BMB 555 Exam 1

2. What is the smallest distance two points can be separated and still resolved using light microscopy?

0.2um.

14. The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted byproducts back out. Which term describes the process by which external materials are captured inside transport vesicles and brought into the cell?

endocytosis

2. Which of the following is a process that delivers material to the lysosome?

endocytosis (heterophagy, includes pinocytosis and phagocytosis), autophagy.

2. Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are

endosymbionts.

14. Cells that are specialized for the secretion of proteins are likely to have which of the following features?

enlarged endoplasmic reticulum

4. Stepwise condensation of linear DNA happens in five different packing processes. Which of the following four processes has a direct requirement for histone H1?

formation of the 30-nm fiber.

3. The cell organelle that contains acid hydrolases is:

lysosome.

6. Phagocytes play an important role in the prey of foreign objects into the cell body, so that the most organelles within phagocytes is/are:

lysosome.

7. Cholesterol serves several essential functions in mammalian cells. Which of the following are influenced by cholesterol?

membrane permeability, membrane fluidity, and membrane rigidity.

4. The _____ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

nuclear envelope.

6. Which type of lipids are the most abundant in the plasma membrane?

phospholipids.

4. Ca2+-pumps in the plasma membrane and endoplasmic reticulum are important for:

preventing Ca2+ from altering the activity of molecules in the cytosol.

5. The major functions of autophagy are:

recycling of unnecessary or dysfunctional organelles.

5. Which of the following sequences is a peroxisomal target signal?

serine-lysine-leucine (or SKL)

10. After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode?

soluble secreted proteins; ER membrane proteins; plasma membrane proteins.

5. A large protein that passes through the nuclear pore must have an appropriate:

sorting sequence (NLS), which typically contains the positively charged amino acids lysine and arginine.

1. Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of the material "burned" and the form of energy produced during cellular respiration?

sugar, ATP; fatty acids, ATP; pyruvate, ATP

12. Which of the following components of the electron-transport chain does NOT act as a proton pump?

ubiquinone (or coenzyme Q), cytochrome c

3. Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by:

using the energy of ATP hydrolysis to move nucleosomes.

8. Diversity among the oligosaccharide chains found in the carbohydrate coating of the cell surface can be achieved in which of the following ways?

varying the types of sugar monomers used; varying the types of linkages between sugars; and varying the number of branches in the chain.

3. You have generated antibodies that recognize the extracellular domain of the Ca2+-pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+?

Ca2+-pumps in the endoplasmic reticulum membrane keep cytosolic calcium levels low.

11. Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?

ER -› Golgi -› plasma membrane.

6. Proteins that are fully translated in the cytosol do not end up in:

ER, Golgi, and transport vesicles.

14. The mitochondrial ATP synthase consists of several different protein subunits. Which subunit binds to ADP + P, and catalyzes the synthesis of ATP as a result of a conformational change?

F1 ATPase head.

7. The chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and randomly occupy any territories in the nucleus. True or False?

False.

8. Which of the following statements describes the mitochondrial intermembrane space?

It contains proteins that are released during apoptosis.

7. Which of the following statements describes the mitochondrial inner membrane?

It contains the electron transport chain, ATP synthase, and transporters for ATP molecules.

6. What is the role of the nuclear localization sequence in a nuclear protein?

It is bound by cytoplasmic proteins (receptors) that direct the nuclear protein to the nuclear pore.

6. Which of the following statements describes the mitochondrial outer membrane?

It is permeable to molecules with molecular mass as high as 5000 daltons.

2. Which of the following is true of the N-terminal "tail" of the histones?

It is subject to covalent modifications; It extends out of the nucleosome core; It helps DNA pack tightly (or loosen for transcription).

10. Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

K+.

7. Which of the following organelles is not part of the endomembrane system?

Mitochondria; chloroplasts.

3. The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances?

NADH, FADH2, oxygen, proton.

11. Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant outside a typical mammalian cell?

Na+.

9. Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran-GAP to activate TP hydrolysis. What is the most likely effect of this drug on nuclear transport?

