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Ch 10-12 Genetics
Ch 10-12
| Question | Answer |
|---|---|
| Hermann Henking | 1891, observed the X chromosome and called it the X body |
| Clarence McClung | Observed the X chromosome in grasshoppers and called it the accessory chromosome. The name later changed to X chromosome. |
| Nettie Stevens and Edmund Wilson | 1905, they described the XX-XO system in grasshoppers. XX = female XO = male |
| homogametic | the sex that produces gametes that are alike with regard to sex chromosomes. |
| heterogametic | the sex that produces two types of gametes with regard to sex chromosomes. |
| Hermann Henking | 1891, observed the X chromosome and called it the X body |
| Clarence McClung | Observed the X chromosome in grasshoppers and called it the accessory chromosome. The name later changed to X chromosome. |
| Nettie Stevens and Edmund Wilson | 1905, they described the XX-XO system in grasshoppers. XX = female XO = male |
| homogametic | the sex that produces gametes that are alike with regard to sex chromosomes. |
| heterogametic | the sex that produces two types of gametes with regard to sex chromosomes. |
| pseudoautosomal region | X and Y chrom. are not homologous, but are able to pair and segregate into diff. cells in Mei. They can pair b/c they are homologous at small regions called pseudoautosomal regions. |
| sex determining region Y (SRY) | on Y chromosome only. |
| TDF | testes determining factor |
| Wolfian Duct | Develops with the presence of testosterone (male). |
| Mullerian Duct | no testosterone, so mullerian duct develops (female) |
| mullerian inhibiting factor/substance (MIF/MIS) | gene on Y chromosome causes gonads to secrete MIF, which leads to the degeneration of female reproductive ducts. |
| Structures that develop from Wolfian Duct | prostate, vas deferens, penis and testes |
| Structures that develop from Mullerian Duct | uterine tube, ovary, uterus, and vagina |
| These structures can sometimes form compartments during development during fusing of Mullerian ducts. | Uterus and vagina (rarely) |
| Sex determination is determined by | testosterone. no testosterone, default female. |
| dihydrotestosterone (DHT) | is an androgen, synthesized primarily in the prostate gland, testes, hair follicles, and adrenal glands by the enzyme 5α-reductase.is responsible for the formation of secondary sex characteristics in men. |
| sex-reductase (5 alpha) | an enzyme that reduces testosterone to DHT (very potent) |
| haplodiploidy | instead of sex chromosomes, sex is determined by haploid (male) and diploid (female) |
| dosage compensation | equalization in males/fem of the amt of protein produced by X-linked genes. In placental mamm, dosage comp is accomplished by random inact. of 1 X chrom in cells of females. |
| Thomas Hunt Morgan | first studied sex linked inheritance of Drosophila melanogaster. concluded that white eyes was inherited through X-linked inheritance. |
| hemizygous | possession of a single allele at a locus. Males of organisms XX-XY sex determination are hemizygous for X-linked loci, bc cells possess a single X chrom. |
| completely normal | no signs of disease and not a carrier |
| appears normal | could be a carrier |
| hemophilia | mutant F8 & F9 genes, code for clotting factors VIII & IX. |
| penetrance | % of individuals w/a particular genotype that express the expected phenotype. |
| expressivity | degree to which a character is expressed. |
| sex influenced traits | same gene works differently depending on sex. determined by autosomal genes, inherited according to Mendel's principle. Ex: male pattern baldness, autosomal allele dom. in males and recessive in females. |
| sex limited traits | may be X linked or autosomal. Extreme form of sex-influenced inheritance w/ zero penetrance in one sex. ex: changes during puberty and cock feathering(autosomal recessive trait sex-limited to males) |
| precocious puberty | male-lim. males with this autosomal dom. allele undergo pub. at a early age, usually before 4 yrs. receptor for LH is mutated and on even in the absence of LH. same genes have no effect on fem. |
| LH | Luteinizing hormone. stimulates the production of testosterone. |
| cytoplamsic inheritance | inheritance of characteristics encoded by genes found in cytoplasm. cytoplasm is usually contributed by only one parent so these characteristics are inherited from only one parent. |
| LHON | result from mutations in mtDNA. experience rapid loss of vision from death of optic nerve cells, usually in early adulthood. |
| genetic maternal effect | (not cytoplasmic inher) genotype of mother determines the phenotype of children. |
| genomic imprinting | the differential expression of genetic material depending on whether it is inherited from the male or female parent. ex) expression of Igf2, only expressed when transmitted by dad. |
| epigenetics | phenomena due to alterations to DNA that don't include changes in the base seq. affect the way dna seq is expressed. such alterations are stable and heritable. |
