6. In two or three sentences, describe how scientists identified these genes. 7. Why do you think it is important to analyze the DNA of many dogs when doing this research? 8. Humans have SNPs too. In general, how might GWAS studies with dogs benefit humans?

Biology: The Unity and Diversity of Life (MindTap Course List)
14th Edition
ISBN:9781305073951
Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr
Publisher:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr
Chapter15: Studying And Manipulating Genomes
Section: Chapter Questions
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Associated SNPs
outside of gene
no effect on protein
production or function
T
G
Associated SNPs
within gene
no effect on protein.
production or function
Regulatory sequences
A
Coding region
C
T
www.Biolnteractive.org
Noncoding SNP:
changes amount of
protein produced
Unassociated SNP
far from gene
Causative SNPs
within gene
on same chromosome
or different chromosome
Protein
Coding SNP:
changes amino
acid sequence
Figure 3. A diagram
showing various ways.
in which a SNP could be
associated with a
certain gene and its
trait.
GWAS in the News
Read the following news release, which describes a GWAS study with dogs. Note that a dog's coat refers to its
fur or hair.
Variants in Three Genes Account for Most Dog Coat Differences
Variants in just three genes acting in different combinations account for the wide range of coat textures seen in
dogs from the poodle's tight curls to the beagle's stick-straight fur. A team led by researchers from the
National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, reports these
findings today in the advance online issue of the journal Science.
"This study is an elegant example of using genomic techniques to unravel the genetic basis of biological
diversity," said NHGRI Scientific Director Eric Green, M.D., Ph.D. "Genomics continues to gain new insights from
the amazing morphological differences seen across the canine species, including many that give clues about
human biology and disease."
Until now, relatively little was known about the genes influencing the length, growth pattern and texture of the
coats of dogs. The researchers performed a genome-wide scan of specific signposts of DNA variation, called
single nucleotide polymorphisms, in 1,000 individual dogs representing 80 breeds. These data were compared
with descriptions of various coat types. Three distinct genetic variants emerged to explain, in combination,
virtually all dog hair types.
"What's important for human health is the way we found the genes involved in dog coats and figured out how
they work together, rather than the genes themselves," said Elaine A. Ostrander, Ph.D., chief of the Cancer
Genetics Branch in NHGRI's Division of Intramural Research. "We think this approach will help pinpoint multiple
genes involved in complex human conditions, such as cancer, heart disease, diabetes and obesity."
Updated November 2020
Page 3 of 7
Activity
Student Handout
hhmi Biolnteractive
Mapping Genes to Traits in Dogs Using SNPs
Artificial selection, at the heart of breeding for desirable traits in domesticated animals, has
yielded rapid change in a short span of canine history. While researchers estimate that modern dog breeds
diverged from wolves some 15,000 years ago, the genetic changes in the dog genome that create multiple coat
types are more likely to have been pursued by breeders in just the past 200 years. In fact, short-haired breeds,
such as the beagle, display the original, more wolf-like versions of the three genes identified in the study.
Modern dog breeds are part of a unique population structure, having been selectively bred for many years.
Based on this structure, the researchers were able to break down a complex phenotype-coat - into possible
genetic variations. "When we put these genetic variants back together in different combinations, we found that
we could create most of the coat varieties seen in what is among the most diverse species in the world the
dog," Dr. Ostrander said. "If we can decipher the genetic basis for a complex trait such as the dog's coat, we
believe that we can do it as well with complex diseases."
-Excerpt from a National Institutes of Health (NIH) News Release published August 27, 2009
Answer the following questions to check your understanding of the reading.
