Chapter 5- Protein Function

Monoclonal antibodies

bind the same epitope. synthesized by a population of identical cells (a clone). have the same antigen

Which molecule is NOT described by the Bohr effect? a.) All of these molecules are described by the Bohr effect. b.) O2 c.) 2,3-bisphosphoglycerate d.) H+ e.) carbon dioxide

c.) 2,3-bisphosphoglycerate

Which of the following are bound to hemoglobin when hemoglobin is in the R-state? - Fe3+ - 2,3-bisphosphoglycerate - Fe2+ - CO2 - oxygen

Fe2+ oxygen

Why does myosin generate force for muscle contraction?

Hydrolysis of ATP promotes a conformational change in myosin.

Microtubules

component of cilia and flagella thick, hollow, and rigid bind GTP

Microtubules

dimers polymerize into protofilaments that then associate side by side monomers bind GTP 13 protofilaments associate to form a hallow tube polymer of globular subunits fibers polymerize and depolymerize quickly all the nucleotide-binding sites point the same direction

Which biochemical principle is NOT true of immunoglobulins as examples of protein structure and function? a.) There is 100% sequence homology between the two antigen binding sites. b.) Amino acid chain flexibility and bond rotation permit optimal epitope binding. c.) Disulfide linkages strengthen the quaternary protein structure. d.) There are two specific and identical binding sites with high affinity on the same molecule. e.) Because the antigen-binding domain has high affinity, there is no observed induced fit.

e.) Because the antigen-binding domain has high affinity, there is no observed induced fit.

What is the difference between polyclonal and monoclonal antibodies?

Polyclonal antibodies are generated against multiple epitopes of one antigen, while monoclonal antibodies are generated against one epitope of one antigen.

Intermediate filaments

keratin filaments cross linked by disulfide bonds

What factors are associated with sickling of red blood cells in sickle cell disease?

low pH high temperature dehydration

Which molecule is a homotropic modulator of oxygen binding to hemoglobin?

oxygen

Polyclonal antibodies

respond to different epitopes within the same antigen produced by different B cells responding to a specific antigen have the same antigen

According to the sliding-filament model, what parts of a skeletal muscle shorten during contraction?

sarcomeres

Microfilaments

structure is a double chain of subunits monomers bind ATP polymer of globular subunits fibers polymerize and depolymerize quickly all the nucleotide-binding sites point the same direction

Microfilaments

with myosin, enable cell movement. double chain of subunits actin

Which of the following statements are true about the structure of microfilaments? - Polymerizing microfilaments contain more bound ATP whereas older microfilaments contain more bound ADP. - Polymerization of actin generally occurs more slowly at the (-) end of the actin polymer. - Microfilaments, which are about 120 A in diameter, are larger in diameter than intermediate filaments. - The polymerized form of actin is called F-actin. - Microfilaments are motor proteins.

- Polymerizing microfilaments contain more bound ATP whereas older microfilaments contain more bound ADP. - Polymerization of actin generally occurs more slowly at the (-) end of the actin polymer. - The polymerized form of actin is called F-actin.

Select the true statements regarding antibody (specifically, immunoglobulin G) structure. - Both the Fab and Fc fragments have variable domains. - The heavy and light chains are linked by non covalent and disulfide bonds. - The antigen-binding site is formed as a combination of variable domains from one heavy and one light chain. - Both the Fab and Fc fragments contain constant domains. - The antigen-binding site is located in the Fc fragment.

- The heavy and light chains are linked by non covalent and disulfide bonds. - The antigen-binding site is formed as a combination of variable domains from one heavy and one light chain. - Both the Fab and Fc fragments contain constant domains.

Which of the following are true statements about myosin? - During muscle contraction, thick and thin filaments slide past each other causing an overall lengthening of the muscle. - The myosin-actin reaction cycle is powered by ATP hydrolysis. - The head of the myosin molecule acts as a molecular lever, whereas the tail binds ATP. - Each myosin head has a binding site for actin and ATP. - The interaction between myosin and actin converts chemical energy to mechanical work. - In a muscle cell, actin filaments that bind to head domains of myosin are called thin filaments.

- The myosin-actin reaction cycle is powered by ATP hydrolysis. - Each myosin head has a binding site for actin and ATP. - The interaction between myosin and actin converts chemical energy to mechanical work. - In a muscle cell, actin filaments that bind to head domains of myosin are called thin filaments.

What are the functions of the cytoskeleton?

Assists in cellular movement Provides the structural support system for the movement of organelles in the cell. Maintains the shape of the cell.

Rigor mortis is a phenomenon that occurs in a body after death. What is the physiological cause of rigor mortis?

Cellular respiration ceases and eliminates available ATP to joints and muscles.

What is the smallest functional unit involved in muscle contraction?

The motor unit, composed of one motor neuron and all the muscle fibers it controls

Why is sickle cell anemia common in central Africa?

There is a selective advantage to being a heterozygous for the mutation causing sickle cell anemia.

What are antibodies?

Y-shaped proteins that recognize and help destroy foreign substances.

The sliding filament theory was described in two papers published in 1954. These papers described actin and myosin sliding past each other during muscle contraction. What are the steps of the sliding filament model of muscle contraction in the correct order?

1. Myosin bound to actin 2. ATP binds to myosin 3. Myosin releases actin 4. Hydrolysis of ATP 5. Myosin head "cocks" 6. Myosin weakly binds to actin 7. Myosin releases Pi 8.) Myosin tightly binds to actin 9.) Power stroke 10.) Myosin releases ADP 11.) Myosin bound to actin

Describe the recruitment in muscle contraction.

More motor neurons and larger motor units are activated to stimulate a greater number of muscle fibers for a more powerful muscle contraction.