AP Bio Chapter 15

Vocab:

chromosomal theory of inheritance: - Mendelian genes have specific loci along chromosomes,chromosomes undergo the law of segregation and independant assortment
Drosophilia melanogaster: - fruit fly
mutant phenotypes: - variatioin in normal physical appearnce of a population
sex-linked gene: - gene on either sex chromosome
Duchenne muscular dystrophy: - a sex linked disorder where the muscles and coordination skills weaken, males rarely live past their 20s, the dystrophin absence is due to a malformed _X chromosome
hemophilia: - a sex linked disorder where there is an absence of proteins required for blod clotting, bleeding can cause pain and damage
Barr body: - inside nuclear envelope, inactive X in a female's cells
linked genes: - located on the same chromosome and most likely inherited together during cell division
genetic recombination: - production of offspring with genetic traits diffrent from both parents
parental types: - offspring that inherited the same phenotype as one of their parents
recombinant types: - offspring with phenotypes different from either parents
genetic map: - an ordered list of the genetic loci along a particular chromosome
linkage map: - genetic map based on recombination frequencies
map units: - unit expressing the distances between genes as equal to a 1% recombination frequency
cytogenic map: - locates genes according to chromosomal features, slighly more acurate on specific locations of chromosomes rather than linkage maps
chromosomal nondisjunction: - members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to seperate during meiosis II
aneuploidy: - incorrect number of chromosomes
monosomic: - when fertilized eggs have 1 copy of a chromosome
trisomic: - when fertilized eggs have 3 copies of a chromosome
polyploidy: - condition of having more than 2 complete sets of chromosomes, forming a 3n or 4n individual, common in plants rare in animals
deletion: - when a chromosomal fragment is lost, resulting in a chromosome with missing genes
duplication: - when a chromosomal segment is repeated
inversion: - when a chromosomal fragment breaks off and reattaches to its origional position, but backwards so the part of the fragment that was origionally at the attachment point is now at the end of the chromosome
translocation: - when the deleted chromosome fragment joins a nonhomologous chromosome
Down syndrome: - an anueploid condition due to an extra chromosome 21, includes characteristic facial features, short stature, heart defects, and developmental delays
Klinefelter syndrome: - an anueploid condition where a male inherits an extra X chromosome (XXY), includes higher levels of estrogen, and sterile male sex organs
Turner syndrome: - a monosomic condition where females inherit only one X sex chromosome, making them sterile because their reproductive organs do not mature
genomic imprinting: - a variation in the phenotype depending on if the allele was passed from the mother or father
extranuclear (cytoplasmic) genes: - located in cytoplam/mitochondria, inherited from maternal parent brcause the egg contains the zygote's cytoplasm

answers to study guide questions:

1. _-The chromosomal thoery of inheritances states that Mendelian genes have specific loci along chromosomes, and chromosomes undergo the law __--of segregation and independant assortment. This is supported by pea chromosomes in gametes undergoing meiosis in the P and F1 generations, __--the behavior of homologous chromosomes can account for the segregation of the alleles at each genetic locus to different gametes.
2. _-Sex linked traits are more common in males rather than females because males only have one X chromosome, they will express the allele on the __--chromosome inherited from their mother. Y chromosomes contain genes responsible for proteins that make testes.
3. _-A sex linked gene is a gene on either sex chromosome, a linked gene is located on the same chromosome and most likely inherited together __--during cell division. Both have genes on one chromosome but sex linked genes are for sex chromosomes.
4. _-Meiosis accounts for genetic recombination by the independant assortment of chromosomes and when they cross over to exchange different __--alleles. This increases the chances for not inheriting the same phenotype.
5. _-Linkage maps are made by recombination data, and they're based off the assumption that the probabilty of a crossover between two genetic loci __--is proportional to the distance seperating them. The recombination frequencies are obtained from doing crosses (like finding the testcross __--offspring data from fruit flys). Map units define the distances between genes, one is equal to a one percent recombination frequency, then the __--genes are arranged in the chromosome based off the data.
6. _-Nondisjunction can lead to aneuploidy ( having one or extra chromosomes) because the chromosomes aren't corectly seperated during meiosis, __--leading to the gametes having odd/uneven numbers of chromosomes, altering the karyotype of an individual.
7. _-Trisomy means there are three copies of a chromosome, Triplody means three complete sets of chromosomes, and Polyploidy means there are __--more than 2 complete sets of chromosomes (3n, 4n).
8. _-Deletions- when a chromosomal fragment is lost, resulting in a chromosome with missing genes
__--Duplications- when a chromosomal segment is repeated
__--Inversions- when a chromosomal fragment breaks off and reattaches to its origional position, but backwards so the part of the fragment that was __--origionally at the attachment point is now at the end of the chromosome
__--Translocations- when the deleted chromosome fragment joins a nonhomologous chromosome

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9. _--Genomic Imprinting is a variation in the phenotype depending on if the allele was passed from the mother or father. This occurs during the __---formation of gametes, where one of the alleles inherited is silenced, and a zygote expresses only one allele of an imprinted gene. Methlylation of __---the DNA in one of the alleles may contribute to the silence, but on the contrary it has also activited allele expression for certain genes.
10. _-The inheritance of extranuclear genes doesn't fit the Mendelian patterns of inheritance beacause the genes are located in the __---mitochondria/plastids. The inheritance is ruled by the maternal parent because the zygote's cytoplasm comes from the egg.
11. _-Down Syndrome and Klinefelter Syndrome are examples of chromosomal abnormalities because the chromosomes don't seperate correctly __---during meoisis (nondisjunctions), leading to odd numbers of certain chromosomes. Klinefelter Syndrome includes a Y chromosome and a single __---X chromatid along with 3 others (making the sex chromosome XXY), and Down Syndrome includes cells that are trisomic for chromosome 21.