Exam 2 (chapter 8, 16) Flashcards
A metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway
Feedback Inhibition
Alters an enzyme’s function by changing it’s shape
Noncompetitive Inhibitor
Takes the place of a substrate in the active site
Competitive Inhibitor
Addition of a phosphorus
Phosphorylation
Some are organic ions (vitamins)
Coenzymes
Some are inorganic ions (zinc, copper, iron)
Cofactors
What denatures an enzyme?
Changes in salt concentration, temperature, and pH
A very specific place on the enzyme where the reactants bind
Active Site
- Lower activation energy
- Mostly proteins, highly specific for certain molecules
- Speed up reactions
- Do not affect energetic differences between reactants and products
- Not used up or altered by reaction
- Does not change the chemical relationship between reactants and products
Enzymes
The energy required to initiate a reaction
Activation Energy
Using the energy released in exergonic reactions to drive essential endergonic reactions
Energy Coupling
Absorbs energy, products rich in potential energy
Endergonic Reactions
Releases energy, products have less potential energy
Exergonic Reactions
Beating of cilia and flagella, movement of an entire cell, contraction of muscle
Mechanical Work
Moving substances “uphill” across a membrane, from low to high concentration
Transport Work
Building of polymers to monomers
Chemical Work
Stored energy (electrical gradient, energy stored in bonds)
Potential Energy
Energy that is actually doing work, motion
Kinetic Energy
The entropy (degree of disorder) is always increasing
- Energy is lost when it is transformed from one form to another
- Energy is generally lost as heat
Second Law of Thermodynamics
The total amount of energy in the universe is constant
- Energy cannot be destroyed or created, it can only be changed from one form to another
- Energy from life comes from the sun (Plants convert light energy to chemical energy via photosynthesis)
First Law of Thermodynamics
The capacity to do work
*All organisms required it to stay alive
Energy
The total of all the chemical reactions that take place in a multicellular organism
Metabolism
Showed that killed pathogenic bacteria could transfer virulence to non-pathogenic bacteria; This newly acquired trait of pathogenicity was inherited by all the descendants of the transformed bacteria
Frederick Griffith (1928)
Identified the transforming substance as DNA
Avery, McCarty, MacLoed (1944)
Concluded that DNA was injected by the phage must be the molecule carrying the genetic information that makes the cells produce new viral DNA and proteins
*Provided powerful evidence that nucleic acids, rather than proteins, are the hereditary material, at least for certain viruses
Hershey and Chase (1952)
Chargaff’s Rules: A=T, C=G
Erwin Chargaff (1950)
Made an x-ray diffraction photograph of DNA which showed the helical structure; Concluded that the sugar- phosphate backbone was on the outside, died in 1958
Rosalind Franklin (1953)
- Determined base pairing
- Determined that the two strands of DNA were involved-double helix
- Determined that the strands ran in opposite directions-antiparallel
Watson and Crick
2 rings
Purine
1 ring
Pyrimidine
The genetic information of the cell
*Carries instructions for every protein
*Carries regulatory sequences
The order of the bases on a strand of DNA specifies the primary structure of all of the proteins the organism is capable of making
*The instructions for one protein is carried by one gene
(one gene, one polypeptide)
DNA
The DNA strands separate, enzymes use each strand as a template to assemble the new strands
Template Model
- Catalyze the addition of nucleotides on the 3’ end of the growing chain of nucleotides (from 5’ to 3’ end)
- If nucleotides pair incorrectly, it is removed and replication occurs
DNA Polymerase
Synthesizes continuously, DNA replication occurs in the same direction as the replication fork
Leading Strands
Has fragments going in the opposite direction
Lagging Strands
Where split is occurring
Replication Fork
The daughter strands are ?? to the parent molecule
Identical
Breaks hydrogen bonds between complementary pairs (unzips DNA)
Helicase
Adds a RNA primer to initiate replication
Primase
Adds nucleotides after RNA primer
DNA Polymerase III
Removes RNA primer
DNA Polymerase I
Joins okazaki fragments
DNA Ligase
Helps with the untwisting of DNA
Topoisomerase
Binds to single strands to keep them from rejoining
Single Strand Binding Protein
Cuts out bad DNA segments
Nuclease
If a segment of DNA is able to replicate, it must include ??
at least one origin of replication
