Plant Biology Exam Notes PDF

Star Slides for Exam 1 Stars mark slides that contain key concepts or summaries. I might ask about anything that was on any slide, but the bulk of questions will come from star slides. Focusing on star slides will help you study most efficiently. WHAT MAKES A PLANT A...

Star Slides for Exam 1 Stars mark slides that contain key concepts or summaries. I might ask about anything that was on any slide, but the bulk of questions will come from star slides. Focusing on star slides will help you study most efficiently. WHAT MAKES A PLANT A PLANT? Contain chlorophyll for absorbing light for photosynthesis – or descended from photosynthetic ancestors Adapted for life on land – descended from land-adapted ancestors Composed of many cells Cell walls contain cellulose 1 Energy Flow Overview (will see this again and get more detail later) Energy stored in bonds might be used quickly, or might be used much later 2  Plants and Energy Plants – Lower carbon dioxide (CO2) in the atmosphere convert into organic compounds stored in organisms, soil and fossils – Coal - Fossil Fuel, Ancient plants – Wood, other plant parts—Biofuels (more later) – Are hosts for bacteria that consume atmospheric methane Greenhouse Gases: Carbon dioxide, methane and water vapor Greenhouse Effect Infared radiation (heat) from sun passes in through glass (atmosphere) Traps infared inside Interior warms 3  Fruit develops from ovary (special leaf-like structure) after fertilization Bud for new Contains seeds branches and flowers Above ground Organ Systems Below ground Plant Growth Growth from: 1) production of new cells and tissues 2) cell enlargement. Primary meristems generate new primary tissues at tips of roots and shoots (apical) and at site of new branches (axillary bud) – consist of several layers of cells that generate tissues that make up organs 4 Primary apical meristems Axil: angle Angle between stem and leaf stalks Plant Growth Growth from: 1) Production of new cells and tissues Meristems: consist of several layers of cells that generate tissues that make up organs Primary (increase length) Apical-Tips of Roots and Shoots Shoot apical meristem makes stems, leaves and axillary buds (for branches) Secondary (increase girth of stems and roots) Vascular cambium and cork cambium Only in Woody plants (trees, shrubs, woody vines) 5  Plant Cell expansion Cell expansion – increase amount of cytoplasm and number of organelles. – plant cells can take up a lot of water into central vacuole and expand cell walls. – expansin proteins unlock linkages between cell wall components allowing wall to stretch. Bamboo can grow > 1 meter/day due to cell expansion and meristem activity What plant structure? Cauliflower-mass of Brussels sprouts- shoot meristems axillary buds Carrots--Roots Potato-stem w buds Grapes--Fruits 6  Plant Growth Growth from: 1) Production of new cells and tissues Meristems: consist of several layers of cells that generate tissues that make up organs Primary (increase length) Apical-Tips of Roots and Shoots Shoot apical meristem makes stems, leaves and axillary buds (for branches) Secondary (increase girth of stems and roots) Vascular cambium and cork cambium Only in Woody plants (trees, shrubs, woody vines) Plant Cell expansion Cell expansion – increase amount of cytoplasm and number of organelles. – plant cells can take up a lot of water into central vacuole and expand cell walls. – expansin proteins unlock linkages between cell wall components allowing wall to stretch. Bamboo can grow > 1 meter/day due to cell expansion and meristem activity 7  Plant Structure Plant bodies contain: – Cells, Tissues, Organs, Organ Systems Plants grow by: – Production of new cells Primary apical meristems: apical (tips of shoot and axillary buds) – Expansion of cells New material Water uptake Covalent bonds Form between atoms that share electrons. Some atoms may share more than one pair of electrons – Double and triple bonds possible 8  Covalent bonds Covalent bonds Carbon has 4 electrons to share – – can share two electrons with an oxygen atom or another carbon atom; – Or each electron can be shared with a different atom. – Carbon can form many different compounds. 9  Ionic bonds One atom gives up one or more electrons and becomes positively- charged Other atom takes electrons and becomes negatively-charged Attraction between these oppositely- charged ions is called the ionic bond. – Example: Na + Cl forms the compound NaCl which can form the ions Na+ and Cl- Hydrogen bonds When electrons shared between two atoms that differ significantly in size; electrons spend more time traveling around the larger atom, so that part of the molecule has a partial negative charge, – Polar – water molecules. The partial negative charge on one molecule is attracted to the partial positive charge on another molecule; this is called a hydrogen bond. These bonds are relatively weak – very important in determining the characteristics of water – maintaining the correct structure of genetic material 10  Hydrophilic and Hydrophobic Hydrophilic: Water-loving – Dissolve in water – Charged or Polar Hydrophobic: Water-hating – Don’t dissolve in water (often do in lipids) – Uncharged or nonpolar 11 Bond strength: Hydrogen bond  Ionic Bond  Covalent Bond Hydrogen bond: Partial charge (polar), water Ionic bond: Full charge, salt, acids, bases Covalent bond: Shared electrons, Carbon Bond 1 2 3 4 Monosaccharides flexible from single bonds at C. 5 6 C1 reacts with –OH of C 5. Ring formation releases 6 energy (more stable). 