Heredity! Chapter 4, Lesson 1- McLain

Heredity- the process of traits being passed on to offspring.

Traits include: face shape hair color eye color blood type These are a few examples of traits that are passed on to offspring.

Traits that are not passed on by heredity are acquired traits Traits that are not passed on by heredity are acquired traits. They form after an organism is born.

The “pink” of flamingos is an acquired trait The “pink” of flamingos is an acquired trait. They get their pink from shrimp and algae.

Some acquired traits are learned, such as riding a bicycle.

Where do inherited traits come from? They come from DNA.

What is DNA? DNA is in the nucleus within a cell. It is a strand that looks like a helix. It transfers genetic information.

When a cell divides to create more cells, the thicker strands form rod like structures called Chromosomes.

Humans have 46 chromosomes in each cell.

Cells that are used for reproduction are called gametes Cells that are used for reproduction are called gametes. These are either egg or sperm.

Human gametes contain 23 chromosomes Human gametes contain 23 chromosomes. When they combine and reproduce, they make 46!

Short segments of DNA are genes! There are hundreds of genes in one chromosome.

A basic unit of DNA is called a nucleotide.

The sides of DNA nucleotide are made up of the sugar molecules The sides of DNA nucleotide are made up of the sugar molecules. The steps of the ladder are made up of pairs of nitrogen bases.

Before a cell divides, the DNA is replicated (copied).

When a mistake is made in copying (replication) a mutation occurs.

Some mutations can cause diseases and birth defects.

Some diseases are caused by genes Some diseases are caused by genes. Examples are Cystic Fibrosis, and Sickle Cell Anemia.

Some mutations can be helpful Some mutations can be helpful. For example, colorful corn for fall and the Granny Smith Apple!

Let’s draw a model of DNA!