Difference between revisions of "AY Honors/Heredity/Answer Key"
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==4A. What is meant by the term "allele"?== | ==4A. What is meant by the term "allele"?== | ||
| − | An allele is any one of a number of viable DNA codings of the same gene occupying a given position on a chromosome. Humans have paired chromosomes in their somatic cells, and these contain two copies of each gene. In some cases the two copies of the gene are identical — that is, have the same allele. In other cases, the two copies are different. | + | An allele is any one of a number of viable DNA codings of the same gene occupying a given position on a chromosome. Humans have paired chromosomes in their somatic cells, and these contain two copies of each gene. In some cases the two copies of the gene are identical — that is, have the same allele. In other cases, the two copies are different. Humans inherit two copies of every gene, one copy comes from the mother, and the other comes from the father. |
==4B. How does a dominant allele differ from a recessive allele?== | ==4B. How does a dominant allele differ from a recessive allele?== | ||
Revision as of 23:59, 13 May 2006
Heredity
1. What is meant by the term "heredity"?
Heredity refers to the transfer of biological characteristics from a parent organism to offspring, and is practically a synonym for genetics, as genes are now recognized as the carriers of biological information.
2. Draw a picture of an animal cell and label the following parts: Cell membrane, cytoplasm, nucleus, nuclear membrane, ribosomes.
3A. What is a chromosome and where are they located?
A chromosome is a very long, continuous piece of DNA which contains many genes. Chromosomes are located within the nucleus of a cell.
3B. What is a gene and where is it found?
Genes are the units of heredity in living organisms. They are encoded in the organism's genetic material (usually DNA or RNA), and control the physical development and behavior of the organism. They are located on the chromosomes.
4A. What is meant by the term "allele"?
An allele is any one of a number of viable DNA codings of the same gene occupying a given position on a chromosome. Humans have paired chromosomes in their somatic cells, and these contain two copies of each gene. In some cases the two copies of the gene are identical — that is, have the same allele. In other cases, the two copies are different. Humans inherit two copies of every gene, one copy comes from the mother, and the other comes from the father.
4B. How does a dominant allele differ from a recessive allele?
Characteristics associated with a certain allele can sometimes be dominant or recessive, but often they are neither. A dominant trait will be expressed when only one allele of its associated type is present, whereas a recessive trait will only be expressed when both alleles are of its associated type.
4C. Determine which allele you have of the following genetic traits:
Widow's Peak
A widow's peak is a descending V-shaped point in the middle of the hairline (above the forehead). The trait is inherited genetically and dominant. The term comes from English folklore, where it was believed that this hair formation was a sign of a woman who would outlive her husband.
Free earlobe
The free earlobe is a dominant trait, but geneticists are unsure if it is the result of a single gene or if multiple genes are involved.
