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| Define "human genome". | It's our complete set of genetic information and is made up of tens of thousands of genes. |
| What were some of the first human genes to be identified? | The ones that control blood type were among the first human genes to be identified. |
| What does Rh stand for? | Rh stands for rhesus monkey, the animal in which the Rh factor was discovered. |
| What is the Rh factor? | It is a single gene that has 2 alleles, a positive and a negative. The + allele is dominant. |
| Give the 3 alleles for the ABO group. | See page 344, last paragraph. This program doesn't allow me to do exponents or subscripts. Know which ones are codominant and which is recessive. |
| What is an antigen? | Alleles produce molecules known as antigens on the surface of red blood cells. The antigen that is produced determines a person's blood type (see pg. 344, last paragraph). |
| Describe PKU. | PKU is phenylketonuria; PKU babies lack an enzyme that breaks down phenylalanine, an amino acid found in milk & many other foods. The phenylalanine builds up in tissues during a child's first years & causes severe mental retardation. |
| How are babies with PKI helped now? | They are tested at birth, and if they are a PKU baby, they are put on a low-phenylalanine diet that prevents most of the effects of PKU. |
| How is PKU caused? | It is caused by an autosomal recessive allele carried on chromosome 12. |
| What is Tay-Sachs Disease? | Its an autosomal recessive disorder caused by an allele in mainly Jewish families of central & eastern European ancestry. It causes the nervous system to breadown and the child dies in the first few years of life. |
| Name other disorders caued by recessive alleles. | Albinism, Cystic Fibrosis, Galactosemia, PKU, Tay-Sachs. (Look on pg. 345 for the chart) |
| Describe achondroplasia. | It's a genetic disorder caused by an autosomal dominant allele. It's a form of dwarfism. |
| Describe Huntington's disease. | It's a genetic disorder caused by an autosomal dominant allele; it causes a progressive loss of muscle control & mental function until death occurs. |
| Name a disease that is caused by codominant alleles. | Sickle cell disease that's found in 1/500 African Americans. |
| What does hypercholesterolemia do? | It produces excess cholesterol in the blood and heart disease. |
| What discovery have scientists made about cystic fibrosis and sickle cell disease? | They learned that a small change in the DNA of a single gene affects the structure of a protin, causing a serious genetic disorder. |
| What is cystic fibrosis caused by? | It's caused by a recessive allele on chromosome 7. Most cases are caused by the deletion of 3 bases in the middle of a sequence for a protein (see 346). Theis causes the protein to fold improperly, preventing cells from transporting chloride ions; as a result, tissues throughout the body malfunction. |
| How does CF manifest itself? | Children with this have serious digestive problems. Additionally, they produce a thick, heavy mucus that clogs their lungs and breathing passageways. |
| What problems do the bent & twisted shape of red blood cells create? | They tend to get stuck in capillaries, so blood stops moving through these vessels, demaging cells, tissues, organs. |
| What physical damage is done by sickle cell disease? | Weakness, and damage to the brain, heart, and spleen. In some cases, it may be fatal. |
| What is the difference between hemoglobin allele and the sickle cell allele? | One DNA base is changed. The amino acid valine is substituted for glutamic acid, causing a decrease in blood oxygen levels. As a result, many of the hemoglobin molecules to come out of solution and stick together. |
| How can the sickle cell allele be beneficial? | In areas where malaria is a major health problem, the sickle cell allel is beneficial in heterozygous persons. |
| In CF, what are the 2 phenotypes (being only 2 makes one dominant over the other)? | 1) the normal phenotype; 2) the CF phenotype. The normal allele is dominant. |
| How many phenotypes are involved in sickle cell disease? Is one of them dominant over the others? | 1) There are 3 phenotypes; 2) The sickle cell allele and the normal allele are considered codominant. |
