Chapter 1

The overview of Genetics

  • The Human Genome

    • A complete set of human chromosomes (ppl have 2 sets one from mom n dad)

    • The human genome is found in cell nucleus

  • The Human Genome Project

    • Began in the USA in 1990

    • The NIH and the DOE joined forces with international partners to decipher the massive amount of information contained in our genome

      • Genome- The DNA found within all of our chromosomes

  • DNA is the molecule of life

  • The adult human body is composed of trillion of cells.

    • Most human cells contain the following:

      • 46 human chromosomes found in 23 pairs

      • 2 meters of DNA

      • Apprx. 20,000 genes coding for the proteins that perform most life functions

      • apprx. 3 billion DNA base pairs per set of chromosomes containing the bases A,T,G,C

  • How might a better understanding of our genes be used in the field of medicine?

    • Understanding our genes may help to diagnose inherited disease

    • May lead to the development of drugs to help combat disease

      • For example: Human insulin which is synthesized in strains of Escherichia Coli bacteria that have been gentically altered by the addition of genes that code the polypeptides that form this hormone

    1.1 The Molecular Expression of genes

    • Genetics focuses on heredity and variation

      • It allows us to understand how life can exist at all levels of complexity, ranging from the molecular to the population level.

    • Genetic variation is the root of the natural diversity that we observe among members of the same species and among different species.

    • A gene is defined as a unit of heredty (can be a very vague definition)

    • At the molecular level, a gene is a segment of DNA that contains the information to produce a functiona product

      • The functional product of most genes is a polypeptide

    • At the organism level, genes are commonly described according to the way they affect traits

      • “Characteristics of an organism”

Living cells are composed of Biochemicals

  • Every cell is constructed from intricately organized chemical substances

  • small organic molecules such as glucose adn amino acids are produced by the linkage of atoms via chemical bonds

  • Chemical properties of organic molecules are essential for cell vitality in 2 ways

    • 1. During the degradation of small molecules, the breaking of chemical bonds provides energy to drive cellular processes

    • 2. These small organic molecules have a role of building blocks for the synthesis of larger molecules

      • 4 important categories of larger molecules include

        • 1. Nucleic acid (i.e., DNA + RNA) (Macromolecule)

        • 2. Proteins (Macromolecule)

        • 3. Carbohydrates (Macromolecule)

        • 4. Lipids

  • The formation of cellular structures relies on the interaction of molecules and macromolecules:

    • Nucleotides are small organic molecules

    • Nucleotides are linked to each other and form the building block of DNA

    • DNA is a component of chromosomes, which also contains proteins that contribute to chromosome structure

    • Within a eukaryotic cell, the chromosomes are contained in a compartment called the cell nucleus,

      • the nucleus is bounded by a double membrane that is composed of lipids and proteins and shields the chromosomes from the rest of the cell

        • The nucleus is an organelle

    • Cellular molecules, macromolecules and organelles are organized to make a complete living cell

  • DNA Is a macromolecule

Each cell contains Many different proteins that determine cell structure and function

  • The entire collection of proteins that a cell makes at a given time is called proteome

  • Enzymes are a protein that functions to accelerate chemical reactions within the cell

DNA stores the information for protein synthesis

  • The genetic material of living organisms is composed of DNA ( deoxyrionucleic acid)

    • DNA stores the info needed for the synthesis of all cellular proteins

  • The DNA’s ability to store info is based on its structure

    • 1. DNA is composed of A (adenine), T (Thymine), G (guanine), C (cytosine)

    • 2. The specific order of bases (adenine, thymine, cytosine, and guanine) along a DNA molecule contains instructions for the cell. This sequence provides the information needed to build proteins and regulate cellular processes.

    • 3. DNA sequences within most genes contain the info to direct the order of amino acids within polypeptides

    • 4. The sequence of amino acids in a ploypeptide causes it to fold into a particulat structure.

The infor in DNA ia Accessed in During the process of gene expression

  • A cell must be able to access the info that is stored within its DNA to be able to synthesize its proteins

  • Gene expression- the process by which the information within a gene is accessed, first to synthesize RNA and polypeptides, and eventually to affect the properties of cells and the phenotype of multicellular organisms.