BIO 110 Final Exam Flashcards
Complied questions and answers of past exams
Explain why hydrogen bonds can form between two water molecules. What forces make up this bond?
Electronegativity differences between O and H create regions of partial positive and negative charges. The attraction between these partial charges make up hydrogen bonds
During the formation of a peptide linkage, a(n) ____ is formed.
molecule of water
What is the general chemical formula for carbohydrates?
(CH2O)n
What does Keq indicate? What is the relationship between delta G and Keq?
- Keq indicates the tendency of a chemical reaction to go to completion, it is the ratio of products to reactants at equilibrium. Delta G is a log version of Keq
- Delta G = [energy]products - [energy]reactants
- Delta G is negative if the reaction is spontaneous
Starch and glycogen, which are both polysaccharides, differ in their functions in that starch is ____, whereas glycogen _____.
the main energy storage of animals; is a temporary compound used to stare glucose
A “typical” adult human has about 1 day supply of energy stored in the form of carbohydrates but 3 months energy stored as lipids. Explain the logic behind this observation. Why store more energy as lipids and not sugars?
Lipids (specifically tricylglycerides) are more efficient way to store energy because the carbons are less oxidized than sugars, so more ATP per carbon is derived from lipids than carbohydrates. Lipids also take up less space since they are hydrophobic (water doesn’t take up extra space)
What are purines?
one of two classes of bases found in nucleic acids, contains two rings; adenine and guanine
Double-stranded DNA looks like a ladder that has been twisted into a helix, or spiral. Describe the two outer rungs of this ladder.
The backbone is composed of alternating phosphate groups and deoxyribose
Telomerase is a ___ dependent ___ polymerase.
RNA, DNA
Primase is a ___ dependent ___ polymerase.
RNA, DNA
Transcription uses a ___ dependent ___ polymerase.
DNA, RNA
During formation of the mitotic spindle, there is/are ___ centriole(s) while each chromosome consists of ___ chromatid(s), ___ centromere(s), and ___ kinetochore(s).
4;2;1;2
When you slowly and carefully increase the temperature of a chromosome, you notice that some regions become single stranded at lower temperatures than other regions. What is the likely cause of these differences?
Those regions that become single stranded dat lower temperatures likely have a lower GC content. These are likely regions that ‘unzip’ frequently - such as the origin or replication of promotor regions.
Why is RNA incorporated into the DNA molecule during DNA replication?
DNA polymerase cannot begin a new strand, but can only add on to the 3’ end of the preexisting nucleic acid strand. RNA polymerase can begin a new strand, so the replication is begun as a short RNA primer onto which DNA polymerase can add.
Describe the changes that occur for a molecule of hemoglobin as it travels through the blood, beginning as it enters the lungs and then transported to exercising muscles and then back to the lungs. Include in your description the changing structure of hemoglobin, its association(s) with oxygen and any factors that may be influencing the structure and function of hemoglobin.
Entering lungs, without O2 hemoglobin is the T-state, which has a low affinity for oxygen. In the lungs, oxygen concentration is high. Binding of O2 to one subunit will cause it to convert to the R-state by moving the Fe in the heme, causing the attached histidine residue to move - causing the alpha helix which that histidine is located to bend slightly - causing a change in subunit confirmation. That change in confirmation is translated to the other subunits which increase the binding of O2. pH can also influence T versus R state via changes in ionic interactions between subunits. Lower pH (in active tissues) will cause hemoglobin to be in the T state and release oxygen easier. Higher pH will ten to stabilize the R state.
What is negative cooperativity of binding? Give an example when this is an appropriate strategy for ligand binding.
Negative cooperativity occurs when a ligand binds to a protein and decreases the affinity of the same protein for a second ligand binding. The insulin receptor uses this strategy.
What is a cofactor? List a specific enzyme that uses a cofactor - what is the role of that cofactor?
Cofactors are parts of proteins but are not composed of amino acids and are required for protein function. They include metal ions, NAD+, FAD, heme, cytochromes. When a coenzyme is covalently bound to an enzyme, it is called a prosthetic group.
Describe the different steps involved in translation elongation.
bind - binding of new charged tRNA to A site of ribosome
bond - peptide bond formation between AA in A site to AA/peptide in the P site
move - move mRNA 3 bases (one codon) downstream
A mutation occurs such that a spliceosome cannot remove one of the introns in a gene. What effect will this have on that gene?
Translation will continue, but a nonfunctional protein will be made
Translation of messenger RNA into protein occurs in a ____ direction, and from the ___ terminus to the ___ terminus.
5’ to 3’, N, C
Which of the following statements about transfer RNA is true?
Activating enzymes (aminoacyl-tRNA synthases) link together a specific amino acid with a specific tRNA
The expression of the gene that encodes cyclin A varies considerably across the cell cycle, reaching a peak at the G2 phase. Based on this information, one can conclude that cyclin A is:
encoded by an inducible gene
Describe all the major environmental conditions under which the Lac Operon is normally expressed. If glucose is then added to the bacterial culture, what protein(s) will change structure and function?
Lactose must be present and glucose absent. Adding glucose would change the confirmation of the CAP protein (due to reduce cAMP levels)
During carbohydrate catabolism, one molecule of glucose can be used to produce up to ___ mole of ATP. For each mole of glucose, substrate level phosphorylation is used to create __ moles of ATP during ____, while __ moles of GTP are produced during ____. Most of the ATP made from oxidizing glucose is produced by the enzyme called ____, which is located in the ____ membrane of the ____. Before most of the ATP is produced, high energy molecules called _____ are produced during several stages of carbohydrate catabolism including ____, _____, and the krebs cycle. These high energy molecules are used to create a ____ which is used to produce the majority of the ATP.
32; 2; glycolysis; 2; the krebs cycle; ATP synthase; inner; mitochonria; NADH (e-carriers); glycolysis; pyruvate dehydrogenase; proton gradient
Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide. After inhalation, the oxygen missing from the air will mostly be found in:
water
What are all the direct products of pyruvate oxidation?
CO2, NADH, Acetyl-CoA
Both mitochondria and chloroplasts employ an electron transport chain. Compare and contrast both of these electron transport chains.
both use the energy from high energy electrons to pump protons to create a proton gradient which is used to make ATP. The mito ETC begins with NADH ands with O2, while chloroplast ETC uses electrons from H2O and ends with NADPH
How does the reduction of pyruvate to lactic acid during fermentation allow glycolysis to continue in the absence of oxygen?
it regenerates NAD+. Glycolysis requires NAD+ and stops without it.
