7th Grade Science

Cell Division and Meiosis

Chromosomes>Genes>DNA• The nucleus of a cell

contains long chains of information called DNA(Deoxyribonucleic Acid).

• The DNA of a cell is like a set of instructions that “build” an organism.

Chromosomes>Genes>DNA• The instructions for the

cell are organized in parts called chromosomes.

• The number of chromosomes varies within the five kingdoms.

• Humans = 46• Fruit Fly = 8

Chromosomes>Genes>DNA• Chromosomes are broken

up into genes.• Which genes an organism

has determines which traits it has.

• One (or more) genes “codes” for each trait we have. (ex. Hair, eye color, shape of features)

Chromosomes>Genes>DNAGenes: Certain parts of each chromosome that code for how to build structures in your body.

Asexual Reproduction• Some living things

undergo asexual reproduction, that is where ONE individual is needed to produce offspring.

• Go to p152 in the Life Science Textbook

Sexual Reproduction• Male sperm unite

with female eggs in sexual reproduction.

• A variety of living things undergo sexual reproduction including many types of plants and animals.

Sexual Reproduction• Males have sperm,

which contain HALF of the genetic information.

• Females have eggs, which contain HALF of the genetic information.

• 1/2 + 1/2 = ?

Cell Division• Cells can divide in

two ways.• Mitosis: A cell

divides to create two identical copies. This happens in growth of human cells and in asexual reproduction.

Cell Division• Another type of cell

division is meiosis. • In meiosis, cells are

produced that have HALF of the genetic information.

• This occurs in the creation of sperm and egg.

Chromosomes>Genes>DNA