EOCT Review

1. EOCT Review Biology EOCT- Tuesday and Wednesday 5/7-5/8

2. Two types of cells… • Prokaryotes- single-cell organisms that lack membrane-bound organelles. Ex- bacteria • Eukaryotes- single-celled and multi-celled organisms with organelles, nucleus. Ex- plants, animals, fungi, protists

3. Major Cell Organelles • Nucleus- contains DNA, regulates cell function • Chloroplasts- capture solar energy for photosynthesis • Golgi body (apparatus)- modifies, sorts, and ships proteins and lipids around the cell. • Mitochondria- produces ATP (energy) • Ribosomes- makes proteins, by assembling chains of amino acids (polypeptide chain)

4. Cell Membrane • Lipid bilayer • Has selective permeability- allows certain substances to pass, while blocking others • Passive transport- movement of a substances across the cell membrane without energy. Moves from high to low concentration. • Types: diffusion, osmosis (water) and facilitated diffusion.

5. Cell transport that requires energy! • Active transport- drives molecules across a membrane from a region of lower concentration to higher. • Endocytosis- cell surrounds and takes in material from its environment. • Exocytosis- cell surrounds and removes material from inside the cell

6. Enzymes • Enzymes- speed up (catalyze) specific reactions without being used up in the reaction. Enzymes are proteins. • Substrates- molecules that a specific enzyme can recognize and bind to. Fits together at the active site. Fits together like a lock-and-key-mechanism. • If the concentration of enzyme is low- slows reaction

7. Enzymes Continued… • Activation energy- amount of energy substrate molecules must have when they collide to produce a reaction. • Many enzymes lower activation energies by holding the molecules close together in the correct orientation.

8. Biomolecules • Carbohydrate- a simple sugar or a molecule composed of two or more simple sugars. Used for energy. Contains C, O, and H. Cellulose is used for support in plants. • Mono- one; oligo- few; poly- many • Lipids- more C-H bonds, less oxygen; fats and oils, insoluble in water, nonpolar. Used for long-term energy storage, major component of cell membranes. Waxy covering in cuticle (plants)

9. Biomolecules • Proteins- made of chains of amino acids, important in muscle contraction, transporting oxygen in the blood, part of cell membranes. • Nucleic Acids- store and transmit genetic information. Made of chains of nucleotides. Ex- ATP, NAD+, DNA, RNA

10. Energy • The primary source for energy is the sun. • Photosynthesis- converts this solar energy into chemical energy in the form of carbohydrates. • All life processes require energy! • ATP- adenosine triphosphate is a special molecule that stores and releases energy stored in its bonds to meet the energy needs of a cell. Happens when ATP releases a phosphate and becomes ADP (diphosphate) • ATP is produced in the mitochondria.

11. Photosynthesis • Autotrophs- organisms that manufacture their own energy-providing food, most through photosynthesis. Plants, cyanobacteria, algae • Chlorophyll- pigment in chloroplasts that absorbs energy from sunlight. • General equation for photosynthesis: 6CO2 + 6H2O + sun  C6H12O6 (glucose) + 6O2 * Two main reactions of photosynthesis: light reactions and Calvin cycle.

12. Reactions of Photosynthesis • Light reactions- take place in the chloroplasts. Splits water molecules, providing hydrogen and an energy source for the Calvin cycle. Occurs in the thylakoids of chloroplasts. • Calvin cycle- forms simple sugars (glucose) using carbon dioxide from the air and the hydrogen from water. Occurs in the stroma of chloroplasts.

13. Cellular Respiration • Glucose is broken down into carbon dioxide, water, and energy (ATP). Occurs in the mitochondria. Both plant and animal cells must do this! C6H12O6 (glucose) + 6O2  6CO2 + 6H2O + energy * Glycolysis- anaerobic (w/out oxygen) process that occurs in the cell’s cytoplasm before cellular respiration can occur. Produces 2 ATP and pyruvic acid. Low ATP production, but can be used repeated in anaerobic situations- lactic acid fermentation.

