Chemical Biosynthesis in Living Things Haide Liza B

Chemical Biosynthesis in Living Things Haide Liza B. Sabinorio IV-BS Chemistry for Teachers Semester I, SY 2012 -2013

Outline of Discussion… Introduction Photosynthetic Pathway in Plants Biosynthesis of Carbohydrates Fermentation Pathway

Characteristics of Living Things: • • Highly ordered Organized into units called cells Use energy from their environment Respond to stimuli Develop Reproduce themselves Contain genetic information

Photosynthetic Pathway in Plants

Role Photosynthesis

Photosynthesis Ø is the synthesis of organic molecules using the energy of light. ØThe overall reaction for Photosynthesis is 6 CO 2 + 6 H 2 O ----light---> C 6 H 12 O 6 + 6 O 2 Ø It involves two sets of chemical events, termed the light and dark reactions.

Photosynthesis Sunlight on leaves The spectrum of visible light and parts used by plants

Photosynthesis - Site

Light Reaction • Refers to the set of reactions in which the energy of absorbed light is used to generate ATP and reducing power (NADPH)

Light Reactions § The light strikes chlorophyll to excite electrons to higher energy state. § In the series of reaction energy is converted into ATP and NADPH. § Water is split in the process, releasing oxygen as by-product of the reaction. § 6 CO 2 + 6 H 2 O ----light---> C 6 H 12 O 6 + 6 O 2

Photosynthetic Pathway

Dark Reaction • The dark reactions use this reducing power and energy to fix carbon, that is, to convert carbon dioxide to glucose. • 6 CO 2 + 6 H 2 O ----light---> C 6 H 12 O 6 + 6 O 2 • Biochemically, converting CO 2 to glucose without light is possible if a supply of reducing equivalents and ATP are available.

Dark Reaction • Also known as the Calvin cycle occurs in the stroma of chloroplast. • Carbon dioxide is captured by the chemical ribulose bisphosphate (Ru. BP) a 5 -C chemical. • Six molecules of carbon dioxide enter the Calvin cycle, eventually producing one molecule of glucose.

Photosynthetic Pathway

Calvin Cycle

Calvin Cycle • Six molecules of CO 2 combine with six molecules of Ru. BP with the aid of rubisco. • Resulting complexes split into twelve 3 PGA molecules. • NADPH and ATP supply energy and electrons that reduce 3 PGA to 12 GA 3 P. • Ten of the twelve GA 3 P molecules are restructured into six Ru. BP molecules

Carbohydrates • Organic molecules with the general formula of CHO in 1: 2: 1 ratio. • Provides the raw fuel for cellular energy production. • A single unit of sugar, monosaccharides are the smallest carbohydrates.

Carbohydrates Galactose, the sugar found in milk

Carbohydrates Glucose – is the sugar in our blood.

Carbohydrates Fructose - the sugar that sweetens fruit

Carbohydrates

Biosynthesis of Carbohydrates

Biosynthesis of Carbohydrates Photosynthesis Gluconeogenesis

Gluconeogenesis • Ubiquitous pathway for synthesis of glucose from noncarbohydrate precursors. • Three irreversible reactions of glycolysis must be bypassed, or circumvented, in gluconeogenesis.

Gluconeogenesis

Fermentation Pathway

on Fermentation is any process that releases energy from sugars or other organic molecules by oxidation, does not require O 2.

Fermentation Pathway

Fermentation • Lactic acid fermentation pyruvic acid is reduced by NADH to lactic acid. • lactic acid fermenters include Streptococcus and Lactobacillus). • Lactic acid can be fermented to propionic acid and O 2 by Propionibacterium freudenreichii (Swiss cheese). •

Fermentation • In alcohol fermentation, acetaldehyde is reduced by NADH to produce ethanol • alcohol fermenters include yeasts and bacteria. • Ethanol can be fermented to acetic acid (vinegar) by Acetobacter. • Acetic acid can be fermented to methane by Methanosarcina. •

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