5 4 1 3 2 All C’s have 4 bonds All O’s have 2 bonds OH = O—H 12  6 5 4 1 3 2 Dehydration synthesis of disaccharide SUCROSE Table sugar Major sugar transported in plants 13  Polysaccharides Made by dehydration Not water soluble (not hydrophilic) – Good for storage – Good for building structures Starch – Abundant polysaccharide in grains and root vegetables – Up to 1000 glucose molecules in chain C6 C6 C6 C6 Starch - alpha bonds C1 to C4 14  C6 C6 C6 C6 Starch - alpha bonds C1 to C4 Polysaccharides Cellulose-structural – Plant cell walls Also polymer of glucose, but arranged differently – Alternate sugars flipped We can’t digest this – Some fungi and bacteria can – Still need for fiber in diet 15  C6 C6 C6 C6 Cellulose - beta bonds C1 to C4 C6 C6 C6 C6 Cellulose - beta bonds C1 to C4 16  C6 C6 C6 C6 1 2 3 4 5 Starch - alpha bonds C1 to C4 6 C6 C6 6 5 C6 C6 4 1 3 2 Cellulose - beta bonds C1 to C4 From last time… C6 C6 C6 C6 1 2 3 4 5 Starch - alpha bonds C1 to C4 6 C6 C6 6 5 C6 C6 4 1 3 2 Cellulose - beta bonds C1 to C4 17 From last time… Lipids Dehydration Reaction From last time… 18 From last time… Proteins Large molecules made of 20 different amino acids. Most important role “machines” of the cell Also some storage roles Amino acids composed of carbon, hydrogen, oxygen, nitrogen and sometimes sulfur Central carbon group bonded to a carboxylic acid group (COOH), an amino group (NH2), and a side chain (R) R Four levels of organization Primary – sequence of amino acids; Secondary – helical or pleated sheet structures maintained by hydrogen bonds; Tertiary – folding of protein with shape maintained by covalent bonds between sulfur atoms; Quaternary – two or more polypeptide chains held together by hydrogen bonds. 19 20 Cell-membrane Carrier Protein 21  Membrane Functions Transport of water by osmosis – diffusion of water across cell membranes – Water moves into or out of the cell depending on : concentration of dissolved substances (solutes) on both sides of the membrane pressure or physical force exerted on water Does not need a carrier Osmosis Isotonic solutions - same solute concentration as inside the cell – Some water will pass through the membrane in each direction. Balanced Hypotonic solutions - lower concentration of solutes (higher concentration of water) than the inside of cell. – Water diffuses into the cell Hypertonic solutions - higher concentration of solutes (lower concentration of water) than the cell – Water diffuses out of the cell. 22  OSMOSIS: ISOTONIC Isotonic solute concentration outside cell same as inside cell Fig. 4.10 OSMOSIS: HYPOTONIC Hypotonic solute lower outside than inside cell (water concentration higher outside than inside). Water diffuses into the cell until the cell bursts…OR… Burst cell Fig. 4.10 23  OSMOSIS: HYPOTONIC Water diffuses into the cell until the cell membrane is pushed up tightly against the cell wall pressure prevents the entry of more water OSMOSIS: HYPERTONIC Hypertonic solutions - higher concentration of solute (lower concentration of water) outside than inside the cell – Water diffuses out of the cell. 24  Isotonic solutions – – Solute same inside and outside – Water Same inside and outside – No water movement Hypotonic solutions – – Solute low outside, high inside – Water high outside, low inside – Water diffuses in Hypertonic solutions - – Solute High outside, low inside – Water Low outside, high inside – Water diffuses out of the cell. Motor proteins – Some motors travel on microtubules and some travel on actin – Carry cargo 25 From last time… Proteins From last time… 26 From last time… From last time… Cell-membrane Carrier Protein 27 From last time… Isotonic solutions – – Solute same inside and outside – Water Same inside and outside – No water movement Hypotonic solutions – – Solute low outside, high inside – Water high outside, low inside – Water diffuses in Hypertonic solutions - – Solute High outside, low inside – Water Low outside, high inside – Water diffuses out of the cell. Motor proteins – Some motors travel on microtubules and some travel on actin – Carry cargo 28  Chloroplasts Chloroplasts – Double membrane – Contain chlorophyll (pigment needed for photosynthesis) – cells may have 40-50 Internal membranes (thylakoids) contain chlorophyll and other molecules important for photosynthesis. Watery stroma contains other enzymes for photosynthesis. Chloroplast Figure 4.27 29  Mitochondria Mitochondria- “Powerhouse of the cell” – Folds of inner membrane (cristae) contain enzymes and other molecules important for energy metabolism. – Watery matrix contains other enzymes for energy metabolism. Believed to be descended from ancient bacteria engulfed by another cell. – Reproduce by binary fission like bacteria. – Ribosomes and small amounts of DNA similar to those in prokaryotes. Mitochondrion 30