Principles of Genetics Chapter 1

Study Notes

DNA is composed of nucleotides, which include phosphate, sugar, and bases (guanine, adenine, thymine, cytosine), serving as the blueprint of life contained in the nucleus.
Heredity refers to the passing of traits from parents to offspring, with observable variations in families.
Variations among individuals arise due to unique combinations of genes, where errors in gene pairing can lead to conditions like Down syndrome.
Genetics is the scientific study of heredity and variation, focusing on mechanisms of inheritance and their effects on organisms.

Genes are the fundamental units of inheritance and are composed of DNA, directing protein formation and influencing traits.
The difference in protein structure accounts for individual variations.
Gregor Mendel is recognized as the father of genetics, known for his experiments with pea plants, establishing the framework for Mendelian genetics.

Genetics differs from genealogy, which studies the lineage and relationships among families.
Alleles are various forms of the same gene; mutations can create different alleles.
Chromosomes consist of organized DNA segments, with humans possessing 46 chromosomes (23 pairs), including 22 autosomes and 1 pair of sex chromosomes (XX for females and XY for males).
Karyotype is an individual’s complete set of chromosomes.

Population genetics explores allele frequencies within populations, contributing to evolutionary understanding.
The gene pool includes all alleles of a population; individuals possess two alleles for each gene.
Phenotype refers to the observable traits resulting from an individual's genotype, which is the combination of alleles.

Somatic cells are body cells, while germline cells produce gametes and can contribute to both somatic and germline lineage.
Differentiation is the process through which cell types develop distinct structures and functions based on gene expression.

Risk assessment evaluates the likelihood of a particular health condition based on genetic background, family history, and other factors.
Relative risk compares the likelihood of developing a condition between individuals with risk factors versus those without.
Empiric risk is derived from observations rather than theoretical principles, based on how often conditions have occurred in similar family histories.

Multifactorial traits stem from multiple genes and environmental influences, while Mendelian traits are linked to single genes.
Applications include forensics, healthcare (disease prediction and treatment), and agricultural advancements through crop and animal breeding.

Bioethics addresses the moral implications of genetic research and its applications, emphasizing privacy, discrimination, and individual rights stemming from advances in medical technology.

Autosome: Chromosome not involved in determining sex.
Dominant allele: Functions even when only one copy is present; recessive alleles require two copies for expression.
Gene expression is the process by which information from genes is used to synthesize proteins.
Polymorphism describes variations in the genome present in at least 1% of the population.
Sex chromosomes determine the biological sex of an organism.

The human genome contains approximately 3 billion base pairs and around 28,000-34,000 genes; only 1.5% encode proteins.
Non-coding sequences play roles in regulating gene expression, turning proteins on and off as needed.