DNA Structure Review

DNA Structure1. What is DNA?

DNA is a nucleic acid found in every living thing. It contains the genetic information for cell growth, division, and function.

DNA StructureThis structure represents a polymer.

2. What are the individual units called?

They are called monomers

DNA Structure3. What does poly mean?

4. What does mono mean?Mono means ‘one’ and monomer means ‘one piece.’

Poly means ‘many’ and polymer means ‘many pieces.’

DNA Structure5. What does DNA stand for?

6. In what area of a eukaryotic cell is it found?

In eukaryotes DNA is found in the nucleus.

Deoxyribonucleic acid

Some examples of eukaryotes are people, cats, mice, birds, lizards, frogs, trees, flowers, bees, spiders, molds, yeast, and paramecia.

7. In what area of a prokaryotic cell is it found?

Because prokaryotes do not have a nucleus, DNA is found floating free in the cytoplasm.

Bacteria are prokaryotes

DNA Structure8. How does DNA differ between eukaryotes (like people) and prokaryotes (like bacteria)?

a. Prokaryotes have much less DNA than do eukaryotes.

b. Prokaryotes have only one chromosome, which is circular. Eukaryotes have multiple chromosomes, which are rod-shaped.

DNA Structure8. How does DNA differ between eukaryotes (like people) and prokaryotes (like bacteria)?

c. In eukaryotes strands of DNA are wrapped around packaging molecules called histones, forming bead-like structures called nucleosomes.

Prokaryotes do not use packaging molecules, so their DNA is referred to as ‘naked DNA.’

DNA Structure9. How is DNA the same in eukaryotes (like people) and prokaryotes (like bacteria)?

a. The DNA in both prokaryotes and eukaryotes is made of exactly the same components.

b. The DNA in both prokaryotes and eukaryotes has the same double helix shape.

DNA Structure10. List the four nitrogenous bases that make up DNA.

Adenine

Thymine

Guanine

Cytosine

DNA Structure11. State the base-pairing rule.

Adenine always pairs with Thymine

Cytosine always pairs with Guanine

DNA Structure

A nucleotide

12. Using the components of DNA shown below, draw a cytosine nucleotide.

DNA Structure13. Redraw the six nucleotides below to form a DNA molecule.

Notice how one strand has to be upside down.

DNA Structure14. Identify the types of bonds between the molecules.

A.

C.

B.

DNA Structure

Hydrogen bond

Covalent bond

Phosphodiester bond

14. Identify the types of bonds between the molecules.

DNA Structure15. Increasing temperatures will cause DNA to vibrate placing stress on its chemical bonds. Which bond type shown below would be the first to break?

Hydrogen bonds would break first because the forces of attraction are much weaker than those of covalent bonds.

Covalent bond

Hydrogen bond

DNA Structure16. What term describes the fact that one strand in DNA runs one way while the other strand runs in reverse?

Antiparallel

DNA Structure17. What term describes the shape of DNA?

Double Helix