Fundamentals of Genetics and Cell Biology

Fundamentals of Genetics and Heredity

Genes: Units of Heredity

Genes are the fundamental units of heredity.

Mendel's Experiments on Inheritance

To test his hypotheses, Mendel crossed pure strains differing in a single character (e.g., tall or dwarf plants, green or yellow seeds—up to seven different traits). He approached the problem quantitatively and with patience.

For each variety studied, he found, surprisingly, that the first generation (F1) were all identical. All offspring resembled one character from the father or the mother.

After crossing the F1 generation with each other, he found that the grandchildren (F2) were not all identical.

He also noted that if the parents differed by more than one character, each character is transmitted independently of the others.

Conclusion on Inheritance

Each character is transmitted independently, which can lead to the formation of different individuals (Law of Independent Assortment).

The Cell and Its Components

The Cell: Fundamental Unit of Life

The cell is the fundamental unit of living organisms. Key components include:

• Cell Wall: Controls the exchange of substances with the outside environment.
• Nucleus: Contains DNA, which directs the synthesis of proteins and the mechanism of heredity.
• Cytoplasm: Contains various organelles, such as ribosomes and mitochondria.

Chromatin and Chromosomes

Flemming discovered a substance in the nuclei of cells that takes color, calling it chromatin. During cell division, known as mitosis, chromatin separates into filaments, which were later named chromosomes.

Gametes

Gametes are reproductive cells.

Molecular Biology and Genomics

DNA (Deoxyribonucleic Acid)

The DNA molecule is constituted by two strands of a large number of chemical compounds called nucleotides.

DNA Duplication (Replication)

Genes are copied, and the DNA molecule doubles. The double helix divides into two, and each chain serves as a template to generate a daughter strand identical to the original.

What Are Genes Made Of?

The composition of genes was historically debated:

• Protein
• DNA
• A mixture of both

Key Genetic Concepts

Genome

The set of all genetic information of an organism.

Genomics

The branch of biology that studies genomes.

Epigenetics

The branch of genetics studying features of an individual that are not determined by the underlying sequence of DNA nucleotides.

PCR (Polymerase Chain Reaction)

A technique that has played a key role in the advancement of genetics knowledge.

Biotechnology and Protein Manufacture

This industry applies genetic engineering for the production of commercial products, such as proteins.