Developmental Psychology Essay

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

Genotype vs. Phenotype
- Genetic makeup of the individual

- 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


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


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
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

Reproductive Choices
Genetic counseling
 Prenatal diagnosis and fetal medicine

Genetic engineering & gene therapy

 Reproductive Technologies


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