DNA Guided Reading and Practice (11.1)

  1. DNA determines an organism’s traits by controlling the structure of ______.
  1. DNA is contained in the ______.
  1. Proteins that control the rate of chemical reactions are called ______.
  1. The subunits of DNA are called______.
  1. The three parts of a nucleotide are:

a.

b.

c.

  1. The four nitrogen bases in DNA are:

a.

b.

c.

d.

  1. DNA is made of ______chains of nucleotides.
  1. The structure of DNA was discovered by
  1. The shape of DNA is described as a ______.
  1. Their discovery of this shape was based on the research of ______.
  1. In DNA the nitrogen bases pair together in a particular order. The type of bond that holds them together is a ______.
  1. The complementary bases that always pair together in DNA are
  2. ______and ______
  3. ______and ______
  1. The genetic information carried in DNA not only depends on the nucleotides present, but the nucleotide ______.
  1. Generally, the more similar the nucleotide sequence is in organisms, the more ______the organisms.
  1. Chromosomes are copied in a process called ______.
  1. The newly formed chromosomes are ______to the original unless a mutation occurs.

DNA – Structure and Function

DNA is a nucleic acid. Nucleic acids are large macromolecules. DNA stands for deoxyribonucleic acid. DNA is made up of a deoxyribose sugar, a phosphoric acid group (sometimes called an acid group) and nitrogen bases. There are four nitrogen bases. They are: Adenine (A)

Thymine (T)

Guanine (G)

Cytosine (C)

DNA is a very large macromolecule. This means that it is made up of smaller sub units. The small sub units that make up DNA are called nucleotides. Nucleotides are named for the nitrogen bases that they contain. The individual nucleotides bond together to make up the large DNA structure. The DNA structure looks like a twisted ladder. This structure is called a double helix. Nucleotides are attached t each other with covalent bonds to make up the side of the DNA ladder. Nitrogen bases join together with weak hydrogen bonds to make up the rungs of the DNA ladder

Questions – Part 1

1. What does DNA stand for?

2. What is DNA made of?

3. What does the word macromolecule mean?

4. What small subunits make up DNA?

5. List the 4 nitrogen bases.

Part 2 – Base Pair Rule

Nitrogen bases pair up in a special way. Adenine only bonds with Thymine and Guanine only bonds with Cytosine.

If one side of a DNA molecule looks like this:

ATTAGCGGCTAGA

The other side will look like this:

TAATCGCCGATCT

And the entire molecule will look like this:

ATTAGCGGCTAGA

TAATCGCCGATCT

Complete the DNA molecules.

1. ATCTCGTAGCAC 2. GCGACTCGCTCG

3. CCAGATTGCTAT 4. GGCAATGATACT