Chapter 7 Post-lecture

Inhalation and exhalation move air into and out of the lungs. What happens when you inhale and exhale? Drag the labels to the correct locations on the flowchart to identify the steps of inhalation and exhalation.

Gas exchange involves the transport of two respiratory gases, oxygen and carbon dioxide. Review how each gas is transported between the atmosphere and the cells of your body by completing this exercise. Drag each statement into the appropriate bin depending on whether it applies to oxygen only, carbon dioxide only, or both oxygen and carbon dioxide.

Oxygen shows cooperative binding to hemoglobin. Cooperative binding has the following effects on the binding and release of oxygen: Oxygen binding to hemoglobin: When one molecule of oxygen binds to one of hemoglobin's four subunits, the other subunits change shape slightly, increasing their affinity for oxygen. Oxygen release from hemoglobin: When four oxygen molecules are bound to hemoglobin's subunits and one subunit releases its oxygen, the other three subunits change shape again. This causes them to release their oxygen more readily. These two graphs show how cooperative binding differs from a hypothetical situation where binding is not cooperative. The x-axis shows the partial pressure of oxygen (PO2). This is a measure of the amount of oxygen present in a tissue. The blue arrows on the x-axis show the partial pressure of oxygen in various tissues of the body. The y-axis shows the oxygen saturation of hemoglobin (O2 saturation). This is the percentage of oxygen-binding sites on hemoglobin molecules that are actually bound to oxygen. https://session.masteringchemistry.com/problemAsset/1943614/6/MB_1187932_005.jpg The table below walks you through a comparison of cooperative binding and noncooperative binding. By completing the table, you will learn why cooperative binding is an important adaptation that makes gas exchange more efficient. Drag the labels to their appropriate locations on the table. Labels can be used more than once.

Increase in pH from 7.2 to 7.4

Decrease in PCO2 from 30 to 10 mmHg

Dissociation into monomer polypeptide chains

Decrease in 2,3-BPG concentration from 6 mM to 4 mM in red cells.

https://session.masteringchemistry.com/problemAsset/2751234/13/MC_2751234_A.jpg Analyze the binding curve by completing the following sentences. Match the words in the left column to the appropriate blanks in the sentences on the right.

https://session.masteringchemistry.com/problemAsset/2751234/13/MC_2751234_A.jpg Use the oxygen binding curve to complete the information about data points at various sites in the graph. Match the words in the left column to the appropriate blanks in the sentences on the right.

Calculate the fractional saturation for hemoglobin when the partial pressure of oxygen is 78 mm Hg. Assume hemoglobin is 50% saturated with oxygen at a partial pressure of 22 mm Hg and that the Hill coefficient is 3. Express your answer to two significant figures.

The diagram below depicts the transport of carbon dioxide in blood, from body tissues to the lungs. Drag the labels to their appropriate locations on the diagram.

How is hemoglobin's affinity for oxygen affected by the presence or absence of oxygen? Rank hemoglobin molecules with the described conditions from most likely to bind oxygen molecules to most likely to release oxygen molecules. (For help approaching this problem, open Hint 1.)

https://session.masteringchemistry.com/problemAsset/1100272/38/1100272_003.jpg Given what you know about the Bohr shift, what is the difference in O2 saturation of hemoglobin in the lungs versus hemoglobin in exercising tissues, as represented on this graph? Keep in mind that the pH of blood in the lungs is not the same as the pH of blood in exercising tissues. Express your answer in percent, but do not include the percent sign in your answer.

Why might crocodiles have a hemoglobin that is responsive to HCO3− instead of 2,3-BPG? Recall that crocodiles hold their prey underwater to kill them. Match the words in the left column to the appropriate blanks in the sentences on the right.

Suppose your biking partner claims that hyperventilating at the bottom of steep hill climbs is a good idea because it will "increase the O2 saturation of the blood" and thereby provide "more O2 for leg muscles during the climb." Hyperventilation reduces the CO2 content of blood. Given this fact, is hyperventilation likely to increase O2 delivery to muscles (as your biking partner claims) or not? Match the words in the left column to the appropriate blanks in the sentences on the right.

If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. Sort the items into the appropriate bins.

Label the four mutated DNA segments shown below according to the type of point mutation each represents. Use the codon table above to determine how each mutation would affect the amino acid coding for each segment. Drag the labels to their appropriate locations to identify the type of point mutation shown.

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?

What peptides are expected to be produced when an unknown hormone (Asp−Glu−Ser−Met−Gln−Tyr−Asn−Arg−Glu−Ser−Lys−Pro−Leu) is cleaved by trypsin Enter your answers separated by a comma(s). Name peptides using the one-letter abbreviations.

What peptides are expected to be produced when an unknown hormone (Asp−Glu−Ser−Met−Gln−Tyr−Asn−Arg−Glu−Ser−Lys−Pro−Leu) is cleaved by cyanogen bromide Enter your answers separated by a comma(s). Name peptides using the one-letter abbreviations.

What peptides are expected to be produced when an unknown hormone (Asp−Glu−Ser−Met−Gln−Tyr−Asn−Arg−Glu−Ser−Lys−Pro−Leu) is cleaved by thermolysin Enter your answers separated by a comma(s). Name peptides using the one-letter abbreviations.

There is another melanocyte-stimulating hormone called β -melanotropin. Cleavage of β-melanotropin with trypsin produces the following peptides plus free aspartic acid. WGSPPK, DSGPYK, MEHFR If you assume maximum sequence similarity between α-melanotropin and β-melanotropin, then what must the sequence of the latter be? (α -melanotropin: Ser−Tyr−Ser−Met−Glu−His−Phe−Arg−Trp−Gly−Lys−Pro−Val) Drag the appropriate labels to their respective targets so that the maximum sequence similarity to the order of α-melanotropin will be shown.

The iron ions are chelated by which complex of the myoglobin and hemoglobin family?

The ________ binding of oxygen to hemoglobin is facilitated by changes in protein conformation upon oxygen binding to one subunit that affect the binding of oxygen to another subunit.

Hemoglobin (Hb) can be viewed as having two quaternary states, a low oxygen affinity state (T), and a high oxygen affinity state (R). Which of the following statements about the binding of O2 by Hb are true? 1 Upon binding a molecule of oxygen, Hb undergoes a conformational change that makes the binding of subsequent O2 molecules more favored. 2 The conformational change induced in Hb upon binding oxygen is the result of a small movement (0.2 Å) of the iron cation into the center of heme. 3 Site-directed mutagenesis studies have indicated that the cooperativity of O2 binding in Hb is attributable to the movement of the F helix in Hb. 4 Site-directed mutagenesis studies in which the proximal His residues of the F helix have been replaced by glycines have indicated the mutant protein still shows cooperativity of O2 binding.

Fetal hemoglobin has a(n) ________ affinity for oxygen than does maternal hemoglobin because it has a higher affinity for the allosteric regulator 2,3-bisphosphoglycerate.

The production of carbon dioxide during respiration in aerobic tissues lowers the pH in erythrocytes, which in turn ________ the affinity of oxygen binding to hemoglobin.