Chapter 11

Question 1

What is the key criteria for genetic material?

Answer 1

1. Information - must contain information necessary to construct entire organism
2. Replication - must be accurately copied in a process known as replication
3. Transmission - genetic material is passed from parent to offspring and in the case of cell division, cell to cell, after replication
4. Variation - Differences in genetic material are responsible in variation between species

Question 2

What is a chromosome?

Answer 2

A discrete unit of genetic material composed of DNA and associated proteins. Eukaryotes have chromosomes in their cell nuclei and in plastids and mitochondria.

Question 3

What does transformation mean in regards to genetic material?

Answer 3

A type of gene transfer between bacteria in which a segment of DNA from the environment is taken up by a competent cell and incorporated into the bacterial chromosome.

Question 4

What is genetic material?

Answer 4

DNA

Question 5

What are nucleic acids?

Answer 5

An organic macromolecule composed of nucleotides. The two types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Question 6

What is a nucleotide?

Answer 6

An organic molecule having three components: one or more phosphate groups, a five-carbon sugar (either deoxyribose or ribose), and a single or double ring of carbon and nitrogen atoms known as a base.

Question 7

What is a strand of a nucleic acid?

Answer 7

A structure of DNA (or RNA) formed by the covalent linkage of nucleotides in a linear manner.

Question 8

What does the double helix shape refer to?

Answer 8

Two strands of DNA hydrogen-bonded with each other. In a DNA double helix, two DNA strands are twisted together to form a structure that resembles a spiral staircase.

Question 9

What are the purines?

Answer 9

Either of the bases adenine (A) and guanine (G), which have a fused double ring of carbon and nitrogen atoms

Question 10

What are the pyrimidines?

Answer 10

Any of the bases thymine (T), cytosine (C), and uracil (U), which have a single ring of carbon and nitrogen atoms

Question 11

What is a phosphodiester linkage?

Answer 11

Refers to a double linkage (two phosphoester bonds) that holds together adjacent nucleotides in DNA and RNA strands. Bond is between the sugar of one nucleotide and the phosphate group of other nucleotide.

Question 12

What does directionality mean in regards to nucleic acids?

Answer 12

In a DNA or RNA strand, refers to the orientation of the sugar molecules within that strand. Can be 5′ to 3′ (top to bottom) or 3′ to 5′.

Question 13

What are the levels of DNA structure?

Answer 13

• Nucleotides
• Strand
• Double helix DNA
• Gene
• Chromosomes
• Genome

Question 14

What is a base pair?

Answer 14

The structure in which two bases in opposite strands of DNA are held together by hydrogen bonding to each other.

Question 15

What does antiparallel mean?

Answer 15

The arrangement in DNA where one strand runs in the 5´ to 3´ direction and the other strand is oriented in the 3´ to 5´ direction.

Question 16

What is the major groove?

Answer 16

A wider groove that spirals around the DNA double helix; provides a location where a protein can bind to a particular sequence of bases and affect the expression of a gene.

Question 17

What is the semiconservative mechanism?

Answer 17

The correct model for DNA replication; double-stranded DNA is half conserved following replication, resulting in new double-stranded DNA containing one parental strand and one daughter strand.

Question 18

What does bidirectional replication mean?

Answer 18

The process in which DNA replication proceeds outward from the origin in opposite directions.

Question 19

What is a replication fork?

Answer 19

The area where two DNA strands have separated and new strands are being synthesized.

Question 20

What is the leading strand?

Answer 20

During DNA replication, a DNA strand made in the same direction that the replication fork is moving. The strand is synthesized as one long continuous molecule.

Question 21

What is the lagging strand?

Answer 21

During DNA replication, a DNA strand made as a series of small Okazaki fragments that are subsequently connected to each other to form a continuous strand.

Question 22

What are Okazaki fragments?

Answer 22

Short segments of DNA synthesized in the lagging strand during DNA replication.

Question 23

What does proof reading mean in reference to DNA replication?

Answer 23

The ability of DNA polymerase to identify a mismatched nucleotide and remove it from the daughter strand.

Question 24

What is a telomere?

Answer 24

A region at the ends of eukaryotic chromosomes where a specialized form of DNA replication occurs.