Transcribed Image Text:Associated SNPs outside of gene no effect on protein production or function T G Associated SNPs within gene no effect on protein. production or function Regulatory sequences A Coding region C T www.Biolnteractive.org Noncoding SNP: changes amount of protein produced Unassociated SNP far from gene Causative SNPs within gene on same chromosome or different chromosome Protein Coding SNP: changes amino acid sequence Figure 3. A diagram showing various ways. in which a SNP could be associated with a certain gene and its trait. GWAS in the News Read the following news release, which describes a GWAS study with dogs. Note that a dog's coat refers to its fur or hair. Variants in Three Genes Account for Most Dog Coat Differences Variants in just three genes acting in different combinations account for the wide range of coat textures seen in dogs from the poodle's tight curls to the beagle's stick-straight fur. A team led by researchers from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, reports these findings today in the advance online issue of the journal Science. "This study is an elegant example of using genomic techniques to unravel the genetic basis of biological diversity," said NHGRI Scientific Director Eric Green, M.D., Ph.D. "Genomics continues to gain new insights from the amazing morphological differences seen across the canine species, including many that give clues about human biology and disease." Until now, relatively little was known about the genes influencing the length, growth pattern and texture of the coats of dogs. The researchers performed a genome-wide scan of specific signposts of DNA variation, called single nucleotide polymorphisms, in 1,000 individual dogs representing 80 breeds. These data were compared with descriptions of various coat types. Three distinct genetic variants emerged to explain, in combination, virtually all dog hair types. "What's important for human health is the way we found the genes involved in dog coats and figured out how they work together, rather than the genes themselves," said Elaine A. Ostrander, Ph.D., chief of the Cancer Genetics Branch in NHGRI's Division of Intramural Research. "We think this approach will help pinpoint multiple genes involved in complex human conditions, such as cancer, heart disease, diabetes and obesity." Updated November 2020 Page 3 of 7 Activity Student Handout hhmi Biolnteractive Mapping Genes to Traits in Dogs Using SNPs Artificial selection, at the heart of breeding for desirable traits in domesticated animals, has yielded rapid change in a short span of canine history. While researchers estimate that modern dog breeds diverged from wolves some 15,000 years ago, the genetic changes in the dog genome that create multiple coat types are more likely to have been pursued by breeders in just the past 200 years. In fact, short-haired breeds, such as the beagle, display the original, more wolf-like versions of the three genes identified in the study. Modern dog breeds are part of a unique population structure, having been selectively bred for many years. Based on this structure, the researchers were able to break down a complex phenotype-coat - into possible genetic variations. "When we put these genetic variants back together in different combinations, we found that we could create most of the coat varieties seen in what is among the most diverse species in the world the dog," Dr. Ostrander said. "If we can decipher the genetic basis for a complex trait such as the dog's coat, we believe that we can do it as well with complex diseases." -Excerpt from a National Institutes of Health (NIH) News Release published August 27, 2009 Answer the following questions to check your understanding of the reading.
6. In two or three sentences, describe how scientists identified these genes.
7. Why do you think it is important to analyze the DNA of many dogs when doing this research?
8. Humans have SNPs too. In general, how might GWAS studies with dogs benefit humans?
PART 2: Applying GWAS to Dog Fur Color
Let's explore how a GWAS works using a simple example that compares two groups of dogs: dogs with black fur
and dogs with white fur. Table 1 shows the dogs' SNP alleles at 17 specific locations in the genome. These
specific locations in the genome are called loci (singular: locus). The SNP alleles at each locus are represented by
two nucleotides, one from each parental chromosome.
Table 1. SNP alleles at 17 different loci in dogs with black fur (first four rows) and dogs with white fur (last four rows).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
CC AT CC GG AA TC TT CC GG AA TT GT AG AA CC GG AT
4
*
A
5:3
333
569
CC AT AC GG GG TT TT CC GG AG TT GG AG AG CC GG AT
CC AA AC CG GG TT TT CT GG AA TT GT AG AG CC TT AT
CC AA AC GG AG TT TT CT GG GG TT GG AG AG CC GT AT
CC AT CC CG|AA|TT|AA|CT|GG|AA|TT|GT|AA|AA|CC|GT AT
CC AT CC GG AATTAA TC|GG|AA|TT|GG|AG AA CC GG TT
CC AT CC GG AA TT AA CC GG AA TT GG AA AA CC GT AT
CC AA CC GG AG TT AA TC|GG|GG|TT|GG|AA|AA|CC|TT| AT
If a SNP is found much more frequently in dogs with white fur than in dogs with black fur, the SNP is associated
with the white fur color.
