History and Development of Genetics - The word 'genetics' stems from the ancient Greek γενετικός (genetikos) meaning genitive/generative, which in turn derives from γένεσις (genesis) meaning origin. - The observation that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. - The modern science of genetics began with the work of Gregor Mendel in the mid-19th century. - Imre Festetics, a Hungarian noble, used the word 'genetic' in a hereditarian context before Mendel. - Festetics argued that organisms inherit their characteristics, not acquire them. - Mendel's work provided examples where traits were definitely not blended after hybridization, showing that traits are produced by combinations of distinct genes. - The importance of Mendel's work did not gain wide understanding until 1900, after his death. - William Bateson coined the word 'genetics' in 1905. - Bateson popularised the usage of the word 'genetics' to describe the study of inheritance.

Molecular Genetics - DNA is the molecular basis for biological inheritance. - Genes are known to exist on chromosomes, which are composed of both protein and DNA. - Scientists did not know which of the two components, protein or DNA, was responsible for inheritance. - Nettie Stevens discovered that sex is a chromosomal factor and is determined by the male. - Thomas Hunt Morgan argued that genes are on chromosomes based on observations of a sex-linked white eye mutation in fruit flies.

Gene Structure and Function - Gene structure and function are studied within the context of the cell, the organism, and the population. - Variation and distribution of genes are important areas of study in genetics. - Gene structure and function play a role in traits, behavior, and development. - Molecular genetics is a subfield of genetics that focuses on the structure and function of genes. - Epigenetics is another subfield of genetics that studies how gene expression can be influenced by factors other than changes in DNA sequence.

Nature vs. Nurture - Genetic processes work in combination with an organism's environment and experiences to influence development and behavior. - The intracellular or extracellular environment of a living cell or organism can affect gene transcription. - The example of genetically identical corn seeds growing to different heights in different climates illustrates the interaction between genes and the environment. - The study of nature vs. nurture explores the relative contributions of genetics and environmental factors in shaping traits and behavior. - Genetics has provided insights into the complex interplay between nature and nurture in determining an organism's characteristics.

DNA Structure and Inheritance - Frederick Griffith discovered transformation in 1928. - Avery-MacLeod-McCarty experiment identified DNA as the molecule responsible for transformation in 1944. - Hershey-Chase experiment confirmed DNA as the genetic material of viruses in 1952. - James Watson and Francis Crick determined the structure of DNA in 1953. - DNA structure showed how genetic information is encoded in nucleotide sequences. - DNA is used as a template to create messenger RNA (mRNA). - mRNA carries the genetic code for protein production. - Nucleotide sequence of mRNA determines the amino acid sequence in protein. - Translation between nucleotide sequences and amino acid sequences is known as the genetic code. - DNA controls the process of protein production through mRNA. - Tomoko Ohta proposed the nearly neutral theory of molecular evolution in 1973. - Frederick Sanger developed chain-termination DNA sequencing in 1977. - Kary Banks Mullis invented the polymerase chain reaction (PCR) in 1983. - Human Genome Project sequenced the human genome in 2003. - Department of Energy, NIH, and Celera Genomics also contributed to genome sequencing. - Gregor Mendel studied segregation of heritable traits in pea plants. - Inheritance occurs through passing discrete heritable units called genes. - Each individual plant has two copies of each gene, inherited from each parent. - Dominant and recessive alleles determine observable traits (phenotypes). - Mendel's first law or the Law of Segregation explains the random inheritance of alleles. - Geneticists use symbols and diagrams to describe inheritance. - Genes are represented by letters, with + symbol for non-mutant allele. - Punnett square is a common diagram used to predict cross-breeding results. - Pedigree charts are used to represent the inheritance of traits in humans. - Multiple generations and relationships are shown in pedigree charts. - DNA is composed of deoxyribose, a phosphate group, and four types of bases: adenine, cytosine, guanine, and thymine. - Bases pair specifically (T&A, C&G) between two backbones, forming like rungs on a ladder. - Nucleotides connect to make long chains of DNA. - DNA exists as a double-stranded molecule, coiled into a double helix structure. - Each nucleotide in DNA pairs preferentially with its partner nucleotide on the opposite strand. - DNA wraps around proteins called histones to form chromosomes. - Genes exist as stretches of sequence along the DNA chain. - Bacteria have a single circular genophore, while eukaryotic organisms have DNA arranged in multiple linear chromosomes. - Chromatin, composed of nucleosomes, organizes and controls access to DNA. - The full set of hereditary material in an organism is called the genome. - Nonchromosomal genes can be found outside of the nucleus in organisms like plants (chloroplasts) and other organisms (mitochondria). - These genes can be passed on by either partner in sexual reproduction. - Nonchromosomal genes control a variety of hereditary characteristics that replicate throughout generations. - Ruth Sager helped in the discovery of nonchromosomal genes. - These genes remain active throughout generations. - Most animals and many plants are diploid, containing two copies of every gene