| genomic imprinting | whether the gene passes thru the egg or sperm determines how much methylation takes place. methylation remains on dna thru mitosis and ult. determines if gene is expressed in offspring. |
| epigenetic marks | reversible changes to DNA that influence the expression of traits. may be responsible for cancer. |
| SCID | (bubble boy). X-linked mutant "interleukin 2 receptor gamma" (IL2RD). No bubble girls b/c boys are isolated. also, 1 normal X comes from mom which is makes enough normal to have normal immune system. |
| Possible solution for SCID | Bone marrow transplant to replace faulty immune cells. |
| Duchenne Muscular Dystrophy (DMD) | mutation in dystrophon gene. males have short lifespan. |
| DMD in females | produces a protein that stays in cell (heterozygous carrier). Some cells can have normal X and some have mutant X activated. Women will have active patches of muscle and abnormal patches. Random areas are affected. |
| X-linked diseases | hemophilia, SCID, DMD and colorblindness. Females can be homo or heterozygous. Males are hemizygous. |
| male pattern baldness | a sex influenced trait. autosomal allele dominant in males and recessive in females. |
| If a male is hetero/homozygous for male pattern baldness... | the male will start balding later/earlier in life. |
| If a woman is heterozygous for baldness... | female will not bald, gene behaves like recessive allele. |
| If a woman is homozygous for baldness... | She will bald later in life. |
| cock-feathering | autosomal recessive trait sex-linked to males. hh = bald male Hh/hh= hen feathering in males. hh/Hh/HH = hen feathering in females. |
| dominant lethal alleles | tend to disappear b/c carriers will die before reproductive age. ex: Y alleles for coat color in mice is recessive for fatality, need 2 copies . exception: huntingtons disease. |
| lethal alleles | tend to be recessive |
| multiple alleles (allelic series) | more than 2 alleles in population, but only 2 in an individual. inherince sim. to when 2 alleles are present, but greater variety. ex: ABO blood group system. |
| antigens | molecules recognized by the immune system. |
| Universal blood acceptor | AB |
| Universal donor | Type O |
| Type A blood has type__antigen and produces type__antibody and will attack type__antibodies. | A, B, A |
| Cross and Type Match Test | mix blood from donor and acceptor to see if clumping occurs (bad) |
| Type AB has type__antigen and produces__antibody and will attack__antibody | AB, none, none |
| Rh (Rhesus) factor | Dominant allele, D. Has 3 genotypes and 2 phenotypes. DD/Dd = + and dd = -. |
| dominant lethal alleles | tend to disappear b/c carriers will die before reproductive age. ex: Y alleles for coat color in mice is recessive for fatality, need 2 copies . exception: huntingtons disease. |
| lethal alleles | tend to be recessive |
| multiple alleles (allelic series) | more than 2 alleles in population, but only 2 in an individual. inherince sim. to when 2 alleles are present, but greater variety. ex: ABO blood group system. |
| antigens | molecules recognized by the immune system. |
| Universal blood acceptor | AB |
| Universal donor | Type O |
| Type A blood has type__antigen and produces type__antibody and will attack type__antibodies. | A, B, A |
| Cross and Type Match Test | mix blood from donor and acceptor to see if clumping occurs (bad) |
| Type AB has type__antigen and produces__antibody and will attack__antibody | AB, none, none |
| Rh (Rhesus) factor | Dominant allele, D. Has 3 genotypes and 2 phenotypes. DD/Dd = + and dd = -. |
| Rhogam | an antibody given to mother to destroy RBC that come from baby that may enter mothers blood stream so she doesn't become sensitized. |
| IgM | Larger and doesn't cross placenta. |
| IgG | Smaller and may cross the placenta. |
| bombay phenotype | recessive epistasis. supresses the expression of alleles at ABO locus. The ABO locus is hypostatic to the recessive h allele. functions as O. |
| FUT1 (fuctosyl transferase) | The recessive allele h prevents synthesis of complete H substance-lacks fucose moeity so enzymes made by A and B alleles can't add appropriate sugars. |
| recessive epistasis | 9:3:4 homozygous recessive allele for a gene masks the expression of another gene at a different loci. ex: labs and bombay phenotype. |
| dominant epistasis | 12:3:1 The dominant allele at one locus masks the effect of alleles at another locus. ex: fruit color in summer squash. |
| duplicate recssive epistasis | 9:7 both genes are epistatic to each other. ex: albinism in snails |
| cytoplasmic inheritance | DNA from sperm enters oocyte to form male pronucleus in fertilized egg, but all mitochondria are provided by oocyte. mito segregate randomly in cell div. |
| heteroplasmy | mix of mitochondria w/wild type and mutated genes. |
| homoplasmy | either all mtio w/wild type or all mutated genes |
