1. Module 6

1.35. Page 5

Lesson 7

Module 6—Mendelian Genetics: The Transmission of Traits to the Next Generation

Lesson Summary

 

During this lesson, you explored the following focusing question:

  • How does the environment affect the expression of genes?

Through your research for the discussion post, and from your exploration of temperature and gecko hatchings, you should see that there can be a strong and dynamic influence by the environment on gene expression. This influence accounts for some of the variance in traits, such as height. Whether this environmental effect on the expression of genes is stronger than the very inheritance of those genes is still up for debate.

 

Lesson Glossary

 

Consult the glossary in the textbook for other definitions that you may need to complete your work.

 

autosomal recessive: a condition caused by a gene found on an autosome (non-sex chromosome), which only occurs in those with the homozygous recessive genotype

 

environment: all non-genetic factors that affect a person’s characteristics (e.g., how he or she was raised, light levels, friends, temperature, good and bad experiences, diet and nutrients available, and so on)

 

expression: refers to the transcription and translation of the gene to produce the requested protein

 

Whether or not an allele will be expressed is affected by whether or not the allele is dominant; whether the product is needed by the cell; the stage of the life cycle; and, to some degree, the environmental conditions. In undifferentiated cells, all genes are expressed; in differentiated cells only some genes are expressed.

 

innate: a characteristic one is born with

 

malaria: a disease of warm, wet areas caused by the plasmodiumprotist found in the Anopheles mosquito

 

When the mosquito bites a person, the plasmodium enters the blood stream and lays its eggs in red blood cells. Sickled red blood cells typical of those people with sickle cell anemia (SCA) are harder for the plasmodium to attack, so those with SCA are less likely to die of malaria. The homozygous recessive condition (ss) confers a disadvantage (SCA) and an advantage (protection from malaria).

 

nature: in reference to the nature versus nurture debate, refers to the components of an individual’s phenotypes that are determined by his or her genes (e.g., approximately 50% of intelligence is thought to be due to nature)

 

nurture: refers to the component of one’s phenotypes that are determined by one’s environment