BI101 – Genetics and DNA Biology

Genetics and DNA Biology Overview

  • Key Concepts
    • Importance of chromosomes in genetic transmission: Humans have 46 chromosomes; potatoes have 48.
    • DNA structure: Helical strands with sugar and phosphates; complementary base pairing (A-T, G-C).

DNA Replication

  • Process: Semi-conservative replication produces two daughter strands from one template strand.

Transcription and Translation

  • mRNA synthesis occurs, translating genetic code into proteins through ribosomes.

Genetics in Inheritance

  • Meiosis: Critical for sexual reproduction; produces gametes with half the chromosome number.
  • Distinction between dominant and recessive inheritance, including Mendelian and non-Mendelian patterns.

Chromosome Pairing and Alleles

  • Diploid Organisms: Humans inherit two copies of each chromosome (2n), with varying alleles from each parent.
  • Alleles: Variants of genes can be homozygous or heterozygous.

Karyotypes and Chromosome Characteristics

  • Karyotypes depict chromosome arrangements; sex chromosomes (XX or XY) influence biological sex.

Development and Hormones

  • Differentiation into male/female occurs around 6-10 weeks gestation; driven by hormones (specifically SRY gene).

Pedigrees and Genetic Counseling

  • Pedigrees track trait inheritance; use symbols to represent gender and affected individuals.
  • A method to track familial diseases or traits using standardized symbols.

Non-Mendelian Inheritance Patterns

  • Traits may involve incomplete dominance, codominance, or polygenic inheritance (e.g., skin color).
  • Sickle cell disease demonstrates complex interactions of genetics and environment.

Evolution and Disease

  • Sickle cell trait provides malaria resistance; interactions between genetics and evolution in populations.
  • Current challenges related to diseases like FAP and strategies for genetic testing within families.