BIO260 Unit 4 Resource 3 - Aerobic and Anaerobic Respiration

29, 32

Relevant info on ATP (?)

• NOT transported from cell to cell

• ea cell must make its own ATP supply

• NOT stored by cell

• a cell uses energy from carbo, lipids, and other things to add inorg phos to ADP to make ATP

What are the 3 mechanisms of ATP production?

• anaerobic glycolysis

• phosphagen use

• aerobic catabolism

  • from env

  • from preexisting sources in the body

Anaerobic Respiration

• energy-making chem pathway, functions w/o oxygen

• glycolysis and phasphagens (in animals) are major pathways

• fast rate of accel

• non-steady state, not always active

• ATP yield is moderate

• (says rate is slow on slide 5 but says diff on slide 7)

Glycolysis

• occurs in cytoplasm

• directly makes ATP by substrate lvl phosphorylation

  • syn of ATP by direct transfer of phosphate group from high energy intermed to molec of ADP

• animals: glucose is the most common starting point for glycolysis

• plants: sucrose is starting point for glycolysis

  • chloroplastic glycolysis: makes ATP in the dark & makes precursors for syn of primary metabolites

How much molec of ATP is produced per molec of surcorse?

60

Gluconeogenesis

• important in plants, specifically in seeds that store C in forms of oil

  • oil is converted by gluconeogenesis into sucrose that can be transported to other sites in the germinating plant

    • req add enzymes not found in animals

• in animals, it occurs primarily in liver

Glycolysis in plants and animals

• can be div into 2 general steps: energy consuming, energy generating

What is phosphofructokinase?

• rate limiting enzyme

  • controls rate of glycolysis for plants and animals

• 4 ID monomers

• binds substrates: ATP and Fructose-6-phosphateat catalytic sites

• F-6 + ATP → F-1,6-P + ADP

General Process of Glycolysis (?)

• binds AMP at allosteric activation site to promote ATP-F6 binding

• when at high lvls, ATP binds at allosteric inhibition site ,lowering the affinity of the enzyme for F-6-P

• high levels of citrate bind at allosteric inhibition site, lowering the affinity of the enzyme for F-6-P

What happens in the energy producing steps of glycolysis?

• electrons move thru protein complexes in bio systems via special molec that pick up electrons at one place and deliver them to another (NAD)

What is nicotinamide adenine dinucleotide (NAD)?

• coenzymes syn from vit niacin

• exists in 2 forms

  • oxidized (NAD+/oxidizing agent): accepts electrons and becomes reduced

  • reduced (NADH/reducing agent): donates electrons and becomes oxidized

• involved in redox rxns

Oxidative rxn in glycolysis

• doesn’t req O2

• occurs at the same time of oxidation of G3P → release of 2H atoms → red of NAD when the 2H+ are transferred to NAD

• the only net redox step

General process of energy extraction steps of glycolysis

• ea Glyceraldehyde 3-Phosphate is then phosphorylated → yielding 1, 3-diphosphoglycerate

• then 1 phosphate is transferred to ADP, water is given off then final phosphate is transferred to ADP

Glycolysis alt end product in plants

• alt end product is malate

What are 2 pathways after glycolysis?

• fermentation: process of making ATP w/o oxygen

• aerobic respiration: process of making ATP w/ oxygen

Process of making ATP w/o oxygen (fermentation)

• cytochromes and other parts of the electron transport chain become fully red-electrons, cannot be discharged

• ox-phos cannot take place

• NADH+H+ and FADH2 cannot become oxidized by electron transport chain so glycolysis stops

• only certain tissues have alt mechanisms to make ATP w/o O2

  • human brain cannot

Aerobic respiration in plants

• oxygenated air in soil is alr present

  • oxygen present among soil particles diffuses into root hairs

  • from root hairs, oxygen is transported to all parts of the roots for respiration

• also used to syn other org matter such as citric acid, oxalic acid, lactic acid

• plants use alcohol fermentation and most animals use lactic acid fermentation

Glucose → Alc + CO2 + 2ATP

Glucose → Lactic acid + 2ATP

Similarities b/w Anaerobic respiration in plants and animals

• both take place in absence of molec oxygen

• in both, 2 ATPs are made

• both involve the incomplete breakdown of respiratory substrate

• the NADH made in both glycolysis processes is often used

• electron transport chain is absent in both processes

• both are enzyme-catalyzed rxns

Oxygen regulators vs Oxygen conformers

• animals faced w/ red O2 avail show conformity

• oxygen regulators display steady state of aerobic respiration regardless of O2 lvls

• conformer’s aerobic respiration rate will more closely correlate w/ O2 lvls

Anaerobic respiration: Phosphagens

• provide additional mechanisms of ATP production w/o ocygen by

• substrate lvl phosphorylation

• non-steady state

• small yield

• peak rate is very fast

• serve as temp stores of high energy intermed

  • creatine phosphate (phosphagen of vertebrate muscle)

    • doesn’t exist in plants

  • arginine phosphate (phosphagen of invertebrates)

What are the rxns in aerobic catabolism?

• glycolysis

• krebs cycle

• electron transport

• oxidative phosphorylation

Vertebrates breath

• use ventilation to deliver oxygen to the lungs

• oxygen diffuses the lung spaces (alveoli) and into the blood where it is circulated to cells

Plant respiration in lenticels

• plants respire with the help of lenticels and stomata

• lenticels

  • pores in fruits, petiole, roots, and the stem of a woody plants that allow gas exchange b/w atmosphere and the internal tissues

  • always open

  • don’t contain chlorophyll

  • active at night

  • have no guard cells

Plant respiration in stomata

• stomata

  • exist in stems non-woody plants and leaves

  • carry out the function of gaseous exchange in those organs

  • they can open and close-reg

  • contain chlorophyll and can carry out photosyn

  • active during the day

  • have guard cells

Where is pyruvate transported if oxygen is present?

mitochondria

What happens in the cystol?

• pyruvate is oxidized into an acetyl group and CO2

• acetyl group is them transferred to CoA by pyruvate dehydrogenase complex

• acetyl CoA serves as the starting compound for the Kreb cycle

In the Kreb Cycle

• pyruvate to acetyl CoA

  • 2NADH

  • 2CO2

• Krebs cycle

  • 6NADH

  • 2FADH2

  • 2ATP

  • 6CO2

Unique features of the Kreb Cycle

• the step that catalyzed by succinyl-CoA synthetase makes ATP in plants and GTP in animals

• plants have malic enzymes in mitochondrial matrix of plants that catalyzes the rxn: Malate + NAD+ → pyruvate + CO2 + NADH

  • allows plants to operate alternative pathways for the metabolism of pyruvate derived from glycolysis

Oxidative phosphorylation

• uses oxygen to oxidize the electron carriers NADH and FADH2 in order to generate ATP

• ATP is made thru a mechanical process

The general process of Aerobic respiration