Chapter Seven Mastering Biology Homework

Which organelle is the primary site of ATP synthesis in eukaryotic cells? vacuole mitochondrion lysosome Golgi apparatus peroxisome

mitochondrion

Part complete Which of these organelles manufactures proteins bound for secretion out of the cell? Golgi apparatus rough endoplasmic reticulum lysosomes nucleolus

rough er

Proteins coded for by nuclear DNA but found within mitochondria move from the cytoplasm into mitochondria using _____. attachment of ribosomes to outer mitochondrial pores and direct deposition into the inner mitochondrial compartment random transport vesicles signal sequences (peptides) mRNAs that are manufactured in the nucleus, but translated by mitochondrial ribosomes

signal sequences (peptides)

Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids? ribosome smooth endoplasmic reticulum contractile vacuole lysosome mitochondrion

smooth endoplasmic reticulum

Where is calcium stored? microtubules mitochondria rough endoplasmic reticulum smooth endoplasmic reticulum centrioles

smooth er

Which of these organelles carries out cellular respiration? nucleolus chromatin mitochondrion smooth endoplasmic reticulum ribosomes

mitochondrion

Which of the following results provided evidence of a nuclear localization signal in the nucleoplasmin protein? After cleavage of the protein, only the tail segments appeared in the nucleus. The protein was small and easily slipped through the nuclear pore complex. The SRP bound only to the tail, not the core segment. Removing the tail allowed the core segment to enter the nucleus.

After cleavage of the protein, only the tail segments appeared in the nucleus.

Which of the following statements is true? View Available Hint(s) Larger cells have less surface area than smaller cells. As cells get larger, the surface area increases more than the volume. As cells get larger, the volume increases more than the surface area. Larger cells have less volume than smaller cells.

As cells get larger, the volume increases more than the surface area.

Using concepts from Chapter 3, which statement best explains why proteins—and not RNA, DNA, carbohydrates, or lipids—are the molecules responsible for "reading" the array of molecular zip codes in cells? View Available Hint(s) Because proteins can have diverse structures and chemical properties, different proteins can "read" different zip codes by interacting specifically with them. Because proteins store and process information, they can "read" different zip codes via base pairing. Because proteins can store energy, they provide the energy to transport other proteins with zip codes to their correct destinations. Because protein enzymes can have a diversity of active site structures, they can "read" different zip codes by specifically degrading them.

Because proteins can have diverse structures and chemical properties, different proteins can "read" different zip codes by interacting specifically with them.

What central theme of biology helps explain why various cells can look so different from one another? View Available Hint(s) All cells need to engage in energy transformations. Cells must be small in size. Different cells contain different macromolecules as their genetic material. Cells correlate structure with function.

Cells correlate structure with function.

Which molecules do not normally cross the nuclear membrane? View Available Hint(s) mRNA Proteins DNA Nucleotide triphosphates

DNA

Part complete What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell? Golgi → ER → lysosome ER → Golgi → nucleus nucleus → ER → Golgi ER → Golgi → vesicles that fuse with plasma membrane ER → lysosomes → vesicles that fuse with plasma membrane

ER → Golgi → vesicles that fuse with plasma membrane

Pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. Photographic emulsions are prepared at different times during the chase. Where would the black spots appear on an emulsion prepared 3 hours after the pulse? View Available Hint(s) Golgi apparatus Secretory vesicles Rough ER Exterior of the cell

Exterior of the cell

_____ are surface appendages that allow a bacterium to stick to a surface. Fimbriae Mitochondria Ribosomes Cell walls Flagella

Fimbriae

What is the first step in a pulse-chase experiment? View Available Hint(s) Preparing cells for electron microscopy Examining cells for the location of the labeled molecules Incubating cells with an unlabeled molecule Incubating cells with a labeled molecule

Incubating cells with a labeled molecule

Which answer most accurately summarizes the (1) structural and (2) functional properties of actin filaments, intermediate filaments, or microtubules? View Available Hint(s) Microtubules: (1) two subunit types; (2) one cellular role Intermediate filaments: (1) many subunit types; (2) diverse cellular roles Intermediate filaments: (1) many subunit types; (2) one cellular role Actin filaments: (1) one subunit type; (2) one cellular role

Intermediate filaments: (1) many subunit types; (2) one cellular role

What can you infer about a high molecular weight protein that cannot be transported into the nucleus? It lacks a nuclear localization signal (NLS). It is too large. It contains errors in its amino acid sequence It lacks a signal sequence.

It lacks a nuclear localization signal (NLS).

