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Scientific Method

Explore the scientific method, organic compounds, enzymes, cellular structures, and processes like photosynthesis and cellular respiration. Learn about chemical bonds, cell division, and more in this comprehensive guide.

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Scientific Method

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  1. Scientific Method • Steps • Observation • Hypothesis • Experiment • Analysis and Conclusion • If wrong form new hypothesis

  2. Scientific Method • Controlled experiment • Tests effect of a single variable while keeping all other variables the same • Any observed differences should be caused only by the single changed variable

  3. Scientific Method • Observations • (qualitative and quantitative) • Quantitative– involve numbers, counting, measuring objects. • Qualitative– involve characteristics that cannot be easily measured or counted such as color or texture

  4. Scientific Method • Hypothesis– a possible explanation, a preliminary conclusion, or even an “educated” guess about some event in nature • Theory– As evidence builds up, a particular hypothesis may become so well supported that scientists consider it a theory. Atomic theory

  5. Chemistry • Organic Compounds • Carbohydrate-main source of energy for animals • Monomer = monosaccharide (single suger) • Polymer = Starch, Cellulose • Protein-functional or structural • Monomer = Amino Acid • Polymer = Protein • NucleicAcid-controls inheritance • Monomer = Nucleotide • Polymer = DNA, RNA

  6. Chemistry • Enzymes • Biological Catalyst • Speeds up chemical reactions • Lowers Activationenergy (energy needed to get reaction started • Not used up during reaction • A specialized protein • functional protein

  7. Chemistry • pH • Measured on a scale of 1-14 • Below 7 acid • Above 7 base • pH of 7 = neutral • Speeds up chemical reactions • Lowers Activation energy (energy needed to get reaction started

  8. Chemistry ReactantsandProducts Reactants Products

  9. Chemistry • Solutions • Solute-“stuff” that is dissolved • Solvent –the liquid that does the dissolvin

  10. Chemistry Chemical bonds– links that hold atoms together. Two main types Covalent bonds– formed by sharing electrons between two atoms • Bond found in organic compounds

  11. Chemistry Ionic bonds- formed by transfer of 1 more electrons from 1 atom to another • Ion– (+) or (-) charged atom that results from gaining or losing electron

  12. Cells • Organelles

  13. Nucleus- control center of cell. Contains DNA (genetic material). Found in eukaryotic cells.

  14. Ribosome- organelle where proteins are made. Free-floating and some on Endoplasmic reticulum

  15. Golgi apparatus- Cells “post office”. Packages proteins

  16. Endoplasmic reticulum- Cells transport system. Help make proteins (rough E.R.)

  17. Lysosome- “clean-up” crew of cell. Contains enzymes to break down old cell parts, digest food, etc.

  18. Cell membrane- flexible, and semi-permeable membrane surrounding cell.

  19. Cells • Cell membrane- composed of lipid bi-layer (2 layers of lipids) Lipid layer also called phospholipids

  20. Cells • Semi-permeable- allows some things to pass through but not others Diffusion- movement from areas of high concentration to areas of low concentrations Osmosis- diffusion of water

  21. Cells • Active transport-takes energy (endocytosis and exocytosis) • Passive transport-no energy required (diffusion and osmosis)

  22. Cells Prokaryotes and Eukaryotes- Scientists divide cells Into two groups depending on whether they have a nucleus or not. 1. Prokaryotes-nonucleus • Smaller and simpler than cells of eukaryotes • Do have cytoplasm and cell membrane • Example: Bacteria

  23. Cells Eukaryotes- do contain nucleus and membrane bound organelles (includes plants, animals, fungi) • Contain cytoplasm and cell membrane • Contains organelles

  24. Cells Homeostasis-maintain constant internal conditions (example: blood sugar levels, blood pressure, shivering/sweating)

