Grade 8 Science ­ Chapter 10.notebook

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Grade 8 Science

Unit 4: Cells, Tissues, and Organ SystemsChapter 10

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Cells and Living ThingsWhat are living things made of?

‐ Early Idea: all living things are made of air, fire and water‐ Now: all living things are made of cells (cell theory)

Cell: the basic functional unit of life

The Cell Theory states: 1) The cells is the basic unit of life2) All living things are made of one or more cells3) All cells come from other living cells

Grade 8 Science ­ Chapter 10.notebook

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Characteristics of Living ThingsAll living things:

1) Grow: the cells in your body increase in number, new cells will grow to replace old cells that die

2) Move: a change in position, shape or location (locomotion)

3) Respond to Stimuli: stimuli are anything that causes an organism to react; it may be external, internal

4) Reproduce: producing more of the same kind (offspring)

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The Compound Light Microscope

Grade 8 Science ­ Chapter 10.notebook

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Microscope MagnificationThe eyepiece lens has a magnification of 10x

The objective lenses can change:‐ Low (4x)‐ Medium (10x)‐ High (40x)

To calculate the total magnification, we use the following formula:

Total Magnification = power of objective lens x power of eyepiece lens

Example: you are observing an onion cell under medium power. What is the total magnification?

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You Try!!!Example 2: You are looking at a hair root under high power. What is the magnification?

Bookwork: Page 397 ‐ #'s 1 & 4Page 401 ‐ #'s 1, 2, 6, 7, 8, and the pause and relfect

Grade 8 Science ­ Chapter 10.notebook

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March 19, 2014

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Cell Organelles1) Cell Membrane: surrounds and protects the contents of the cell and controls the movement of materials in and out of the cell

‐ Found in both plant and animal cells

2) Cytoplasm: a jell‐like fluid in which the organelles float, it helps to move materials like food to different parts of the cell

‐ Found in both plant and animal cells

3) Cell Wall: a tough, rigid structure that give plant cells their box‐like shape, mostly made of cellulose

‐ Only found in plant cells

4) Nucleus: the "control centre" of the cell, it is a large round structure that is often visible and it contains chromosomes

‐ Found in both plant and animal cells

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Cell Organelles5) Vacuole: balloon‐like spaces in the cytoplasm that store materials that are not needed right away

‐ Found in both plant and animal cells (many small ones in plant cells, few large ones in animal cells)

6) Mitochondrion: oval, bean‐like structures that produce energy by breaking down food particles

‐ Found in both plant and animal cells

7) Chloroplast: green structures that contain chlorophyll, they capture the sun's energy for photosynthesis

‐ Found only in plant cells

Grade 8 Science ­ Chapter 10.notebook

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Cell Organelles

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Plant vs. Animal Cells

Bookwork: Page 415 ‐ #'s 1‐10, 13‐15 Page 416 ‐ #'s 9‐13

Grade 8 Science ­ Chapter 10.notebook

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March 19, 2014

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Dividing CellsCells division is necessary for growth and reproduction

New cells will replace cells that are dead or in need of repair

How does this happen? Through a process called mitosis!!

Mitosis occurs only in body cells NOT in sex cells (eggs and sperm reproduce through meiosis ‐ but more on that next year!)

Bacteria cells reproduce through mitosis!

Prophase Metaphase TelophaseAnaphase

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Energy for CellsCells need energy for all the life processes

The energy in the cell is stored in food called glucose (a type of sugar)

To release energy, cells must carry out cellular respiration which takes places in the mitochondrion; here the energy is converted to other forms of energy (most often it is heat energy)

Oxygen is necessary for cellular respiration!

Carbon dioxide and water vapor are wastegases produced. These are removed from the cell.

Bookwork: Page 415 ‐ # 16 Page 416‐417 ‐ All Qs