Untitled Biology Concepts PDF

Got it! Here’s a simplified explanation of each concept: 1. PCR (Polymerase Chain Reaction): PCR is a lab method used to copy DNA. It has three steps: 1.​ Denaturation: Heat splits the DNA into two strands. 2.​ Annealing: Primers (short DNA pieces) attach to the strands. 3.​ Extension: D...

Got it! Here’s a simplified explanation of each concept: 1. PCR (Polymerase Chain Reaction): PCR is a lab method used to copy DNA. It has three steps: 1.​ Denaturation: Heat splits the DNA into two strands. 2.​ Annealing: Primers (short DNA pieces) attach to the strands. 3.​ Extension: DNA polymerase builds new DNA strands. 2. Darwin and Wallace’s Theory: They proposed that species change over time because traits that help survival are passed on. This challenged the old idea that species never change. 3. Allele Frequency (Hardy-Weinberg): Allele frequency measures how common a specific gene variant (like "A") is in a population. You calculate it using frequencies of gene combinations (like AA,Aa,aaAA, Aa, aa). 4. Adaptive Radiation: One species evolves into many species to fill different roles in an environment. Example: Galapagos Finches evolved different beaks for eating different foods. 5. Reinforcement in Hybrid Zones: When hybrids (offspring of different species) are less fit, natural selection reduces mating between the species, lowering gene flow. 6. Convergent Evolution: Unrelated species develop similar traits because they live in similar environments. Example: Cacti and Euphorbia both store water and have spines. 7. Darwin and Lyell: Lyell wrote a book showing how Earth changes slowly over time (geology), inspiring Darwin to think species might change too. 8. Hardy-Weinberg Conditions: For a population to stay genetically stable (no evolution), it must: 1.​ Be large. 2.​ Have no mutations, migration, or natural selection. 3.​ Have random mating. 9. Artificial Selection: Humans choose which traits to breed for. Example: Breeding apples for sweetness created 7500 apple varieties. 10. Hybrid Breakdown: Hybrids can reproduce, but their offspring are weak or infertile. This stops gene flow between species. 11. Reproductive Isolation: Different mating behaviors (like songs) stop populations from breeding. Example: Crickets with different songs. 12. First Genetic Material: Life likely started with RNA because it can store information and copy itself. 13. Next-Gen DNA Sequencing: A fast method to read DNA. It detects each DNA building block as it’s added during sequencing. 14. Morphological Species Concept: Defines species by physical traits (e.g., size, shape, color). Used for identifying species. 15. Biological Species Concept: Species are groups that can breed and have fertile offspring. Doesn’t apply to fossils. 16. Human Genome: The human genome has about 3 billion base pairs of DNA, containing all genetic instructions. 17. Hardy-Weinberg Genotype Frequency: For p=0.7p = 0.7, the frequency of genotype aaaa is: q2=(1−p)2=0.32=0.09q^2 = (1 - p)^2 = 0.3^2 = 0.09 18. Globin Gene Evolution: The Globin gene family evolved through duplications and mutations, helping create different forms like hemoglobin. 19. Recombinant DNA: Scientists cut DNA with restriction enzymes and insert it into plasmids (circular DNA) to make new combinations. 20. Simple Sequence DNA: Repeated DNA sequences found in centromeres (important for cell division) and telomeres (protect chromosome ends). 21. Earliest Life: The first cells (primitive life) appeared about 3.5 billion years ago. 22. Mechanical Isolation: Species can't mate because of physical differences. Example: Snails with shells that twist in opposite directions. 23. Vestigial Structures: Traits that ancestors used but are now useless. Example: Human tailbone (remnant of tails). 24. Evolution of Complex Traits: Complex features (like eyes) evolve in small, useful steps over time. 25. Human Genes: Humans have around 21,000 genes that code for proteins. 26. Fossil Limitations: You can’t test fossil species’ ability to breed, so the biological species concept doesn’t work for them. 27. Genetic Bottleneck: A disaster (e.g., earthquake) drastically reduces population size, leaving only a small, less diverse gene pool. 28. Sanger Sequencing and ddNTPs: In this method, ddNTPs stop DNA copying at specific points, creating DNA pieces of different lengths for sequencing. 29. Stabilizing Selection: Natural selection favors the "average" traits and eliminates extremes. Example: Birds with 4-5 eggs survive better. 30. Frequency-Dependent Selection: Rare traits survive better because predators focus on the common ones. Example: Rare snail patterns avoid predators. 31. Genome Definition: The genome includes all DNA in an organism, including coding and non-coding regions. 32. Fossil Formation: Hard-bodied organisms (e.g., squirrels) are more likely to fossilize than soft-bodied ones like worms. 33. Retrotransposons: These are "jumping genes" that copy themselves using reverse transcriptase and move to new locations in the genome. 34. Sexual Selection: Females may choose males with long calls because it shows they’re strong enough to attract mates and avoid predators. 35. Herbicide Resistance: Resistant weeds survived the herbicide and passed their resistance genes to their offspring. 36. Gene Flow: When populations mix genes (migration), they become more genetically similar. 37. Adaptive Evolution: Natural selection is the only process that consistently improves how well organisms fit their environment. 38. Sympatric Speciation: New species form in the same area, often due to differences in mating preferences. 39. Mammal Diversity: Mammals became much more diverse around 65 million years ago after dinosaurs went extinct. 40. Punctuated Equilibrium: Evolution happens in quick bursts of change followed by long periods of stability.