Term
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Definition
| Chromosomes that occur in homologous pairs in both males and females and that does not bear the genes determining sex. |
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Term
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Definition
| Either of the pairs of chromosomes that usually determine the sex of an organism, for example the X and Y chromosome in mammals. |
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Term
| Why are the sex chromosomes considered homologous although they don't carry the same complement of genes? |
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Definition
| A small part of the sex chromosomes are homologous |
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Term
| In organisms with XX females and XY males, which parent determines the sex of the offspring and why? |
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Definition
| The males because the females have two X chromosomes so every egg receives one X chromosome. The father can give either his X or Y chromosome. |
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Term
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Definition
| Genes that are on one sex chromosome but not on the other. |
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Term
| How are males and females affected by genes on the X chromosome? |
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Definition
| Females can either be homozygous or heterozygous for genes on the X chromosome, and dominant versus recessive relationships among alleles will be expressed. Men can either be dominant or recessive for a trait depending on which trait is passed down by the mother because the Y chromosome does not contain that specific trait. |
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Term
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Definition
| A pattern of inheritance in which the heterozygous phenotype is intermediated between the two homozygous phenotypes. Human hair texture is influenced by a gene with incompletely dominant alleles. |
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Term
| How many alleles does an individual carry for a particular trait? |
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Definition
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Term
| What are multiple alleles? Give an example. |
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Definition
| Many alleles of a single gene, perhaps dozens or hundreds as the result of a mutation. Human blood types are an example of multiple alleles of a single gene. |
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Term
| How many alleles exist for the gene that determines blood type on chromosome 9? What are they? Describe the relationship between. |
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Definition
| Three different alleles exist - A, B, and O. A and B code for different sugars to be added to the ends of glycoproteins that protrude from the surface of red blood cells. Type O codes for a nonfunctional enzyme that doesn't add any sugar molecules. |
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Term
| How are the glycoproteins on the red blood cells different in people with Type A, B, AB, and O blood? |
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Definition
| They have different sugars in type A and B. Type O does not have a sugar and type AB has both sugars. |
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Term
| Which type of blood is the universal donor? Why? |
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Definition
| Type O is the universal donor because it can carry antibodies to both A and B glycoproteins and is the only blood type O individuals can receive transfusions. |
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Term
| Which blood type is the universal recipient? |
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Definition
| Type AB is the universal recipient because it can receive all blood types. |
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Term
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Definition
| A pattern of inheritance in which the interactions of two or more functionally similar genes determines a phenotype. Ex: body type, skin color, height, eye color, weight |
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Term
| What is pleiotropy? Give an example. |
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Definition
| A situation in which a single gene influences more than one phenotypic characteristic. Ex: The SRY gene on the Y chromosome |
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Term
| Give an example of how the environment influences the expression of genes. |
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Definition
| Height is influenced by nutrition and skin color is modified by sun exposure. |
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Term
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Definition
| A diagram showing genetic relationships among a set of individuals, normally with respect to a specific trait. |
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Term
| What can be learned from pedigrees? |
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Definition
| They can reveal whether a particular trait is inherited in a dominant recessive, or sex-linked pattern. Understanding of new genetic disorders is also learned by pedigrees. |
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Term
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Definition
| A person who is heterozygous for a recessive gene trait. |
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Term
| What is the danger of inbreeding? |
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Definition
| People inherited some of their genes from recent common ancestors, and so are more likely to carry a defective allele and/or a genetic disorder. |
