Florida Biology 1 EOC DNA and genetics: a complete overview of DNA, protein synthesis, meiosis, Mendelian and non-Mendelian inheritance, and biotechnology

What the DNA and genetics content demands

The DNA and genetics content of the Florida Biology 1 EOC spans two reporting categories: the molecular part (DNA and protein synthesis) sits in Molecular and Cellular Biology (about 35 percent of the exam), and heredity (meiosis, Mendelian and non-Mendelian inheritance, biotechnology) sits in Classification, Heredity, and Evolution (about 25 percent). The recurring themes are information (the DNA code) and patterns (how traits are inherited). This is the most quantitative biology content, so practice the calculations until they are automatic.

This guide ties together the matching topic pages, each with its own practice questions: DNA structure and replication, protein synthesis: transcription and translation, meiosis and genetic variation, Mendelian genetics and Punnett squares, the modes of inheritance, and biotechnology.

DNA structure and replication

DNA is a double helix of two strands made of nucleotides (sugar, phosphate, and one of four bases). The strands are held together by complementary base pairing: A with T, and G with C. In replication, the helix unzips and each strand templates a new complementary strand, producing two identical molecules each with one old and one new strand (semiconservative). This is how genetic information is copied accurately and passed to each new cell.

Protein synthesis

A gene becomes a protein in two steps: DNA to RNA to protein. In transcription, DNA is copied into mRNA in the nucleus (using A-U and G-C, because RNA uses uracil). In translation, the ribosome reads the mRNA three bases at a time (each three-base codon codes for one amino acid, delivered by tRNA), joining amino acids into a protein. Because the genetic code is universal, a gene moved into another organism makes the same protein, which is the basis of genetic engineering and evidence of common ancestry.

Meiosis

Meiosis makes gametes: it takes one cell and makes four cells with half the chromosome number (46 to 23 in humans). The halving lets fertilization restore the full number. Meiosis differs from mitosis (which makes two identical body cells with the full number) and creates genetic variation through crossing over (homologous chromosomes exchange segments) and independent assortment (random orientation of chromosome pairs).

Mendelian genetics

A gene has versions called alleles; an organism has two, and a dominant allele masks a recessive one. The genotype is the alleles ($TT$, $Tt$, $tt$); the phenotype is the trait. Mendel's laws (segregation and independent assortment) let a Punnett square predict ratios: $Tt \times Tt$ gives a 3:1 phenotype ratio, and $Tt \times tt$ gives a 1:1 ratio. Each offspring's chance of the dominant trait from $Tt \times Tt$ is $\frac{3}{4}$.

The modes of inheritance

Beyond simple dominance: incomplete dominance blends the phenotypes (pink flowers); codominance shows both at once (AB blood, roan cattle); multiple alleles give a gene more than two versions (ABO blood: $I^A$, $I^B$, $i$); sex-linked recessive traits on the X chromosome are more common in males (only one X); and polygenic traits (height, skin color) are set by many genes, giving a continuous range.

Biotechnology

Biotechnology uses living things or their molecules to make products. Genetic engineering moves a gene between organisms (bacteria making human insulin); other tools include GMOs, gene therapy, cloning, DNA fingerprinting, and selective breeding. The benchmark asks you to evaluate: weigh benefits (medicines, yields, diagnosis) against risks and ethics (safety, environment, privacy, access), rather than judging all technology good or bad.

Check your knowledge

A mix of recall and reasoning questions covering DNA and genetics. Attempt them under timed conditions, then check against the solutions.

1. State the DNA base-pairing rules. (2 marks)
2. Explain why DNA replication is described as semiconservative. (2 marks)
3. The DNA template strand reads T-A-C. Write the mRNA sequence. (2 marks)
4. A human body cell has 46 chromosomes. How many are in a gamete made by meiosis? (1 mark)
5. State two ways meiosis increases genetic variation. (2 marks)
6. A cross of $Tt \times Tt$ is carried out. State the phenotype ratio. (1 mark)
7. State the difference between incomplete dominance and codominance. (2 marks)
8. Explain why a recessive X-linked trait is more common in males. (2 marks)
9. State one benefit and one ethical concern of biotechnology. (2 marks)