Cell Basics Page 142 - 149

The Cell – Need to know BasicsAnimal and Plant Organelles

Compare Animal and Plant cells

The Cell – Need to know Basics

Cells are the “building blocks” of the human body.

Every part of your body – bones, skin, nerves, hair, and muscle – is made of cells.

Different cells do different jobs and have different shapes and sizes.

Cells contain smaller “insides” called organelles – all with different jobs.

Organelles The largest and most important organelle

is the nucleus. The nucleus controls everything that

happens inside the cell. (sort-of “the cells brain”)

All cells are surrounded by a protective layer called the cell membrane.

The cell membrane is semi-permeable, which means that it lets some substances pass through it, but not others.

The rest of the cell is called cytoplasm. Cytoplasm is a liquid containing chemicals needed to keep the cell alive as well as hold the floating parts of the cell together.

Organelles and their FunctionsOrganelle Function Animal, Plant,

both

Cell Membrane Protects, determines what can enter and exit the cell Both

Cytoplasm Gel-like substance holds all the organelles of the cell Both

Nucleus Controls the activity of the cell. Contains DNA Both

Vacuole Storage area in cells (water storage) Both

Endoplasmic Reticulum (ER)

Support and makes protein in the ribosomes Both

Mitochondria Uses food to produce

energy Both

Cell Wall Supports cell shape like a skeleton Plant

Chloroplasts Uses Sun energy to make food Plant

Animal Cell and Organelles (page 142)

Plant Cell and Organelles (page

143)

Venn Comparison of Animal and Plant Cells

1. What are the two main types of cells?2. What is an organelle?3. What organelles are common to both types of

cells?4. What are the organelles found only in plant

cells?5. Why do you think that scientists refer to cells as

the ‘basic” unit of life?

AnimalCell

PlantCell

Importance of Cell Division

Have you ever wiped out on your skateboard or bike?

Imagine how terrible it would be if every scratch or flaw on your skin remained.

Cells come from pre-existing cells through the process of cell division.

The Cell Theory (page 147)

All living things are composed of one or more cells.

The cell is the functional unit of life.

All cells come from preexisting cells.

Functions of Cell DivisionPage 148 - 149

Healing and tissue repair. To increase the number of cells

(therefore increase the size of the organism).

To replace dead and worn out cells. To create life (in unicellular

organisms such as bacteria, and multicellular organisms such as humans).

Why don’t cells just expand so we can grow, rather than divide?

If the cell became too large, there would not be enough room to exchange materials through the cell membrane and the nucleus would get smushed therefore not allowing messages to be relayed efficiently.

In short, cell division allows an organism to grow, while still maintaining a cell size that keeps the organism healthy.

Cell division is one of the most studied, yet least understood areas of biology.

Reproduction and Cell DivisionOrganisms of all species reproduce.

They may reproduce asexually or sexually.

In asexual reproduction a single organism gives rise to offspring with identical genetic information. Ex. the cells of the human body, other than those found in the male testes and female ovaries and bacteria use asexual reproduction to produce offspring by the process of mitosis.

Daughter(46)

Daughter(46)

Mother(46)

Mitosis

In sexual reproduction, genetic

information from two cells is combined to produce a new genetically unique organism. Usually, sexual reproduction occurs when two specialized sex cells unite to form a fertilized egg called a zygote.

Egg cell(23)

Zygote(46)

Sperm Cell(23)

Sex Cells