Genetics Overview Quiz

Definition: Study of heredity and variation in organisms.
Key Terms:
- Gene: Basic unit of heredity.
- Allele: Different forms of a gene.
- Genotype: Genetic makeup of an organism.
- Phenotype: Observable characteristics of an organism.
- Homozygous: Having two identical alleles for a trait.
- Heterozygous: Having two different alleles for a trait.
DNA Structure:
- Composed of nucleotides (adenine, thymine, cytosine, guanine).
- Double helix shape.
Inheritance Patterns:
- Dominant: Allele that expresses its trait even when a recessive allele is present.
- Recessive: Allele that expresses its trait only when two copies are present.
Types of Inheritance:
- Autosomal Dominant: One copy of the dominant allele is sufficient to express the trait.
- Autosomal Recessive: Two copies of the recessive allele are needed.
- Codominance: Both alleles are expressed equally in the phenotype.
- Incomplete Dominance: Blending of traits from both alleles.
Molecular Genetics:
- Transcription: Process of copying DNA to mRNA.
- Translation: Synthesis of proteins from mRNA.

Background: Gregor Mendel, an Austrian monk, is known as the father of genetics. Conducted experiments with pea plants in the mid-19th century.
Key Laws:
- Law of Segregation:
  - During gamete formation, allele pairs separate so that each gamete carries only one allele for each gene.
- Law of Independent Assortment:
  - Genes for different traits are inherited independently of each other, assuming they are on different chromosomes.
Mendelian Ratios:
- Monohybrid Cross: 3:1 phenotypic ratio in the F2 generation.
- Dihybrid Cross: 9:3:3:1 phenotypic ratio in the F2 generation for two traits.
Importance:
- Established the foundation for understanding genetic inheritance.
- Provided a systematic approach to studying heredity.
Experiments:
- Used true-breeding pea plants to observe traits such as flower color, seed shape, and plant height.
- Analyzed the inheritance patterns through controlled cross-pollination.
Impact on Science:
- Mendel's work laid the groundwork for modern genetics, influencing fields such as evolutionary biology, medicine, and agriculture.

Study of heredity and variation in organisms, analyzing how traits are passed down through generations.
Key Terms:
- Gene: The fundamental unit of hereditary information.
- Allele: Different variants of a gene that may produce distinguishable traits.
- Genotype: The specific genetic constitution of an organism.
- Phenotype: The physical expression or characteristics of that genotype.
- Homozygous: Condition where an organism has two identical alleles for a given trait.
- Heterozygous: Condition where an organism has two different alleles for a trait.
DNA Structure:
- Comprises nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G).
- Exhibits a double helix conformation, essential for genetic information storage.
Inheritance Patterns:
- Dominant Allele: Expresses its trait even in the presence of a recessive allele.
- Recessive Allele: Only expresses its trait when two copies are present.
- Types of Inheritance:
  - Autosomal Dominant: Requires only one copy of the dominant allele for trait expression.
  - Autosomal Recessive: Requires two copies of the recessive allele for expression.
  - Codominance: Both alleles contribute to the phenotype.
  - Incomplete Dominance: Results in a blending of traits.
Molecular Genetics:
- Transcription: The process wherein DNA is transcribed into messenger RNA (mRNA).
- Translation: The synthesis of proteins from mRNA molecules.

Gregor Mendel, an Austrian monk, established foundational principles of genetics through his research on pea plants in the mid-19th century.
Key Laws:
- Law of Segregation: During gamete formation, alleles segregate so that each gamete carries one allele for each gene.
- Law of Independent Assortment: Genes for distinct traits independently segregate during the formation of gametes, provided they are located on separate chromosomes.
Mendelian Ratios:
- Monohybrid Cross: Produces a phenotypic ratio of 3:1 in the second filial generation (F2).
- Dihybrid Cross: Produces a phenotypic ratio of 9:3:3:1 for two traits in the F2 generation.
Importance:
- His work formed the basis of genetic inheritance understanding and established systematic methodologies in the study of heredity.
Experiments:
- Utilized true-breeding pea plants to study traits including flower color, seed shape, and plant height and performed controlled cross-pollination to analyze inheritance.
Impact on Science:
- Mendel's principles laid the groundwork for modern genetics, significantly influencing fields such as evolutionary biology, medicine, and agriculture.

Study of heredity and variation in organisms, focusing on how traits are passed down through generations.
Genes are the fundamental units of heredity, composed of DNA that encode for specific traits.
Alleles represent the different forms of a gene found at the same locus on homologous chromosomes.
Genotype refers to the genetic constitution of an organism, whereas phenotype describes the observable physical characteristics resulting from the genotype.
Chromosomes are structures made of DNA that house genes; humans have 23 pairs, totaling 46 chromosomes.

Gregor Mendel, known as the Father of modern genetics, established foundational principles through his work with pea plants.
The Law of Segregation states that alleles for a given trait separate during gamete formation, ensuring each gamete carries only one allele per gene.
The Law of Independent Assortment indicates that genes governing different traits assort independently, applicable when genes are located on separate chromosomes or are distantly located on the same chromosome.
A Monohybrid Cross, focusing on a single trait, predicts a phenotypic ratio of 3:1 in offspring.
A Dihybrid Cross, which examines two traits simultaneously, typically results in a 9:3:3:1 phenotypic ratio among the offspring.

Incomplete Dominance occurs when neither allele is fully dominant, leading to a blending of traits, such as pink flowers arising from red and white parent flowers.
Codominance is characterized by both alleles expressing equally in the phenotype; for instance, an individual with type AB blood expresses both A and B antigens.
Multiple Alleles refer to the existence of more than two alleles for a specific gene, evident in the ABO blood group system.
Polygenic Inheritance involves multiple genes affecting a trait, resulting in a continuous range of phenotypes, exemplified by variations in skin color or height.
Epistasis describes the interaction where one gene can overshadow or mask the effect of another gene, impacting traits like coat color in certain animals.
Pleiotropy involves a single gene influencing multiple traits, illustrated by sickle cell disease, which affects red blood cell morphology and various physiological systems.