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This article explores the indirect and direct effects of smoking during pregnancy on fetal development, and how these effects may manifest themselves in adults. It also discusses the correlation of weight, biological siblings, identical twins, fraternal twins, adopted children, and unrelated children in relation to weight and relatedness.
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Development • Homework #2 is due 10/17 • Bonus #1 is due 10/24
So, Smoking during pregnancy may have indirect and/or direct affects on fetal development, and these affects may manifest themselves in adults.
Correlation of weight (BMI) % Biological siblings 34 Parents and children living together 26 Identical twins reared together 80 Identical twins reared apart 72 Fraternal twins reared together 43 Adopted children and parents 4 Unrelated children living together 1 Correlation of weight and relatedness
Nature and Nurture: Are traits coded for by genes fixed while traits coded for by the environment are under our control?
Vertebrate Development: from zygote to adult
Development of a mouse paw: yellow areas show dying cells CB 21.19
Totipotency is limited to early stages of animal development
Gene expression can be controlled at many points between DNA and making the final proteins. • Changes in the various steps of gene expression control when and how much of a product are produced.
Why change gene expression? • Different cells need different components • Responding to the environment • Replacement of damaged/worn-out parts
DNA packaging fluctuates…genes being expressed are unpackaged, genes not needed are tightly packaged.
Normally DNA is loosely packaged During mitosis DNA is tightly packaged as chromosomes and individually visible box 2.1
DNA packaging fluctuates…Some of the tight packaging of DNA is irreversible.
Irreversible packaging of DNA partially explains the loss of totipotency.
Embryonic Stem Cells are totipotent Adult Stem Cells are pluripotent (only form some cell types)
Developmental information can be encoded by both genetic and non-genetic information. Fig 12.2
All humans are female for the first nine weeks of development
All humans are female for the first nine weeks of development
Down’s Syndrome is caused by an extra chromosome 21. Too much information disrupts normal development.
4 whorls of a flower Flower parts: Complexity from a few simple genes
Each whorl expresses a specific combination of three genes CB 21.20
Changing expression of A, B, or C genes changes organ identity CB 21.20
Development • Homework #2 is due 10/17 • Bonus #1 is due 10/24