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Cellular Respiration Other Metabolites & Control of Respiration. Cellular respiration. polysaccharides    glucose. other 6C sugars    glucose. hydrolysis. modified. Beyond glucose: Other carbohydrates. Glycolysis accepts a wide range of carbohydrates fuels.

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Cellular Respiration Other Metabolites & Control of Respiration



Beyond glucose other carbohydrates

polysaccharides    glucose

other 6C sugars    glucose

hydrolysis

modified

Beyond glucose: Other carbohydrates

  • Glycolysis accepts a wide range of carbohydrates fuels

  • ex. starch, glycogen

  • ex. galactose, fructose


Beyond glucose proteins

proteins    amino acids

H

|

—C—

|

H

|

—C—

|

H

H

hydrolysis

C—OH

C—OH

N

N

waste

glycolysis

Krebs cycle

H

H

R

R

O

O

||

||

Beyond glucose: Proteins

2C sugar =

carbon skeleton =

enters glycolysis or Krebs cycleat different stages

amino group =

waste product excreted as ammonia, urea, or uric acid


Beyond glucose fats

fats    glycerol + fatty acids

hydrolysis

glycerol (3C)  G3P  glycolysis

fatty acids 2C acetyl acetyl Krebs

groups

coA

cycle

2C fatty acids

3C glycerol

enters

glycolysis

as G3P

enter

Krebs cycle

as acetyl CoA

Beyond glucose: Fats


Carbohydrates vs fats

fat

carbohydrate

Carbohydrates vs. Fats

  • Fat generates 2x ATP vs. carbohydrate

    • more C in gram of fat

      • more energy releasing bonds

    • more O in gram of carbohydrate

      • so it’s already partly oxidized

      • less energy to release

That’s whyit takes so muchto lose a pound a fat!


Metabolism
Metabolism

  • Coordination of chemical processes across whole organism

    • digestion

      • catabolism when organism needs energy or needs raw materials

    • synthesis

      • anabolism when organism has enough energy & a supply of raw materials

    • by regulating enzymes

      • feedback mechanisms

      • raw materials stimulate production

      • products inhibit further production

CO2


Metabolism1
Metabolism

  • Digestion

    • digestion of carbohydrates, fats & proteins

      • all catabolized through same pathways

      • enter at different points

    • cell extracts energy from every source

Cells areversatile & selfish!

CO2


Metabolism2

pyruvate glucose

Krebs cycleintermediaries

amino

acids

 

acetyl CoA  fatty acids

Metabolism

  • Synthesis

    • enough energy?

      build stuff!

    • cell uses points in glycolysis & Krebs cycle as links to pathways for synthesis

      • run pathways “backwards”

        • have extra fuel, build fat!

Cells areversatile & thrifty!


Carbohydrate metabolism
Carbohydrate Metabolism

The many stops on the Carbohydrate Line

from Krebs cycle back through glycolysis

“gluconeogenesis”


Lipid metabolism
Lipid Metabolism

The many stops on the Lipid Line

from Krebs cycle (acetyl CoA) to a variety of lipid synthesis pathways


Amino acid metabolism
Amino Acid Metabolism

The many stops on the Amino Acid Line

from Krebs cycle & glycolysis to an array of amino acid synthesis pathways

8 essential amino acids12 synthesized aa’s


Nucleotide metabolism
Nucleotide Metabolism

The many stops on the GATC Line

• sugar from glycolysis

• phosphate & N-base from Krebs cycle


Central role of acetyl coa

Glycolysis

Central Role of Acetyl CoA

Glucose

Pyruvate

Glycolysis

  • Acetyl CoA is central to both energy production & biomolecule synthesis

  • Depending on organism’s need

    • build ATP

      • immediate use

    • build fat

      • stored energy

CO2

Pyruvate

oxidation

NAD+

NADH

Krebs

cycle

Protein

ETC

Lipid

Acetyl coA

coenzyme A

acetyl group

Fat

ATP


Control of respiration

Control of Respiration

Feedback Control


Feedback inhibition

enzyme

1

enzyme

2

enzyme

3

enzyme

4

enzyme

5

enzyme

6

Feedback Inhibition

  • Regulation & coordination of production

    • final product is inhibitor of earlier step

      • allosteric inhibitor of earlier enzyme

    • no unnecessary accumulation of product

    • production is self-limiting

A B C D E F G

X

allosteric inhibitor of enzyme 1


Respond to cell s needs
Respond to cell’s needs

  • Key point of control

    • phosphofructokinase

      • allosteric regulation of enzyme

        • why here?

          “can’t turn back” step before splitting glucose

      • AMP & ADP stimulate

      • ATP inhibits

      • citrate inhibits

Why is this regulation important?

Balancing act: availability of raw materials vs. energy demands vs. synthesis


A metabolic economy
A Metabolic economy

  • Basic principles of supply & demand regulate metabolic economy

    • balance the supply of raw materials with the products produced

    • these molecules become feedback regulators

      • they control enzymes at strategic points in glycolysis & Krebs cycle

        • levels of AMP, ADP, ATP

          • regulation by final products & raw materials

        • levels of intermediates compounds in pathways

          • regulation of earlier steps in pathways

        • levels of other biomolecules in body

          • regulates rate of siphoning off to synthesis pathways


It s a balancing act
It’s a Balancing Act

Glycolysis

Glucose

Pyruvate

Glycolysis

  • Balancing synthesiswith availability of both energy & raw materials is essential for survival!

    • do it well & you survive longer

    • you survive longer &you have more offspring

    • you have more offspring & you get to “take over the world”

Pyruvate

oxidation

Krebs

cycle

Protein

ETC

Lipid

Fat

ATP


Compartmentalization in energy processing
Compartmentalization in Energy Processing

Compartmentalization allows for increased cellular efficiency.

  • Different metabolic pathways can occur in different cellular compartments, at different conditions, and not interfere with each other.

  • Groups of related enzymes can also be localized to particular areas


Prokaryotes vs eukaryotes
Prokaryotes vs. Eukaryotes

  • The increased compartmentalization of eukaryotes leads to increased complexity and efficiency.


But don t forget
But Don’t Forget!

Some prokaryotes are able to carry out aerobic cellular respiration, and photosynthesis. They have adapted their cell membrane into quasi-compartments.


Multicellular compartmentalization
Multicellular Compartmentalization

  • Multicellular organisms have compartmentalized organs and organ systems to increase their efficiency.

  • All systems work together to accomplish tasks, including metabolism.


Digestive system
Digestive System

  • Converts and absorbs complex food molecules in to metabolic inputs (ex. starch into glucose)


Respiratory system
Respiratory System

  • Exchanges metabolic gases (oxygen and carbon dioxide)


Circulatory system
Circulatory System

  • Delivery of nutrients and removal of waste products from the cells of the body


Excretory system
Excretory System

  • Removal of metabolic waste products (water and nitrogenous wastes) from the body.


Microbial cooperation
Microbial Cooperation

  • Communities of microbes will use a diversity of functions to cooperatively accomplish metabolic tasks.

    • Ex. Animal Rumen Communities


Got the energy…

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