Biology Chapter 8: Patterns of Inheritance

Chapter 8: Patterns of Inheritance

• Gene: The basic unit of genetic information for a specific trait. It's a segment of DNA, a part of a chromosome, that encodes a functional protein.
• Genome: All the genetic material in a cell.
• Allele: One of two or more alternative versions of a gene. They arise from mutations in DNA.
• Dominant Allele: An allele that has exclusive control over an organism's phenotype when paired with a different allele.
• Recessive Allele: An allele that doesn't have a clear phenotypic effect when paired with a dominant allele.
• Heterozygote: An individual that carries one copy of each of two different alleles (e.g., Aa).
• Homozygote: An individual that carries two copies of the same allele (e.g., AA or aa).
• Trait: An inherited feature of an organism that can be measured or observed.
• Genotype: The genetic makeup of an organism, describing the alleles of a given gene.
• Phenotype: The specific version of a genetic trait that an organism displays.
• Genetic Cross: A controlled mating experiment (usually done with plants) used to study inheritance patterns.
• P Generation: The parent generation in a genetic cross.
• F1 Generation: The first generation of offspring in a genetic cross.
• F2 Generation: The second generation of offspring in a genetic cross.

Mendel's Laws

• Gregor Mendel: First person to analyze patterns of inheritance, discovered the fundamental principles of genetics using garden peas. Peas were easy to manipulate and self-fertilize.
• Cross fertilization: Mendel created true-breeding varieties of plants and crossed them (white male with purple female).
• Monohybrid Cross: Crosses between parent plants that differ in only one characteristic. This suggested dominant and recessive traits.
• Phenotypes: are physical expressions of traits transmitted by alleles
• Capital letters: represent dominant alleles
• Lowercase letters: represent recessive alleles
• Phenotypic ratios: visible characteristics ratios
• Genotypic ratios: gene combination ratios

Laws of Segregation and Independent Assortment

• Law of Segregation: Two members of an allele pair separate independently during gamete production.
• Punnett Square: A tool used to predict the probability of an offspring having a particular genotype, created by Reginald Punnett. It compares alleles from the mother with those from the father.
• Law of Independent Assortment: Two hypotheses
• Dependent: The traits are linked
• Independent: the trait are not linked
• Probability: Segregation and independent assortment follow the rules of probability.
• Multiplication Rule: The probability of two or more independent events occurring together is the product of their individual probabilities
• Addition Rule: The probability of any one or more exclusive events occurring is the sum of their individual probabilities.

Degree of Dominance

• Inheritance: of characters may deviate.
• Alleles: are not always completely dominant or recessive (ex: incomplete dominance) and some genes have more than two alleles.

Gene produces multiple phenotypes

• Complete Dominance: Phenotypes of heterozygote and dominant homozygote are identical.

• Incomplete Dominance: The phenotype of F1 hybrids is an intermediate between the parental varieties. (Ex. If two different types of color flower are crossed, the hybrid color is a mix).

• Codominance: Two or more dominant alleles at one locus are present in the heterozygote, affecting the phenotype in distinguishable ways (ex: blood type).

• Multiple Allelism: Genes that exist in populations with more than two allelic forms, resulting in two or more distinct phenotypes, like blood types.

• Pleiotropy: A gene that affects many traits, such as albinism.

• Epistasis: One gene alters the expression of a second gene.

• Quantitative or polygenic Traits: Traits that are not discrete but instead fall on a continuum, like skin color.

• Traits (quantitive and qualitative): Discrete traits or characteristics which are qualitatively different.

Other Genetic Traits and Disorders

• Pedigree Analysis: A family tree used to study genetic relationships and predict offspring phenotypes.
• Genetic Disorders: Diseases or conditions arising from inherited genetic material, including autosomal recessive, autosomal dominant, and sex-linked disorders. (like cystic fibrosis, Tay-Sachs, hemophilia) A lot of these are recessive disorders where both copies of a gene must have the disease to show up.

Chapter 9: Molecular Biology I

• DNA: Double helix structure composed of nucleotides (adenine, thymine, cytosine, and guanine). Determines the sequence of amino acids in proteins.

• DNA Replication: The process of duplicating genetic material. The parent DNA strand serves as a template for new DNA molecules, creating two identical copies (semi-conservative).

• DNA Repair: Mechanisms to identify and correct errors during DNA replication.

• Flow of Genetic Information: Information flows from DNA to RNA to proteins.

• Transcription: Copying information from DNA to RNA.

• Types of RNA: Messenger RNA (mRNA, contains the codons/ genetic code), Transfer RNA (tRNA), Ribosomal RNA (rRNA)

• Translation: The process of converting RNA into proteins.

• Protein synthesis: Conversion of translation into the production of proteins.

• Central Dogma: The flow of information from DNA to RNA to proteins, which is the fundamental principle of molecular biology.

Chapter 10: Molecular Biology II

• Prokaryotic Genomes: Usually organized into one chromosome, with metabolically related genes often grouped together.

• Eukaryotic Genomes: Usually organized into more than one chromosome, with a mixture of coding (genes) and non-coding regions of DNA.

• Genome Size: The total amount of DNA within a species (often measured in base pairs). The number of genes doesn't directly correlate with the size of the gene sequence.

• Spacer DNA: Regulatory mechanisms in eukaryotes. Mechanisms to regulate gene expression occurs when a gene is actively being synthesized and used by a cell. These processes, from DNA to RNA to translation to protein, are usually controlled at each stage.

• Regulatory Mechanisms in Prokaryotes & Eukaryotes: Mechanisms to regulate gene expression, which are more complex in eukaryotes. Often controlled at the level of transcription by the binding of regulatory proteins to DNA sequences (like promoters and operators, which control the start of gene transcription in prokaryotes).

• Transcription factors: Proteins that turn genes on or off.

Gene Regulation (in more detail)

• Constitutive Genes: Genes expressed at a steady rate (e.g., genes coding for proteins needed for cell function). Gene expression happens at a set pace.
• Inducible Genes: Genes expressed only when needed (e.g., genes turned 'on' when a certain molecule is present). Gene expression is affected by environmental factors.
• Repressible Genes: Genes usually expressed, but 'turned off' when a certain molecule is present (e.g., genes for producing certain substances, turned off when there's enough of them present). Repressable genes are involved in controlling metabolic processes and pathways.

Cell Processes

• Control of mRNA Transcription (constitutive or inducible/repressible genes). Regulation of how much of each protein needed

• Transcription Regulation: Levels of regulation happen at different stages of the process, from DNA to protein. Processes that effect the expression of specific genes

• Levels of Regulation: These affect the overall expression of genes. Levels of regulation can happen at many stages, from DNA packaging and the transcription itself.

Test your knowledge on the patterns of inheritance in biology with this quiz focused on key concepts such as genes, alleles, and genotype vs phenotype. Understand the roles of dominant and recessive alleles and learn how these factors influence traits. Perfect for students studying genetics in biology!