6 Microbial Metabolism: Fueling Cell Growth

energy

capacity to cause change (do work)

metabolism

All the chemical reactions that occur inside an organism

Enables cells to accomplish two fundamental tasks:

• harvest chemical energy from organic molecules to regenerate ATP to power reactions

• biosynthesis: synthesize new parts; to make larger molecules from smaller components

  • eg. cell walls, membranes, ribosomes, nucleic acids in cell division

catabolism

½ component of metabolism

Degradative reactions that break larger molecules into smaller components

• breaks bonds → releases energy

• released energy is captured in order to make ATP

• exergonic reaction: reaction that releases energy

anabolism

2/2 component of metabolism

• building large molecules by bonding simpler ones together

• creation of bonds = input of energy

• endergonic reaction: reaction that uses energy

Metabolic pathway

A sequence of chemical reactions that converts a starting molecule to an end-product

• each reaction is carried out by a specific enzyme

• a [___] may be:

  • linear → one product

  • branched → feed into different pathways/different products

  • cyclic → cycles between end product and starting product

enzyme

¼ components of Metabolic pathways

Function as biological catalyst: item that speeds up chemical reactions without being consumed by the reaction

• reactions without [__] would occur very slowly

  • speeds up activation energy: energy needed to start a reaction

specific

Enzymes are highly [___] for their substrate: reactant they are catalyzing

• active site: substrate binding site

  • only the substrate will be able to fit into that site

ATP

2/4 components of Metabolic pathways

Adenosine triphosphate. The universal energy carrying molecule

Nucleotide with an adenine sugar and three phosphates attached to it

• attached by high energy bonds → catalysis of terminal phosphate bond creates large bouts of energy

• this energy is used to fuel endergonic reactions →

• → such as anabolism in the addition of phosphate to adenosine diphosphate (ADP)

glucose

Most common organic molecule broken down in metabolic pathways

Oxidizes (loses its electrons) to carbon, which is reduced (gains the electrons)

aerobic respiration

Water is produced from oxygen through a process known as [__]

electron

¾ components of Metabolic pathways

Chemical energy source that is released is found in the [__](s)

• compound is broken down to release energy → releases e-

• transfer of e- during chemical reactions releases the energy stored in organic molecules

• released energy is used to synthesize ATP

oxidation

Loss of electrons

reduction

Gaining of electrons

electron carriers

4/4 components of Metabolic pathways

Picks up both electrons and protons

• NAD+ «» NADH

• FAD «» FADH₂

• NADP⁺ «» NADPH