Ch 4: A Tour of the Cell

Question 1

Which structure is found in only plant cells, only animal cells, or found in both?

cellulose cell wall
central vacuole
centriole
chloroplast
cytoskeleton
endoplasmic reticulum
Golgi apparatus
mitochondrion
nucleus
plasma membrane

Answer 1

plant cell only - cellulose cell wall, central vacuole, chloroplast

animal cell only - centriole

BOTH - mitochondrion. nucleus, Golgi apparatus, endoplasmic reticulum, plasma membrane, cytoskeleton

Question 2

Where in the cell are lipids synthesized?

Answer 2

smooth ER

Question 3

What are 3 main function of the smooth ER?

Answer 3

lipid synthesis
drug/poison detoxification
calcium ion storage

Question 4

What is the main function of the rough ER?

Answer 4

synthesis of proteins

Question 5

Cisternal maturation and protein modification and sorting are associated with what cellular structure?

Answer 5

the Golgi apparatus

Question 6

What are 2 functions of lysozomes?

Answer 6

macromolecule digestion
autophagy

Question 7

Most proteins that function in the cytosol (such as actin) or in the nucleus (such as DNA polymerase) are synthesized by _____ ribosomes. Proteins that function within the endomembrane system (such as lysosomal enzymes) or those that are destined for secretion from the cell (such as insulin) are synthesized by _____ ribosomes.

Answer 7

free

bound

Question 8

As a protein destined for the endomembrane system is being synthesized by a ribosome, the first amino acids in the growing polypeptide chain act as a signal sequence. That signal sequence ensures that the ribosome binds to the outer membrane of the ER and that the protein enters the ___ _____

Answer 8

ER lumen

Question 9

In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are ____________

Answer 9

microtubules

Question 10

Many cell organelles, most notably the nucleus, are anchored by ____________ which are assembled from a diverse class of proteins.

Answer 10

intermediate filaments

Question 11

Centrosomes are sites where protein dimers assemble into __________

Answer 11

microtubules.

Question 12

The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of ______________

Answer 12

microfilaments

Question 13

The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the ______________

Answer 13

intermediate filaments

Question 14

During muscle contractions, myosin motor proteins move across tracks of _____________

Answer 14

microfilaments

Question 15

The ________electron microscope is especially useful for detailed study of the topography of a specimen. The electron beam scans the surface of the sample, usually coated with a thin film of ____. The beam excites electrons on the surface, and these secondary electrons are detected by a device that translates the pattern of electrons into an electronic signal sent to a video screen. The result is an image of the specimen’s surface that appears three-dimensional.

Answer 15

scanning electron microscope (SEM)

gold

Question 16

The ________electron microscope is used to study the internal structure of cells. The TEM aims an electron beam through a very thin section of the specimen, much as a light microscope aims light through a sample on a slide. For the TEM, the specimen has been stained with atoms of _____ ______, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cell more than others. The electrons passing through the specimen are scattered more in the denser regions, so fewer are transmitted.

Answer 16

transmission electron microscope (TEM)

heavy metals

Question 17

All living cells have…

Answer 17

…a plasma membrane, ribosomes, cytoplasm (with cytosol semifluid), and chromosomes (which carry genes in the form of DNA)

Question 18

Usually, the largest compartment in a plant cell is…

Answer 18

…the central vacuole.

p. 88

Question 19

The nuclear envelope is continuous with the ______ ER, which is also continuous with the ______ ER.

Answer 19

rough

smooth

Question 20

In mitochondria, the inner membrane is convoluted into infoldings called ________.

Answer 20

cristae

Question 21

What is contained within the mitochondrial matrix?

Answer 21

enzymes, mitochondrial DNA, and ribosomes

p. 90

Question 22

Inside a chloroplast is another membranous system in the form of flattened interconnected sacs called __________. In some regions, these are stacked like poker chips. Each stack is called a ______.

Answer 22

thylakoids

granum

p. 91

Question 23

The machinery for translating RNA into proteins lies ________ the nucleus.

The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA) that carries information from the DNA.

The mRNA is then transported to the cytoplasm via the nuclear pores. Once an mRNA molecule reaches the cytoplasm, _________ translate the mRNA’s genetic message into the primary structure of a specific polypeptide.

Answer 23

outside

ribosomes

Question 24

What two structures have their own DNA and can replicate independently of the nucleus?

Answer 24

Mitochondria and chloroplasts

Question 25

Vacuoles do not fuse with other membranes the way that vesicles do.

Question 26

Microtubules are ______ and are made up of ______. This material is a dimer made up of ________ and ________.

Answer 26

hollow

tubulin

α-tubulin, β-tubulin

Question 27

The best analogy for the shape of actin filaments is a…

Answer 27

…string of pearls.

