Campbell Mastering Biology: The Cell

Which of these structures stores, modifies, and packages products?

A (The Golgi apparatus modifies, stores, and packages products of the ER.)

Choose the letter that indicates the organelle that contains most of a cell's DNA.

C (The nucleus contains most of a cell's DNA.)

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.

C (The plasma membrane is selectively permeable.)

Which molecules do not normally cross the nuclear membrane? A) mRNA B) Proteins C) DNA D) Nucleotide triphosphates

C) DNA (All processes involving DNA take place in the nucleus.)

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? A) The cytoplasmic protein contains a nuclear localization signal. B) One of the fusion proteins entered the nucleus by passive transport. C) Only one of the two fusion proteins possesses a nuclear localization signal. D) Nucleoplasmin does not have a nuclear localization signal.

C) Only one of the two fusion proteins possesses a nuclear localization signal. (The nuclear localization signal is only present in the fusion protein that enters the nucleus.)

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

C) The nuclear envelope is continuous with the Golgi apparatus (This statement is false; the nuclear envelope is continuous with the endoplasmic reticulum.)

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules? A) To make the proteins bigger B) To give the protein molecules energy C) To make the proteins easy to see D) To target the proteins to the nucleus

C) To make the proteins easy to see (Fluorescent tags make the location of the proteins easy to visualize.)

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

C) cell wall (The cell wall is a rigid supporting structure.)

Ribosomal subunits are manufactured by the _____. A) smooth endoplasmic reticulum B) peroxisome C) nucleolus D) lysosome E) rough endoplasmic reticulum

C) nucleolous (Ribosomes are manufactured by the nucleolus.)

To understand how cells function as the fundamental unit of life, you must first become familiar with the individual roles of the cellular structures and organelles. Drag the labels on the left onto the diagram of the animal cell to correctly identify the function performed by each cellular structure.

a: synthesizes lipids b: assembles ribosomes c: defines cell shape d: produces secretory proteins e: modifies and sorts proteins f: digests proteins g: generates ATP

The primary role of _____ is to bind animal cells together. A) the cytoskeleton B) desmosomes C) tight junctions D) plasmodesmata E) gap (communicating) junctions

B) desmosomes (The primary role of desmosomes (anchoring junctions) is to bind cells together.)

Which of these cell junctions form a barrier to the passage of materials? A) desmosomes (anchoring junctions) B) keratin fibers C) tight junctions D) gap (communicating) junctions E) plasmodesmata

C) tight junctions (Tight junctions form a barrier that prevents fluids from moving between cells.)

Where is a bacterial cell's DNA found? A) ribosomes B) nucleus C) peroxisome D) nucleoid region E) capsule

D) nucleoid region (Bacteria lack a nucleus; their DNA is found in the nucleoid region.)

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____. A) translation of a DNA nucleotide sequence into a sequence of amino acids B) linking of nucleotides to form a polypeptide C) removal of introns from RNA and the stitching together of exons D) transferring of information from DNA to messenger RNA E) translation of an RNA nucleotide sequence into a sequence of amino acids

D) transferring of information from DNA to messenger RNA (Transcription is the first of the two main steps of protein synthesis.)

Which of these provides the cell with structural support?

D (Microfilaments are a component of the cytoskeleton.)

The DNA-containing region of this bacterial cell is indicated by the letter _____.

D (The nucleoid region contains DNA.)

_____ aid in the coordination of the activities of adjacent animal cells. A) Keratin fibers B) Desmosomes C) Tight junctions D) Plasmodesmata E) Gap (communicating) junctions

D) Gap (communicating) junctions (Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.)

_____ are the sites of protein synthesis. A) Microfilaments B) Peroxisomes C) Golgi apparatuses D) Ribosomes E) Mitochondria

D) Ribosomes (Ribosomes are the site of protein synthesis.)

The _____ is composed of DNA and protein. A) centriole B) flagellum C) ribosome D) chromatin E) mitochondrion

D) chromatin (Chromatin is composed of DNA and protein.)

The cellular organization and extracellular environments of plants and animals are very different. Drag the labels to their appropriate locations in the table below. Use only pink labels for the pink targets. Labels may be used more than once. 1) Membrane protein complexes that strengthen the adhesion between adjacent cells, like rivets, to protect against pulling forces. 2) Small channels that form across the plasma membranes of adjacent cells; especially important in intercellular communication. 3) Membrane proteins that create a watertight seal between cells. 4) Small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells. 5) A polysaccharide that is used to synthesize cell walls, which protect cells and help maintain their shape. 6) Long fibers of protein found in the extracellular matrix that provide structural support for cells.

1) desmosomes / animal 2) gap junctions / animal 3) tight junctions / animal 4) plasmodesmata / plant 5) cellulose / plant 6) collagen / animal (A primary distinction between plant cells and animal cells is the fact that plant cells are surrounded by cell walls. If it were not for plasmodesmata, the cell walls would essentially imprison the plant's cells, making intercellular communication and the distribution of nutrients nearly impossible. Animal cells have a variety of intercellular junctions, including tight junctions, desmosomes, and gap junctions. The gap junctions of animal cells are most similar to the plasmodesmata of plants. Gap junctions tend to be limited to tissues that require rapid and coordinated signal relay systems, such as heart muscle; they play no role in nutrient distribution.)

