Answer:
The correct answer is C. The tertiary structure of a polypeptide is the overall three-dimensional shape of a fully folded polypeptide.
Explanation:
A polypeptide is a molecular chain composed of at least 10 amino acids (which are the molecules that make up proteins). When we talk about its tertiary structure, it refers to the complete overall three-dimensional structure of the polypeptide units of a given protein, where the polypeptide chain is fully folded and compacted. This folding is facilitated by unions called disulfide bonds, which are created from the cysteine residues, these bonds (called disulfide bridges as well) help to stabilize many polypeptides.
1. In the heart, an action potential originates in the (E) sinoatrial node.
The cardiac action potential is a term referring to the change in the membrane potential of heart cells causing the heart to contract. Cardiac action potentials are created by a group of specialized cells capable of generating automatic action potentials and are located in the right atrium of the heart. These cells are called sinoatrial node and sometimes are referred to as the natural pacemaker of the heart. This characterization originates from the fact that sinoatrial node continuously provides action potential and sets the rhythm of the heart function.
2. The sequence of travel by an action potential through the heart is (A) sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers.
As explained above, the cardiac action potential originates from the sinoatrial node. This action potential then travels through the atrioventricular node, which belongs to the electrical conduction system of the heart and is located between the atria and the ventricles. It is responsible for the electrical connection between the right atrium and the right ventricle. The action potential then travels to the atrioventricular bundle (or bundle of His), another part of the electrical conduction system of the heart. The atrioventricular bundle transmits the electrical impulses from the atrioventricular node to the bundle branches. The bundle branches then send the signal to the Purkinje fibers which send the electrical impulses to the ventricles, causing them to contract.
3. The correct answer is A.
The generation of an action potential in the sinoatrial node causes the contraction of the atria. When the action potential passes from the sinoatrial node to the atrioventricular node, it slows down. This causes the transport of the electrical impulse from the atria to the ventricles to slow down. This delay enables the blood (from the contraction of the atria) to fill the ventricles before their contraction.
4. This statement is true.
The interventricular septum is a structure which divides the two ventricles of the heart and it is composed of two branches, the left bundle and the right bundle branch. When the action potential reaches the interventricular septum, it then travels to the apex of the heart from where it travels upwards along the walls of the ventricles and the ventricular contraction begins.
5. This statement is true.
The bundle branches gradually become Purkinje fibers located in the interior of the ventricular walls. Purkinje fibers are specialized cells and are responsible for conducting cardiac action potentials from the bundle branches to the ventricular walls. This signal transduction causes the muscle of the ventricular walls to contract.
Adenylate cyclases (ACs) are the membrane-bound glycoproteins that convert ATP to cAMP and pyrophosphate.
When activated by G-protein Gs, adenylate cyclases (ACs), which are membrane-bound glycoproteins, catalyze the synthesis of cAMP from ATP.
Different AC isoforms are widely expressed in various tissues that participate in regulatory systems in response to particular stimuli.
Humans have 9 different AC isoforms, with AC5 and AC6 thought to be particularly important for cardiac activities.
Nitric oxide has an impact on the activity of AC6, hence the protein's nitrosylation may control how it works. However, little is known about the structural variables that affect nitrosylation in ACs and how they relate to G's.
We predict the cysteines that are prone to nitrosylation using this 3D model, and we use virtual ligand screening to find potential new AC6 ligands.
According to our model, the AC-Gs interface's Cys174 in G's and Cys1004 in AC6 (subunit C2) are two potential residues that could experience reversible nitrosylation.
Learn more about glycoproteins here brainly.com/question/9507947
#SPJ4
