Chapter 5

Cards (10)

Chromosomes - strands of hereditary material
Each human nucleus has 23 pairs
Egg and sperm cells have 23 unpaired chromosomes  
Genes - sections along each chromosome that controls the chemical reactions that direct development
Invisible traits
XX - Female
XY - Male 
Sex-linked genes are normally found on the X chromosome
Sex-linked genes impact males more than females
Dominant Trait - expressed in a person even if they only have one copy of that gene
Brown Eyes
Freckles
Dimples
Straight Hairline
Recessive Trait - requires two copies of the gene to be expressed.
Widows Peak
Blue Eyes
Left-Handedness
Color Blindness
Genetic (hereditary) condition
Pass along the X Chromosome
Recessive Trait
Red/Green colorblindness affects men more than women
Most colorblind women have full colorblindness
Monozygotic Twins - one egg is fertilized and splits into two
Identical Genes
Shared placenta
Identical Twins
Dizygotic Twins - two separate eggs are fertilized at the same time
Share half their genes
Separate placenta
Fraternal Twins
Cross-Sectional - compares groups of individuals with different ages at the same time 
Longitudinal - follows a single group of individuals as they develop
Sequential Design - compares different people at different ages as they develop 
Combines Cross-Sectional and Longitudinal
Zygote - fertilized egg cell
Embryo - unborn child until the end of the seventh week following conception, pregnancy is detectable
Fetus - eight weeks after conception until birth
Infants' Hearing
Habituation - decreased response to a repeated stimulus
Dishabituation - when a change in a stimulus increases a previously habituated response 
Habituation - initially an infant may be startled with a stimulus, but after time they still hear the stimulus but they have adjusted to it and are no longer startled
Dishabituation - if the frequency of the sound changes, the infant is once again startled

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