Exam #2 (Chapter 9)

Question 1

What is genetics?

Answer 1

The study of heredity

Involves the transmission of biological traits from parent to offspring, expression and variation of those traits, and the structure and function of genetic material.

Question 2

Define genome.

Answer 2

Total of genetic material

Question 3

What is a chromosome?

Answer 3

DNA tightly packaged using proteins

Question 4

Describe the eukaryotic genome.

Answer 4

In nucleus, multiple, linear chromosomes (single or paired)

Includes mitochondria with circular, single or multiple chromosomes and chloroplasts with circular, single chromosome.

Question 5

What is the typical prokaryotic genome structure?

Answer 5

Most have a single, circular chromosome; some have multiple or linear chromosomes

Also includes plasmids, which are small, circular, usually multiple, and contain non-essential genes.

Question 6

What types of genetic material do viruses contain?

Answer 6

DNA or RNA (sometimes both), single or double-stranded

Question 7

What are the three basic categories of genes?

Answer 7

• Genes that code for proteins (structural genes)
• Genes that code for RNA
• Genes that control gene expression (regulatory genes)

Question 8

What is the genotype?

Answer 8

The genetic makeup of an organism

Question 9

What is the phenotype?

Answer 9

The observable traits of an organism

Question 10

What is the smallest known virus size in terms of genes?

Answer 10

4-5 genes

Question 11

How many genes does E. coli have?

Answer 11

4,288 genes

Question 12

What is the basic unit of DNA structure?

Answer 12

Nucleotide

Question 13

What are the components of a nucleotide?

Answer 13

• A deoxyribose sugar
• A phosphate group
• A nitrogenous base (adenine, guanine, thymine, cytosine)

Question 14

What type of bonds connect adenine and thymine?

Answer 14

2 hydrogen bonds

Question 15

What type of bonds connect guanine and cytosine?

Answer 15

3 hydrogen bonds

Question 16

Describe the structure of DNA.

Answer 16

Double-stranded helix, antiparallel strands

Question 17

What is the role of DNA gyrase in prokaryotes?

Answer 17

Coils the chromosome into a tight bundle

Question 18

What is chromatin?

Answer 18

Loosely coiled, nondividing cells

Question 19

What is the significance of DNA structure?

Answer 19

• Maintenance of code during reproduction
• Providing variety in RNA and protein synthesis

Question 20

What is the process of DNA replication?

Answer 20

Semiconservative process where each strand serves as a template for new strand synthesis

Question 21

What is transcription?

Answer 21

The process of passing genetic information from DNA to RNA

Question 22

What is translation?

Answer 22

The process of using RNA to produce proteins

Question 23

What is a codon?

Answer 23

A group of three consecutive bases on DNA that codes for a specific amino acid

Question 24

What is the role of messenger RNA (mRNA)?

Answer 24

Carries DNA code to ribosome in RNA form

Question 25

What is the role of transfer RNA (tRNA)?

Answer 25

Carries amino acids to ribosome during translation

Question 26

What is ribosomal RNA (rRNA)?

Answer 26

Structural component of ribosomes

Question 27

What are the stages of gene expression?

Answer 27

* Transcription (DNA to mRNA) * Translation (mRNA to protein)

Question 28

What initiates transcription?

Answer 28

RNA polymerase binds to the promoter region

Question 29

What happens during the elongation stage of transcription?

Answer 29

RNA polymerase reads the DNA template and adds nucleotides complementary to the DNA template strand

Question 30

What is a polyribosome?

Answer 30

A mass of ribosomes that simultaneously translate multiple copies of mRNA

Question 31

What are operons?

Answer 31

Regulatory units in prokaryotes that control gene expression

Question 32

What is an inducible operon?

Answer 32

Operon that is turned ON by substrate (default is off)

Question 33

What is a repressible operon?

Answer 33

Operon that is turned OFF by the product synthesized (default is on)