Tower: The Human Genome
Activities related to several aspects of human genetics are found on levels 7 - 11 of the Tower. The Genome is introduced by a Gallery of Human Chromosomes. The difference between inheritance of nuclear and mitochondrial genes is illustrated, and human pedigrees are presented for analysis. There is a link to the report on the sequencing Craig Venter's genome. Experiments with the inheritance of human blood types and eye color are found in this section. Variations in human karyotypes are also included. The importance of genomic organization is illustrated by comparisons between the karyotypes of humans and those of several other species.
The Chromosome Cafe:
Level 7 of the Tower contains models of all 24 human nuclear chromosomes. The models are scaled according to the number of nucleotides in each chromosome. Clicking on each of the chromosomes produces the number of nucleotides and number of genes on the chromosome, and also offers a notecard with information about one or more specific genes on the chromosome. The position of the gene on the chromosome is indicated by an arrow.
The mitochondrial genome is also represented, although not to the same scale.
An informational sign, "The Human Genome," gives a notecard with general information about features of the human genome.
Patterns and Pedigrees: Level 8 of the Tower contains several activities about inheritance in humans.
Grandma's Chromosomes is an activity that traces the fate of a set of chromosomes over 6 generations. The difference between the inhertance of nuclear and mitochondrial chromosomes is included.
The Pedigree Analysis activity presents a selection of 10 numbered human pedigrees. Visitors can browse through the pedigrees and try to identify the inherited trait as dominant or recessive, and whether the trait is on one of the sex determining chromosomes or not.
One Man's Chromosomes is a link out to a Science Friday interview with Craig Venter, whose genome was fully sequenced in 2007. A nearby sign offers a landmark for the Science Friday island.
A Teleport Panel, which links to other sites on Genome Island, is located in this room.
Human Karyotypes: On level 9 of the Tower are a group of microscopes displaying human karyotypes.
The normal male and female karyotype is displayed when one of the microscopes is clicked.
Karyotype Variants are displayed by three other microscopes. Students can compare these with the normal karyotypes to identify which chromosomes might be missing or represented by an extra copy.
An informational sign, "Variations in Human Karyotypes," explains how karyotype variants arise and describes some of the more common viable variants.
Comparative Genomics: Level 10 of the Tower contains several posters that compare the organization of the human karyotype with that of several other species. On each, the syntenic regions (chromosome segments with the same genes) are color coded to compare the locations of specific chromosome segments.
Humans vs. Chimpanzees: comparison of the chromosome banding patterns in these two primates shows the importance of chromosomal rearrangements to differences between species.
Humans vs. Macaques: compare the human/macaque differences with those of human/chimp. The location of breaks between syntenic regions are also marked on this poster.
Humans vs Mouse: Each mouse chromosome is "painted" with reference colors representing human chromosome regions.
Mouse vs Rat: the malleability of the rodent genome is probably related to the large number of rodent species.
Teleports on Level 7: This room links to several other parts of Genome Island and to the neighboring island, Biome.
The Eukaryotic Boardwalk: representative genomes of other eukaryotes.
The Bioinformatics Kitchen: bioinformatics activities on the platform adjacent to the tower.
The Animal Diversity section of the Tree of Life on Biome. Biome contains activities related to biodiversith and ecology.
Human Genetic Variants: On level 8 are several activites related to the inheritance of specific human traits.
Human Genetic Variants:
This activity offers a spreadsheet describing several inheritable traits in humans. Visitors can survey themeselves, or their friends and families for possession of these traits.
Human ABO Blood Groups:
This activity includes an informational sign, four pedigrees with mothers of different blood types, and slides representing the blood types of the progeny of each mothers. The informational notecard explains the inheritance of human ABO blood groups. The A and B types are both dominant to the type O. However, neither is dominant to the other, so individuals with both A and B alleles are type AB.
Cards representing mothers with blood types A, B, AB or O produce blood samples for three children of that mother. The blood type of the father is not given.
Visitors can perform blood typing to identify the blood types of the children and then suggest possible blood types for the father of the children.
This activity is also linked to a web simulation for matching blood transfusion donors and recipients.
Human Eye Color:
The inheritance of human eye color is complex, and involves at least 16 different genes. A simplified three-gene model is explained in an informational notecard and slide show about the inheritance of blue, gray, green, hazel or brown eyes. Four different human matings are represented in the activity. The eye colors of the parents are displayed. Clicking on one of the crosses produces the eye colors of the progeny. Visitors can then suggest the genotypes of the parents.
Mutant Genes and Mutant Proteins:
Human beta globins are used as the model to illustrate the relationship between changes in DNA and changes in amino acid sequence. Although a few beta globin variants, like the one that results in sickle cell disease, are well known, many others have been reported. Indeed there are single amino acid replacements known at 130 of the amino acid positions in this 146 amino acid polypeptide. Ten of these variants are described. In the activity, the original DNA codon producing the "consensus" amino acid at a given position is identified and visitors are asked to suggest the mutation the produced the amino acid substitutions described.
What is a Mutation? Clicking on this informational box produces a notecard that. describes different types of mutations: single nucleotide substitutions, indels (insertions or deletions in the normal sequence), "nonsense" mutations that terminate protein products early, and frame shift mutations that can produce multiple amino acid replacements. Visitors can return to the chromosome gallery to identify different types of mutations described there.
Beta Globin Mutations:
Beta globin is a relatively sturdy protein, and about 130 humanvariants have been reported. Twelve of these are listed on the mutant chart. All of the variants are changes in one of the first 8 amino acids of the protein. On the chart, both the normal (+) amino acid and the substitution (m) are listed.The location where the mutation was reported is also given, along with the effectsof the altered amino acid sequence, if any.
The normal codons for each amino acid are listed on a notecard given by the informational sign. The task is to identify the normal amino acid and its normal codon, and then to predict what change in the codon would have produced the amino acid substitution observed. For example, if the original codon was GTG (for valine) and the mutant amino acid was glycine, whose codons are GGT, GGC, GGA and GGG, then the simplest substitution would be to change the original GTG for GGG, that is a change of the middle T for a G.