Biol Exam 2

Metabolism

Reactions that occur in cells

Cells require (metabolism)

Constant input of energy for reactions

Metabolic reactions can

require energy (endergonic) or release energy (exergonic)

Endergonic reaction

Reaction that requires energy from surroundings to occur

Exergonic reaction

reaction that releases energy when it takes place

Important exergonic reaction

Hydrolysis of ATP to ADP and phosphate

The structure of ATP

Hydrolysis of ATP

ATP Cycle

Not broken down to CO2 and Water

Coupled Reactions

An unfavorable reaction (ender) is linked to very favorable reaction (exer) such as ATP cleavage. Favorable ATP cleavage of ATP allows unfavorable reaction to proceed.

What is an example of a coupled reaction?

Glutamate + NH3 (Unfavorable)

ATP -> ADP + Pi (favorable)

Coupled reaction takes place and cell can make glutamine

Enzymes characteristics

Biological catalysts, Proteins, Depend on their shape for activity

Example of reaction

AB & CD (reactants)

AC & BD (products)

Exergonic reactions

spontaneous under certain conditions but not all conditions, we are burning glucose all the time

Example of exergonic reaction

Substrate -> Products

Sucrose + h2O -> glucose + fructose

Substrate binds on enzyme at active site, binding produces "induced fit" to enzyme

Factors that affect enzyme activity

1. temperature and pH

2. cofactors (non protein helpers)

3. enzyme inhibitors, molecules inhibiting activity

competitive inhibition

active site is blocked

noncompetitive inhibition

inhibitor binds away from active site changing protein shape

Metabolic control

most metabolic pathways are regulated, enzyme activity is controlled

Regulated enzymes

possess active and inactive forms, regulation is reversible

allosteric regulation

regulatory molecule binds away from the active site, regulatory molecule may be an activator or inhibitor

Feedback inhibition

Sometimes controls pathways, often regulated by allosteric binding of the product of the pathway

Cellular Respiration

Breakdown sugars, release energy. Energy is used to form ATP. Sugars formed by photosynthesis.

Aerobic Respiration

Glucose + O2 to CO2 plus H2O, Glucose has 6 carbons- so one glucose produces 6 CO2 molecules

Aerobic Respiration Energy

Produces the high energy molecules NADH and ATP, NAD+ picks up electrons from glucose during glycolysis and the Krebs cycle forming NADH, NADH donates electrons to O2 forming H2O, consumes glucose and O2, energy released makes 36 ATP from ADP and phosphate, CO2 and H2O are produced

Oxidation Reduction

Electrons gained

Oxidation

Electrons lost

Glycolysis

Starting Glucose -> 2 ATP-> 2ADP-> 2 Triose phosphates-> 2NAD-> 2NADH -> 4ADP-> 4ATP-> 2 Pyruvate

Glycolysis Location

Cytoplasm

Krebs Cycle Location

From matrix to inter membrane space

Electron Transport Location

Inner Membrane

Krebs cycle from two pyruvate

To Acetyl CoA- 0 ATP, 2 NADH, 0 FADH2

Krebs Cycle- 2 ATP, 6 NADH, 2 FADH2, TOTAL- 2 ATP, 8 NADH, 2 FADH2

Electron transport

electrons come from NADH and go to O2 giving H2O and NAD+, the last protein cytochrome oxidase gives electrons to O2, another protein ATP synthase is needed to make ATP

Electron Transport Steps

Location produces electrochemical potential gradient, H+ is like water behind a dam, Protons are transported through the ATP synthase which captures energy to make ATP

ETC making ATP

1 NADH = 3 ATP; 1 FADH2 =2 ATP

Energy molecules from one glucose

Glycolysis: 2 ATP, 2 NADH, 0 FADH2, 6 TOTAL ATP,

Krebs: 2 ATP, 8 NADH, 2, FADH2, 30 TOTAL ATP,

totals: 4 ATP, 10 NADH, 2 FADH2, 36 TOTAL ATP

TOTAL REACTION

C6H1206 + 6O2 -> 6 CO2 + 6 H2O

Fermentation- No oxgen

Mitochondrion cannot process pyruvate without O2, pyruvate is converted to lattice acid or alcohol with oxidation of NADH, fermentation nets 2 ATP per 1 glucose, regenerations NAD to permit continuation of glycolysis

