3A: DNA & Genes

3A

DNA & GENES

The Need for Information

• Cells need information in order to live, grow, and reproduce.

• DNA is a kind of nucleic acid that stores the information needed to make all of the complex cellular machinery.

• A DNA molecule looks like a twisted ladder.

Multiple Choice

The shape of a DNA molecule can be described as a ________.

• loop-de-loop

• sea star

• trapeze swing

• twisted ladder

Nucleotides

The sides of the ladder are made of phosphates and a sugar known as deoxyribose.

The smaller subunits are called nucleotides. Each nucleotide consists of a sugar, a phosphate, and a base.

Multiple Select

Each nucleotide is made up of three parts: a sugar, a phosphate, and a base. True or false?

• True

• False

The bases come in pairs:

• Guanine is always paired with cytosine.

• Adenine is always paired with thymine. 

Multiple Choice

In DNA molecule, adenine always pairs with _________.

• cystosine

• guanine

• thymine

• uracil

Gene

• a section of a DNA molecule that codes for a unique protein/trait.

Multiple Select

A chromosome is a section of DNA that codes for a unique protein. True or false?

• True

• False

The Hidden Meaning of DNA

• Different nucleotides are arranged in differing orders to convey the information that cells need to build proteins.

• Which protein gets built depends on which nucleotides are present in the gene and what order they’re in.

Multiple Select

Changing the order of the nucleotides in DNA leaves the protein that is built unaffected as long as the same nucleotides are present. True or false?

• True

• False