Cellular Respiration & Protein Synthesis

Anabolism • Anabolism (add)• Large molecules are synthesized from

smaller molecules• Dehydration Synthesis – H2O is

released when bonds are formed• Connects monosaccharides to form

polysaccharides• Connects fatty acids to glycerol • Joins nucleotides together• Joins amino acids together = peptide

bonds

Catabolism

• Catabolism (cut)• Reverse of anabolism• Large molecules are broken down

into smaller molecules• Hydrolysis reaction – requires H2O

to break molecules• Breaks down polysaccharides into

monosaccharides & disaccharides• Removes fatty acids from glycerol• Breaks down polypeptides into amino

acids• Breaks down nucleic acids into

nucleotides

Requirements for reactions• Activation energy• Energy needed to start a reaction-may be heat

• Enzymes• Characteristics of enzymes• Almost always proteins• Catalyze (speed up) reactions• Reusable-not consumed by reaction• Anabolic & catabolic reactions require different enzymes• Specificity- each enzyme acts only on one molecule or substance• End in ___ase• Examples:• Lipase digests lipids• Protease digests proteins

Metabolic Pathway

Energy

• Energy = capacity to change something, or to do work• Examples of energy: heat, sound, light, electrical, chemical, mechanical• Energy cannot be created or destroyed. Only changed or transferred

Adenosine Triphosphate (ATP)

Currency of energy for cellsNucleotide with 3 high energy phosphate bonds

Phosphate bond can be broken, releasing energy for cell• Hydrolysis reaction releases Phosphate & transfers energy• Product = Adenosine Diphosphate (ADP)

IMPORTANT PROCESS

• Cellular Respiration• Transfer of energy from chemical bonds

of molecules to make available for cellular use• Oxidation reaction- controlled burning of

molecules. Chemical bonds are broken releasing energy. Energy is used by cells.

Through CELLULAR RESPIRATION

Phosphate bond can be added to ADP to reuse ATP• Phosphorylation = adding phosphate to

ADP• Requires energy to add Phosphate to

ADP• Makes ATP reusable

• Phosphorylation: ADP + Phosphate + Energy → ATP

• Hydrolysis: ATP → ATP + Phosphate + Energy

Cellular Respiration

•Anaerobic• Does not require Oxygen•Makes only little energy (ATP)

•Aerobic • Requires Oxygen•Makes more energy (ATP)

• Steps of Respiration• Glycolysis• Conversion of pyruvate into Acetyl CoA• Citric Acid Cycle• Electron Transport Chain

What you’ll need to know:

The order they occur1. Does it require oxygen?2. Where is the reaction?3. What do you start with and what do you end with in each reaction step4. Which one creates the most ATP

Electron Carrier Molecules

• NAD+ + 2H: → NADH: + H+ (NADH: carries electrons)• FADH2

• FAD + 2H: → FADH2: (FADH2: carries electrons) • NADH & FADH2 carry electrons from metabolic reactions to electron

transport chain

1.Glycolysis

• Breaking of glucose • Occurs in cytosol• Anaerobic • Yields:• 2 ATP (net gain)• 1 NADH molecule• 2 Pyruvic Acids

2. Synthesis of Acetyl CoA• Synthesis of Acetyl CoA• Aerobic Reaction• Occurs within Mitochondria• Primes 3 Carbon Pyruvic Acid for Citric Acid Cycle

Reaction3 Carbon Pyruvic Acid is decomposed into 2 Carbon Acetic Acid

Releases 1 CO2 molecule as wasteReleases 1 NADH molecule (carries 2 electrons to ETC)

Acetic Acid synthesizes with Coenzyme A (CoA) → Acetyl CoAAcetyl CoA = substrate for Citric Acid Cycle

3. Citric Acid Cycle or Kreb Cycle• Aerobic Reaction • Occurs within Mitochondria• Begins & ends with Oxaloacetic Acid• 8-9 total reactions involved• Reaction

• Oxaloacetic Acid (4 Carbon) + Acetyl CoA (2 Carbon) → Citric Acid (6 Carbon)

• Citric Acid is converted to new Oxaloacetic Acid in a series of reactions

• Oxaloacetic Acid is used in the next Citric Acid cycle• Yields

• 2 CO2 waste• 1 ATP• 3 NADH• 1 FADH2

• 3 NADH + 1 FADH2 = carries 8 electrons to electron transport chain

4. Electron Transport Chain• Occurs on inner mitochondrial membrane

• Cristae = folding of inner membrane

• Requires Oxygen as final electron acceptor• Involves 4 Proteins

• 3 Transport Chain Complex Proteins• Powered by e- transfer from NADH or FADH2• Uses energy from e- transfer to power ATP Synthase

• ATP synthase

• Enzyme• Converts ADP + Phosphate → ATP• Obtains energy from Transport Chain Complexes

 Protein SynthesisDNA →transcription→ RNA → translation → Proteins

4 Nitrogenous bases

•Purines: Adenine (A) Guinine (G)•Pyrimidines: Thymine (T) Cytosine (C)•Complimentary Base Pairs•A pairs with T•C pairs with G

DNA ReplicationCreates a copy of DNA moleculeOccurs within NucleusDNA must unwind & separateCatalyzed by DNA polymerase

DNA polymerase uses one strand of DNA as template & adds a new 2nd DNA strandSemiconservative = half of replicated DNA is new, half is original DNA

StepsH bonds break & DNA strands separateDNA Polymerase adds new DNA strand to templateYields 2 new DNA strands from 1

Ribonucleic Acid (RNA)•Single Stranded•Bases: • Adenine (A) Uracil (U)•Cytosine (C) Guinine (G)

•Uracil Replaces Thymine. •A & U are Complimentary base pairs

Transcription DNA→RNA

• Messenger RNA (mRNA) is transcribed from DNA• Steps• Hydrogen bonds of DNA break & strands separate• RNA Polymerase builds mRNA using DNA as template• mRNA transcript is transported to ribosomes in cytoplasm

• Video

mRNA transcript

•Begins with AUG•Codon = 3 bases code for 1 amino acid•GGG = glycine•AUG = methionine

Translation mRNA→protein

• Occurs on ribosomes in cytosol• Ribosome = ribosomal RNA + protein

• Transfer RNA (tRNA) carries amino acids to mRNA on ribosomes• Anticodons on tRNA bind to codons on mRNA• Sequence of codons on mRNA determines amino acid sequence• Ribosomes link amino acids together by peptide bonds• tRNA releases amino acid & picks up another amino acid

• Video