Genes, DNA, and Genetic Disorders

Genes: Answers & Questions

DNA Code and Genes

  • Chromosome: A thread-like structure made mostly of DNA, found in the nucleus of a cell.

  • DNA: Stands for deoxyribonucleic acid.

  • Gene: A segment of DNA that controls protein production. Thousands of genes can exist in a single DNA molecule.

Composition of Genes

  • Genes consist of DNA.

  • DNA comprises four chemical letters.

  • A cell contains chromosomes, organized into 23 pairs.

  • Chromosomes contain genes.

Genome and Protein Synthesis

  • Genes contain instructions for making proteins.

  • Proteins perform many cellular functions, acting alone or in complexes.

  • The relationships can be visualized as:

    • Cell

    • Chromosomes

    • Genes

    • DNA (composed of A, T, C, G)

    • Proteins

DNA Composition and Genetic Code

  • DNA is made up of four types of molecules:

    • Adenine (A)

    • Thymine (T)

    • Cytosine (C)

    • Guanine (G)

  • The order in which the A, T, C, and G molecules are arranged is called the genetic code.

  • Each person has their own unique genetic code.

DNA Screening

  • DNA screening is used to determine if someone has a genetic disorder by analyzing their DNA.

  • A karyotype, which is a micrograph of the chromosomes, is taken and analyzed.

Genetic Disorder Diagnosis/Screening

  • Diagnosis/Screening: Tests can be performed before a baby is born (prenatal) or after birth.

  • These tests reveal signs and symptoms.

  • Signs and Symptoms: Indicate what a person will experience daily, including physical signs and potential for a shorter lifespan.

  • Treatment Options: Include ways to 'cure' the disorder or manage the symptoms.

  • Photo: Visual representation of the disorder or disease.

Group Discussion: DNA Screening

  • Is DNA screening (or genetic screening) a positive medical tool? Why or why not?

Medical Advances and DNA

  • BRCA Genes: Produce tumor suppressing proteins.

  • Women who inherit a harmful BRCA1 mutation have a 55 to 65 percent risk of developing breast cancer by age 70.

  • Women who inherit a harmful BRCA2 mutation have around a 45 percent risk of developing breast cancer by age 70.

Social Issues of DNA Screening

  • DNA screening is controversial and encompasses social issues.

  • Genetic information is:

    • Personal

    • Powerful

    • Potentially predictive

    • Pedigree-sensitive

    • Permanent

    • Prejudicial

Altering Genes/Transgenic Organisms

  • Transgenic Organisms: Organisms with altered genes, also known as genetically modified organisms (GMOs).

  • Genetic Engineering: The process of combining DNA from different species.

  • Uses for GMOs?

  • Concerns about GMOs?

Cloning

  • Cloning: The process of creating identical genetic copies of an organism.

  • A possible solution to the problem of needing new organs or cells.

Mutations

  • Mutation: A change in the order of A, C, T, G building blocks in a gene.

  • Mutagens: Substances that cause mutations.

    • Examples: radiation (x-rays, UV rays), chemicals (mercury in fish, tar in cigarettes).

  • Examples of diseases caused by mutations:

    • Sickle cell anemia

    • Albinism