Biology: Basic Knowledge Compilation

Biology: Basic Knowledge Compilation

This article will summarize basic biological knowledge, focusing on key concepts and processes related to genetics, cell structure, and function.

# Nucleic Acids

• DNA: The largest nucleic acid in the cell. The molecular structure of DNA is characterized by the presence of the nucleotide thymine (T).

• RNA: A nucleic acid involved in protein synthesis. RNA contains uracil (U) instead of thymine.

• Complementary Base Pairs: In the DNA molecule, adenine (A) binds to thymine (T) with two hydrogen bonds, and guanine (G) binds to cytosine (C) with three hydrogen bonds. The base pairs U and T do not have complementary bonds.

# Genetic Code

• Universality: The genetic code is used almost identically in all organisms, demonstrating the unity of the living world. This explains why the human insulin gene can be transferred into bacteria and bacteria can still synthesize the insulin protein.

# Mechanisms of Heredity

• DNA Replication: The main mechanism for transmitting genetic information from the parent cell to the daughter cell. During replication, each DNA molecule produces two new DNA molecules, each new DNA molecule containing 50% of the parent DNA.

• Transcription: The process of synthesizing RNA from a DNA template. The RNA produced during transcription acts as a template for translation.

• Translation: The process of protein synthesis from an RNA template. Translation requires the participation of mRNA, tRNA, and ribosomes.

• mRNA: Carries genetic information from DNA to ribosomes.

• tRNA: Transports amino acids to the ribosomes for polypeptide chain synthesis.

• Ribosomes: The site of translation.

# Regulation of Gene Activity

• Lac Operon: A classic example of gene regulation in bacteria. When lactose is present, the repressor protein is inactivated, allowing the genes that synthesize the lactose-degrading enzyme to function.

# Gene Mutation

• Gene Mutation: A change in the nucleotide sequence of a gene. Gene mutations can occur in both somatic cells and germ cells.

• Beneficial or Harmful Effects of Gene Mutations: Depends on the environment and the genotype of the organism.

# Chromosome Structure

• Nucleosome: The basic structural unit of a chromosome.

• Chromosome Structural Mutation: A change in the structure of a chromosome. Types of chromosome structural mutations include inversion, deletion, translocation, and duplication.

• Inversion: A segment of a chromosome breaks off, rotates 180 degrees, and reattaches to the original position.

• Deletion: A segment of a chromosome breaks off and is lost.

• Translocation: A segment of a chromosome breaks off and attaches to a new location on the same chromosome or a different chromosome.

• Duplication: A segment of a chromosome is duplicated and repeated on the same chromosome.

• Applications of Chromosome Structural Mutation: Deletion can be used to eliminate unwanted genes and determine the location of genes on chromosomes. Duplication can enhance or decrease the expression of traits.

# Genetics

• Gene: The basic functional unit of heredity, carrying genetic information.

• Allele: Different states of the same gene.

• Genotype: The combination of alleles an organism carries.

• Phenotype: The physical expression of the genotype.

• Independent Assortment: Genes located on different chromosomes will segregate independently during meiosis.

• Linkage: Genes located on the same chromosome will be inherited together.

# Crosses

• Test Cross: Crossing an individual with a dominant phenotype with an individual with a recessive phenotype to determine the genotype of the dominant individual.

• Reciprocal Cross: Crossing two pure-breeding lines with different phenotypes, then switching the roles of the parents to investigate the role of sex in inheritance.

# Other Important Concepts

• Homozygote: An organism carrying two identical alleles of the same gene.

• Heterozygote: An organism carrying two different alleles of the same gene.

• Pleiotropy: A gene influencing the development of multiple different traits.

• Yield: The ability of an organism to produce, depending on its genotype and environment.

Conclusion

This article has summarized basic biological knowledge, including cell structure, nucleic acids, genetic code, mechanisms of heredity, gene mutation, chromosome structure, genetics, and other important concepts. Understanding these concepts is the foundation for accessing and gaining a deeper understanding of specialized areas of biology.