Term
| What is a gene? What is an allele? What does it mean to be homo- and heterozygous? |
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Definition
| A gene is a chain of DNA that codes for one mRNA for a protein. Alleles are two different sequences of nucleotides in the DNA for one gene. The two chromosomes in a homologous pair can have the same allele (homozygous) or different alleles (heterzygous). |
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Term
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Definition
| The transmission of different alleles between generations by meiosis and sexual reproduction. |
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Term
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Definition
| The study of heredity and how heredity variation is passed through generations. |
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Term
| What does true breeding mean? What does hybridization mean? |
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Definition
| True breeding is when a species always create offspring with the same trait. Hybridization is when two true breeding organisms (with different alleles) are crossed. |
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Term
| What is the law of segregation? |
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Definition
| Each gamete receives one copy of a gene (out of two possible copies, due to homologous chromosomes). |
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Term
| Give an example of a dihybrid genotype. |
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Definition
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Term
| Define the Law of Independent Assortment |
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Definition
| Non-linked genes are inherited independently. |
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Term
| How would you calculate the chance of getting YYRr from YyRr and YyRr? |
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Definition
Chance of getting YY from YyxYy = 1/4
Chance of getting Rr from RrxRr = 1/2
Chance of getting YYRr from YyRrxYyRr = 1/4 * 1/2 = 1/8 |
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Term
| Give three types of Mendelian inheritance complications. |
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Definition
1. incomplete dominance - need 2 dominant alleles for full dominant phenotype
2. co-dominance - both alleles have phenotype effect (ex. blood type)
3. polygenetic inheritance - one gene has several effects on phenotype (ex. sickle-cell disease) |
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Term
| What is a pedigree analysis? |
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Definition
| The following of phenotypes over generations to reveal genotypes |
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Term
| What is the position of a gene on a chromosome called? |
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Definition
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Term
| True or false? Linked genes do not assort independently in meiosis. |
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Definition
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Term
| How are wild type and mutant alleles named? |
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Definition
| Wild type alleles have a superscipt +. The letter denoting the allele is named after the first mutant (ex. first mutant of body color = black; wildtype = b^+, mutant = b). |
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Term
| What is recombination? When do two genes have a low recombination factor (RF)? When do they have a high RF? |
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Definition
Recombination is the restructuring of chromosomes during crossover in prophase I.
Two linked genes have a low RF if they are close together on the chromosomes. Two linked genes have a high RF if they are far apart on a chromosome (more of a chance they will be separated in crossover). |
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Term
| How do you calculate recombination frequency (RF)? What does 1 RF mean in terms of length on a chromosome? |
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Definition
(# recombinations (sum of both small #'d phenotypes)/ total # offspring) * 100%
1 RF = 1 map unit = 1 centimorgan |
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Term
| Genes on ___ chromosomes are sex linked. |
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Definition
Genes on the X chromosomes are sex linked.
The Y chromosome has very few genes, not as important. |
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Term
| Why are males more likely to have many sex-linked disorders? |
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Definition
| Sex-linked disorders are normally recessive. Because males only have one X chromosome, they only need one copy of the recessive allele to have the disorder, whereas females need two, because they have 2 X chromosomes. |
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Term
| What is a Barr body? How does this relate to women being "mosaics"? |
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Definition
A Barr body is nature's answer to females having two X chromosomes (two chromosomes with sex-linked genes). One X chromosome per cell is turned into a Barr body and becomes inactive. This causes different phenotypes in different areas of the organism depending on which allele was inactivated (ex. spotted colors of cat hair).
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Term
| What is non-disjunction? How does it relate to aneuploidy and polyploidy? |
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Definition
Non-disjunction is an error in chromosomal inheritance. It is a failure of chromosomes to seperate correctly during meiosis (homologs don't sep. in meiosis I, sister chrom. don't sep. in meiosis II)
Gametes with the wrong number of chromosomes are called aneuploidy. Monosomy is when a gamete is missing one chromosome. Trisomy is when gametes have an extra chromosome.
Polyploidy is when there are extra sets of chromosomes. |
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Term
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Definition
| An ordered display of chromosomes from a cell in mitosis |
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Term
| What is X-ray crystallography used for? |
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Definition
| To give information on the 3D structure of molecules. |
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