BS 162 Organisms and Populations Material for Exam 1 Chapter 4 Biology of the Cell Cell Theory All organisms are composed of one or more cells Cells are the smallest living things basic unit of organization Cells only arise by division of a previously existing cell Surface Area to volume ratio as a cell s size increases its volume increases by a factor of 10 Light Microscopes Electron Microscopes stronger than light microscopes Prokaryotes single celled organisms has nucleoid no interior organization Eukaryotes complex organisms have nucleus that encloses DNA Cells are very organized Bacteria have cell wall Organelles Parts of the Cell Plasmodesmata openings in the cell wall that function in cell to cell communication Tonoplast membrane that surrounds the central vacuole In plant cells Chromatin complex structure made up of chromosomes containing DNA The structure of the chromatin affects the function of DNA Ribosomes synthesize proteins Place where genetic code is translated into the amino acid sequence Ribosomal RNA rRNA form a functional ribosome only when synthesizing proteins Messenger RNA mRNA carries coding information from DNA Cells uses this information to direct the synthesis of a protein Transfer RNA tRNA carries amino acids Rough ER site of protein synthesis has ribosomes Smooth ER stores Ca2 in cells Detoxification Chromatin DNA associated proteins Mitochondrion Site of cellular respiration Large oxygen demand More mitochondria in cells that require more energy Contain its own DNA and ribosomes reproduce on their own Cristae folds Matrix space in between the folds Chloroplast Thylakoids Granum stack of thylakoids Stroma space between the thylakoids Has its own DNA and ribosomes Movement Actin filaments Microfilaments long fibers about 7 nm in diameter Each is composed of two protein chains that are composed of the protein actin They exhibit polarity Microtubules largest of the cytoskeletal elements Hollow tubes about 25 nm in diameter Composed of a ring of 13 protein protofilaments Intermediate Filaments Most durable Very stable and hardly ever broken down Composed of many different cytoskeletal fibers like vimentin and keratin Centrioles barrel shaped organelles found in animals and protists Occur in pairs Microtubules of flagellum are derived from a basal body Flagella of Eukaryotic cells is completely different than that of prokaryotic it has a 9 and 2 arrangement nine microtubules surrounding two central microtubules Prokaryotic Flagella smaller made of a single spiral of protein somewhat rigid rotates rather than whips Plant cells cellulose based cell wall Kinesin motor molecules that walk along microtubules Causes flagellum or cilia to whip Integrins cell surface proteins that are involved in the adhesion of cells to substrates part of the cell membrane Influence behavior and alter gene expression Connection Communication Glycolipids lipids with carbohydrate heads Adhesive juntions mechanically attach the cytoskeleton of a cell to the cytoskeletons of other cells Found in muscle and skin Adherens junctions based on protein cadherin Joins adjacent cells together Found in animals Desmosomes cadherin based junction unique to vertebraes Contain the cadherins desmocolin and desmoglein Join adjacent cells Unique to VERTEBRAES Hemidesmosomes and focal adhesions connect cells to the basal lamina or other ECM Proteins integrins Septate junctions form a barrier that can seal off a sheet of cells Tight junctions proteins claudins Unique to VERTEBRAES Gap Junctions can open or close in response to a variety of factors Ca2 and H ions Invertebrates formed by pannexins Vertebrates also have protein connexon Cell to cell junctions in plant cells only occur at holes or gaps in the wall Plasmodesmata cytoplasmic connection in plants Class Notes 1 12 Science a process that attempts to find natural causes Foundation on observations involves discovery inductive Involves distinctive reasoning type hypothetical deductive and testing predictions Ways of collecting evidence Descriptive studies comparisons without manipulation experiments with manipulation controls treatments meta analysis reviews Laboratory v Field v Natural Experiments Deduction logic moves from broad to specific Induction logic moves from specific to broad Class Notes 1 14 Living things Ability to reproduce ability to grow are organized ability to metabolize ability to evolve respond to natural selection Hierarchy of Life Molecules Organelles Cells Tissues Organs Organism Population Community Ecosystem Biosphere Planet Gaia Principle Reductionism to understand the whole you must study the parts Reduces complexity Done when conducting most experiments Holism Emergent properties are important as you go up the hierarchy The whole is greater than the sum of its parts Challenging to do this in experiments Gaia Principle the ultimate holism Viruses made up of genes and protein Not alive Prions made of just protein Ex mad cow disease chronic wasting disease Creutzfeldt Jakob disease Prokaryotes cell membrane circular continuous DNA ribosomes Includes eubacteria and Achaea Do not have nucleus or most organelles Eukaryotes Cell membrane ribosomes true nucleus with membrane DNA in chromosomes chunks not circular organelles Animal cells centrioles flagella cilia Plant cells Cell wall cellulose chloroplasts central vacuole Flagella propel in the direction of the flagellum flagella pull the cell in sperm cells opposite pull in direction of cell Cilia can move in any direction lots of tiny hairs on the outside of the cell Chapter 14 DNA the Genetic Material Transformation transfer of virulence from one cell to another Transfers genetic material Bacteriophages viruses Have a simple structure composed of a core of DNA surrounded by a coat of protein 3 Main components of DNA five carbon sugar phosphate group PO4 and a nitrogen base Purines Adenine and Guanine Pyrimidine Thymine and Cytosine proportion of A and T are always equal and G and C are always equal Phosphate gp Is attached to the 5 carbon atom of sugar and the base is attached to the 1 carbon atom A free OH is attached to the 3 carbon atom DNA polymerase enzyme that matches the DNA bases and nucleotides and links them together to ake the new strand Endonucleases cut DNA internally Exonucleases chew away at the end of a DNA strand Helicases enzymes that use energy from ATP to unwind the DNA template Topoisomerases enzymes that act to relieve the torsional strain caused by