M200 Chapter 7

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1

Metabolism

  • All chemical reactions and workings of a cell
  • Typically occurs in a series of connected, enzyme catalyzed reactions called “biochemical pathways”
2

Catabolism

Break the bonds of larger molecules to release energy

3

Anabolism

Biosynthesis: synthesis of cell molecules and structures

Builds

4

Metabolism of Microbes =

getting energy to build new cells

5

Exergonic reactions

(energy given OUT)

  • Release energy as they go forward
  • Energy is available for doing cellular work
6

Endergonic reactions: (energy taken IN)

Require the addition of energy (ATP)

7

Phototrophy

biochemical reactions that capture energy from light

8

Chemotrophy

reactions that yield energy stored in the chemical

bonds of molecules

9

Organotrophy

metabolism in which the food molecules are organic

10

Lithotrophy

metabolism in which the food molecules are inorganic

11

Central Metabolic Pathways

  • Produce ATP
  • Generate reducing power:

• NADH, FADH2, NADPH (“charging” electron carriers)

• Make precursor metabolites • aka building blocks

12

Common catabolites

Carbohydrates

lipids

proteins

13

How much of our caloric intake is provided by bacteria?

15%

14

Catalysts

speed up reaction by lowering activation energy

15

All organisms use common energy carriers such as:

Adenosine triphosphate (ATP) and

Nicotinamide adenine dinucleotide (NAD/NADH)

16

Adenosine triphosphate (ATP) and

Nicotinamide adenine dinucleotide (NAD/NADH)

are energy carriers that can be transformed by many catabolic pathways

17

NADH

carries electrons that can make energy

18

in bacteria the main pathway for glucose catabolism is

glycolysis

19

In glycolysis

one molecule glucose breaks down into 2 molecules of pyruvate

20

Glycolysis occurs in 2 stages

  • Stage 1 consumes energy (2 ATP).
  • Stage 2 yields a net of 2 ATP and 2 NADH.
21

Ways to breakdown glucose

  • Glycolysis
  • Entner- Doudoroff
  • Pentose Phosphate
22

Fermentation

electrons of NADH are put back onto pyruvate, forming waste products such as lactic acid. No oxygen is consumed.

LOW ENERGY * ANAEROBIC*

23

Respiration

NADH donates electrons to the electron transport system(ETS),which ultimately transfers them to O or to an alternative inorganic molecule

HIGH ENERGY *AEROBIC*

24

Fermentation to humans

Used for food preservation

Used in the industry

slows growth

25

Krebs Cycle aka TCA cycle

Transferring All Electrons to NADH

26

Break down of glucose requires?

breakdown of pyruvate to CO2 and acetyl CoA

27

Breakdown of pyruvate

removes 2 hydrogens, transferring 2e– to form NADH

28

Respiration

reduction of a terminal electron acceptor (such as O2)

29

Oxidative phosphorylation

hydrogen ions return to the cell via ATP synthase, driving formation of ATP

30

Glucose respiration

  • generates a relatively large number of ATP molecules per molecule of glucose, far more than in fermentation.
31

Carbon Dioxide Fixation

transformation of (many molecules of) CO2 into glucose and other metabolites such as amino acids

32

Requirements for biosynthesis

Assemble carbon skeletons

Fix nitrogen, sulfur, and phosphorus

Spend energy

Reduce carbon skeletons (add electrons)