which of the following has the cellular components arranged in order of increasing size?
Amino acids < Proteins < Ribosomes < Mitochondria
The macromolecules that serve in the storage and transmission of genetic information are:
nucleic acids
Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of:
dynamic steady state
The major carrier of chemical energy in all cells is:
adenosine triphosphate
The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions. which of the following is not considered a noncovalent interaction?
carbon-carbon bonds
which of the following is not among the four most abundant elements in living organisms?
phosphorous
The bacterium E.coli requires simple organic molecules for growth and energy - it is therefore a:
chemoheterotroph
Energy requiring metabolic pathways that yield complex molecules from simpler precursors are:
anabolic
In eukaryotes, the nucleus is enclosed by a double membrane called the:
nuclear envelope
6 characteristics of life
chemically complex and highly organized, ability to extract energy from the environment, capacity for self-replication and self assembly, exploit chemical interplay with the environment, express programmatically defined functions, and evolve to new forms
Purpose of the plasma membrane
it is a barrior to the free passage of materials into or out of the cell, contains proteins that transfer specific ions or molecules, and contains proteins that transmit signals.
How is gram negative determined?
It has little affinity for the gentian violet dye used in gram staining
Gram negative bacteria:
have an outer membrane and peptidoglycan layer
Gram positive bacteria:
does not have an outer membrane but has a thick peptidoglycan layer
4 types of noncovalent interations
hydrogen bonds, ionic interactions between charged groups, van der waals interactions, and hydrophobic interactions
importance of noncovalent interactions in 3-D structures of macromolecules
they are weak interactions so they can form, break, and reform rapidly with less energy input which helps maintain flexibility
Relationship between living organisms and its surroundings in terms of both matter and energy
living organisms are open systems & exchange both matter and energy. It is not in equilibrium with its surroundings, and acquires energy from surroundings.
what is feedback inhibition and why is it important?
it is the regulation of a biochemical pathway in which a reaction inhibits an earlier step in the pathway. It is important because it ensures that energy is not wasted by an organisms producing molecules that it does not need.
what is the rationale significance of the Miller and Urey experiments?
it established that amino acids are the building blocks of life
Describe the elements of "chemical evolution
simple organic molecules condensed to form more complex molecules (NH3, CH4, H2, H2O)
Define the "Dynamic Steady State
Constant chemical state of the organism. Molecules are synthesized and broken down by continuous reactions. Constant flux of mass and energy between the system and the environment.
Catabolism
chemical reaction that results from the breakdown of more complex organic molecules into simpler substances -> release energy.
Anabolism
simpler substances are combined to form more complex molecules -> requires energy
Difference between prokaryotic and eukaryotic cells
eukaryotic cells have nucleus and prokaryotes do not
describe the feedback mechanism
maintaining homeostasis by molecules signaling to decrease product production (negative feedback) or increase product production (positive feedback)
Major difference between plant cells and animal cells:
Plant cells have a cell wall, fixed shape, and large vacuole. Animal cells do not have a cell wall and have an irregular shape.
Two types of cell fractionation
1. Differential centrifugation - centrifugation at different speeds to break open the cell and separate organelles based on size and density.
2. Density gradient centrifugation - gradient of concentration of solution throughout the test tube with low conc
A true statement about hydrophobic interactions is that they:
are the driving force in the formation of micelles of amphipathie compounds in water.
Hydrophobic interactions make important energetic contributions to
all of the above
Osmosis is movement of a:
water molecule across a membrane
Which of the following is true about the properties of aqueous solution?
Hydrogen bonds form readily in aqueous solution
the pH of a sample of blood is 7.4, while gastric juice is pH 1.4. The blood sample has:
a million times lower [H+] than the gastric juice
The aqueous solution with the lowest pH is:
0.1M HCl
Which of the following statements about buffers is true?
When pH = pKa, the weak acid and salt concentrations in a buffer are equal.
The Henderson-Hasselbalch equation:
relates the pH of a solution to the pKa and the concentrations of acid and conjugate base.
Consider an acetate buffer, initially at the same pH as its pKa (4.76). When sodium hydroxide (NaOH) is mixed with this buffer, the:
ratio of acetic acid to sodium acetate in the buffer falls
Which of the following is considered as a noncovalent bond?
All of the above (electrostatic interactions, hydrogen bonds, and van der waals interactions)
The energies for hydrogen bonds are approximately:
4-20 kJ/mol
What pairs of atoms in bases are involved in hydrogen bonds?
N-H and O-H
Typical van der waals energies are about
2-4 kJ/mol
What two properties of water are important for biological interactions?
the polarity of water and the cohesive properties of water
What happens to nonpolar molecules in water?
They aggregate together
which of the following is the Henderson-Hasselbach equation?
pH = pKa + log ([A-]/[HA])
What are the primary chemical components present in the phosphate buffer at pH 7.4?
H2PO4- and HPO4 (2-)
Hydrogen bond
weak electrostatic attractions between one electronegative atom and a hydrogen atom covalently linked to a second electronegative atom
Electrostatic interaction
relatively weak charge-charge interactions between two ionized groups
hydrophobic interactions
the forces that tend to bring together two hydrophobic groups
van der Waals interactions
weak interactions between the dipoles that two close-spaced atoms induce in each other
isotonic
solution has the same water concentration as the inside of the cell
hypotonic
The solution has greater water concentration than the cell. -> water will diffuse into the cell causing it to swell and possible burst.
hypertonic
The solution has lower concentration than the cell. -> water will diffuse out of the cell and into the solution causing the cell to shrink
The chirality of an amino acid results from the fact that its alpha carbon:
is bonded to four different chemical groups
of the 20 standard amino acids, on ____ is not optically active. The reason is that its side chain____.
glycine; is a hydrogen atom
two amino acids of the standard 20 contain sulfur atoms. they are?
methionine and cysteine
all of the amino acids that are found in proteins, except proline, contain:
amino group