Page 153 - Science Course 3 (Book 1)

Mo4-L3: Key Concept Organizer

Direction: On the line before each statement, write T if the statement is true or F if the statement is false

1. Genetic information is encoded in a molecule called DNA.

2. This molecule is shaped like a twisted ladder, a shape that is called a triple helix.

3. James Watson and Francis Crick discovered the structure of this molecule after studying
gamma-ray images of the molecule.

4. The sides of the ladder are made from joined molecules called bases.

5. The combination of a nitrogen base, a sugar, and a phosphate group is a unit called a gene.

6. The base guanine always joins with the base cytosine.

7. An organism’s genes are located in cell structures called chromosomes.

8. The process by which the molecule of heredity makes copies of itself is called transcription.

9. Most genes encode information for the production of proteins.

Direction: Answer the question on the lines provided.

10. How does DNA replicate itself?

Mo4-L3: Key Concept Check

Direction: Answer each question on the lines provided.

1. How many human chromosomes are there?

2. Approximately how many human genes are there?

3. What is a mutation?

4. Which four causes of mutations are discussed in the lesson?

145