Biotechnology

Transcription

• Copying DNA into RNA

• Nucleus (eukaryotes)

• DNA

• mRNA (or tRNA/rRNA)

• RNA polymerase

• Initiation, elongation, termination

• A, U, G, C (RNA uses U instead of T)

Translation

• Converting RNA into protein

• Cytoplasm/ribosome

• mRNA

• Polypeptide (protein)

• Ribosome (uses tRNA)

• Initiation, elongation, termination

• Amino acids

Predicting Complementary DNA Strand

• Rule: A ↔ T, G ↔ C

• Example:
  DNA template: 5’–A T G C C A–3’
  Complementary: 3’–T A C G G T–5’

Predicting Complementary RNA Strand

• RNA uses U (uracil) instead of T.

• Rule: A → U, T → A, G ↔ C

• Example:
  DNA template: 3’–T A C G G T–5’
  mRNA: 5’–A U G C C A–3’

What A, G, T, C stand for

• A → Adenine

• G → Guanine

• T → Thymine

• C → Cytosine

• U (in RNA) → Uracil

DNA

• Deoxyribose

• A, T, G, C

• Double-stranded

• Stores genetic info

RNA

• Ribose

• A, U, G, C

• Single-stranded

• Protein synthesis, regulation

Role of Soap and Ice-Cold Ethanol in DNA extraction

• Soap: Breaks down cell membranes and nuclear envelope (lipid disruption)

• Ice-cold ethanol: DNA is insoluble in ethanol, so it precipitates out of solution

• Together, they allow the DNA to separate visibly from the rest of the cell contents.

Appearance of Precipitated DNA

• White, stringy, mucus-like material

• Can often be spooled onto a rod or pipette tip

Gel Clectrophoresis and DNA Separation

• DNA has a negative charge (from phosphate groups)

• When an electric field is applied: DNA moves toward the positive electrode

• Separation principle: Smaller fragments move faster/farther; larger fragments move slower/shorter distance.

DNA Fragment Size and Speed

• Small fragments → move fastest and farthest

• Large fragments → move slowest and shortest distance

Paternity Test Interpretation

• Compare child’s DNA bands with mother and potential fathers.

• Rule: Child inherits half of DNA from mother, half from father

• Match bands to see which male shares the complementary set of bands with the child.

Crime Scene DNA Analysis

• Compare DNA bands from crime scene to suspects.

• Rule: All bands in the sample must match the suspect’s DNA to indicate guilt.

• Partial mismatch → suspect is excluded.