DNA: The Basis of Life's Diversity

• DNA is the basis of the diversity of living things

Key Vocabulary

• DNA is the hereditary material in humans and almost all other organisms
• Nucleotide is the basic building block of nucleic acids, composed of a sugar, a phosphate group, and a nitrogenous base
• Nitrogenous Base is an organic molecule with a nitrogen atom that has the chemical properties of a base
• Double Helix describes the appearance of double-stranded DNA, which is shaped like a spiral staircase
• Helicase are enzymes that bind and may remodel nucleic acid or protein
• DNA Polymerase are enzymes that synthesize DNA molecules from deoxyribonucleotides, the building blocks of DNA
• Primase is a type of RNA polymerase that synthesizes short RNA sequences called primers, which serve as a starting point for DNA synthesis
• Ligase is an enzyme that catalyzes the joining of two large molecules by forming a new chemical bond
• Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)
• Translation is the process by which a cell makes proteins using the genetic code carried by messenger RNA (mRNA)
• Amino Acid are organic compounds that contain amino and carboxyl functional groups
• Gene is a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring
• Allele is one of two or more versions of a gene
• Genotype is an individual's collection of genes
• Phenotype is an individual's observable traits
• Homozygous means having two identical alleles of a particular gene
• Heterozygous means having two different alleles of a particular gene
• Dominant allele produces the same phenotype whether paired with an identical allele or a different allele
• Recessive allele produces its characteristic phenotype only when paired with an identical allele
• RNA is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes
• Protein are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues
• Mutation is an alteration in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA
• Punnett Square is a diagram used to predict the genotypes and phenotypes of offspring in a genetic cross
• Gregor Mendel was the father of modern genetics
• Charles Darwin was a naturalist, geologist and biologist, best known for his contributions to evolutionary biology
• Codominance is a relationship between two versions of a gene
• Incomplete Dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele
• Mutagen is a chemical or physical agent that changes the genetic information, usually DNA, of an organism and increases the frequency of mutations above the background level
• Gene Mutation is an alteration in the nucleotide sequence of a gene
• Gene Pool is the stock of different genes in an interbreeding population
• Chromosomal Mutation is any change in the structure or number of chromosomes
• Point Mutation is a mutation affecting only one or very few nucleotides in a gene sequence
• Frameshift Mutation is a genetic mutation caused by insertion or deletion of a number of nucleotides in a DNA sequence that is not divisible by three
• Natural Selection is the differential survival and reproduction of individuals due to differences in phenotype
• Adaptive Radiation is the diversification of a group of organisms into forms filling different ecological niches
• Selective Pressure is any cause that reduces reproductive success in a portion of a population
• Artificial Selection is the selective breeding of plants and animals to encourage the occurrence of desirable traits
• Gene Editing is a group of technologies that give scientists the ability to change an organism's DNA
• Recombinant DNA is molecules of DNA created by joining DNA segments from different sources
• In Vitro Fertilization is a process of fertilization where an egg is combined with sperm outside the body
• Cloning is the process of producing genetically identical copies of an organism
• Artificial Insemination is a fertility treatment method where sperm is placed inside a woman's uterus to facilitate fertilization
• Gene Therapy is an experimental technique that uses genes to treat or prevent disease
• Biotechnology is the use of living systems and organisms to develop or make products
• Gene Cloning is the process of making multiple, identical copies of a particular gene
• Transgenic Organism is an organism that contains genetic material into which DNA from an unrelated organism has been artificially introduced

DNA

• DNA is made from a repeated piece of nucleotides.
• DNA has a double helix shape.
• The rule for complementary base pairing is: Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C).
• If a chicken's DNA is 26% guanine, then it will be 26% cytosine, 24% adenine, and 24% thymine.
• The function of DNA is to store and transmit genetic information.
• Information from DNA is made into proteins through a process called gene expression, involving transcription and translation.
• If there is a DNA sequence: TACTGCTACATG, the mRNA sequence it would make is: AUGACGAUGUAC
• Transcription happens in the nucleus.
• If there is an mRNA sequence AUGGCCUUA, the amino acids it would code for are: Methionine, Alanine, Leucine
• Translation happens in the ribosome.
• Types of mutations include point mutations, frameshift mutations, and chromosomal mutations.
• Examples of mutations: Beneficial - some mutations allow the host to become resistant to specific diseases. Neutral - eye colour. Harmful - disorders like sickle cell anemia.

Heredity

• Gregor Mendel is the father of modern genetics.
• Mendel studied pea plants to find patterns of inheritance.
• Some of the traits Mendel observed include seed shape, seed color, flower color, and plant height.
• Punnett Squares can be used to determine genotypes and phenotypes of offspring when given standard dominant and recessive traits, two distinct dominant and recessive traits (dihybrid crosses), co-dominant traits, incompletely dominant traits, or multiple alleles.

Natural Selection

• Charles Darwin developed his theory of evolution by natural selection based on observations made during his voyage on the HMS Beagle, including the diversity of life and the struggle for survival.
• Adaptive radiation refers to the diversification of a group of organisms into forms filling different ecological niches, requiring variation and selective pressures.
• Adaptation in biology refers to a trait with a current functional role in the life of an organism that is maintained and evolved by means of natural selection.
• Variations in a population come from genetic mutations and sexual reproduction.
• Examples of selective pressures include competition for resources, predation, and environmental changes.
• A natural selective pressure that might result in smaller size for offspring is limited food availability.
• Extinction is the termination of a kind of organism or of a group of kinds of organism (taxon), usually a species
• Extinction can allow for the development of new species or organisms by opening up ecological niches.

Artificial Selection and Applied Genetics

• Artificial Selection is the process by which humans selectively breed plants and animals to encourage the occurrence of desirable traits.
• Artificial selection differs from gene editing in that it relies on natural genetic variation, while gene editing directly modifies an organism's DNA.
• Natural selection relies on environmental pressures while artificial selection relies on human intervention.
• Artificial selection has provided humans with improved crop yields, domesticated animals, and disease-resistant plants, but it has also led to reduced genetic diversity and potential ethical concerns.
• Be prepared to read and respond to a case study involving an ethical dilemma related to artificial selection or applied genetics.

DNA and Nucleotides

• Key terms: DNA, chromosomes, chromatin, nitrogenous base, sugar-phosphate backbone.
• The three main parts of a nucleotide are a sugar, a phosphate group, and a nitrogenous base.
• The 4 main nucleotide bases are Adenine, Thymine, Guanine, and Cytosine, and they differ in their chemical structures.
• Homologous chromosomes are chromosome pairs (one from each parent) of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci.
• Transcription is the process of copying DNA into RNA, while translation is the process of using RNA to synthesize proteins.

Heredity and Punnett Squares

• The traits were associated with pea plants, and the experimenter was Gregor Mendel.
  • Incomplete Dominance = B
  • Codominance = C
  • Complete Dominance = A