Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Unit 1 Review

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Essential Elements for Life Trace elements  Table 2.1 What are the next four? Which four account for 96% of living matter?

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What IS a covalent bond? Name (molecular formula) Electron- shell diagram Structural formula Space- filling model (c) Methane (CH 4 ). Four hydrogen atoms can satisfy the valence of one carbon atom, forming methane. Water (H 2 O). Two hydrogen atoms and one oxygen atom are joined by covalent bonds to produce a molecule of water. (d) H O H HH H H C Figure 2.11 C, D

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What’s this?

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What’s special about THESE bonds? Figure 2.12 This results in a partial negative charge on the oxygen and a partial positive charge on the hydrogens. H2OH2O –– O H H ++ ++ Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The polarity of water molecules – Allows them to form hydrogen bonds with each other – What important properties does this result in? Hydrogen bonds + + H H + +  – –  – –  – –  – – Figure 3.2

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1. Cohesion Cohesion – Is bonding to neighboring molecules – Is due to H-bonding – Helps pull water up through the xylem of plants Water conducting cells 100 µ m Figure 3.3

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ice … – floats! – insulates the water beneath it! Liquid water Hydrogen bonds constantly break and re-form Ice Hydrogen bonds are stable Hydrogen bond Figure 3.5

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Solvent of Life The different poles of water molecules can dissolve ionic compounds Negative oxygen regions of polar water molecules are attracted to sodium cations (Na + ) Cl – – – – – Na + Positive hydrogen regions of water molecules cling to chloride anions (Cl – ) – – – – – – Na + Cl – Figure 3.6

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Solvent of Life Water can also interact with polar molecules such as proteins This oxygen is attracted to a slight positive charge on the lysozyme molecule. This oxygen is attracted to a slight negative charge on the lysozyme molecule. (a) Lysozyme molecule in a nonaqueous environment (b) Lysozyme molecule (purple) in an aqueous environment such as tears or saliva (c) Ionic and polar regions on the protein’s Surface attract water molecules. ++ –– Figure 3.7

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Water can dissociate – Into hydronium ions and hydroxide ions H Hydronium ion (H 3 O + ) H Hydroxide ion (OH – ) H H H H H H + – + Figure on p. 53 of water dissociating

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The pH scale and pH values of various aqueous solutions Increasingly Acidic [H + ] > [OH – ] Increasingly Basic [H + ] < [OH – ] Neutral [H + ] = [OH – ] Oven cleaner pH Scale Battery acid Digestive (stomach) juice, lemon juice Vinegar, beer, wine, cola Tomato juice Black coffee Rainwater Urine Pure water Human blood Seawater Milk of magnesia Household ammonia Household bleach Figure 3.8

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The pH Scale The pH of a solution: – low in an acid (0-7) – high in a base (7-14) – [H + ] [OH - ] = as [H + ] rises, [OH - ] …? pH = -log [H + ] – if [H + ] = 10 -3, pH = 3 – if [OH - ] =10 -3, pH = 11

Carbon has FOUR unpaired valence electrons... Why is this important?? 2. Carbon atoms are the most versatile building blocks of molecules Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 4.3

hydroxyl group (-OH): polar covalent bonds improve __? improve solubility-esp. mono & di saccharides! Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

carbonyl group (C=O): “aldelhyde” if carbonyl group is on the end. “ketone” if elsewhere. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 12 3

carboxyl group (-COOH): “carboxylic acids” acids because electronegativities of the two adjacent oxygen atoms increase dissociation of H +. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

amino group (-NH 2 ): “amines” base because … ammonia can pick up a hydrogen ion (H + ). Amino acids, the building blocks of proteins, have amino and carboxyl groups. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

sulfhydryl group (-SH): “thiols” How are these important in protein structure? What other functional group is similar? Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

phosphate group (-OPO 3 2- ): “phosphates” usually anions (-2) in solution. Functions? Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

disaccharide: two monosaccharides joined by a dehydration reaction. Sucrose (table sugar) = glucose + fructose… the major transport form of sugars in plants. Maltose (malt sugar) = glucose + glucose Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.5a

Starch: glucose storage polysaccharide of plants: Plants store carbs in this form because… starches are NOT _________ in water. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.6a

glycogen: glucose storage polysaccharide of animals: highly branched vertebrates store about a one-day supply of glycogen in the liver and muscles. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Insert Fig. 5.6b - glycogen Fig. 5.6b

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.8 ?

Chitin: used in annelid bristles (setae) and arthropod exoskeletons (insects, spiders, crustaceans, …). like cellulose, but with a N-containing branch on each monosaccharide. part of the cell walls of many fungi. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.9

fatty acid: carboxyl group attached to a hydrocarbon skeleton, often 16 to 18 carbons. fat: glycerol + three fatty acids SEE NEXT SLIDE 1. Fats: What are they good for? Type of reaction here?

hydrophobic due to nonpolar C-H bonds The three fatty acids may differ in: length presence of C=C bonds Fig. 5.10b

GOOD: Oleic acidBAD: Elaidic acid Oleic acid is a cis unsaturated fatty acid that comprises 55-80% of olive oil. Elaidic acid is a trans unsaturated fatty acid often found when vegetable oils are hydrogenated. These fatty acids are geometric isomers (chemically identical except for the arrangement of the double bond). You’ve heard lots about trans fats lately… produced during hydrogenation of polyunsaturated fats poorly metabolized  cardiovascular damage Which one would be solid at room temp?

two fatty acids & one charged phosphate group attached to a glycerol. Additional small groups may attach to PO What is this phospholipid made of?

Phospholipid Bilayers form cell membranes… What part is hydrophilic? What part is hydrophobic? Fig. 5.12b ? What am I?

Steroids: lipids with a carbon skeleton of four fused carbon rings. Different steroids are created by? attachment of different functional groups. What am I? Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.14

Amino acids: What’s R? How many R’s are there? What’s an essential amino acid? 1. What am I? Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 23

Fig MUST KNOW:The 4 levels of protein structure… H-bonds between sections of the backbone Interactions between R-groups

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 3 o : Tertiary structure due to R-group interactions… R to R, or R to backbone H-bonds ionic bonds hydrophobic interactions (interior) disulfide bridges- strongest of these interactions Fig. 5.22

nucleotides: monomers that chain into nucleic acids. consist of three parts: a nitrogen base a pentose sugar a phosphate group. 2. A nucleic acid strand is a polymer of nucleotides Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 5.29