Term
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Definition
◦ Small circular naked ssRNAs
No protein component
~250 – 450 nucleotides
Base pairs with self
◦ Found in plants
Can cross cell walls and membranes
Use mRNA transcription machinery to make copies of self |
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Term
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Definition
◦ ‘Infectious’ proteins
Misfolded versions of normal protein
No genetic material
Very stable
Can’t be destroyed by normal sterilization
◦ Example: scrapie
PrPc – normal protein
PrPSc – scrapie protein |
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Term
| What is prior propagation? |
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Definition
Prion protein induces normal protein to
misfold into more prion protein
Autocatalytic
Misfolded proteins aggregate and interfere
with normal neuronal cell function
Cells die leaving brain looking like a sponge |
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Term
| What do prions cause and how do they pass? |
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Definition
◦ Cause degenerative brain diseases
Kuru – taking ancestor worship to a new level
Creutzfeld-Jacob Disease (CJD)
Mad cow disease (BSE: bovine spongiform encephalopathy –
literally ‘spongy diseased brains in cattle’)
Chronic wasting disease
◦ Can be passed trans-species
Scrapie → BSE → vCJD |
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Term
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Definition
◦ Sum of all of the chemical reactions
that take place within a cell
◦ Involve pathways of sequential
enzymatic reactions (metabolic
pathways) |
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Term
| What is a catabolic pathway? |
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Definition
| Release energy by breaking down complex molecules |
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Term
| What is an anabolic pathway? |
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Definition
| Consume energy to build complex molecules |
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Term
| Describe energy, kinetic energy and potential energy |
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Definition
◦ Capacity to cause change
◦ Kinetic Energy
Energy of motion
Thermal energy (heat)
◦ Potential Energy
Stored energy
Chemical energy (within structure)
Membrane potential |
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Term
| What is the first law of thermodynamics? |
|
Definition
◦ Conservation of Energy
◦ Energy cannot be created nor destroyed
It is converted from one form to another |
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Term
| What is the second law of thermodynamics? |
|
Definition
◦ Entropy
◦ Overall disorder will always increase in closed systems
Some energy converted into heat
Always loss of ‘usable’ energy |
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Term
| What are the two laws of thermodynamics? |
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Definition
First Law: Quantity of energy unchanged
Second Law: Average ‘quality’ is always reduced
◦ Heat is energy of the lowest quality, most disordered |
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Term
| What is apparent contradiction? |
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Definition
| Life is inherently ordered |
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Term
| Describe how an organism is not a closed system |
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Definition
◦ Energy and materials are exchanged with
surroundings
◦ One specific aspect of disorder (entropy) can
decrease if the overall disorder increases |
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Term
|
Definition
◦ Portion of system’s energy available to do work
G (Gibbs’ Free Energy)
ΔG – change in Free Energy
ΔG = Gfinal – Ginitial
◦ Spontaneous processes have a negative ΔG (<0)
(energetically favorable, not instantaneous - may still
take a very long time)
ΔG = ΔH – TΔS
ΔH – Total Energy (Enthalpy)
ΔS – Disorder (Entropy)
T – Temperature (heat) |
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Term
| Describe an exergonc vs endergonic reaction |
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Definition
◦ Exergonic : energy given off
- ΔG – spontaneous,
releasing energy
◦ Endergonic : energy taken in
+ ΔG – non-spontaneous,
requires energy |
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Term
|
Definition
◦ In closed systems, ΔG will be
negative until all potential
usable energy is exhausted,
then nothing more can
happen
ΔG ≯ 0
ΔG = 0 ⇒ dead
◦ Organisms are open systems
– receive energy from
surroundings
Equilibrium never reached |
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Term
|
Definition
◦ Adenosine with three phosphate groups
Adenine base
Ribose sugar (as found in RNA)
Three phosphate groups linked by high-energy
bonds |
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Term
|
Definition
◦ Energy carrier molecule
◦ Created with the energy from exergonic reactions
◦ Hydrolyzed to carry out endergonic
reactions |
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Term
|
Definition
◦ ‘Phosphorylate’ (add a phosphate group to) molecules
Phosphorylated compound has higher free energy (but
lower than what was stored in ATP – entropy)
◦ Remove phosphate to release energy |
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Term
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Definition
| ◦ ATP is continually being made and used |
|
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Term
|
Definition
◦ Biological macromolecules that act as catalysts to speed
up reactions
usually protein, sometimes RNA
◦ Not consumed by reaction
◦ Substrate specificity |
|
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Term
| Describe enzyme specificity |
|
Definition
◦ Unique protein shape
Specific ionic, polar and hydrophobic interactions
between substrate and protein
Isomer-specific
◦ Substrate binds active site
‘lock & key”
induced fit |
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Term
| What is activation energy |
|
Definition
◦ Energy required to initiate reaction
◦ Bring reactants to transition state
◦ Lowered by enzymes |
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Term
| What lowers activation energy? |
|
Definition
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Term
| How do enzymes lower activation energy? |
|
Definition
◦ Provide proper environment
◦ Increase local concentration of reactants
◦ Stress bonds
◦ Participate directly in reaction |
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Term
| Describe the catalytic cycle |
|
Definition
1-substrate enter active site
2-substrates are held in active site by weak interactions
3-active site can lower Ea and speed up a reaction
4-substrates are converted to products
5-products are released
6 active site is available for two new substrate molecules |
|
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Term
| give an example of the catalytic cycle |
|
Definition
◦ Lactase
Made in small intestine
Breaks down lactose into glucose and galactose
High expression in infancy
Lactase persistence vs lactose intolerance |
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Term
| What are factors that affect enzyme activity? |
|
Definition
◦ Affecting structure
Temperature
pH
◦ Cofactors
Assist enzymes in reactions
called ‘coenzymes’ if organic
50% of enzymes require
cofactors
Metal ions
Vitamins
Nucleotide derivatives |
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