Ch 34 Genetics and heredity
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Created by:
jessnjs Plus on November 27, 2011
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15 terms
Terms | Definitions |
|---|---|
 Who was the first person to discover the basic mechanism by which traits are transmitted from parent's to offspring? | A monk; Gregor Mendel in the 1860's. |
| Describe albinism in relation to dominance, recessiveness, and genotype. | Albinism is a recessive gene. It will require each parent to pass on an ("a" genotype) making the offspring (aa) in order to have the phenotype of albinism. A person with a genotype of (AA) will not have the gene for albinism but a normal melanin production phenotype. A person with a genotype of (Aa) will still not have albinism but will be a genetic carrier for it. |
| Explain the difference between a genotype and a phenotype | A genotype is the genes on a chromosome from each parent cell (susceptibility to skin cancer). A phenotype is how those genes are expressed; (red hair). |
| Define codominance, and give an example of a condition that demonstrates codominance. | Codominance means the offspring's genotype has two dominant genes; the result will be a balance between the two. For example both light skin and dark skin are dominant genes. Therefore the offspring will have a balance of skin color between the two. |
| If a certain trait is identified as X-linked recessive, describe the genotype of a female expressing the given trait. | The genotype would be two X-linked recessive genes (xx). |
| Identify several genetic mutagens | chemicals, radiation, viruses |
| How can mutations be beneficial to a species? | they can allow an organism to adapt to a new environment allowing survival of species that can spread throughout several generations. |
| What role do environmental factors play in relation to certain genetic diseases? | Environment is the main cause of genetic diseases through chemicals and radiation. They can be both beneficial or harmful. As with skin cancer; you may have a gene that makes you predisposed to contracting it. It is in active until there is a trigger such as overexposure to the sun. |
| Explain the "mistake" in meiosis that results in the condition called trisomy | Nondisjunction during meiosis can cause trisomy. This means a pair of chromosomes fail to separate resulting in three instead of the "pair". |
| Describe the genetic inheritance of cystic fibrosis, phenylketonuria (PKU), and Tay-Sachs disease | All three are caused by recessive (autosomal) single-gene inheritance. |
| Identify the chromosomal disorder that involves trisomy 21 | Down syndrome; will have 47 chromosomes due to #21 having 3 instead of the normal pair. |
| Differentiate between oncogenes and tumor suppressor genes | Oncogenes are altered (mutated) forms of normal genes thought to cause some forms of cancer through environmental conditions transforming the cell or viruses transmitting oncogenes to the cells. A tumor suppressor gene is thought to regulate cell division. It can become non-functioning due to environmental conditions thus allowing the cell to divide abnormally or fail entirely in dividing and when this occurs it could cause cancer. |
| How are gene replacement and gene augmentation therapies used to treat genetic diseases? | In gene replacement the goal is to alter existing body cells in hope of eliminating the cause of genetic disease. A virus can insert new genes into the human genome. It is used to insert normal genes so that normal proteins can "replace" the abnormal, disease causing proteins. Gene augmentation also utilizes virus altered cells. In this case they are injected into the blood or implanted under the skin to produce increased amounts of missing protein. |
| Define the term genome | The entire set of chromosomes in a cell. There are 46 chromosomes in a cell or you can say there are 22 autosome pairs and 1 pair of sex chromosomes. |
| When is a disorder classified as congenital? | When the disorder is present at birth or before birth. |
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