Shop Windows to the Universe

The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
These are what the chromosomes of a human look like. Chromosome pairs like these are in every human cell. The last pair determines the gender of the person.
Courtesy of the National Library of Medicine and NIH

Chromosomes, DNA and Genes: Tiny Things That Have a Huge Effect on Who We Are!

Do you look a bit like your brothers and sisters? Do you look a bit like your parents? The similarities are because, unless you were adopted, you and the other members of your family have genetic material in common.

Some characteristics, or traits, result from interactions with the environment, others are determined from the genetic material in your chromosomes. Chromosomes are the keepers of the genetic material in eukaryotic cells. An organism has the same chromosomes for its entire life. The chromosomes are located within each cell nucleus. They provide the directions for how the cell is supposed to function and determine some characteristics about how the individual looks. Each chromosome contains a very complex molecule called DNA. The DNA molecule contains genes, which direct how an organism's body is built and maintained.

Heredity is the passage of DNA from the chromosomes of one generation to the chromosomes of the next. Chromosomes in your body are in pairs. One chromosome of each pair came from your mother and one from your father. There are many genes within each chromosome. Different genes determine different traits. For each gene there can be many varieties. For instance, one variety might tell the body that eyes should be blue while another variety tells that eyes should be brown. (The dominant gene determines the actual color of the person's eyes.) Each variety is called an allele.

There might be many types of alleles for each type of gene. Each animal or plant has two alleles of each gene. One allele is inherited from its mother and the other is inherited from its father. This means that an organism has two varieties of every gene, but they might not be the same type.

Last modified October 15, 2011 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

"Science, Evolution, and Creationism", by the National Academies, provides fascinating background on these topics for all, and is particularly useful for the Earth and space science classroom. Check our other books in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Meiosis: How Gametes Are Made

Plants, animals and many other species within the domain Eukaryota are able to make offspring, or young, by sexual reproduction. Their offspring are made from gametes. Gametes are special cells that have...more

Fish Adapting to a Changing World

Scientists have been studying stickleback fish to learn more about how animals cope when their environment changes. Since the Earth is changing quickly because of global warming and other global changes,...more

Can there be Life in the Environment of Jupiter?

Jupiter's atmospheric environment is one of strong gravity, high pressure, strong winds, from 225 miles per hour to 1000 miles per hour, and cold temperatures of -270 degrees to +32 degrees (freezing temperature)....more

The possible discovery of Life on Mars

In July, 1996, it was announced that Dr. David McKay, along with a team of scientists at Johnson Space Center (a division of NASA), had discovered possible fossils of bacteria in a meteorite named ALH84...more

The Environment of Saturn

Saturn's atmospheric environment is one of strong gravity, high pressure, strong winds, from 225 miles per hour to 1000 miles per hour, and cold temperatures of -270 degrees to +80 degrees. With winds...more

Can there be Life in the Environment of Titan?

Titan's atmosphere is a lot like the Earth's, except that it is very cold, from -330 degrees to -290 degrees! Like the Earth, there is a lot of Nitrogen and other complex molecules. There also may be an...more

Autotrophs

Autotrophs are organisms that can "make their own food" from an inorganic source of carbon (carbon dioxide) given a source of energy. Most autotrophs use sunlight in the process of photosynthesis to make...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF