Developmental Psychology Essay

770 Words May 9th, 2015 4 Pages
Biological & Environmental
Foundations
Chapter 2
Developmental Psychology

Genotype vs. Phenotype
Genotypes:
- Genetic makeup of the individual

Phenotypes:
- Directly observable characteristics Genetic Foundations
Some definitions…
 Genes: Basic unit of genetic information
 Chromosomes: rod-like portions of DNA which store/transmit genetic information




46 chromosomes in each cell (23 pairs)

DNA: deoxyribonucleic acid; chemical substance that makes up genes, chromosomes Mitosis
DNA duplicates itself through mitosis
 Permits a one-celled fertilized ovum to develop into a human being


Sex Cells







Gametes: sex cells (sperm, ovum); each have 23 chromosomes; combine to
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bined trait (intermediate between the two)
Ex: sickle cell trait

X-linked inheritance:


Harmful allele is carried

on X-chromosome


More likely to affect

males


Ex: hemophilia

Genetic Inheritance (cont)


Genetic Imprinting







Alleles are imprinted (chemically marked) so that one member of the pair is activated regardless of makeup
Often imprint is temporary
Ex: fragile X syndrome

Mutation



Sudden change in a segment of DNA
Can affect 1 or 2 genes or many

Genetic Inheritance (cont)


Polygenic Inheritance



Many genes influence the characteristics
(phenotype)
Complex, much still unknown about it

Chromosomal Abnormalities


Down Syndrome






Most common chromosomal disorder
1/800 live births
Extra chromosome on 21st pair

Fragile X Syndrome



Injured gene on X c’some
Example of genetic imprinting

Chromosomal/Genetic Disorders


Sickle-cell Anemia






Blood disorder
1/400 individuals have the disease
Incomplete dominance

Klinefelter’s syndrome




Affects males (1/400)
Extra X chromosome
Sex-chromosome abnormality


Others include, Turner Syndrome (missing 2nd X c’some), Extra Y c’some (XYY), and three X c’somes
(XXX)

Reproductive Choices
Genetic counseling
 Prenatal diagnosis and fetal medicine




Genetic engineering & gene therapy

Adoption
 Reproductive Technologies






Donor

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