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Term
| What two ways are dominant genetic diseases passed to offspring? |
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Definition
1. Some are caused by dominant alleles or a mutant allele. One parent must have the disease or a mutation must occur.
2. Some are sex-linked caused because the X chromosome has many genes that have no pairs on the Y chromosome. |
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Term
| Which sex is most often affected by recessive sex-linked traits carried on the X chromosome. Why> |
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Definition
| Males because males only receive one X chromosome and only one allele for each of the genes. |
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Term
| Example of a recessive X-linked trait |
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Definition
| Hemophilia, muscular dystrophy |
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Term
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Definition
| The physical location of a gene on a chromosome. |
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Term
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Definition
| The unit of heredity; a segment of DNA located at a particular place on a chromosome that encodes the information for the amino acid sequence of a protein and, hence, particular traits. |
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Term
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Definition
| Chromosomes of diploid organisms that occur in pairs. Both of the homologues carry the same genes, located at the same loci, but the nucleotide sequences may differ. |
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Term
| Why aren't homologous chromosomes identical? |
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Definition
| The nucleotide sequences may differ. |
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Term
| What are alleles? What makes them different from each other? |
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Definition
| Alleles are one of several alternative forms of a particular gene. Different genes or sequences of bases makes them different. |
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Term
| How do new alleles arise? |
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Definition
| Mutations that slightly change the spelling of nucleotide sequences. |
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Term
| How many alleles do diploid organisms carry for each gene? |
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Definition
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Term
| Differentiate between homozygous and heterozygous alleles at a particular gene locus on homologous chromosomes. |
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Definition
| Homozygous alleles are two alleles that are the same at that locus. Heterozygous alleles are different alleles of a certain gene. |
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Term
| What is another name for heterozygous? |
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Definition
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Term
| What do the following notations stand for in genetics experiments? P, F1, F2 |
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Definition
P-parental generation
F1-first generation "first filial"
F2-Second generation |
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Term
| Distinguish between dominant and recessive alleles. |
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Definition
| Dominant alleles "mask" the expression of a recessive allele when paired together. |
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Term
| What is the law of segregation? |
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Definition
| The principle that each gamete receives only one of each parent's pair of alleles of each gene. |
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Term
| How many alleles for each trait does the resulting zygote have after fertilization? |
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Definition
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Term
| What type of alleles would be found in the gametes of an individual who is homozygous at a particular gene (Ex: AA). |
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Definition
| The same allele would be found in the gametes of an individual who is homozygous at a particular gene. |
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Term
| What type of allele will be found in the gametes of an individual who is heterozygous at a particular gene? |
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Definition
| Half of the gametes would contain one allele and half of the gametes would contain the other allele. |
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Term
| What is a genotype? Give an example of a genotype for a flower with purple petals. |
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Definition
| The actual combination of alleles carried by an organism. Ex: PP or Pp |
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Term
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Definition
| The organism's traits, including its outward appearance, behavior, digestive enzymes, blood type, or any other observable or measurable feature. |
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Term
| What are Punnett Squares used for? |
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Definition
| They are used to predict the genotypes and phenotypes of offspring. |
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Term
| What is the purpose of a test cross? |
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Definition
| The purpose is to see if an organism who's phenotype is the dominant phenotype is heterozygous or homozygous for that allele. |
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Term
| How is a test cross performed? |
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Definition
| The organism tested is crossed with organisms recessive for the trait being tested. If some of the offspring show the recessive phenotype, then the organism is heterozygous; however, if all the organisms show the dominant trait, then it is homozygous. |
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Term
| What is Mendel's Law of independent assortment? |
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Definition
| The independent inheritance of two or more traits, assuming that each trait is controlled by a single gene with no influence from genes controlling the other trait; states that the alleles of each gene are distributed to the gametes independently of the alleles for other genes; this law is true only for genes located on different chromosomes or chromosomes that are very far apart on a single chromosome. |
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Term
| Explain why Mendel's Law of Independent Assortment occurs. |
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Definition
| When paired homologous chromosomes lineup during metaphase I, which homologue faces which pole of the cell is random, and the orientation of one homologous pair does not influence other pairs. Therefore, when the homologues separate during anaphase I, which allele of a gene on homologous pair 1 moves "north" and does not affect which allele of a gene onhomologous pair 2 that also moves "north." The alleles of genes on chromosomes are distributed independently. |
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Term
| What happened after Mendel presented his theories of inheritance to the Brunn Society of Natural Science? |
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Definition
| They were published the following year, but did not make any impression at all on the study of biology during his lifetime. |
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Term
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Definition
| The inheritance of certain genes as a group because they are parts of the same chromosome. Linked genes do not show independent assortment. |
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Term
| What process during meiosis can caused linked alleles to be inherited independently? |
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Definition
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Term
| Describe the relationship between the distance separating genes on chromosomes and the change of crossing over and and independent assortment. |
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Definition
| The farther apart the genes are on a chromosome, the more likely it is that crossing over will occur between them. If two genes are close together, they will rarely be separated by crossing over, but if two genes are far apart, crossing over between the genes occurs so often that they seem to be independently assorted. |
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