DNA: The Molecule of Heredity

Chapter 11 Section 1

What is DNA DNAProteinsEnzymes

Protein- Large complex polymer that is composed of carbon, hydrogen, oxygen, nitrogen and sometime sulfur- ( muscles, skin, and bones)

Enzymes- type of protein found in living things that changes rate of chemical reactions (eating and running)

DNA – information of life, instructions for manufacturing all the proteins for an organism.

Structure of Nucleotides DNA- polymer made of subunits that

repeat called nucleotides Nucleotide have three parts: simple sugar,

phosphate group and a nitrogenous base. Oxygen surrounds the phosphate group. 4 oxygen surround the phosphate group. Nitrogenous base- is a carbon ring

structure that has or contains one or more nitrogen.

Nitrogenous Bases Nitrogenous bases- Adenine (A),

Guanine (G), Cytosine (C), and Thymine (T).

Joining TogetherTo get a nucleotide you need: A phosphate

group bonding with the deoxyribose sugar of an adjacent nucleotide.

Now the phosphate group and sugar of the backside sticks out. On the backside you are going to have your nitrogenous base.

Adenine is always equal to the amount of thymine, and the amount of guanine is always equal to the amount of cytosine.

A-T GC

Structure of DNA Two Chains of nucleotides held together

by nitrogenous bases and hydrogen bonds.

These two strands are right beside each other. On one side you have to have adenine (A) and on the other side thymine (T) like a zipper.

These are twisted like a spring called a helix. Since there are two strands it’s a double helix.

Importance of Nucleotide Sequences

You are going to have four different nitrogenous bases, which can equal four different nucleotides.

The closer the relationship of the sequence, the more similar the DNA sequences are.

Replication of DNA Through meiosis an egg is fertilized,

while the egg grows through mitosis, each cell has a copy of DNA from the original fertilized egg.

In prophase it makes a copy of its chromosomes. This is completed before the cell duplicates.

When it is making copies of its chromosomes, it makes copies of its DNA, called DNA replication.

Replication of DNA cont. Without DNA replication, we would

only have half of the DNA from our parents. Because of this we could not survive.

How DNA replicates Each strand serves as a template to

make new DNA molecules. 1. The enzymes break down the

hydrogen bonds between the bases. Known as unzipping the DNA.

2. Other floating nucleotides will pair up and attach to their base pair by using hydrogen bonding.

How DNA replicates cont. 3. Unzipping will continue until the

whole molecule is replicated. Now you have a copy of the original strand.

4. Once the replication is finished genetic information(DNA) will be able to be passed on to different cells/generations through mitosis or meiosis.