12.1.2. Outline how genes can influence human characteristics. Notes

12.1.2: How Genes Influence Human Characteristics in Athletics

1. Role of Genes in Athletic Performance

• Definition: Genes are segments of DNA that determine the production of proteins, which influence physiological and anatomical traits.
• Genetic Basis of Athleticism: Athletic performance is a result of a combination of genetic and environmental factors, including training, diet, and lifestyle.

2. Need for Several Characteristics in Athletics

• Complex Traits: Athletic performance depends on multiple interrelated traits, such as:
  • Muscle Strength: Influenced by fiber composition and size.
  • Endurance: Dependent on oxygen transport and utilization.
  • Flexibility: Affected by joint structure and connective tissue properties.
  • Coordination: Controlled by nervous system efficiency.
• No single gene determines athletic performance; it results from the interaction of multiple genes and external factors.

3. Gene Expression

• Definition: Gene expression is the process by which genetic information is used to synthesize proteins that carry out specific functions.
• Influence on Performance:
  • The type and level of protein production impact traits like muscle composition, oxygen uptake, and recovery.
  • For example, genes regulate the development of Type I (slow-twitch) and Type II (fast-twitch) muscle fibers.

4. Production of Proteins

• Genes serve as blueprints for making proteins through:
  • Transcription: DNA is transcribed into messenger RNA (mRNA).
  • Translation: mRNA is translated into proteins at ribosomes.
• Proteins are critical for:
  • Muscle Growth and Repair: Structural proteins like actin and myosin.
  • Energy Systems: Enzymes involved in aerobic and anaerobic metabolism.
  • Transport: Hemoglobin for oxygen transport in endurance athletes.

5. Gene Switching On and Off

• Epigenetics: Environmental factors can influence whether certain genes are "switched on" (expressed) or "off" (silenced).
  • Training, nutrition, and stress can modify gene expression without altering the DNA sequence.
• Examples in Athletics:
  • Intense resistance training can upregulate genes involved in muscle hypertrophy.
  • Endurance training can increase the expression of genes promoting mitochondrial biogenesis (e.g., PGC-1α).

Example:

• What is ACTN3?
  • The ACTN3 gene encodes alpha-actinin-3, a protein found in fast-twitch muscle fibers, which are responsible for explosive power and speed.
  • Commonly referred to as the "speed gene."