The cytoskeleton of a eukaryotic cell plays a major role in organizing the structures and activities of the cell. The cytoskeleton consists of three main types of fibers: microfilaments, intermediate filaments, and microtubules. The three types of fiber differ in size, composition, and the functions they perform in the cell. 1) In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are ___. 2) Many cell organelles, most notably the nucleus, are anchored by ___ which are assembled from a diverse class of proteins. 3) Centrosomes are sites where protein dimers assemble into ___. 4) The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of ___. 5) The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the ___. 6) During muscle contractions, myosin motor proteins move across tracks of ___.

1) microtubules 2) intermediate filaments 3) microtubules 4) microfilaments 5) intermediate filaments 6) microfilaments

Which of these organelles produces H2O2 as a by-product? A) peroxisome B) centrioles C) flagellum D) nucleus E) mitochondrion

A) peroxisomes (Peroxisomes produce hydrogen peroxide as a by-product of their metabolic processes.)

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

A) plasma membrane (The plasma membrane is selectively permeable.)

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

A) plasma membrane (The plasma membrane regulates the passage of material into and out of the cell.)

In a bacterium, where are proteins synthesized? A) ribosomes B) nucleus C) peroxisome D) nucleoid region E) capsule

A) ribosomes (Ribosomes are involved in the manufacture of polypeptides (proteins).)

Which of these organelles carries out cellular respiration? A) smooth endoplasmic reticulum B) mitochondrion C) ribosomes D) nucleolus E) chromatin

B) mitochondrion (Mitochondria convert the chemical energy of organic molecules to chemical energy in the form of ATP.)

Which of these manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane? A) ribosomes B) rough endoplasmic reticulum C) lysosomes D) Golgi apparatus E) nucleolus

B) rough endoplasmic reticulum (As membrane proteins grow from ribosomes on rough ER, the proteins are embedded into the rough ER membrane.)

_____ is/are identical in structure to centrioles. A) Chromatin B) Basal bodies C) Mitochondria D) Microfilaments E) Nuclear envelopes

B) Basal bodies

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. A) True B) False

B) False (Cytoplasmic proteins called importins bind to large proteins containing an NLS and mediate their transport across the nuclear membrane through an active transport (energy-requiring) process.)

_____ are surface appendages that allow a bacterium to stick to a surface. A) Ribosomes B) Fimbriae C) Cell walls D) Flagella E) Mitochondria

B) Fimbriae (Fimbriae enable bacterial cells to stick to a surface.)

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? A) Active transport B) Passive transport C) Osmosis

B) Passive transport (A 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.)

The cilia and flagella of eukaryotic cells are composed of _____. A) microfilaments B) microtubules C) intermediate filaments D) pili E) tonofilaments

B) microtubules (Eukaryotic cilia and flagella are composed of microtubules.)

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

D) They are the sites of reactions that convert solar energy into chemical energy. E) They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. F) They contain the green pigment chlorophyll. (The chloroplast and the chemical reactions associated with it are extremely important for all living things. The photosynthetic reactions are responsible for converting solar energy into chemical energy that is used not only by the cells in which photosynthesis occurs but also by other organisms. For example, all of the foods you eat can be traced back to a plant or other photosynthetic organism. Furthermore, the chloroplast and its reactions have had a profound influence on the constitution of Earth's atmosphere due to the fact that oxygen is a byproduct of photosynthesis.)

Which of these are hollow rods that shape and support the cell? A) plasma membrane B) peroxisomes C) chloroplasts D) microtubules E) microfilaments

D) microtubules

Which of these is the double membrane that encloses the nucleus?

E (This is the nuclear envelope.)

What is the function of a bacterium's capsule? A) propulsion B) adhesion C) DNA storage D) protein synthesis E) protection

E) protection (A bacterium's capsule has a protective role.)

Where is calcium stored? A) centrioles B) rough endoplasmic reticulum C) mitochondria D) microtubules E) smooth endoplasmic reticulum

E) smooth endoplasmic reticulum (In addition to storing calcium, the smooth ER also plays a role in detoxification and lipid synthesis.)

Plant cells and animal cells share many of the same structures, but each type of cell also has unique structures. In this activity, you will indicate which cell structures are found only in plant cells, only in animal cells, or in both plant and animal cells. Drag each cell structure to the appropriate bin. If a structure is found in both plant cells and animal cells, drag it to the "both" bin.

plant cell only: -cellulose cell wall -central vacuole -chloroplast animal cell only: -centriole both: -mitochondrion -endoplasmic reticulum -Golgi apparatus -plasma membrane -nucleus -cytoskeleton

Drag the correct description under each cell structure to identify the role it plays in the plant cell.

plant cell wall: strong, protective structure made from cellulose fibrils central vacuole: regulates cytoplasm composition, creates internal pressure, and stores cell compounds chloroplast: makes sugar by converting light energy into chemical energy mitochondrion: produces chemical energy (ATP) that can power the cell Golgi apparatus: modifies and packages proteins

Two fundamental types of cells are known to exist in nature: prokaryotic cells and eukaryotic cells (like the one shown in the Tour of an Animal Cell animation). Both prokaryotic and eukaryotic cells carry out all of the processes necessary for life, but they differ in some important ways. In this activity, you will identify which cell structures are found only in prokaryotic cells, only in eukaryotic cells, or in both types of cells. Drag each cell structure to the appropriate bin.

prokaryotic only: -nucleoid eukaryotic only: -nucleolous -lysosome -mitochondria both: -plasma membrane -ribosomes -flagella