What path does a protein in the secretory pathway take, starting from its site of synthesis? View Available Hint(s) Rough ER, Golgi apparatus, secretory vesicles, plasma membrane Plasma membrane, secretory vesicles, Golgi apparatus, rough ER Golgi apparatus, rough ER, secretory vesicles, plasma membrane Rough ER, secretory vesicles, Golgi apparatus, plasma membrane

Rough ER, Golgi apparatus, secretory vesicles, plasma membrane

Which of the following statements about the nuclear envelope is false? View Available Hint(s) The nuclear envelope is continuous with the Golgi apparatus. The nuclear envelope is composed of two lipid bilayers. Molecules pass into and out of the nucleus through nuclear pores. Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex.

The nuclear envelope is continuous with the Golgi apparatus.

Which statement most accurately describes what happens to proteins that lack an ER signal sequence? View Available Hint(s) They are inserted into the plasma membrane. They are inserted into the ER membrane but do not enter the ER lumen. They are released into the cytosol. They bypass the ER but enter the Golgi apparatus.

They are released into the cytosol.

How are these signals read? They are glycosylated by enzymes in the Golgi apparatus. They bind to motor proteins. They bind to receptor proteins. They enter transport vesicles.

They bind to receptor proteins.

What three distinct elements make up the cytoskeleton in eukaryotic cells? View Available Hint(s) actin filaments, intermediate filaments, and microtubules flagella, cilia, and centrosomes microfilaments, intermediate filaments, macrofilaments carbohydrates, lipids, and nucleic acids

actin filaments, intermediate filaments, and microtubules

_____ is/are identical in structure to centrioles. Chromatin Microfilaments Mitochondria Basal bodies Nuclear envelopes

basal bodies

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell? capsule pili cell wall flagella nucleoid region

cell wall

Which of the following cell structures is only found in algal and plant cells? View Available Hint(s) Golgi apparatus chloroplasts a cytoskeleton cell walls

chloroplasts

The _____ is composed of DNA and protein. ribosome flagellum mitochondrion chromatin centriole

chromatin

Which features are common to all cells? Check all that apply. All cells have cytoskeleton lysosomes the plasma membrane vacuoles mitochondria the nucleus the cell wall photosynthetic membranes genetic information (DNA) in chromosomes flagella and fimbriae the cytoplasm the endoplasmic reticulum chloroplasts ribosomes

cytoskeleton plasma membrane genetic information (DNA) in chromosomes cytoplasm ribosomes

Lysosomes that lack mannose-6-phosphate receptors _____. have unstable membranes stick to transport vesicles and impede the transfer of enzymes receive "modified" enzymes and are thus unable to break down carbohydrates do not receive enzyme shipments from the Golgi apparatus

do not receive enzyme shipments from the Golgi apparatus

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy. View Available Hint(s) True False

f

True or false? Proteins produced during the "chase" phase of a pulse-chase experiment are labeled with radioactive material. View Available Hint(s) True False

false

Molecules move into and out of the nucleus through the _____. View Available Hint(s) chromatin nucleoid nucleolus nuclear pores

nuclear pores

Where is a bacterial cell's DNA found? ribosomes nucleus peroxisome nucleoid region capsule

nucleoid region

Ribosomal subunits are manufactured by the _____. rough endoplasmic reticulum lysosome peroxisome nucleolus smooth endoplasmic reticulum

nucleolus

A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place? View Available Hint(s) Active transport Osmosis Passive transport Submit

passive transport

Which of these organelles produces H2O2 as a by-product? nucleus centrioles flagellum mitochondrion peroxisome

peroxisome

The _____ is a selective barrier, regulating the passage of material into and out of the cell. chloroplast nuclear envelope lysosome plasma membrane nucleus

plasma membrane

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell. plasma membrane nucleoid region ribosome pili cell wall

plasma membrane

All of the following are part of a prokaryotic cell EXCEPT _____. DNA a plasma membrane an endoplasmic reticulum ribosomes a cell wall

the endoplasmic reticulum

What is the function of the nuclear pore complex found in eukaryotes? It assembles ribosomes from raw materials that are synthesized in the nucleus. It synthesizes the proteins required to copy DNA and make mRNA. It regulates the movement of proteins and RNAs into and out of the nucleus. It selectively transports molecules out of the nucleus, but prevents all inbound molecules from entering the nucleus.

It regulates the movement of proteins and RNAs into and out of the nucleus.

Which motor protein(s) can move cargo-containing vesicles along microtubule tracks? View Available Hint(s) Myosin and dynein Kinesin only Kinesin and myosin Kinesin and dynein Submit

Kinesin and dynein

What scientific hypotheses can be tested by a pulse-chase experiment? View Available Hint(s) The steady-state amount of protein in a cell Solubility of a molecule The amino acid sequence of a protein Movement of molecules through a cell over time

Movement of molecules through a cell over time

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results? View Available Hint(s) The cytoplasmic protein contains a nuclear localization signal. Only one of the two fusion proteins possesses a nuclear localization signal. One of the fusion proteins entered the nucleus by passive transport. Nucleoplasmin does not have a nuclear localization signal.

