Corn and bean seedlings grown in the light or the dark

TLS Online TPP Program

#Id: 2243

#Unit 11. Evolution and Behavior

The loci that encode hemoglobins are members of a gene family, which is a set of loci that arose by duplication.

TLS Online TPP Program

#Id: 2244

#Unit 11. Evolution and Behavior

When a nonfunctioning duplicate is fixed in the population, or a functioning gene becomes nonfunctional, the result is a genetic skeleton called a pseudogene.

Deletions are important in shaping the genome.

TLS Online TPP Program

#Id: 2245

#Unit 11. Evolution and Behavior

Deletion plays a key role in gene trafficking.which is the movement of genes to new sites in the genome.

TLS Online TPP Program

#Id: 2246

#Unit 11. Evolution and Behavior

Some people have an allele called Δ32 at the CCR5 locus in which 32 bp are deleted.

CCR5 that plays a role in inflammatory response. Unfortunately, this protein is also a key to human immunodeficiency virus (HIV) infection. The virus binds to a loop of the CCR5 protein and then enters the cell.

The missing part of the gene codes for the loop in the protein to which the virus attaches. 

TLS Online TPP Program

#Id: 2247

#Unit 11. Evolution and Behavior

People who are Δ32 homozygous for the deletion are highly resistant to HIV, while heterozygotes are partly resistant.

TLS Online TPP Program

#Id: 2248

#Unit 11. Evolution and Behavior

These pieces— the exons —are separated by stretches of noncoding DNA— the introns