9. Give two possible reasons for why a SNP would be associated with a trait like fur color.
To determine whether any of the SNPs in Table 1 are associated with fur color, you can compare the SNPs of the
dogs with black fur to those of the dogs with white fur. A SNP is completely associated with fur color if all
dogs with white fur share the same alleles at that position, and all dogs with black fur share different alleles
at that position. A SNP that is completely associated with a trait is likely located within or close to a gene
responsible for that trait.
10. Which SNP in Table 1 do you think is completely associated with fur color? Explain the reasoning for your
choice.
A SNP is completely unassociated with fur color if its alleles occur with equal frequency in dogs with black fur
and dogs with white fur. A SNP that is completely unassociated with a trait is unlikely to be located within or
near the gene responsible for that trait.
11. Which SNPs in Table 1 do you think are completely unassociated with fur color? Explain the reasoning for
your choices. (Hint: There are five in total.)
The other SNPs in Table 1 have varying strengths of association with fur color. You'll learn more about how to
evaluate the strength of an association in the next part of this activity. For the question below, make your best
guess based on what you've learned so far.
12. Which SNP in Table 1 do you think has the next strongest association with fur color, after the completely
associated SNP you identified in Question 10? Explain the reasoning for your choice.
Transcribed Image Text:6. In two or three sentences, describe how scientists identified these genes. 7. Why do you think it is important to analyze the DNA of many dogs when doing this research? 8. Humans have SNPs too. In general, how might GWAS studies with dogs benefit humans? PART 2: Applying GWAS to Dog Fur Color Let's explore how a GWAS works using a simple example that compares two groups of dogs: dogs with black fur and dogs with white fur. Table 1 shows the dogs' SNP alleles at 17 specific locations in the genome. These specific locations in the genome are called loci (singular: locus). The SNP alleles at each locus are represented by two nucleotides, one from each parental chromosome. Table 1. SNP alleles at 17 different loci in dogs with black fur (first four rows) and dogs with white fur (last four rows). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 CC AT CC GG AA TC TT CC GG AA TT GT AG AA CC GG AT 4 * A 5:3 333 569 CC AT AC GG GG TT TT CC GG AG TT GG AG AG CC GG AT CC AA AC CG GG TT TT CT GG AA TT GT AG AG CC TT AT CC AA AC GG AG TT TT CT GG GG TT GG AG AG CC GT AT CC AT CC CG|AA|TT|AA|CT|GG|AA|TT|GT|AA|AA|CC|GT AT CC AT CC GG AATTAA TC|GG|AA|TT|GG|AG AA CC GG TT CC AT CC GG AA TT AA CC GG AA TT GG AA AA CC GT AT CC AA CC GG AG TT AA TC|GG|GG|TT|GG|AA|AA|CC|TT| AT If a SNP is found much more frequently in dogs with white fur than in dogs with black fur, the SNP is associated with the white fur color. 9. Give two possible reasons for why a SNP would be associated with a trait like fur color. To determine whether any of the SNPs in Table 1 are associated with fur color, you can compare the SNPs of the dogs with black fur to those of the dogs with white fur. A SNP is completely associated with fur color if all dogs with white fur share the same alleles at that position, and all dogs with black fur share different alleles at that position. A SNP that is completely associated with a trait is likely located within or close to a gene responsible for that trait. 10. Which SNP in Table 1 do you think is completely associated with fur color? Explain the reasoning for your choice. A SNP is completely unassociated with fur color if its alleles occur with equal frequency in dogs with black fur and dogs with white fur. A SNP that is completely unassociated with a trait is unlikely to be located within or near the gene responsible for that trait. 11. Which SNPs in Table 1 do you think are completely unassociated with fur color? Explain the reasoning for your choices. (Hint: There are five in total.) The other SNPs in Table 1 have varying strengths of association with fur color. You'll learn more about how to evaluate the strength of an association in the next part of this activity. For the question below, make your best guess based on what you've learned so far. 12. Which SNP in Table 1 do you think has the next strongest association with fur color, after the completely associated SNP you identified in Question 10? Explain the reasoning for your choice.
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