  25. Photosynthesis • Equation • Energy from sunlight converts carbon dioxide and water into high energy sugar (glucose) • Takes place in chloroplast (organelle) • Affected by: • 1. Light intensity • 2. Amount of water • 3. Temperature • Autotroph-Can make their own food (plants) light 6CO2 + 6H2O C6H12O6 + 6O2

  26. Cellular Respiration • Heterotroph- can not make their own food. Need to eat something else to obtain energy (fungi, animals, most bacteria • Equation • Fermentation- still make energy when no oxygen present. Two types: alcoholic and lactic acid fermentation • Mitochondria-where respiration takes place 6O2 + C6H12O6 6CO2 + 6H2O + Energy

  27. Cellular Respiration Series of events: Glycolysis → krebs cycle →electron transport ENERGY

  28. Cellular Respiration Compared to Photosynthesis

  29. Cell Division Cell cycle- series of event cell goes through as it grows and eventually divides. Interphase- When cell grows and develops, getting ready to divide again Mitosis-Division of cell nucleus (forms diploid (2N) cells) Cytokinesis-cell splits in two PMAT

  30. Cell Division • Meiosis- cell division forming sex cells (gametes) • Results in 4 genetically different cells • Gametes are N (haploid-half the number of chromosomes)

  31. Cell Division • Cell growth (cell gets bigger, volume increases faster than surface area) so has to divide

  32. DNA, RNA, and Protein Synthesis • Replication- DNA making DNA • Transcription- DNA making RNA • Translation- RNA making Proteins

  33. DNA, RNA, and Protein Synthesis DNA-double helix 3 kinds ofRNA

  34. DNA, RNA, and Protein Synthesis • Complementary bases • DNA: C-G A-T • RNA: C-G A-U

  35. DNA, RNA, and Protein Synthesis Codon- three letter “word” on mRNA specifying a particular amino acid anticodon codon

  36. Genetics • homozygous same letters (TT or tt) • heterozygous different letters (Tt) • Genotype- the alleles (letters) i.e. Tt, TT, tt • Phenotype- physical characteristics (Tall, short)

  37. Genetics • Gamete- sex cell (N) haploid. • Zygote-fertilized egg • Fertilization-process when sperm and egg join

  38. Genetics • Dominant / Recessive cross-one allele is dominant over another. I.e. T-tall (dominant) over t-short (recessive) TT X tt gametes T T All tall offspring t t

  39. Genetics • Incomplete dominance-one allele is not completely dominant over another (RR-red crossed with WW-white yields all RW-pink flowers) RR X WW R R W W

  40. Genetics • Co-dominance-both alleles are dominant. RR-red hair, WW-white hair, RW-roan RR X WW R R W W

  41. Genetics • Dihybrid cross-Mendel’s two-factor experimental results were very close to 9:3:3:1 ratio predicted by punnett square. Proved that genes that segregate independently do not influence each other’s inheritance. • Principle of Independent Assortment 9:3:3:1

  42. Genetics • Multiple Alleles-ABO blood type is an example. A and B or co-dominant.

  43. Genetics • Crossing over- when “legs” of chromosomes cross over each other during meiosis and exchange parts of themselves.

  44. Genetics • Non-disjunction- when chromosomes fail to separate during meiosis. Resulting in missing or extra chromosomes in gametes

  45. Genetics • “Code of Life”-Reading codons and the amino acids they code for Example: CGA UGC AAU Arg – Cys - Asn

  46. Genetics • Cloning-a member of a population of genetically identical cells produced from a single cell

  47. Genetics Human Chromosomes- body cells contain 46 chromosomes (23 from sperm, 23 from egg. Join in diploid zygote) • Karyotype- picture of chromosomes cut out from photographs and grouped together in pairs • Sex chromosomes- two of 46- these determine sex of individual XX=female and XY=male • autosomes- remaining 44 chromosomes

  48. Genetics Egg cells contain a single X chromosome. Sperm cells contain either one X chromosome or one Y chromosome. Approximately half of the zygotes are XX (female) and half XY (male)

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