Biology 203 Flashcards

Question

Hydrogen Bonds

Answer 1

A hydrogen bond Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom • In living cells – The electronegative partners are usually oxygen or nitrogen atoms

Answer 2

Van der Waals interactions – Attractions between molecules that are close together as a result of these charges • If electrons are distributed asymmetrically in molecules or atoms – They can result in “hot spots” of positive or negative charge • Collectively, such interactions can be strong – As between molecules of a gecko’s toe hairs and a wall surface

Answer 3

Carbohydrates Serve as Fuel and Building Material Carbohydrates – Sugars – Polymers of sugars ``` • Simplest carbohydrates – Monosaccharides or single sugars • Carbohydrate macromolecules – Polysaccharides • Polymers composed of many sugar building blocks ```

Answer 4

• Monosaccharides – Molecular formulas usually multiples of CH2O ``` • Glucose (C6H12O6) – Most common monosaccharide • Grape sugar • Corn sugar • Blood sugar – One of the main products of photosynthesis – Source of energy • Glycolysis ``` Monosaccharides are classified by – The location of the carbonyl group (as aldose or ketose) – The number of carbons in the carbon skeleton

Answer 5

Contain Carbon, Hydrogen and Oxygen in the | ratio CH2O

Answer 6

The simplest Carbohydrates are the Simple Sugars, these are classified by: Type of Carbonyl group  Ketone  Ketose Aldehyde  Aldose ``` or by Number of Carbon atoms: 3 C’s  Triose 4 C’s  Tetrose 5 C’s  Pentose 6 C’s  Hexose Note: suffix …ose indicates a sugar ```

Answer 7

Though often drawn as linear skeletons, in aqueous solutions many sugars form rings – Chemical equilibrium between the linear and ring structures greatly favors the formation of rings • Monosaccharides serve as a major fuel for cells and as raw material for building molecules

Answer 8

Disaccharide formation – Dehydration reaction joins two monosaccharides • This covalent bond is called a glycosidic linkage • Maltose – Malt sugar • Sucrose – Table sugar • Lactose – Galactose and Glucose – Milk sugar

Answer 9

Polysaccharides – The polymers of sugars – Storage and structural roles • Structure and function of a polysaccharide – Determined by its sugar monomers and the positions of glycosidic linkages

Answer 10

Starch – Storage polysaccharide of plants – Consists entirely of glucose monomers • Plants – Store surplus starch as granules • Within chloroplasts and other plastids – Unbranched • Amylose – Branching • Amylopectin –(16) Slide 8

Answer 11

``` Glycogen –Storage polysaccharide in animals – More branched then amylopectin • Humans and other vertebrates – Store glycogen mainly in liver and muscle cells • Granules in the cytoplasm ``` • Glycogen debt – “Hitting the wall” – Marathon runners • Extreme fatigue

Answer 12

The polysaccharide cellulose – Major component of the tough wall of plant cells – Most abundant organic compound on Earth – Alternative fuel source • Cellulose is a polymer of glucose – Like starch – Glycosidic linkages differ • The difference is based on two ring forms for glucose: alpha () and beta ()

Answer 13

Polymers with (alpha) glucose are helical • Polymers with (beta) glucose are straight • In straight structures • H atoms on one strand can bond with OH groups on other strands • Parallel cellulose molecules held together this way are grouped into microfibrils • Form strong building materials for plants • Major constituent of paper • Only component of cotton