4. Development is characterized by lifelong plasticity
4
Chapter 3
Biological Beginnings (Genetic foundations)
What is a gene & what does it code for? Define DNA, chromosome, allele.
Gene:
a segment of DNA that codes for synthesis of a proteins
o
Found in the cell’s nucleus as part of a chromosome
o
Protein enzymes are the body’s tools (synthesize, breakdown, change)
The protein a cell has determines its function
o
Genes hold the instructions for building proteins
Does NOT code for behavior
DNA:
blue print, the master plan for the body
o
Passed from parents to offspring
o
Two copies of each gene, one from each parent
o
Double helix structure
o
A particular sequence of nucleotide pairs
Adenine – Thymine; Guanine – Cytosine
Every 3 rungs of this is an amino acid
Chromosome:
a threadlike structure made largely of DNA molecules wound tightly
around clumps of proteins
o
Humans have 23 pairs of chromosomes, 46 in total
o
The 23
rd
chromosome is the sex chromosome
Girl: XX Boy: XY
Allele:
various forms of a particular gene (may be several), options for a particular form
of a gene, variants are alleles
o
Example:
eye color--- many options, such a green, blue, brown, etc.