Only one of the two fusion proteins possesses a nuclear localization signal.q

Scientists have found that polypeptides that are normally synthesized in the endoplasmic reticulum are about 20 amino acids longer when they are synthesized by ribosomes not attached to the endoplasmic reticulum. What is a possible explanation for the greater length of these polypeptides? The 20-amino-acid sequence helps the endoplasmic reticulum package these proteins for shipping to the Golgi. Ribosomes attached to the endoplasmic reticulum require fewer amino acids to function. The protein has a different function in the cytosol than in the endoplasmic reticulum. The 20 amino acids serve as a signal (peptide) sequence that directs the forming polypeptides to the endoplasmic reticulum, where they are cleaved off during processing.

The 20 amino acids serve as a signal (peptide) sequence that directs the forming polypeptides to the endoplasmic reticulum, where they are cleaved off during processing.

For prokaryotic cells, which statement is correct concerning how the structure of a particular cell component correlates with its function? View Available Hint(s) The cell wall is a tough, fibrous layer that protects the cell and gives it shape and rigidity. The cell wall represents infoldings of the plasma membrane that protect the cell and give it shape and rigidity. Photosynthetic membranes are composed of crosslinked polymers like peptidoglycan that provide extensive surface area for photosynthesis. Photosynthetic membranes contain magnetite that allows the cell to convert magnetic field energy into chemical energy.

The cell wall is a tough, fibrous layer that protects the cell and gives it shape and rigidity.

During a pulse-chase experiment, photographic emulsions were prepared at different times during the chase, and radioactive spots were detected at the following times and locations: 5 minutes: rough ER; 10 minutes: Golgi apparatus; 40 minutes: endosomes; 70 minutes: lysosomes; 140 minutes: lysosomes. Which of the following conclusions can be drawn from these results? View Available Hint(s) The final destination of the proteins was the lysosome. The proteins traveled from lysosomes to endosomes. The proteins were secreted. The proteins did not travel through the Golgi apparatus

The final destination of the proteins was the lysosome.

Which statements are true for chloroplasts? Select the three that apply. View Available Hint(s) Their inner membrane has infoldings called cristae. They are the sites of reactions that convert chemical energy from food molecules to ATP. Their matrix contains enzymes that function in cellular respiration. They are the sites of reactions that convert solar energy into chemical energy. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. They contain the green pigment chlorophyll.

They are the sites of reactions that convert solar energy into chemical energy. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. They contain the green pigment chlorophyll.

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules? View Available Hint(s) To make the proteins bigger To give the protein molecules energy To make the proteins easy to see To target the proteins to the nucleus

To make the proteins easy to see

The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you most likely expect to be the immediate consequence? the inability of the nucleus to divide during cell division a change in the shape fo the nucleus failure of chromosomes to carry genetic information inability of the ribosomes to produce proteins the loss of all nuclear function

a change in the shape of the nucleus

All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes? Select all that apply. View Available Hint(s) insulin ER protein lysosomal enzyme actin ribosomal protein DNA polymerase

insulin ER protein lysosomal enzyme

Which of the following contains hydrolytic enzymes? peroxisome vacuole Golgi apparatus mitochondrion lysosome

lysosome

Which of these are hollow rods that shape and support the cell? microfilaments plasma membrane peroxisomes microtubules chloroplasts

microtubues

) Movement of vesicles within the cell depends on what cellular structures? actin filaments and microtubules centrioles and motor proteins actin filaments and motor proteins microtubules and motor proteins actin filaments and ribosomes

microtubules and motor proteins

Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane? amino acids DNA phospholipids mRNA

mrna

What is the function of a bacterium's capsule? propulsion protein synthesis adhesion DNA storage protection

protection

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules? proteins nucleic acids cellulose lipids glycogen

proteins

Which of the following is present in a prokaryotic cell? Endoplasmic Reticulum ribosome nuclear envelope mitochondrion chloroplast

ribosome

In a bacterium, where are proteins synthesized? ribosomes nucleus peroxisome nucleoid region capsule

ribosomes

_____ are the sites of protein synthesis. Peroxisomes Microfilaments Ribosomes Mitochondria Golgi apparatuses

ribosomes

Which structure is the site of the synthesis of proteins that may be exported from the cell? free cytplasmic ribosomes golgi vesicles plasmodesmata lysosomes rough ER

rough ER