2013-14 Academic Decathlon Science Component Section I Prepared by Ms. Aguilar

1. 2013-14 Academic DecathlonScience Component Section IPrepared by Ms. Aguilar

2. Section I History Overview Early Hypothesis Aristotle: Male provides a miniature individual through the blood. Female provide the environment for growth. Idea Persisted for >2000 years Hippocrates: every organ in our body originated from a “gemmule” that accumulate in the male & female reproductive organs during sexual maturity. Pangenesis: Upon conception gemmules combined & blended together to form different parts of the new individual (Proposed by Darwin) Kolreuter: studies genetic crosses in tobacco plant & came up with Blending Inheritance. Formed the basis for Darwin’s theory of evolution

4. Mendel: 1850’s-60’s experimented with pea plant. Formulated a set of principles & described the “inheritance factor” later called the gene. Darwin: along with Wallace developed the theory of “Natural Selection” Note! neither men had knowledge of chromosomes and so Mendel’s work was ignored for decades

5. Major Discoveries WWI • Genetics Blossomed • 1900-1914 Mendel’s work was rediscovered & Natural Selection validated. • Correns, deVries, & Tschermakhybridized: mated two different plant species to generate an offspring with traits from both parents thereby marking the rediscovery of Mendel’s work • Sutton & Boveri: chromosomes in nucleus segregate in meiosis. So Mendel’s “factor” was linked to the chromosome.

6. 1905 term “genetics” is coined by William Bateson. Together with Reginald Punnett discover linked genes. • Stevens and Wilson discover chromosome differences w/ male & female. • 1902 Archibold Garrod notices 1st “inborn error in metabolism” caused by the lack of an enzyme due to a recessive trait.

7. Morgan worked with Drosophila melanogaster to study pattern of eye color inheritance and realized it was a sex-linked carried on the X since most males had white eyes.

8. Controversy Late 19th century/ early 20th century • Social Darwinism becomes popular; “Survival of the Fittest” • Eugenics Movement: R.A. Fisher becomes a strong advocate for improving the genetic composition of humans. NOTE!! Used during WWII commit acts of genocide.

9. Discovery of Cells • Microscope; most important tool that aided humans in viewing the microscopic world. • Robert Hook: 1st to observe cork cells and call them “cells” • Anton van Leeuwenhoek was the 1st to observe live cells. • Robert Brown observed and coined the “nucleus”

10. Father of Taxonomy, Carolus Linnaeus (1700’s) was the first to classify everything living into 3 kingdoms: Vegetable, Animal or Mineral • Today we use a system derived from the rRNA comparison of organisms. (molecular biology)

11. Live in extreme conditions; very hot, salty, acidic, methane rich places. Large diversity of bacteria some can perform photosynthesis

12. Conditions of Early Earth • 1923: Hypothesis by Oparin suggested that the atmosphere only contained ammonia, hydrogen gas, water vapor, & methane. - This gases reacted under extreme temperatures & conditions to form simple organic compounds.

13. 1953: Miller & Urey set up an experiment to • test Oparin’s hypothesis. • - The experiment produced a variation of • organic compounds, including amino • acids and nucleotides.

14. 1953: Miller & Urey set up an experiment to test Oparin’s hypothesis. - The experiment produced a variation of organic compounds, including amino acids and nucleotides.

15. Sidney Foxheated amino acids to form protein chains. When allowed to cool self-assembled into small spheres that were selectively permeable. They were calledmicrospheres. Microsphere demonstrate excitability, absorb materials from their surroundings & respond to changes in osmotic gradients From Molecules to Cell-Like Structures

16. Cells • Cell Theory • Schleiden, Virchow, Schwann • The Cell is the basic unit of life • All living things are made of cells • All cells arise from pre-existing cell Eukaryote Highly organized membrane-bound organelles & nucleus with specific functions. Have an outer barrier, and a fluid filled space. Found in protist, fungi animals & plants. Prokaryote 3.8 by First cells, bacteria, lack a nucleus. Have nucleoid region and no membrane bound organelles. Might have cell wall, capsule, pili or flagella Animal Round in shape have centrioles, lysosomes, & some have flagella. Plant Squared in shape, have cell wall, chloroplast, large vacuole.

