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BIO 230 Exam 1 - Moberly Questions AND ANSWER
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BIO 230 Exam 1 - Moberly Questions AND ANSWER
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BIO 230 Exam 1 - Moberly_____ controls the cell's function and structure - correct answer-DNA
(Covalent/noncovalent) modifications control a protein's behavior. Which is it? - correct
answer-covalent
A transmitter must be quickly removed to enable the postsynaptic cell to engage in other
cycle of neurotransmitter release, binding, and signal generation. How can they be
removed? - correct answer-Glial cells (cells that support nerves) can remove the
neurotransmitter, enzymes can remove it, or it can be pumped back into the presynaptic cell
Compare and contrast collagen and elastin - correct answer-They are both fibrous proteins
that are elongated,. THey are found in the intracellular fluid and extracellular matrix.
Collagen strongly holds tissues together and makes a triple helix, while elastin forms
meshwork, allowing recoil. Unstretched elastic regions have many unstructured loops in
them, and covalent cross linkages prevent the elastin from breaking when being stretched.
Compare and contrast single bonds and double bonds - correct answer-Both are covalent
bonds, but single bonds are longer allow for more rotation, while double bonds are shorter
and stronger, more rigid, and less flexible
Compare and contrast the two types of membrane transport proteins - correct
answer-*Transporters* and *channels* both are proteins that don't require energy.
Transporters use noncovalent interacts to bind solutes and they change shape to move them
across the membrane. They only transfer molecules or ions that specifically fit into the
binding sites and they are slower than channels. Chnnels form tiny hydrophilic pores using
amino acid side chains that are polar and hydrophilic. They are gated and have no shape
change whenever they open up; they discriminate on basis of size and charge, so ions or
molecules with the right size and charge can pass
Covalent bonds form ________, while ionic bonds form _____ - correct answer-molecules;
salts
Define genome - correct answer-the entire sequence of nucleotides in an organism's DNA
Describe 2-d gel electrophoresis - correct answer-The separation of nucleic acids or
proteins, on the basis of their size and electrical charge, by measuring their rate of
movement through an electrical field in a gel.
Describe affinity chromatography - correct answer-it exploits binding interactions to isolate
proteins inside the cell that associated with a certain protein. this means it has high
selectivity, but it also has great resolution. proteins associated with a certain protein (i.e.
protein X) will bind to the matrix-bound protein X. unassociated proteins will pass through the
column, and X-binding proteins will be purified by either elution with a high salt or a change
in pH
,Describe antibody molecules - correct answer-They are made of 4 polypeptide chains (2
heavy and 2 light) with disulfide bonds holding the molecule together and stabilizing the
molecule when it is outside of the cell. There are two antigen bonding sites with
hypervariable loops (amino acid sequence varies highly here); this adds to the antibody's
specificity to the antigens that it binds to.
Describe carbohydrates - correct answer-AKA sugars, they are made up of carbon,
hydrogen, and oxygen; they are used for energy sources, structural materials, and signaling
and recognition; types include monosaccharides, disaccharides, and polysaccharides
Describe carbon's binding behavior - correct answer-Each carbon atom can form covalent
bonds with up to 4 atoms. Organic compounds contain carbon bound to hydrogen and
possibly other elements
Describe how a glucose-Na+ symporter works - correct answer-It uses the electrochemical
gradient of sodium made by the Na+/K+ pump to drive the active import of glucose. When
the pump is open to the extracellular environment where sodium is more highly
concentrated, Na+ binds to the symporter, leading to a higher affinity for glucose. Glucose
binds to the symporter, and then the pump opens and moves them into the inside of the cell.
The pump has to have both the Na+ and glucose to be closed
Describe how cells evolve - correct answer-Through mutations in self-replication, which
occurs through the relationship of DNA, RNA, and proteins. When DNA replication occurs,
mutations can happen where there's a change in the nucleotide sequence, causing daughter
cells to vary from the parent cell. Mutations can create offspring that have changed for the
worse (died due to harmful mutations, i.e. most frameshift mutations), better, or no change at
all. Any survivors' genes will be given to the next generation
Describe how glucose is transported into the cell - correct answer-Since glucose is
uncharged, it follows its concentration gradient. The membrane potential has no effect on the
movement of glucose; it moves from the outside to the inside of the cell because there's
higher concentration of glucose outside of the cell
Describe how immune cells can migrate out of the blood and into infected tissues - correct
answer-Through the recognition of cell-surface carbohydrates on neutrophils (white blood
cells); the neutrophil is bonded to an oligosaccharide that binds to lectin (a receptor
transmembrane protein). This leads to a conformation change in the neutrophil, allowing it to
roll along blood vessel walls and squeeze between two cells to carry out its immune function
at the site of infection
Describe how proteins are able to fold - correct answer-The protein backbone and side
chains interact through many weak covalent interactions like electrostatic attractions,
hydrogen bonds, and van der waals forces that help them fold and maintain shape.
Polypeptides with nonpolar and polar side chains form themselves in a way to where polar
side chains can form hydrogen bonds with water, and nonpolar side chains are packed into a
hydrophobic core region. Hydrogen bonds can form from backbone-backbone,
backbone-side chain, or side chain-side chain interactions.
, Describe how the carbonic acid-bicarbonate buffer system works. - correct answer-It works
to control pH of blood. When blood pH rises, carbonic acid dissociates to form bicarbonate
and hydrogen protons. When blood pH drops, bicarbonate binds to hydrogen protons to form
carbonic acid.
Describe hydrogen bonds - correct answer-They form between a hydrogen atom and
another atom taking part in a separate covalent bond; the molecule has no net charge; they
are imoortant for many biological molecules, and although they sre individually weak, they
are collectively strong because they stabilize structures of large molecules
Describe lipids - correct answer-They are hydrophobic, nonpolar hydrocarbons that are used
for cell membranes, major sources of energy (more energy-dense than carbs), and structural
materials
Describe mass spectrometry - correct answer-Peptides produced by tryptic digestion have
their masses measured using a mass spectrometer. The proteins predicted from genome
sequences are searched for matches with theoretical masses calculated for all
trypsin-released peptides. Identification of the protein allows the corresponding gene to be
isolated, and the gene sequence allows large amounts of the protein to be obtained by
genetic engineering techniques
Describe nucleotides - correct answer-They are the subunits of RNA and DNA, and they
function as energy carriers (ATP), building blocks for nucleic acids, coenzymes, and
chemical messengers. They're made of a 5 carbon sugar (pentose), phosphate group,
nitrogenous base
Describe peptide bonds - correct answer-They link amino acids together and are formed by
a dehydration reaction; they are covalent bonds that link the carboxyl group of one amino
acid with the amino group of the next amino acid. Many of them allow free rotation, which
allows for flexibility in polypeptide chains
Describe protein islands - correct answer-Plasma membrane-associated proteins are
clustered into domains called islands attached to the cytoskeleton for
formation/maintenance. The islands are cholesterol-enriched and separated into raft and
non-raft regions; raft protein islands are not as connected as non-raft protein islands so more
movement occurs there.
Describe the alpha helix - correct answer-It is what results from hydrogen bonding in the
polypeptide's hydrophilic backbone. The backbone is shielded by nonpolar side chains
Describe the beta pleated sheet - correct answer-Like alpha helices, they result from
hydrogen bonding in the polypeptide background. Its strands are held together by hydrogen
bonds between adjacent strands, which forms a rigid pleated structure. They can be parallel
or antiparallel. They can stack to form an amyloid structure, which can damage cells and
tissues.
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