Comprehension Questions

Section 20.1

Question 20.1

What is the difference between a genetic map and a physical map? Which generally has higher resolution and accuracy and why?

Question 20.2

What is the difference between a map-based approach to sequencing a whole genome and a whole-genome shotgun approach?

Question 20.3

What are some of the ethical concerns arising out of the information produced by the Human Genome Project?

Question 20.4

What is a single-nucleotide polymorphism (SNP)? How are SNPs used in genomic studies?

Question 20.5

What is a haplotype? How do different haplotypes arise?

Question 20.6

What is linkage disequilibrium? How does it result in haplotypes?

Question 20.7

How is a genome-wide association study carried out?

Question 20.8

What is copy-number variation? How does it arise?

Question 20.9

(a) What is an expressed-sequence tag (EST)? (b) How are ESTs created? (c) How are ESTs used in genomics studies?

Question 20.10

How are genes recognized within genomic sequences?

Section 20.2

Question 20.11

What are homologous sequences? What is the difference between orthologs and paralogs?

Question 20.12

Describe several different methods for inferring the function of a gene by examining its DNA sequence.

Question 20.13

What is a microarray? How can it be used to obtain information about gene function?

Question 20.14

Explain how a reporter sequence can be used to provide information about the expression pattern of a gene.

Question 20.15

Briefly outline how a mutagenesis screen is carried out.

Section 20.3

Question 20.16

What is the relation between genome size and gene number in prokaryotes?

Question 20.17

What is horizontal gene transfer? How might it take place between different species of bacteria?

Question 20.18

DNA content varies considerably among different multicellular organisms. Is this variation closely related to the number of genes and the complexity of the organism? If not, what accounts for some of these differences?

Question 20.19

More than half of the genome of Arabidopsis thaliana consists of duplicated sequences. What mechanisms are thought to have been responsible for these extensive duplications?

Question 20.20

What is a segmental duplication?

Question 20.21

The human genome does not encode substantially more protein domains than do invertebrate genomes, yet it encodes many more proteins. How are more proteins encoded when the number of domains does not differ substantially?

Question 20.22

(a) What is genomics and how does structural genomics differ from functional genomics? (b) What is comparative genomics?

Section 20.4

Question 20.23

How does proteomics differ from genomics?

Question 20.24

How is mass spectrometry used to identify proteins in a cell?

For more questions that test your comprehension of the key chapter concepts, go to for this chapter.