17. Plasma Membrane • Bilayer of phospholipids; charged phosphate heads and hydrophobic fatty acid tail. • Several proteins function as enzymes, transporters, receptors, recognition sites or anchoring

18. Cytoplasm • Fluid filled space w/ cell membrane and nucleus. • Initial breakdown of glucose takes place here. (glycolysis) • All other reactions critical to the cell take place in specialized compartments (organelles)

19. Nucleus Double membrane • Delegates orders to the rest of the organelles. • Stores genetic info • DNA organized in chromosomes. • Has nucleolus inside; rRNAsynthesis

20. Ribosomes • Composed > 70 proteins • Can be free-floating or attached to the rough ER • Function is to synthesize proteins • Proteins made by free floating ribosome stay and work inside the cell • Proteins made by attached ribosome go through an assembly line, travel through membrane system, & are directed to various destinations (50S) (30S)

21. Endomembrane System • Consists of the nuclear envelop, rough & smooth ER, Golgi body and transport vesicles. • Vesicles shuttle proteins from one location to another through the endomembrane system. • At each location the protein undergoes modifications that prepare it for a specialized function

22. Rough ER • Made of tightly compacted membranes • Ribosomes attached to its surface • Have many enzymes responsible for varied rxn’s

23. Golgi Complex • Receives proteins from the Rough ER • Process, concentrate, & modifies proteins & sends them to their final destination.

24. Lysosome • Digestive organelle • Digests particles, gets rid of aged and worn out structures and recycles the parts • Lacking in plant cells, use vacuole in its place.

25. Vesicle • Produced from the ER or Golgi membrane, but can also form from the cell membrane when the cell takes IN material • Section pinches off producing a membrane-enclosed compartment. • Temporarily store and transport proteins to their destination

26. Smooth ER • Site of steroid, lipid, & carbohydrate synthesis • Has enzymes that break-down toxins • Detoxification of drugs, alcohol, pesticides and other toxins

27. Cytoskeleton • Made of protein fibers that provide support, aid in transport, anchor organelles & act as tracts for motor proteins -microtubules: largest, provide support, form tracks for transportation & aid in cell division -Intermediate Filaments: made of flexible protein that keep organelles in place - Microfilaments: thinnest, look like string of beads, found around the periphery of the cell to provide shape, strength & motility. Play role in cell taking in material.

28. Centrioles • Found in pairs near the nucleus and only in animal cells. • Microtubule organizing center • Play an important role in cell division. • Divide during cell division, move to opposite poles and form the spindle fibers

29. Cilia and Flagella • External projections of the plasma membrane • Used in movement, adhesion, & movement of material outside cell • Internally made of microtubules • Sperm: long tail that propels a cell • Cilia: small, numerous, projections

30. Mitochondria • Double membrane • Generate energy: Converts chemical energy from food into ATP • Contains its own DNA & ribosomes • Believed to have evolved from prokaryotic cell

31. Chloroplast • Double Membrane • Have own DNA & ribosomes • Produce & store food material • Contain chlorophyll & carotenoids that trap light for photosynthesis • Found only in plant cells • Believed to have evolved from prokaryotic cell

32. Vacuole • Found in plants and some protist • Help support the cell wall • Store water, food, salts, pigments & toxic byproducts • Help eliminate excess water & maintains proper salt content in cytoplasm • have similar role to lysosome in animal cell • Very small in animal cells but large in plant cells (90% of space)

34. Edosymbiosis • Theory that explains the origin of the mitochondria & chloroplast which are both double membrane bound organelles with their own DNA. • Evolved from prokaryotes that entered and began living symbiotically within eukaryotic cells.

35. Organelles Involved in Cell Division • Nucleus, centrosomes, microtubules, cell membrane and cell wall. • Microtubules organized by newly formed centrosomes move and transport chromosomes.

