AP Biology Chapter 15 – Flashcards
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The chromosomal basis of inheritance is the idea that genes are located on chromosomes as well as the idea that the behavior of chromosomes during Meiosis accounts for Mendel's Laws of Segregation and Independent Assortment.
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What is the chromosomal basis of inheritance?
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Wild type is the genotype that is most commonly observed in the population.
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What is the meaning of the term "wild type"?
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Fruit flies were a good choice for Morgan's experiments because Morgan was able to clearly distinguish the link between eye color and biological sex.
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Why was Morgan's choice of fruit fly such a good one for genetic experiments?
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The trait of white eyes only appeared in males, so Morgan was able to link the trait with sex chromosomes in males.
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How did Morgan associate traits with the sex of the fruit fly?
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When we say there is "linkage" between genes that means that we have determined a dominant or recessive allele attached to an X or Y chromosome (non-autosomal).
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What does it mean when genes are linked or we can say there is linkage?
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Recombinants would form in Prophase i, called crossing over, where genes assort themselves.
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In what step of meiosis would recombinants form and why?
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A genetic map is an ordered list of genetic loci along specific chromosome. A linkage map is a map based on recombination frequencies. A cytogenic map is a map that locates genes with respect to chromosomal features, such as stained bands that can be seen in the microscope.
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What is the difference between a genetic map, a linkage map, and a cytogenic map?
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XY is the method of sex determination in mammals. Sex chromosomes are XX in females and XY in males, and the sex of the offspring is determined by male sperm.
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What is the chromosomal basis of sex determination in mammals?
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X0 is the method of sex determination in grasshoppers. Sex chromosomes are XX in females and X0 (X-zero) in males, and the sex of the offspring is determined by the male sperm.
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What is the chromosomal basis of sex determination in grasshoppers?
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ZW is the method of sex determination in birds and some fish. Sex chromosomes are ZW in females and ZZ in males, and the sex of the offspring is determined by the female egg.
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What is the chromosomal basis of sex determination in birds and some fish?
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Haplo-Diploid is the method of sex determination in bees and ants. There are no sex chromosomes, females have 2n chromosomes and males have n chromosomes, and a fertilized egg has 2n chromosomes, while an unfertilized egg has n chromosomes.
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What is the chromosomal basis of sex determination in bees and ants?
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The SRY gene is the gene that provides instructions for making a transcription factor called the determing region Y protein. Without a functioning Y protein, the cell will develop as a female with a Y chromosome because the body cannot recognize the Y chromosome without the Y protein. The individual is likely to develop Swyer syndrome and other complications as a result.
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What is the SRY gene and why is it important?
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A sex-linked gene is a gene that is connected to the sex chromosomes.
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What is a sex-linked gene?
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X inactivation is when the X chromosome compacts into a Barr body and genes within become unexpressed. The Barr body lies along the nuclear envelope, and is more likely in females.
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What is X inactivation?
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Most Calico cats are female because coloring is attached to X chromosomes, and in Calico cats one X would have to be inactive for both colors, such that the cat has a phenotype of orange and black.
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Why are most Calico cats female?
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Nondisjunction is where members of a pair of chromosomes do not move apart (Meiosis i) or sister chromatids do not separate (Meiosis ii).
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What is nondisjunction and when in meiosis does it occur?
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Aneuploidy is the condition of an abnormal amount of a particular chromosome exists. Additionally, this condition can have a chromosome either absent or in excess, and can affect more than one chromosome.
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What is the meaning of the term "aneuploidy"?
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Monosomic is the condition of a diploid cell that has only one copy of chromosomes instead of two copies of a chromosome.
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What is the meaning of the term "monosomic"?
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Polyploidy is the condition where there are three or more sets of chromosomes in somatic cells (ex: tetraploidy (4n), triploidy (3n), etc).
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What is the meaning of the term "polyploidy"?
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Deletion-A removal of a chromosomal segment Duplication-A repetition of a chromosomal segment Inversion-A reversal of a chromosomal segment Translocation-A shift of a segment from one chromosome to another
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What are the four types of alterations in chromosomal structure?
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The most common type of translocation in a chromosome is reciprocal translocation where both chromosomes exchange segments. The least common type of translocation in a chromosome is non-reciprocal translocation where only one chromosome gives/receives a segment.
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What is the most common type of chromosomal translocation? Least common?
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Trisomy 21 (Down's syndrome) is a condition where chromosome 21 has three copies (aneuploidy).
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Explain the chromosomal alteration present in Down's syndrome/Trisomy 21.
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Klinefelter's syndrome (XXY) is a condition where there is an extra X chromosome. As a result, the individual is biologically a male, but remains sterile/has altered secondary sex characteristics.
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Explain the chromosomal alteration present in Klinefelter's syndrome.
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Turner syndrome (Monosomy X) is a condition where there is only one X chromosome. As a result, the individual is biologically female, but remains sterile/has altered secondary sex characteristics.
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Explain the chromosomal alterations present in Turner syndrome/Monosomy X.
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Chronic Myelogenous Leukemia (CML) is a condition where reciprocal translocation occurs during Mitosis process of cells that will become white blood cells. In this case, Chromosome 22 and Chromosome 9 switch chromosomal segments.
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Explain the chromosomal alterations present in CML.
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Genomic imprinting is the variation in phenotype depending on whether allele is inherited from mother or father, occuring during gamete formation, resulting in the silencing of particular allele of certain genes.
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What is genomic imprinting?
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Extranuclear genes are genes located in organelles in cytoplasm.
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What are extranuclear genes?
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1. Mitochondrial Myopathy A disease of the mitochondria (inherited from mother), where a defect in the mitochondria results in weakness, intoleration of exercise, and muscle deterioration. 2. Leber's Hereditary Optic Neuropathy A disease resulting in blindness in individuals 20-30 years old.
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What are two diseases carried in maternal mitochondria?
