phenylketonuria A defective enzyme that causes incorrect processing of the

Phenylketonuria a defective enzyme that causes

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- Down’s Syndrome – Has a round face, a flattened skull, an extra fold of skin over the eyelids, a protruding tongue, short limbs, and intellectual and motor disabilities; they contain an extra chromosome 21 - Turner’s Syndrome – A chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted; females are short in stature and have a webbed neck, they may be infertile and have difficulty in mathematics - Klinefelter’s Syndrome – A chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY; males with this disorder have undeveloped testes, and they usually have enlarged breasts and become tallKnow percent of genetic relatedness among parent/child, siblings, and grandparents:- Child to parent 50%- Siblings 50% (average)- Grandchild to grandparent 25%- Identical twin 100%- Fraternal Twins 50%Know Gotileb’s Epigenetic Theory:- Epigenetic View: development is the result of an ongoing, bidirectional interchange between heredity and the environment- Genes and their products interact with the environment to guide development; genes and their environment are partners in directing organisms – they co-act.- Genetic Endowment – Makes outcomes/paths probable- Environmental Factors – Can influence genes and genetic outcomes Define Epigenetics:- Ways in which environmental influences alter the expression of genes; altering the expression of genes without any change in the actual DNA sequence; involves changes instructures associated with chromosomes and DNA that affect gene expression without altering DNA sequenceKnow the two mechanisms discussed in class: Histone Acetylation and DNA methylation:- Histone Acetylation – Acetylation of the lysine residues at the N terminus of histone proteins removes positive charges, thereby reducing the affinity between histones and DNA. This allows RNA polymerase and transcription factors easier access to the promotor region. Therefore, in most cases, histone acetylation ENHANCES transcription, histone deactivation REPRESSES transcription.- Acetyl groups attached to the histones can affect the accessibility of the DNA - DNA Methylation – The addition of a methyl group to the DNA’s cytosine base. It may affect gene transcription through several different mechanisms (usually repression of
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transcription). The methylation pattern is heritable after cell division. Therefore, DNA methylation plays an important role in cell differentiation during development. - Turns off transcription by causing the promotor region to be blocked - Methylated DNA or histones that persist:- Restraint stress in rats- Chronic social defeat in rats- Depression in humans
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