| mitochondrial mutations usually affect only certain tissues... | that require high amts of ATP, require synthesis of sufficient quantities of functional mito proteins (coded for by mtDNA). |
| LHON (Leber's hereditary optic neuropathy) | degeneration of optic nerve accompanied by increasing blindness. Caused by missense mutation of mtDNA gene coding for a subunit of NADH-CoQ reductase |
| Ooplasmic transfer | mitochondria from a healthy woman are injected into the oocyte of women with mitochondrial disorder. |
| maternal effect | (not cytoplasmic inheritance) genotype of mother determines phenotype of progeny. |
| polygenic inheritance | many genes act together for 1 phenotype (skin color, ht, eye color). Continuous characteristic. Effect of alleles is additive or synergistic. |
| polygenic traits | also called "quantitative trait" or "quantitative characteristic" as many phenotypes are possible and any individuals phenotype must be described by quantitative measurement. |
| genomic imprinting | the differential expression of genes depending on whether the gene is inherited from the male or female parent. |
| Igf2 | ex of maternal imprinting. maternal copy is silent. the protein, insulin like growth factor is expressed in fetus and placenta & promotes fetal growth by directing more maternal nutrients thru placenta. |
| H19 | ex of paternal imprinting. allele derived from father is inactive. |
| Consequence of genomic imprinting | imprinted genes are expressed as if there was only one copy present in a cell even though there are 2. causes monoallelic inheritance. no change in DNA seq. |
| How does genomic imprinting occur? | The DNA regulatory regions of imprinted gene is methylated at specific cytosine in a sex specific manner during gamete formation. |
| epigenetic inheritance | a process that affects the expression of genes; often a process that brings about genetic alterations that can be reversed, such as the methylation of DNA. |
| 3 reasons for Pedigree analysis in humans | controlled mating not possible, long generation time, small family size. |
| pedigree | pictorial representation of a family history, a family tree that outlines the inheritance of one or more characteristics. |
| analysis of pedigrees requires.. | recognizing patters associate w/different modes of inheritance. |
| Wardenburg syndrome | autosomal dominant trait. deafness, fair skin, visual problems and a white forelock. |
| autosomal dominant trait appears in... | both sexes w/equal frequence and does not skip generations. unaffected person do not transmit the trait. |
| autosomal recessive trait appears in... | both sexes w/equal frequency and seems to skip generations. are more likely to appear among progeny of related parents. |
| X-linked recessive trait appears in... | more often in males. Not passed from father to son, but can pass to daughters. |
| X-linked dominant trait appears in... | both males and females. Affected male has an affected mother. does not skip generations. Affected female (hetero) pass the trait to about 1/2 their sons and 1/2 daugthers. |
| Y-linked traits | appear only in males. passed only from father to son. |
| amniocentesis | small amt of amniotic fluid is withdrawn from amniotic sac which contains fetal cells which are separated from amniotic fluid, cultured and tested. ` |
| chorionic villi sampling (CVS) | a catheter is used to remove a small piece of chorion. cells of the chorion are used directly for genetic testing. very invasive, can harm fetus, or cause bleeding in placenta. |
| fetal cell sorting | fluorescence/magnetic anti-CD71 to fetal cells. a specific antigen is found only on fetal cells that bind to anti-CD71. |
| blood tests | alpha-fetoprotein is very high in fetuses with neural tube defects. |
| interchromosomal recombination | occurs btwn genes on different chromosomes (ind assortment). Due to random segregation of chromosomes in ana I of meiosis. |
| intrachromosomal recombination | occurs btwn genes located on same chromosomes. Due to crossoing over in pro I of meiosis. |
| complete linkage | leads to nonrecombinant gametes and nonrecombinant progeny. |
| crossing over between linked genes | leads to recombinant gamete and recombinant progeny. frequency depends on gene proximity. |
| With independent assortment, ___the progeny are recombinant and ___are not. | 1/2, 1/2 |
| If genes are completely linked (no crossing over)only _______progeny are produced. | nonrecombinant |
| You can never have more than ___% recombination. | 50% |
| genetic maps are determined by... | calculating recombination frequencies. |
| linkage group | consists of genes located together, less than 50 m.u. apart on same chromosome. |
| In Cis/Trans | phenotype is the same, but rearrangement of genes at chromosomal level is different and affects how genes are passed on. |
| coefficient of coincidence | the ratio of observed double cross overs to expected dbl cross overs. |
Created by:
jriendea