Section 3.4 Flashcards
Each human has how many pairs of chromosomes in the nucleus?
23 pairs.
Dizygotic Twins
Develop from two eggs and share only half their genes.
Aka Fraternal Twins
Can be same or opposite sex
Dominat
A single copy of the gene is sufficient to produce its effect.
Epigenetics
Deals with change in gene expression as a result of environmental influences, without modification of the DNA sequence.
Evolution
A gradual change in the frequency of various genes from one generation to the next.
Gene
Controls the chemical reactions that direct development.
Example : controlling height or hair color
Heritability
An estimate of the variance within a population that is due to heredity.
Monozygotic Twins
Develop from a single fertilized egg (Zygote) and therefore have identical genes.
Aka Identical Twins
Same sex only
Multiplier effect
A small initial advantage in some behavior, possibly genetic in origin, alters the environment and magnifies that advantage.
Phenylketonuria (PKU)
An inherited condition that, if untreated, leads to mental retardation.
Recessive
It’s effect appear only if the dominant gene is absent.
Gene for blue eyes
Sex-Limited Gene
Occurs equally in both sexes but exerts its effects mainly or entirely in one or the other.
Sex-Linked Gene
Genes located on the X or Y chromosome.
X chromosome
A female has 2 of these in each cell, while a male has only one.
Y chromosome
Only makes have this chromosome.
