Mastering Biology - Cell Structure

microtubules

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

Passive transport

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?

transferring of information from DNA to messenger RNA

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

microtubules

Centrosomes are sites where protein dimers assemble into _______.

The cell cytoskeleton is a dynamic network of fibres that can be quickly dismantled and reassembled to change cell shape and the position of cell components.

Choose the best description of the cell cytoskeleton. -The cell cytoskeleton is a dynamic network of fibres that can be quickly dismantled and reassembled to change cell shape and the position of cell components. -Cytoskeleton is made of actin and tubulin, and they are organized similarly to muscle cells. -The cell cytoskeleton serves as permanent scaffolding to anchor cell components into position within the cell cytoplasm. -The cell cytoskeleton is similar to an animal skeleton in providing rigid internal support and structure to the cell.

microfilaments

During muscle contractions, myosin motor proteins move across tracks of _______.

The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes.

Identify the correct statement about differences between rough and smooth endoplasmic reticulum (ER). -The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes. -Smooth ER is responsible for protein modifications, whereas rough ER has many metabolic functions such as lipid synthesis. -Rough ER consists of a network of membranous tubules and sacs called cisternae, whereas smooth ER is less complex. -Smooth ER is part of the endomembrane system of the eukaryotic cell, and rough ER is not.

Ribsomes

In a bacterium, where are proteins synthesized?

To make the proteins easy to see

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?

intermediate filaments

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

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

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

Nucleolus

Ribosomal subunits are manufactured by the _____.

Plant and animal cells both carry out cellular respiration, producing ATP.

Select the correct statement describing cellular structure or function. -Plants might have few mitochondria but they do not rely on mitochondria for ATP production. -Only plant cells contain chloroplasts, and only animal cells contain mitochondria. -Plant and animal cells both carry out cellular respiration, producing ATP. -Mitochondria and chloroplasts are part of the endomembrane system of the eukaryotic cell.

Plasma membrane

The _____ is a selective barrier, regulating the passage of material into and out of the cell.

Chromatin

The _____ is composed of DNA and protein.

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.

Microtubules

The cilia and flagella of eukaryotic cells are composed of _____.

1000:1

The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote. What is the ratio of the volume of typical eukaryotic:prokaryotic cells?

microfilaments

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

intermediate filaments

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

desmosomes

The primary role of _____ is to bind animal cells together.

False

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.

Protection

What is the function of a bacterium's capsule?

Cell wall

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

Nucleoid region

Where is a bacterial cell's DNA found?

Smooth ER

Where is calcium stored?

DNA

Which molecules do not normally cross the nuclear membrane?

Microtubules

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

Products of the ER are usually modified during their transit from the cis to the trans region of the Golgi apparatus.

Which statement correctly describes an endomembrane function? -Products of the ER are usually modified during their transit from the cis to the trans region of the Golgi apparatus. -Secretory proteins in transit from one part of the cell to another are carried in lysosomes. -All proteins processed within the endomembrane system are destined for exocytosis. -The lumen of the endoplasmic reticulum (ER) is continuous with the cell nucleus.

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

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

gap (communicating) junctions

_____ aid in the coordination of the activities of adjacent animal cells.

Fimbrae

_____ are surface appendages that allow a bacterium to stick to a surface.

Ribosomea

_____ are the sites of protein synthesis.

Basal bodies

_____ is/are identical in structure to centrioles.

The nuclear envelope is continuous with the Golgi apparatus.

Which of the following statements about the nuclear envelope is false? -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. -The nuclear envelope is composed of two lipid bilayers.

tight junctions

Which of these cell junctions form a barrier to the passage of materials? -plasmodesmata -gap (communicating) junctions -keratin fibers -tight junctions -desmosomes (anchoring junctions)

Rough endoplasmic reticulum

Which of these manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane? -lysosomes -rough endoplasmic reticulum -nucleolus -Golgi apparatus -ribosomes

Mitochondria

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

Peroxisome

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

Lysosome

Which organelle plays a role in intracellular digestion?