genetics flashcards | IB - Wyatt's Notes
Genetics Flashcards
15 flashcards covering IB Biology genetics — DNA structure, protein synthesis, Mendelian genetics, biotechnology, and evolution.
Key Concepts
DNA Structure: DNA is a double helix with two antiparallel polynucleotide strands. The sugar-phosphate backbone is on the outside (alternating deoxyribose and phosphate groups); nitrogenous bases (A, T, G, C) pair inside via hydrogen bonds (A-T with 2 hydrogen bonds, G-C with 3 hydrogen bonds — G-C pairs are stronger). This complementary pairing is the basis for replication and protein synthesis. Each strand runs 5’→3’ in opposite directions (antiparallel).
Mendelian Genetics: Dominant alleles mask recessive alleles in heterozygotes (Aa shows dominant phenotype). Segregation ensures each gamete carries one allele per gene (Mendel’s first law). Independent assortment means genes on different chromosomes sort independently during meiosis (Mendel’s second law). The Punnett square predicts offspring genotypes and phenotypes. Genotype = genetic makeup (e.g., AA, Aa, aa); phenotype = observable trait (e.g., tall, short).
Protein Synthesis: Transcription copies DNA to mRNA in the nucleus (RNA polymerase binds to the promoter, unwinds DNA, and synthesises mRNA complementary to the template strand). Translation reads mRNA at the ribosome, assembling amino acids into polypeptides using tRNA (each tRNA carries a specific amino acid and has an anticodon complementary to the mRNA codon). The genetic code is universal (same in all organisms), degenerate (multiple codons for one amino acid — 64 codons for 20 amino acids), and non-overlapping (each nucleotide belongs to only one codon).
Biotechnology: Restriction enzymes (endonucleases) cut DNA at specific palindromic sequences, producing sticky ends or blunt ends. DNA ligase joins DNA fragments by forming phosphodiester bonds. Gel electrophoresis separates DNA fragments by size (smaller fragments move faster through the gel). PCR amplifies specific DNA sequences (denaturation at 95°C, annealing at 55°C, extension at 72°C). These tools enable genetic engineering, forensic analysis, and medical diagnostics.
Intuition
Think of DNA as a recipe book. Each gene is a recipe for a specific protein. Transcription is photocopying a recipe (DNA → mRNA) so the chef (ribosome) can read it in the kitchen (cytoplasm). Translation is the chef reading the copy and cooking the dish (mRNA → protein). Mendelian genetics is like following family recipes — some are “dominant” (you always make them) and some are “recessive” (only made if both parents have the recipe). Biotechnology is like editing the recipe book — you can cut out sections, paste in new ones, and make many copies.
Why it matters: Genetics explains how traits are inherited, how proteins are made, and how biotechnology works. It’s essential for medicine (genetic diseases, gene therapy), agriculture (GM crops, selective breeding), forensics (DNA fingerprinting), and evolutionary biology.
Common Pitfalls
- Confusing transcription and translation. Transcription = DNA → mRNA (nucleus — “writing again” in a different language). Translation = mRNA → protein (ribosome — “translating” into a different molecule). The names describe what happens: transcription copies; translation converts.
- Assuming dominant means “better” or more common. Dominance describes how alleles interact, not their value or frequency. Huntington’s disease is caused by a dominant allele but is rare and harmful. “Dominant” just means it masks the recessive allele in heterozygotes.
- Forgetting that the genetic code is degenerate. Most amino acids are coded by multiple codons, which provides some protection against point mutations. A change in the third base of a codon (wobble position) often doesn’t change the amino acid — this is called a silent mutation.
- Confusing DNA replication (DNA → DNA) with transcription (DNA → mRNA). Replication copies the entire genome; transcription copies only the gene needed for a specific protein.
Cross-References
- Cell Biology: Cell biology covers the organelles (nucleus, ribosomes, ER) where transcription and translation occur.
- Molecular Biology: Molecular biology explores DNA, RNA, and protein synthesis at the molecular level.
- Evolution: Evolution explains how genetic variation leads to adaptation and speciation over generations.
- Ecology: Ecology studies how genetic variation within populations affects adaptation and survival.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.