a tour of a cell - dynamic study module

The extracellular matrix of the animal cell has all of the following molecular components except __________.

a middle lamella

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

secrete a lot of protein

Which statement about the cytoskeleton is true?

Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm.

In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?

Eukaryotic cells are compartmentalized, which allows for specialization.

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

Motor proteins

__________ are membrane-bound metabolic compartments that specialize in the production of hydrogen peroxide (H2O2) and its conversion to water.

Peroxisomes

Which of the following is present in a prokaryotic cell? correct Unselected Mitochondrion Unselected ER Unselected Nuclear envelope Correct answer YOU WERE SURE AND CORRECT Ribosomes Unselected Chloroplast Unselected I DON'T KNOW YET

Ribosomes

Which of the following groups is primarily involved in synthesizing molecules needed by the cell?

Ribosomes, rough endoplasmic reticulum, and smooth endoplasmic reticulum

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

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores

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

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. The functional connection between the nucleolus, nuclear pores, and the nuclear membrane is that subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. The nuclear envelope (or nuclear membrane) encloses the nucleus, separating its contents from the cytoplasm. The nuclear envelope is a double membrane. The two membranes, each a lipid bilayer with associated proteins. A prominent structure within the nondividing nucleus is the nucleolus (plural, nucleoli). Here a type of RNA called ribosomal RNA (rRNA) is synthesized from instructions in the DNA. Also in the nucleolus, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes. These subunits then exit the nucleus through the nuclear pores to the cytoplasm, where a large and a small subunit can assemble into a ribosome. At the lip of each pore, the inner and outer membranes of the nuclear envelope are continuous. An intricate protein structure called a pore complex lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNAs, as well as large complexes of macromolecules.

Animal cells have unique organelles called __________ that are composed of structures called __________.

centrosomes; centrioles

Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell they __________.

have no membrane-bounded organelles in their cytoplasm

Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except that mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes.

here is evidence that the ancestral engulfed prokaryotes had two outer membranes, which became the double membranes of mitochondria and chloroplasts. Second, like prokaryotes, mitochondria and chloroplasts contain ribosomes as well as multiple circular DNA molecules associated with their inner membranes. The DNA in these organelles programs the synthesis of some organelle proteins on ribosomes that have been synthesized and assembled there as well. Third, also consistent with their probable evolutionary origins as cells, mitochondria and chloroplasts are autonomous (somewhat independent) organelles that grow and reproduce within the cell.

The network of fibers that organizes structures and activities in a cell __________.

is the cytoskeleton

The endosymbiont theory explains the origins of __________.

mitochondria and chloroplasts

The region of a bacterial cell that contains the genetic material is called the __________.

nucleoid "Nucleus" is incorrect because this is the eukaryotic organelle that contains the genetic material in the form of chromosomes, made up of chromatin. "Nucleolus" is incorrect because this is a structure in the nucleus of a eukaryotic cell that consists of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm for ribosomal subunit assembly. "Nucleosome" is incorrect because this is the basic bead-like unit of DNA packing in eukaryotes. "Capsule" is incorrect because in prokaryotes, this is a dense and well-defined layer of polysaccharide or protein that surrounds the cell and enables it to adhere to substrates or other cells.

Cells are small because __________.

of the geometric relationships between surface and volume

A substance moving from outside the cell into the cytoplasm must pass through __________.

the plasma membrane

Which of the following is false in respect to cells' chromosomes?

Chromosomes are only visible as a cell is about to divide. In all cells, DNA is organized into discrete units called chromosomes, structures that carry the genetic information. Each chromosome contains one long DNA molecule associated with many proteins. The complex of DNA and proteins making up chromosomes is called chromatin. When a cell is not dividing, stained chromatin appears as a diffuse mass in micrographs, and the chromosomes cannot be distinguished from one another, even though discrete chromosomes are present. As a cell prepares to divide, however, the chromosomes coil (condense) further, becoming thick enough to be distinguished as separate structures.

Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why?

The intestinal cells are bound together by tight junctions. At tight junctions, the plasma membranes of neighboring cells are very tightly pressed against each other, bound together by specific proteins. Forming continuous seals around the cells, tight junctions prevent leakage of extracellular fluid across a layer of epithelial cells. For example, tight junctions between skin cells make us watertight by preventing leakage between cells in our sweat glands.

Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________.

human skin cell "Prokaryotic cell" is incorrect because intermediate filaments are found only in the cells of some animals, including vertebrates. "Eukaryotic cell" is incorrect because unlike microtubules and microfilaments, which are found in all eukaryotic cells, intermediate filaments are found only in the cells of some animals, including vertebrates. "Plant cell" and "fungal cell" are incorrect because intermediate filaments are found only in the cells of some animals, including vertebrates.

A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.

in the rough endoplasmic reticulum

The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.

in the rough endoplasmic reticulum and in the Golgi apparatus

The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.

in the rough endoplasmic reticulum and in the Golgi apparatus As a polypeptide chain grows from a bound ribosome, the chain is threaded into the ER lumen through a pore formed by a protein complex in the ER membrane. As the new polypeptide enters the ER lumen, it folds into its native shape. Most secretory proteins are glycoproteins, proteins that have carbohydrates covalently bonded to them. The carbohydrates are attached to the proteins in the ER by enzymes built into the ER membrane. Products of the endoplasmic reticulum are usually modified during their transit from the cis region to the trans region of the Golgi apparatus. For example, glycoproteins formed in the ER have their carbohydrates modified, first in the ER itself, then as they pass through the Golgi. The Golgi removes some sugar monomers and substitutes others, producing a large variety of carbohydrates. Membrane phospholipids may also be altered in the Golgi.

Microfilaments function in cell motility including __________.

muscle contraction, amoeboid movement, and cytoplasmic streaming in plants NOT cilia or flagella or centriole function

The endoplasmic reticulum is part of the endomembrane system, which also includes the __________.

nuclear envelope, the Golgi apparatus, lysosomes, and vesicles

Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________.

plasmodesmata; gap junctions

Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except __________.

that mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes

The function of the rough endoplasmic reticulum (RER) is __________.

to synthesize proteins that are secreted as glycoproteins

Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________.

with motor proteins