ANSWERS TO REVIEW QUESTIONSCHAPTER 22

  1. A genome is all the genetic information of a cell or organism. The human genome consists of 22 pairs of autosomes and one pair of sex chromosomes. The exome is only the DNA sequences that encode protein.
  1. Helped assign genes to specific chromosomes
  1. Cytogenetic maps associate genes with chromosomes or chromosome bands. Linkage maps use recombination frequencies to order genes by relative distances. Physical maps use overlapping DNA sequences to give the physical location of genes. Sequence maps depict the sequence of nucleotides. New types of maps depict gene expression and methylation patterns, protein folding, gene interactions, and SNP distributions.
  1. Positional cloning narrowed down known markers shared by people with the same inherited disease.
  1. Concerns over cost, allocation of scarce research funding, potential benefits and issues of privacy and genetic discrimination.
  1. Pieces must be overlapped to derive the sequence; so several genome copies must be used.
  1. Graphene is a nanomaterial with tiny holes that each of the four DNA bases interacts with differently when passing through.
  1. The bacterium with the synthetic genome can be regarded as creating life because the genome is the instructions for life. However, it is really just synthesizing a very long molecule and putting it into an existing cell.
  1. Less DNA encodes protein than we thought, but more DNA is transcribed than accounts for the proteins, indicating that control DNA sequences are transcribed.
  1. Conserved sequences represent genes selectively retained through evolution.
  1. The minimum gene set required for life, fundamental distinctions among the three domains of life, the basic blueprint of an animal and what makes humans unique.
  1. Genome information can be used for decisions related to health care or future activities.
  1. They were already aware of most based on family history and personal experience. The variants are recessive and they are heterozygotes.

ANSWERS TO APPLIED QUESTIONS

  1. The genome sequence has turned out to be not as interesting, according to many people, as the points in the genome at which people vary. Also, people differ in copy number variants as well as sequence differences.
  1. The human genome project included an ethical, legal, and social implications component, which raises issues that are important in testing for even a single gene. This is because the information is private yet can affect other individuals (family members).
  1. The genome of a species that has recently become extinct might identify a harmful environmental condition.

4. G C T T C G T T A A T A T C G C T A G C T G C A

5. Personal genome sequencing is likely to identify mutations, mostly recessive, that are not obvious in an individual’s family history, and so come as a surprise.

6. I would like to know about cancer mutations. I would not want to know about mutations for neurodegenerative diseases that do not have treatments. A genetic test to identify people who taste bitter substances or eye color is useless because the phenotype is obvious.

7. The first gene is more ancient than the second.

8. Comparative genomics reveals evolutionary relatedness, and may identify useful model organisms. For example, a sea squirt’s primitive kidney is used to test new drugs.

9. Personal genome sequencing can reveal harmless mutations (because they are recessive), disease susceptibilities such as mutations in tumor suppressor genes, and ancestry information.

10. Certain health conditions in an adopted individual that are not in adoptive siblings might have high heritability.

11. Sequence the gene in the parents. If the fetus is a compound heterozygote, each parent will carry one of the genes (different genes). Alternatively, one parent may have both mutations on one chromosome and be a double carrier, with no associated mutant phenotype.

12. The human microbiome includes DNA from many species.

13. A pedigree is still essential to determine the likelihood that certain mutations or traits will occur in certain individuals, and is useful in identifying new mutations.

14. new mutations

15. 1/8

ANSWERS TO WEB ACTIVITIES

1. Paleomics studies extinct species.

2. I would not participate. Knowing some gene variants could suggest medical tests that can be used to catch a disease early enough to treat. On the other hand, knowing about certain mutations might cause undo anxiety because for most traits, penetrance is not complete.

3. Psychological impact and stigma: learning that you have a high risk of developing a certain disease, or that your child-to-be has inherited an illness.

4. Bacillus anthracis(anthrax;)Campylobacter jejuni (foodborne dysentery), Clostridium perfringens(food poisoning),Klebsiella pneumoniae (lung disease), Yersinia pestis(plague).

5. Sequencing on an individual’s genome to the point that 99% of gene variants are identified.

6. 1,094 genomes had been done by late summer 2011.

ANSWERS TO FORENSICS FOCUS

1. Using any of the types of genetic information in forensic profiles would minimize the problem of falsely accusing relatives of criminals who share some of their DNA sequences. More SNPs would be easy to do and meaningful.

2. Forensic scientists have in the past analyzed stomach contents to deduce clues about a dead person’s last meal. Adding gut microbiome sequences could provide additional clues to how and where the person lived. The microbiome tends to stay fairly constant over time, so it could be used to help distinguish people. In fact, collectively the microbiome provides more information (more DNA bases) to consider than individual human genome sequences.

CASE STUDIES AND RESEARCH RESULTS

1. a.AAGCTAAT and TAGCTACT

b.4 and 8

c.1

d.1 due to variability

e.Fish #3

2. Homozygous loci would not have to be compared, minimizing the sequencing necessary to distinguish the two genomes.

3.Imputation prevents duplication of effort in sequencing DNA or identifying SNPs.

4. a. Six copies of her genome were cut up. Then the pieces were overlapped where the sequences coincided, to derive the overall sequence.

b. The future is grim in a geographical sense because the habitat has shrunk, but promising in that the genomes are diverse.

c. We are more closely related to the apes.

d. Orangutans can serve as animal models for some neurodegenerative diseases.