14. Cellular Respiration • Two main reactions of cellular respiration: Krebs cycle and electron transport chain. • Kreb’s cycle- breaks down the products of glycolysis to produce the molecules used in the electron transport chain. Occurs in mitochondria. • Electron transport chain- takes place in the inner membrane of the mitochondria; converts ADP to ATP by transferring electrons. Net production 34 ATP!!!

15. Six Kingdoms • Eubacteria- prokaryotes, “true bacteria”, contains all the bacteria that cause disease and that are beneficial. • Archaebacteria- prokaryotes, found in extreme environments such as deep oceans, hot springs, or swamps.

16. Six Kingdoms • Protists- eukaryotes, uni- or multicellular, lack complex organs systems, live in moist environments. Most diverse kindgom!!! Ex- euglena, amoeba, paramecium. • Fungi- eukaryotes, uni- or multicellular, heterotrophs. Consumers that don’t move; absorb nutrients from decomposing organisms and waste. Ex- mushrooms, yeast

17. Six Kingdoms • Plants- photosynthetic, multicellular eukaryotes. Most have cellulose walls and tissues that are organized into organs and systems. • Animals- multi-cellular eukaryotic consumers (heterotrophs). Do not have cell walls. Tissues organized into complex organ systems- nervous, digestive, etc.

18. Taxonomy • Taxonomy- branch of biology dealing with the naming and grouping of organisms. • Classification- grouping objects based on similarities; used in taxonomy. • Levels of classification from least to most specific: Kingdom, Phylum, Class, Order, Family, Genus, Species * Species- most specific level, animals can reproduce and have reproductively viable offspring.

19. Viruses!!! • Viruses are infectious particles made of a protein shell called a capsid, which contains either DNA or RNA (genetic material). • Not considered living because they are not cells and cannot reproduce outside of a host cell. They must infect a living cell, a host, in order to replicate.

20. Genetics • Genetics- branch of biology that studies that passing on of characteristics from parents to offspring. These characteristics are called traits • DNA- a nucleic acid used for information storage. Made of smaller subunits called nucleotide. Each nucleotide has a deoxyribose, a phosphate group, and a nitrogen base. DNA has 4 bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

21. More on DNA • Nucleotides combine to form two long chains, similar to a ladder, twisted into a spiral. This structure is called double helix. • A-T and G-C bonds. • DNA replication- DNA is “unzipped” by an enzyme and each parent strand is matched to its complementary bases. Forms two identical copies!

22. RNA • RNA is also made of nucleotides. Differences: sugar is ribose, uracil replaces the base thymine, RNA is single stranded. • During transcription, RNA transfers the genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm where the code on the RNA is used to form proteins from amino acids.

23. Transcription and Translation • Transcription- DNA is used as a template to make messenger mRNA, which carries the genetic information from DNA to ribosomes in the cytoplasm. • Translation- process of converting the information in the mRNA into a sequence of amino acids that make proteins. • Transfer RNA (tRNA)- brings the amino acids to the mRNA at the ribosomes so protein synthesis can take place

24. Mendelian Genetics • Gregor Mendel, an Austrian monk, was the first to succeed in predicting how traits are carried from one generation to the next. • Genes are located on chromosomes and can exist in alternate forms called alleles. The dominant trait always expresses, if present. The recessive trait only expresses if both alleles are recessive. • If two alleles in a pair are identical- homozygous Ex- BB, bb • If the two alleles are different, the trait is called heterozygous Ex- Bb

25. More on Genetics • Monohybrid cross- involve one trait. Dihybrid cross- two traits. Punnett squares… • One allele for each trait comes from each parent.

26. Meiosis • Meiosis is the process by which gametes (sex cells, egg and sperm) are produced. • Meiosis produces haploid cells that have half the number of chromosomes as the parent cell. Ex- human body cell = 46 chromosomes human sperm cell = 23 chromosomes *Crossing over- two chromosomes overlap and exchange material, source of variation

27. Mutations- changes in nucleotide sequence • Mutagens agents that harm DNA. Ex- UV, tobacco • Spontaneous mutations may occur as a result of replication errors. • Base-pair substitution- one base is replaced with another • Base insertion- extra nucleotide base inserted into DNA; causes a frame-shift. • Base deletion- removal of nucleotide base, also frameshift.

