DNA
All Organisms have a set of instructions that determine their characteristics.  These instructions are called genes and contain the instructions for life that are passed from parents to offspring during reproduction. 

The inherited instructions that are passed from parent to offspring exist as a code. The DNA molecule which makes up our genes contains this code. 

Asexual v. Sexual Heredity
The DNA molecules must be accurately replicated before being passed on. Asexually reproducing organisms normally pass on this genetic code identically between the parent and offspring, while the offspring of sexual reproduction produce offspring that resemble their parents, but exhibit some variations from them.

Changes in DNA or mutations which occur in non sex cells of a sexually reproducing organism will not be passed on to their offspring.   Mutations which occur in sex cells or gametes will be frequently be passed on to their offspring.

Protein Synthesis
Once the coded information contained in the DNA molecule is passed on, it is used by a cell to make proteins. The proteins that are made become cell parts and carry out most functions of the cell.   The subtle differences in DNA between different human beings and different species results in the production of different proteins.    This is a major reason why we show individual differences.

Genetic Engineering
Throughout recorded history, humans have used selective breeding and other methods to produce organisms with desirable traits. Our current understanding of genetics and heredity allows for the manipulation of genes and the development of new combinations of traits and new varieties of organisms.   This includes various aspects of DNA technology, including recombinant DNA technology.  Scientists have also developed many ways of determining the genetic makeup of different organisms, including humans.

This page and the links at the left are designed to aid students in reviewing the following topics which will appear on the New York State Living Environment Regents Examination; DNA structure, sexual and asexual heredity, protein synthesis, and genetic engineering.  In addition, students may test their knowledge of the material presented here by accessing multiple-choice questions from past Regents Exams.