell.

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

• Mitochondria release energy that the cells use to do their jobs.

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

• The jellylike cytoplasm gives the cell shape and holds the cell parts together.

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

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• The cell wall protects plant cells and helps the plant keep its shape.

Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

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• The chloroplast uses the sun’s energy to make sugar to feed the plant.

Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

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• The vacuole in a plant cell stores water, nutrients, and waste. In animal cells, the vacuole is much smaller.

Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have?

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have? Exit Slip

Text book p.107

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Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have? H.W.

Brain check p.118

Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 1 What Are Cells?

What Parts Do Cells Have? H.W.

Brain check p.119

Cells Divide and Multiply

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• Cell division makes two cells from one.

• Cells divide for two reasons: 1. to grow As cell division occurs,

the organism grows.

Unit 3 Lesson 1 What Are Cells?

Cells Divide and Multiply

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2. to reproduce.

• When organisms reproduce, they make egg and sperm cells through cell division.

Unit 3 Lesson 1 What Are Cells?

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• Chromosomes are structures in the cell’s nucleus made of DNA. DNA is made of sections called genes.

• Genes control an organism’s characteristics.

• An organism’s characteristics, such as height or eye color, come from the parent’s cells when they reproduce.

Unit 3 Lesson 1 What Are Cells?

Cells Divide and Multiply

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• Mitosis is a six-step process that allows the organism to grow.

1. Each chromosome is copied.

2. Chromosome are joined.3. Chromosomes line up in

the middle.4. Chromosomes separate

and move to opposite ends of the cell.

5. A nuclear membrane is formed.

6. Finally, the cytoplasm divides

Unit 3 Lesson 1 What Are Cells?

How Cells Divide

24

Mitosis Animation

http://www.cellsalive.com/mitosis.htm

How Cells Divide

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• Meiosis forms eggs and sperm, or sex cells, which have half as many chromosomes as body cells.

• Egg and sperm cells join to form a new single cell during sexual reproduction.

• The single cell divides by mitosis and grows into a new individual.

Unit 3 Lesson 1 What Are Cells?

How Cells Divide

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Unit 3 Lesson 1 What Are Cells?

Text book p.111

How Cells Divide Exit Slip

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Unit 3 Lesson 1 What Are Cells?

Brain check p.118

How Cells Divide Exit Slip

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Unit 3 Lesson 1 What Are Cells?

Brain check p.120

How Cells Divide H.W.

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Unit 3 Lesson 1 What Are Cells?

Brain check p.120

Where Do Traits Come From?

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• Meiosis causes genetic differences since an organism receives only half of its genes from each parent.

• This results in genetic differences between parents and offspring.

Unit 3 Lesson 1 What Are Cells?

Where Do Traits Come From?

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• Inherited traits are characteristics passed from parents to their offspring.

• Examples of these characteristics might include eye color, hair color, freckles, and face shape in humans, and fur color and texture in animals.

Unit 3 Lesson 1 What Are Cells?

Where Do Traits Come From?

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Unit 3 Lesson 1 What Are Cells?

Text book p. 113

Dominant and Recessive Traits

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• In the 1800s, Gregor Mendel observed height differences in pea plants.

• Mendel investigated how the height trait was passed on from parent plants.

Unit 3 Lesson 1 What Are Cells?

Dominant and Recessive Traits

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Unit 3 Lesson 1 What Are Cells?

Dominant and Recessive Traits

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• Mendel hypothesized that traits in organisms are controlled by a pair of factors and each parent passes on one factor.

• In the pea plants, tallness was a strong, or dominant trait. Shortness was a weak, or recessive trait.

Unit 3 Lesson 1 What Are Cells?

Dominant and Recessive Traits

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Unit 3 Lesson 1 What Are Cells?

Text book p. 115

Where Do Traits Come From? Exit Slip

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Unit 3 Lesson 1 What Are Cells?

Brain check p. 119

Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 1 What Are Cells?