Fermentation Muscles

can do lactic acid fermentation, but brain cannot do fermentation

some bacteria do fermentation

but they live in the absence of O2

Resperation

provides energy needed by cells from carbohydrates

Respiration central role

Breakdown of other molecules for energy, catabolism- break down

Respiration intermediate in synthesis

of molecules needed by cooler anabolism= building

Chlorphyl absorbs

blue and red wavelengths but not green, green wavelengths are reflected or transmitted by leaves

Maximum photosynthesis

produced with wavelengths absorbed by chlorophyll

Light energy

absorbed by pigments in 2 protein complexes: photosystems 1 and 2

Light energy drives

electron transport from H2O to NADP, ATP is formed by chemiosmosis

Calvin Cycle

NADPH and ATP from the light reactions are used to fix CO2 into sugars

Three phases of Calvin Cycle

Rubisco enzyme catalyzes carbon fixation

what is the direct product

Triose phosphate

Glyceraldehyde 3- Phosphate (G3P)

Accumulation in the chloroplasts leads to starch synthasis

Transport into the cytoplasm

Provide energy via glycolysis, used for synthesis of sucrose; transported through out the cell

Rubisco

most abundant protein on earth, catalyzes in two reactions in c3 plants,

C4 Plants

C4 Acid produced in mesophyll cells, Calvin cycle in bundle sheath cells (vein) Extra cycle that happens in the light

CAM plants

Found in desert, & spanish moss. Advantage w/ water because opens at night,

C4 Acid produced at night; stomates closed during the day

Photosynthesis Importance

Photosynthetic organisms produce 160 billion metric tons of carbohydrate per year- energy source of all organisms

O2 concentration

In the atmosphere is maintained at approximately 22% by photosynthesis

In 1958 what did hershey and chase prove?

DNA is responsible for inheritance

Bacteriophage virus

Directs bacteria to produce protein coat and virus DNA

Bacteria cell lyses

New phages released

Avery Conclusions?

A molecule is reprogramming the bacteria making it pathogenic, this properties of this molecule are consistent with DNA or RNA

Hershey and Chase Phages

T2 and related phages use their tail pieces to attach to the host cell and inject their genetic material (TEM)

Phage Coat- Protein (35S)

Injected the radioactive protein into the DNA, and radioactivity was not found in bacteria

DNA - 32P

Labeled phage DNA with 32 P

Injected DNA and radioactivity was found

Hershey and chase conclusions about DNA

DNA is entering bacteria, changing the programming, the genetic molecule

DNA Structure

Polymer of nucleotides

Nucleotide

Deoxyribose sugar

Phosphate group

Nitrogenous base- AG and TC

DNA is double stranded

Two polymers, joined at the nitrogenous bases

Sugar- phosphate backbone

sugar (deoxyribose) & phosphates

Purine + Purine

Too Wide

Pyrmidine + Pyrimidine

Too narrow

Purine + Pyrimidine

Width consistent with X-ray data

Two DNA strands form

Ladder with bonds between bases forming the rungs, opposite directions for strands

Meaning of Ladder

Twisted in an alpha helix (a right twist like a slinky toy)

DNA Replication- Semi Conservative

Replication of DNA molecule produces two molecules, each with one original strand and one new strand

DNA Replication Alternatives

Conservative- 2 new strands

Dispersive- Each strand has new and old

How accurate is replication

One error in one billion base pairs

How fast is replication

Human cell containing 46 chromosomes is copied in a few hours

Replication Mechanism

Involves a number of enzymes and other proteins

DNA Replication in Steps

DNA helix unwinds, provides single-stranded templates

Synthesis of new strands requires primase enzyme to start and DNA polymerase enzyme, DNA polymerase catalyzes matching complimentary nucleotides in 5' to 3' direction- new nucleotides are added to end of 3'

Helicase

Double Helix Unwinds

DNA polymerase

Catalyzes Formation of nucleotide sequence (polymer)

Primase

Adds RNA to start the new strand

DNA polymerase 1

replaces the RNA with SNA and corrects error