28. Mitosis • In mitosis, the DNA is replicated and then equally divided between two daughter cells. • Used for asexual reproduction, grow, repair and replace worn-out cells. • Advantages of asexual reproduction: does not require a partner, faster, identical offspring. Works well in stable environments, which the organism is well-suited for.

29. Sexual Reproduction • Involves much more time than asexual reproduction. Gametes must be formed and mating must occur. • The benefit is the genetic variation that results from meiosis. • This increases the possibility that some organisms will survive and reproduce in a changing environment.

30. Ecology • Ecology- the study of the interactions between different kinds of living things and their environment. • Organism- individual • Population- same species living in a given area • Community- collection of populations (species) living in a given area. • Ecosystem- all biotic (living) and abiotic (nonliving) factors in a given area. • Biomes- group of ecosystems having similar types of vegetation and climate.

31. Population Growth • If a population is provided with ideal conditions, it will increase in number. As the population grows larger, the rate of growth increases. This is called exponential growth and has a J-shaped graph. • As resources become limited, the growth of a population slows and stabilizes. This is called logistic growth and has an s-shaped curve. The point where the population becomes stable is called carrying capacity.

32. Population Growth • When a population reaches its carrying capacity, a number of factors help stabilize it at that size. • Density-dependent limiting factors- stress/ crowding, competition, predation, parasitism • Density-independent limiting factors- weather, fires, droughts, floods, human activities • Niche- organism’s role; what it eats, where it feeds and how it effects energy flow.

33. Energy Flow • Energy is constantly flowing through ecosystems from the sun to producers to consumers to decomposers. • Herbivores- eat plants; carnivores- eat other animals; omnivores – eat plants and animals; decomposers – break down dead organisms.

34. Energy Pyramids • Show how energy decreases at each succeeding trophic level. Only about 10% is transferred to the next trophic level.

35. Succession • Ecosystems are constantly changing. Succession is the natural change that takes place within a community of an ecosystem. • Primary succession- gradual development of a new community where no organisms lived before. • Secondary succession- occurs when a natural disaster or human activity partially destroys a community- soil present

36. Plant Tropisms- response to environment • Even though plants lack nervous systems, they do possess mechanisms that enable them to respond to their environment. • Geotropism- response to gravity- roots grow down, stems up. • Phototropism- grow toward light. • Thigmotropism- response to touch. Ex- ivy growing on wall

37. Theory of Evolution • Lamarck was the first scientist to propose a theory of evolution. He stated that all life forms evolved; changed due to demands of their environment. Problem was he believed organisms passed on acquired characteristics, such as big muscles acquired during a lifetime. • Charles Darwin read Lamarck’s work as well as Lyell (geologist, fossil record) and Malthus (competition) and used his experiences aboard the HMS Beagle to shape his theory of evolution.

38. Evolution • Adaptation- traits that occur in organisms and enable them to be successful in their environment. • Natural selection- when organisms with favorable traits for a particular environment survive, reproduce, and pass those variations to the next generation.

39. Rates of Evolution • Adaptive radiation- species diversity occurs in a relatively short time; occurs when a population colonizes a new area. Ex- Darwin’s finches • Convergent evolution- unrelated species evolve superficial similarities because of adaptations to similar environments. • DNA and other molecular evidence is used to determine evolutionary relationships.

40. Speciation • Speciation is the evolution of a new species that occurs due to changes in gene flow. • Geographic isolation- physical barriers divide populations, can cause speciation. • Gradualism is evolution that occurs over a long time, gradual accumulation of changes. • Punctuated equilibrium- speciation occurs quickly in rapid bursts.

41. Types of Selection • Stabilizing selection- maintains the average characteristics. (2) • Directional selection- environmental conditions favor the survival of one phenotype over another. (3) • Disruptive selection- results in disappearance of forms that are considered intermediate. (1)

42. Fossil Record • The fossil record provides biologists with an incomplete picture of the evolution of plants and animals. • Fossils are dated by relative dating- position in the rock layers and radioisotope (radiometric) dating. • Radiometric dating- uses radioactive isotopes to date fossils; carbon-14 is the primary isotope used. • Transition fossils- intermediate forms, Ex- Lucy, rare in fossil record because they exist for a short time.