Based on the diathesis-stress model schizophrenia is the result of interaction between environmental and biological/genetic factors. According to this model, when the combination of the predisposition (diathesis) and the stress (biological, social, and psychological stressors) exceeds a threshold, the person will develop a disorder.
Water is needed to break the hydrogen bonds in the starch aggregates, allowing ready access to stored energy.
How do the genes in our DNA influence our characteristics? For example, how can a gene determine
whether a person is an albino with very pale skin and hair?
Basically, a gene is a segment of DNA that provides the instructions for making a protein, and
proteins influence our characteristics. This chart describes how two different versions of a gene result
in two different versions of a protein which in turn can result in either normal skin and hair color or
albinism.
DNA Protein Characteristic
Version of the gene that provides
instructions to make
normal protein enzyme
Normal enzyme that makes the
pigment molecule in skin and
hair
Normal skin and hair
color
Version of the gene that provides
instructions to make
defective enzyme
Defective enzyme that does
not make this pigment
molecule
Albinism (very pale
skin and hair)
A gene directs the synthesis of a protein by a two-step process.
The first step is transcription of the gene in the DNA.
Transcription produces a messenger RNA (mRNA) molecule.
The second step is translation of the mRNA molecule.
Translation produces a protein molecule.
During transcription, the sequence of
nucleotides in a gene in the DNA is
copied to a corresponding sequence
of nucleotides in mRNA.
During translation, the sequence of
nucleotides in the mRNA determines
the sequence of amino acids in the
protein.
After translation, the sequence of amino acids in the protein determines the structure and function of
the protein. Differences in protein function can influence characteristics such as normal skin and hair
color vs. albinism.
