Introduction to Biology

• Biology is the scientific study of life.
• It examines the structure, function, growth, origin, evolution, and distribution of living organisms.
• Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species.
• Living organisms must maintain homeostasis to survive.
• Homeostasis is maintaining a stable internal environment despite changes in the external environment.

Subdisciplines of Biology

• Biochemistry studies the chemical processes within and relating to living organisms.
• Botany is the scientific study of plants.
• Cellular biology studies the cell as the fundamental unit of life.
• Ecology studies the interactions of organisms with each other and their environment.
• Evolutionary biology studies the processes that have led to the diversity of life on Earth.
• Genetics studies genes, heredity, and variation in living organisms.
• Marine biology studies life in the oceans.
• Microbiology studies microorganisms, such as bacteria, viruses, and fungi.
• Molecular biology studies the molecular basis of biological activity.
• Physiology studies the functions and mechanisms of living organisms and their parts.
• Zoology is the scientific study of animals.

Key Concepts in Biology

• Cell theory states that all living organisms are composed of cells, cells are the basic units of structure and function in living organisms, and all cells come from pre-existing cells.
• Gene theory states that traits are inherited through genes, which are specific regions of DNA that code for particular traits.
• Evolution occurs through natural selection, where organisms with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring.
• Homeostasis is the maintenance of a stable internal environment in living organisms, which is essential for their survival.
• Energy is required for all life processes, and it flows through ecosystems from producers to consumers.

Genetics

• Genetics is the study of heredity and variation in living organisms.
• It explores how traits are passed down from parents to offspring.
• It studies the structure, function, and inheritance of genes.
• Genes are the basic units of heredity.
• Genes are segments of DNA that contain the instructions for building proteins or performing other functions in the cell.
• Genes are organized into chromosomes.
• Chromosomes are structures within the cell nucleus that carry the genetic information.
• The complete set of genetic instructions for an organism is called its genome.

Mendelian Genetics

• Gregor Mendel is considered the father of genetics.
• He discovered the basic principles of heredity through his experiments with pea plants.
• Mendel's laws of inheritance include the law of segregation and the law of independent assortment.
• The law of segregation states that each individual has two alleles for each trait, and these alleles separate during gamete formation, with each gamete receiving only one allele.
• The law of independent assortment states that the alleles of different genes assort independently of one another during gamete formation.
• A dominant allele is one that expresses its trait even when paired with a recessive allele.
• A recessive allele is one that only expresses its trait when paired with another recessive allele

Molecular Genetics

• Molecular genetics studies the structure and function of genes at the molecular level.
• DNA (deoxyribonucleic acid) is the molecule that carries the genetic information in most living organisms.
• RNA (ribonucleic acid) is a molecule that plays a key role in gene expression.
• The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to protein.
• Transcription is the process of copying DNA into RNA.
• Translation is the process of using RNA to synthesize proteins.
• Mutations are changes in the DNA sequence that can lead to variations in traits.

Population Genetics

• Population genetics studies the genetic variation within and between populations of organisms.
• It examines how allele frequencies change over time due to factors such as natural selection, genetic drift, and gene flow.
• The Hardy-Weinberg principle describes the conditions under which allele and genotype frequencies in a population will remain constant from generation to generation.
• Genetic drift is the random change in allele frequencies due to chance events.
• Gene flow is the movement of genes between populations.
• Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce, leading to changes in allele frequencies over time.

Genomics

• Genomics is the study of the entire genome of an organism, including its genes and non-coding DNA.
• It involves sequencing, mapping, and analyzing genomes to understand the structure, function, and evolution of genes.
• Genomics has applications in medicine, agriculture, and biotechnology.
• Genome sequencing is the process of determining the complete DNA sequence of an organism.
• Genome mapping is the process of locating genes and other DNA sequences on chromosomes.
• Comparative genomics compares the genomes of different species to understand their evolutionary relationships and identify genes that are responsible for specific traits.

Genetic Engineering

• Genetic engineering is the process of modifying the genes of an organism.
• Recombinant DNA technology is used to insert foreign DNA into an organism's genome.
• Genetically modified organisms (GMOs) are organisms whose genes have been altered through genetic engineering.
• Gene therapy is the use of genes to treat or prevent disease.
• CRISPR-Cas9 is a gene editing technology that allows scientists to precisely modify DNA sequences in living organisms.