BIOL 1408, Smartbook Chapter 7: DNA Structure

Select all of the bases that can be present in DNA nucleotides.

thymine; adenine; cytosine; guanine

What role does DNA play in the cell?

store instructions for making proteins

The DNA double helix is made up of two strands of ______ monomers oriented in opposite directions.

nucleotide

Subunits called ______ are the building blocks of DNA.

nucleotides

The instructions in ______ encode the information that a cell needs to produce proteins, which are vital to living things.

DNA

Two strands of DNA within the double helix are said to be complementary to each other because ______ on one strand always pairs with thymine on the opposite strand, and cytosine on one strand always pairs with ______ on the opposite strand.

Blank 1: adenine or A, or a; Blank 2: guanine, G, or g;

The human genome contains about 20,000-25,000 ______ scattered on its 23 pairs of ______.

Blank 1: genes or gene; Blank 2: chromosomes

The DNA double helix resembles a twisted ladder, where the rails of the "ladder" (also called the "backbones") are composed of alternating deoxyribose sugars and ______ groups joined by covalent bonds, while the rungs of the ladder are composed of A-T and G-C base pairs joined by ______ bonds.

Blank 1: phosphate, phosphate group, a phosphate group, or phosphorous; Blank 2: hydrogen

In the 1950s, the biochemist Erwin Chargaff found that in DNA, the amount of the nucleotide base adenine always equals the amount of the nucleotide base ______ , and the amount of the nucleotide base cytosine always equals the amount of the nucleotide base ______.

Blank 1: thymine or T; Blank 2: guanine or G

In the 1950s, the biochemist Erwin Chargaff found that in DNA, the amount of the nucleotide base adenine always equals the amount of the nucleotide base ______, and the amount of the nucleotide base cytosine always equals the amount of the nucleotide base ______.

Blank 1: thymine or T; Blank 2: guanine or G

True or false: Complementary base pairing rules state that in DNA, A pairs with G and T pairs with C.

False

In 1953, James Watson and ______ built a ball-and-stick model of the DNA double helix using two lines of evidence to deduce the structure.

Francis Crick

Select all of the following that are true with respect to genomes.

In prokaryotic cells, the genome usually consists of just one circular DNA molecule; In eukaryotic cells, the genome is usually divided up into multiple chromosomes.

What contains about 6.4 billion base pairs and about 20,000 genes?

The human genome

The ______ pattern generated by Wilkins and Franklin revealed that DNA was comprised of a regular repeating structure of building blocks.

X-ray diffraction

Select all of the following that are true about chromosomes.

can be tightly coiled; contain DNA with no known function; contain DNA and proteins

DNA is coiled around proteins to form discrete packages called ______.

chromosomes

Within the DNA double helix, the so-called backbone is composed of ______ sugars alternating with phosphate groups.

deoxyribose

A DNA molecule consists of two intertwining strands of nucleotides that form a ______.

double helix.

A(n) ______ is a sequence of DNA nucleotides that codes for a specific protein or RNA molecule.

gene

All of the genetic material that is within a cell is called its ______.

genome