Lecture 2 Notes

Lecture 2 Notes - Lecture 2 - Chapters 2, 3 Chapter 2-...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 2 - Chapters 2, 3 Chapter 2- Water accounts for about 70% of a cells weight & most intracellular reactions occur in an aqueous environment life on earth began in the ocean- In each water molecule the 2 H atoms are linked to the O atom by covalent bonds the 2 bonds are highly polar bc the O is strongly attractive for electrons, whereas the H is only weakly attractive when a positively charged region of one molecule (H) approaches a negatively charged region (O) of a second water molecule, the electrical attraction between them can result in a weak bond called a hydrogen bond these bonds are much weaker than covalent bonds and are easily broken by the random thermal motions due to the heat and energy of the molecules it is only because of the hydrogen bonds that link water molecules together that water is a liquid at room temperature, with a high boiling point and high surface tension, rather than a gas molecules carrying plus or minus charges (ions) likewise interact favorably w water and are hydrophilic hydrophobic molecules, by contrast, are uncharged and form few or no hydrogen bonds, and so do not dissolve in water in hydrocarbons, the H atoms are covalently linked to C atoms by a largely nonpolar bond; because the H atoms have almost no net positive charge, they cannot form effective hydrogen bonds to other molecules- All organic molecules are synthesized from and are broken down into the same set of simple compounds cells contain 4 major families of small organic molecules: the sugars, the fatty acids, the amino acids, and the nucleotides o- Glucose = C 6 H 12 O 6 the way that sugars are linked together to form polymers illustrates some common features of biochemical bond formation a bond is formed between an OH group on one sugar & an OH group on another by a condensation reaction, in which a molecule of water is expelled as the bond is formed the bonds created by all of these condensation reactions can be broken by the reverse process of hydrolysis, in which a molecule of water is consumed because each monosaccharide has several free hydroxyl groups that can form a link to another monosaccharide, sugar polymers can be branched, and the number of possible polysaccharide structures is extremely large the monosaccharide glucose is a key energy source for cells in a series of reactions, it is broken down to smaller molecules, releasing energy that the cell can harness to do useful work cells use simple polysaccharides composed only of glucose units principally glycogen in animals & starch in plants as energy stores o o o- A fatty acid molecule has 2 chemically distinct regions one is a long hydrocarbon chain, which is hydrophobic and not very reactive chemically the other is a carboxyl (-COOH) group, which behaves as an acid almost all fatty acid molecules in a cell are covalently linked to other molecules by their carboxylic acid group- Fatty acids are stored in the cytoplasm of many cells in the form of droplets of triacylglycerol molecules,...
View Full Document

This note was uploaded on 11/22/2010 for the course BIOLGY BICD 110 taught by Professor Yiminzou during the Spring '10 term at UCSD.

Page1 / 12

Lecture 2 Notes - Lecture 2 - Chapters 2, 3 Chapter 2-...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online