36. Life Cycle • All living systems must reproduce to maintain the survival of the specie • All cellular reproduction involves replication of the genetic material & even distribution of it to daughter cells • Reproduction can be sexual or asexual • Asexual = Binary Fission • - In Prokaryotes: bacteria have a single circular chromosome that replicates itself to form 2 rings these rings then anchor themselves to the cell membrane. Membrane grows, pinches inward and splits forming 2 identical cells clones to the parent cell. • Bacteria divide every 20 min if conditions are good. • Sexual Reproduction in bacteria is called conjugation and it’s a process that generates diversity.

38. 90% of time is spent preparing for Mitosis in interphase (G1, S, G2) • 10% of time in Mitosis • G1: the cell grows and RNA and protein synthesis because all organelles must replicate • S: diploid genome doubles = DNA replicates. Chromosomes double and each end up with 2 sister connected chromatids • G2: building blocks for organelles are assembled Cell Cycle

40. Mitosis Interphase: chromatin duplicates, sister chromatids are formed Early Prophase: sister chromatids condense & joined at centromere, spindle microtubules appear Late Prophase: nuclear envelop disintegrates, spindle microtubules connect to sister chromatids in kinetochore, centrosomes with anchored spindle fibers migrate to opposite poles

41. Metaphase: chromosomes line up along the metaphase plate • Anaphase: adhesive connecting the sister chromatids disintegrates. The 2 centromere splits separating the sisters. The kinetochore shorten, pulling the chromosomes to opposite poles • Telophase: reverse of prophase. Chromosomes start to unwind, nucleoli reassemble, nuclear envelop reforms, & spindle microtubules and centromeres disintegrate & recycled. • Cytokinesis: point in which cytoplasm divides. • Animals: a cleavage furrow forms halfway w/ the 2 new cells & the cells split. • Plants: require preformed vesicles with cell wall & cellulose material to form a plate

42. Sexual Reproduction • evolved 2 billion years ago • unicellular eukaryotes use mitosis under normal conditions but sexually under unpredictable environments. • germ cells: specialized cells like sperm and egg pass on hereditary information through meiosis. • - Gametogenesis: the formation of the egg and sperm • - spermatogonia: diploid immature male gamete • - oogonia: diploid immature female gamete

43. Similar to mitosis in phases. • Differences: • - 2 cell divisions, 1st necessary for crossing over and creating genetic diversity and the second one dividing the chromosome # by half. • IMPORTANT • Prophase I: Homologous Chromosomes pair up along their length forming a tetrad then crossover to synapse. Genes from the maternal and paternal chromosomes exchange genes leading to genetic diversity. Meiosis

45. Fertilization • Sperm + Egg = zygote or n (haploid)+ n (haploid) = 2n (diploid) • Zygote divides numerous times through mitosis reaching 50 trillion cells • Stem Cells: calls that divide infinitely and can be induced to become any cell type • NOTE! very important to scientist because they can be used to replace damaged cells that do not divide (brain and heart) also some of the genes that program stem cells have been identified so in the future stem cells may be reprogrammed into Pluripotent cells. • cells can be • Totipotent: cell that can become any of 260 cell types • Pluripotent: cells that can differentiate into any cells that we find in an adult human • Multipotent: can only form a small # of specialized cells.

47. Sources of Genetic Variation Mutation: ultimate source of genetic variation. Change in DNA. Crossing Over & genetic recombination: cell can undergo up to 60 crossing over events. Reason we have traits from mom & dad. Independent Assortment: independent shuffling of chromosomes. 46 chromosomes in humans can yield up to 64 trillion possible combinations Random Mating & Fertilization: 1 of 50 million sperm and 1 of 1 million eggs randomly combine during fertilization.

49. Types of Somatic Cells Not all cells divide in our body because the process consumes too much ATP Dividing Cells: needed to replace cells that die. Commonly found in cells lining external & internal structures & go through mitosis often. Non-Dividing Cells: cells that have vital functions and therefore cannot be interrupted with cell division. These cells stay in the G0 phase. Ex: nerve cells, cardiac, hair cells in the ear, & lens cells Reproductively Dormant Cells: cells in the G0 phase but are induced to enter the cell cycle under certain conditions. Ex: embryos in seeds, when organ needs to heal