Chapter 13 + 14 Cell BIOL300

The steps of breaking sugar into…

usable energy through glycolysis, the citric acid cycle, and oxidative phosphorylation in cellular respiration.

Breaking down Yeilding Energy

Glycolysis —→ Citric Acid Cycle ——> Oxidative Phosphorlyation

Stage 1: Glycolysis

-Starting product is glucose

-Occurs in the cytoplasm

-Does not require O₂

- _{(anaerobic product is lactate)}

-End products are:

  2 pyruvate

  2 ATP

  2 NADH

Pyruvate then “pumped” into the mitochondria

-Each step catalyzed by specific enzymes

    (point of regulation!)

Generation of Acetyl Co A starts the..

Citric Acid Cycle (Krebs Cycle)

Pyruvate is oxidixed to..

Acetyl Co A

-This acts as the link between Stage 1 and Stage 2

-(pyruvate→acetyl coA)

-Occurs in the mitochondria (matrix)

-Catalyzed by a large mutli-enzyme complex: pyruvate dehydrongenase complex

Lipids can also be converted to..

Acetyl Co A for energy

They produce 6 times more energy than sugars/weight

Stage 2: Citric Acid Cycle (Krebs Cycle)

-Occurs in the mitochondrial matrix

-Starting product is Acetyl Co A from either pyruvate or lipids

Does not require O₂

What type of pathways begin wit Glycolysis or Citric Acid Cycle?

Biosynthetic Pathways

Stage 3: Oxidative Phosphorylation

• Final Stages of Oxidation of Food Molecules Reduces O₂ to H₂O

• REQUIRES OXYGEN 30 ATP

Gluconeogenesis

glycolysis reaction reverses at time of high energy needs to generate glucose

-Brain cells depend almost completely on glucose!

-Eat before the exam!

-

-Steps 1,3 and 10 are irreversible, and need “bypass” reactions (label A-D) to get around them

-

-Common starting product is lactate!

-

-Takes A LOT of energy

Glycogen

multi-branched polysaccharide comprised of glucose

Glycogen Synthase

Makes Glycogen

Glycogen phosphorylase

Breaks Glycogen

Fat

Fat is stored as droplets of water-insoluable triacylglycerols (red) in specialized adipose tissues

Excess sugar intake is converted into fatty acids and stored

Plant Cells

Starch: branched polymer of glucose similar to glycogen

Fat: like animals, but differs in the types of fatty acids that predominate (unsaturated)

Mitochondria Matrix

concentrated mixture of hundreds of enzymes

including those for oxidation of pyruvate and fatty acids for citric acid cycle

Mitochondria Inner Membrane

It is folded into numerous cristae

Proteins that carry out oxidation reactions for ETC and ATP synthesis.

Mitochondria Outer Membrane

Large channel-forming protein (Porin)

permeable to all molecules 5000 daltons or less

Mitochondria Intermembrane Space

Enzymes that use ATP passing out of matrix to phosphorylate nucleotides

Mitochondria divison

The process through which mitochondria replicate and divide, typically occurring through a mechanism resembling binary fission.

Mitochondria Fission

is a form of asexual reproduction by which a single entity splits into two or more independent entities, commonly observed in mitochondria during division.

Mitochondria Fusion

is the process by which two or more mitochondria combine to form a single, larger mitochondrion, playing a crucial role in mitochondrial function and dynamics.

Energy of an electron can be harnessed…

To produce ATP

Required components:

-membrane

-proton pump

-ATP synthase

-source of high energy electrons (e^-) and protons (H⁺)

ATP is generated across..

a membrane

What yeilds most of the Cellular ATP?

Oxidative Phosphorylation

Chloroplasts resemble what in structure…

Mitochondria

How do plants still use Mitochondria?

Inner membrane of chloroplast impermeable to ATP and NADPH, therefore funneled into carbon-fixation cycle to make sugar

-Sugar can then be make into starch, metabolized, or enter into mitochondria to form ATP