Question 28

Chloroplasts and mitochondria synthesize some of their own ________. Chloroplasts and mitochondria have many features in common. They are not members of the ___________ system. Rather than being bounded by a single membrane like those organelles, they have two membranes surrounding them. (Chloroplasts also have an internal system of membranous sacs.)

Answer 28

proteins

endomembrane system

Question 29

Like prokaryotes, mitochondria and chloroplasts contain ribosomes as well as circular DNA molecules attached to their _____ _________. The DNA in these organelles programs the synthesis of proteins, which are made on the ribosomes inside the organelles. Also consistent with their probable evolutionary origins as cells, mitochondria and chloroplasts are autonomous (somewhat independent) organelles that grow and _________ within the cell.

Answer 29

inner membranes

reproduce

Question 30

Which of the following is/ are possible site(s) of protein synthesis in a typical eukaryotic cell?

a. ) Rough endoplasmic reticulum
b. ) Cytoplasm, rough endoplasmic reticulum, and mitochondria
c. ) Mitochondria
d. ) Cytoplasm and rough endoplasmic reticulum
e. ) Cytoplasm

Answer 30

b.) cytoplasm, rough ER, and mitochondria

Question 31

Which of the following is a more permanent structure than the other two?

intermediate filaments, microfilaments, or microtubules

Answer 31

intermediate filaments

Question 32

_____________ are chains of proteins that resist stretching.

Answer 32

Microfilaments

Question 33

Cilia and flagella move due to the interaction of the cytoskeleton with which of the following?

a. ) actin
b. ) pseudopodia
c. ) motor proteins
d. ) tubulin

Answer 33

c.) motor proteins (like dyneins)

Question 34

Each motile cilium or flagellum has a group of microtubules sheathed in an extension of the plasma membrane. Nine ________ of microtubules are arranged in a ring with two single microtubules in its center. This arrangement, referred to as the “____” pattern, is found in nearly all eukaryotic flagella and motile cilia.

Answer 34

doublets

9 + 2

Remember the 9 are the doublets and the 2 are singles.

Question 35

You would expect a cell with an extensive Golgi apparatus to .

a. ) move rapidly
b. ) store large quantities of ions
c. ) secrete a lot of protein
d. ) absorb nutrients in the GI tract

Answer 35

c.) secrete a lot of protein.

After leaving the ER, many transport vesicles travel to the Golgi apparatus. We can think of the Golgi as a warehouse for receiving, sorting, shipping, and even some manufacturing. Here, products of the ER, such as proteins, are modified and stored and then sent to other destinations. Not surprisingly, the Golgi apparatus is especially extensive in cells specialized for secretion.

Question 36

What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?

Answer 36

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. In the cytoplasm, a large and a small subunit can assemble into a ribosome.

Question 37

Basal bodies are most closely associated with cilia. The microtubule assembly of a cilium or flagellum is anchored in the cell by a basal body, which is structurally very similar to a ________, with microtubule triplets in a “____” pattern. In fact, in many animals (including humans), the basal body of the fertilizing sperm’s flagellum enters the egg and becomes a centriole.

Answer 37

centriole

9 + 0

Question 38

A researcher wants to film the movement of chromosomes during cell division. She should choose a ________ ________ because the specimen is alive.

Answer 38

light microscope

If a researcher wants to film the movement of chromosomes during cell division, then the type of microscope she should choose is the light microscope because the viewed specimen can be alive. A disadvantage of electron microscopy is that the methods used to prepare the specimen kill the cells.

Question 39

Nuclear lamina, keratin are related to intermediate filaments

neurofilaments

desmin - cells that undergo contraction

Premature aging – progeria is r/t intermediate filaments

Question 40

Some cells are attached to the ECM by ECM glycoproteins such as ___________. This glycoprotein and other ECM proteins bind to cell-surface receptor proteins called integrins that are built into the plasma membrane. Integrins span the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton. The name integrin is based on the word integrate: Integrins are in a position to _______ _______ between the ECM and the cytoskeleton and thus to integrate changes occurring outside and inside the cell.

Answer 40

fibronectin

transmit signals

Question 41

Which type of cell junction is most similar to the plasmodesmata of plants?

Answer 41

gap junctions

Gap junctions are necessary for communication between cells in many types of tissues, such as heart muscle, and in animal embryos.

Question 42

Desmosomes (one type of anchoring junction) function like ______, fastening cells together into strong sheets. ___________ filaments made of sturdy keratin proteins anchor desmosomes in the cytoplasm. Desmosomes attach muscle cells to each other in a muscle. Some “muscle tears” involve the rupture of desmosomes.

They hold cells together under mechanical stress.

Answer 42

rivets

Intermediate

Question 43

A disease which affects the extracellular matrix might cause skin hyperextensibility, easy bruising, and fragility. Why is this?

Answer 43

Collagen is a component of the extracellular matrix. Cells cannot resist compression as well, thus the easy bruising/ fragility.