Nuclear transport receptors would be unable to take their cargo in the cytosol.

10. What is the final result of the electron transfers in Stage 1 of the membrane-based processes that drive ATP synthesis in mitochondria?

O2 is reduced to H2O.

12. Different glycoproteins can have a diverse array of oligosaccharides. Which of the statements below about this diversity is TRUE?

Oligosaccharide diversity comes from modifications that occur in the ER and the Golgi of the 14-sugar oligosaccharide added to the protein in the ER.

1. ______ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Peroxisomes

2. Which of the following statements about peroxisomes are TRUE?

Peroxisomes synthesize phospholipids for the myelin sheath; Peroxisomes contain enzymes that help inactivate toxins; Proteins do not need to unfold to enter the peroxisome.

12. The Na*-K* pump is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyzes ATP?

The pump is phosphorylated.

3. Prokaryotic cells do not possess:

a nucleus.

9. Which of the following channels would be expected to generate a change in voltage by movement of its substrate across the membrane where it is found?

a proton channel, a sodium channel, a calcium channel, etc (charged ions).

4. Lysosomes are found in:

animal and plant cells.

4. Which of the following processes do take place in the peroxisomes?

breakdown of very long chain fatty acids (peroxisomal 3-oxidation), peroxidation reaction, reactions for plasmalogen synthesis, detoxification of toxic molecules, production of bile acid.

1. Which is the smallest living unit?

cell.

15. The overall relationship that links bond-forming reactions to membrane transport processes in the mitochondria is called

chemiosmotic coupling.

5. The nucleus, an organelle found in eukaryotic cells, confines the ____, keeping them separated from other components of the cell.

chromosomes.

13. Vesicles from the ER enter the Golgi at the:

cis Golgi network.

4. Which of the following processes do take place in the mitochondria?

citric acid cycle; conversion of pyruvate to activated acetyl groups; oxidation of fatty acids to acetyl CoA.

1. Which of the following choices BEST describes the role of the lysosome?

clean-up, recycling, and disposal of macromolecules

11. Which component of the electron-transport chain is required to combine the pair of electrons with molecular oxygen?

cytochrome c oxidase or Complex IV.

3. Most peroxisomal proteins are synthesized in the:

cytosol

8. Proteins that are fully translated in the cytosol and lack a sorting signal will end up in the:

cytosol

2. New membrane phospholipids are synthesized by enzymes bound to the ______ side of the ______ membrane.

cytosolic; endoplasmic reticulum.

13. During Stage 2 of oxidative phosphorylation, ATP synthesis is powered by movement of ______ ions through the _______.

H+; ATP synthase

1. Which of the following histone proteins does NOT form part of the octameric core?

H1

9. Which of the following statements describes the mitochondrial matrix?

It contains its own DNA and enzymes required for the citric acid cycle and the oxidation of fatty acids.

5. Which of the following statements about the endoplasmic reticulum (ER) is TRUE?

The ER is the major site for new membrane synthesis in the cell; Proteins to be delivered to the ER lumen are synthesized on the rough ER; Steroid hormones are synthesized on the smooth ER; The ER membrane is contiguous with the outer nuclear membrane.

8. Which of the following statements about nuclear transport is TRUE?

a. mRNAs and proteins transit the nucleus through different types of nuclear pores. b. Nuclear import receptors bind to proteins in the cytosol and bring the proteins to the nuclear pores, where the proteins are released from the receptors into the pores for transit into the nucleus. c. Nuclear pores contain proteins with disordered segments that fill the channel and allow small water-soluble molecules to pass through in a non-selective fashion. d. Nuclear pores are made up of many copies of a single protein.

13. Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called:

active transport.

9. In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins?

in the cytosol

1. Where does most new membrane synthesis take place in a eukaryotic cell?

in the endoplasmic reticulum.

5. The concentration of H+ ions inside the mitochondrial matrix is lower than it is in the cytosol or the mitochondrial intermembrane space. What would be the IMMEDIATE effect of a membrane-permeable compound that carries and releases protons into the mitochondrial matrix?

inhibition of ATP synthesis