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Chapter 14 - Coggle Diagram

- - - - mutant phenotypes- they are alleles assumed to have originated as changes, or mutations, in the wild-type allele.
        
        mitochondrial myopathy causes weakness, intolerance of exercise, and muscle deterioration
        
        hereditary optic neuropathy, which can produce sudden blindness in people as young as their 20's or 30's
      - Sex Linked Gene- A gene located on either sex chromosomes
        
        X-linked genes-genes located on the X chromosome
        
        linked genes- genes located close enough together on a chromosome that they tend to be inherited together.
        
        genetic recombination- the production of offspring with combinations of traits that differ from those found in either P generation parent.
        
        recombinant types-an offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself.
        
        crossing over-the reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.
        
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  - - - Barr body- a dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome.
        
        Down syndrome-a human genetic disease usually caused by the presence of an extra chromosome 21; characterized by developmental delays and heart and other defects that are generally treatable or non-life-threatening
        
        Klinefelter syndrome, have male sex organs, but their testes are small and produce little or no sperm.
        
        Turner syndrome, occurs about once in every 2,500 female births and is the only known viable monosomy in humans. Although these X0 individuals are phenotypically female, they usually lack the ability to reproduce because their sex organs do not mature. When provided with estrogen replacement therapy, girls with Turner syndrome do develop secondary sex characteristics.
        
        cri du chat (“cry of the cat”), results from a specific deletion in chromosome 5. A child born with this deletion has a small head with unusual facial features, severe intellectual disabilities, and a cry that sounds like the mewing of a distressed cat. Such individuals usually die in infancy or early childhood.
- - - - Hybridization-mating, or crossing, of two true-breeding varieties
        
        P generation-parental generation
        
        F2 generation-second filial generation
      - Law of Segragation- the two alleles for a heritable character segregate (in other words, separate from each other) during gamete formation and end up in different gametes.
        
        Dominant- the allele that is fully express
        
        Recessive- the allele that has is not observed in the organism.
        
        Alleles- alternative versions of a gene
        
        Alternative versions of genes account for variations in inherited characters. For each character, an organism inherits two versions (that is, two alleles) of a gene, one from each parent. If the two alleles at a locus differ, then one, determines the organism’s appearance; the other, has no noticeable effect on the organism’s appearance.
        
        Punnett square-a diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup. Where lower case letter represent recessive alleles and capital letter the dominant alleles.
        
        Homozygote-An organism that has a pair of identical alleles for a gene encoding a character
        
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        pleiotropy- the ability of a single gene to have multiple effects.
        
        epistasis- the phenotypic expression of a gene at one locus alters that of a gene at a second locus.
        
        Complete Dominance- the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
        
        Incomplete Dominance-some genes, however, neither allele is completely dominant, and the F1 hybrids have a phenotype somewhere between those of the two parental varieties.
        
        CoDominance-two alleles each affect the phenotype in separate, distinguishable ways.
        
        Law of Independent Assortment-two or more genes assort independently—that is, each pair of alleles segregates independently of any other pair of alleles—during gamete formation
        
        monohybrids- they were heterozygous for the one particular character being followed in the cross.
- - - - Achondroplasia- a form of dwarfism that occurs in one of every 25k people.
        
        Huntington’s disease, is caused by a lethal dominant allele that has no obvious phenotypic effect until the individual is about 35 to 45 years old.
        
        Amniocentesis- a test that can determine whether the developing fetus has a serious recessive disease
        
        Chorionic Villus Sampling (CVS)- a physician inserts a narrow tube through the cervix into the uterus and suctions out a tiny sample of tissue from the placenta