A & P HW

Select the TRUE statement. Dense connective tissue includes adipose tissue. Dense connective tissue is often called fibrous connective tissue Bundles of collagen are often found in loose connective tissue. Loose connective tissue includes cartilage.

*Dense connective tissue is often called fibrous connective tissue

The region of molecule B that encodes a polypeptide is 24 nucleotides in length. Consider another such molecule with a coding region of 300 nucleotides. What is a reasonable estimate for the length of the corresponding polypeptide that will be produced during protein synthesis?

100 amino acids Each amino acid corresponds to a codon of 3 nucleotides. Therefore, a coding region of 300 nucleotides contains 100 codons and will produce a polypeptide of 100 amino acids in length.

Which of the numbered cell types is primarily responsible for producing protein fibers found in connective tissue proper?

2 Cell 2 is a fibroblast, which is the primary producer of the major ECM components in connective tissue proper.

Which numbered cell type initiates inflammatory responses to infection or tissue damage?

5 Cell 5 is a mast cell, which produces and secretes inflammation-triggering chemicals such as histamine. Note the secretory granules within the pictured cell.

By which mechanism would a steroid molecule diffuse into the cell?

A Steroid molecules are nonpolar fat-soluble molecules, which would be expected to diffuse directly across the phospholipid bilayer. Such solutes do not require a membrane protein to facilitate transport.

Which set of membrane proteins in this figure depicts the transport of the solute molecules?

A - panel A shows both a passive and active transport processes mediated by integral membrane proteins.

What molecular structure is shown in D, but not in A, B, or C?

A carbohydrate molecular group. Panel D includes a membrane glycoprotein molecule. The carbohydrate components of this molecule are recognized by receptors present in the membranes of other cells.

Which of the following events occurs during transcription?

A molecule of RNA is formed based on the sequence of nucleotides in DNA. During transcription, RNA nucleotides line up with their complementary DNA partners, transcribing the information in DNA into RNA.

What is the difference between active and passive transport across the plasma membrane?

Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane. In active transport, the cell provides the metabolic energy (ATP) needed to move substances across the plasma membrane (against their concentration gradient). In passive transport, substances cross the plasma membrane (down their concentration gradient) using kinetic energy, without any energy input from the cell.

Which of the following statements is NOT characteristic of the areolar connective tissue pictured in the figure?

Areolar connective tissue is avascular. Most connective tissues (except cartilage) contain blood vessels. A capillary is observed in the figure of areolar connective tissue.

Which letter is pointing to an mRNA molecule?

B Molecule B is a complement of the DNA template (A) and contains ribonucleotides, as indicated by the presence of uracil (U). This is consistent with molecule B being an mRNA molecule.

What do the glands shown in A and B both have in common?

Both are exocrine glands. Both glands secrete substances onto body surfaces or into body cavities.

Which layer is composed primarily of dense irregular connective tissue?

C Layer C consists primarily of dense, interwoven fibers of collagen designed to resist tearing from any direction.

Which of the following names the three main parts of a human cell?

Cytoplasm, plasma membrane and nucleus

Which one of the following does not play a role in translation?

DNA DNA contains the instructions for making proteins, but these instructions are transcribed to RNA before translation occurs.

The small circular structure indicated by the letter C represents a ______

DNA molecule The mitochondria each have a small circular DNA chromosome that contains genes for several mitochondrial proteins. These proteins are translated within the mitochondria (on the ribosomes indicated by the small red dots). Most of the DNA in a cell is found in the nuclear chromosomes. Several muscular and nervous system diseases are associated with defects in mitochondrial DNA.

During DNA replication, the covalent bonding of nucleotides into a new strand of DNA is performed by ________.

DNA polymerase DNA polymerase is the enzyme that positions complementary nucleotides along the template strand and then covalently links them together into a new strand of DNA.

Which of the following statements is TRUE?

During exocytosis, substances from inside the cell are moved outside. Vesicular transport processes that eject substances from the cell interior into the extracellular fluid are called exocytosis. Exocytosis is a form of active transport, thus it requires energy, usually in the form of ATP.

Which of the following is a property of epithelial tissue?

Epithelial tissue is innervated. Epithelial tissue is an innervated, avascular tissue that exhibits polarity. Epithelial tissue is also highly regenerative.

Choose the correct pairing for a tissue and its embryonic origin.

Epithelium is derived from all three primary germ layers: ectoderm, mesoderm, and endoderm. Mesoderm forms muscle and connective tissue. Ectoderm forms nervous tissue. Endoderm, mesoderm, and ectoderm all contribute to formation of epithelia.

Pseudostratified epithelium consists of multiple cell layers.

False While pseudostratified epithelium has the illusion of being a multi-layered tissue, it is in fact made up of only one cell layer. The irregular heights of the cells in pseudostratified epithelia give the tissue a layered appearance. In reality, all of the cells in this tissue rest on the basement membrane (i.e., their basal surfaces are in contact with the basement membrane).

Which of the following would Not diffuse through the plasma membrane by means of simple diffusion?

Glucose Glucose, a small polar solute, uses a membrane transporter (a protein carrier) to cross the plasma membrane via facilitated diffusion. In simple diffusion, small nonpolar and lipid-soluble substances (including gases) diffuse directly through the lipid bilayer.

Why are protein carriers required for the movement of glucose into or out of the cell?

Glucose is a hydrophilic molecule. Glucose and other monosaccharides are polar hydrophilic molecules that are not able to traverse the hydrophobic region of the phospholipid bilayer.

Which of the following describes a holocrine gland?

Holocrine glands secrete their products by rupturing. Holocrine glands secrete their products by rupturing. Sebaceous (oil) glands are the only example of holocrine glands in the body.

Which of the following is a difference between primary and secondary active transport?

In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated. In primary active transport, energy comes directly from the hydrolysis of ATP and the subsequent phosphorylation of the primary active transporter. In secondary active transport, the solute (usually Na+) concentration gradient produced by primary active transport provides the (kinetic) energy to move other solutes, such as ions and glucose, against their concentration gradients. For example, glucose can be transported against its concentration gradient through a Na+-glucose symporter as Na+ moves down its concentration gradient (a gradient produced by the Na+-K+ pump).

Which of the following statements correctly describes the plasma membrane? The fluid mosaic model of membrane structure depicts the plasma membrane as an exceedingly thin structure composed of a double layer, or bilayer of lipid molecules with protein molecules "plugged into" or dispersed in it. The proteins, many of which float in the fluid ipid bilayer, form a constantly changing mosaic pattern. The model, a dynamic fluid structure that is in constant flux, is named for this characteristic.

It is a dynamic fluid structure that is in constant flux.

What must happen before a body cell can begin mitotic cell division?

Its DNA must be replicated exactly so that identical copies of the cell's genes can be passed on to each of its offspring. Before a body cell begins mitosis, it must replicate its DNA so that each daughter cell will have the same DNA as the parent cell.

Which of the following describes tight junctions? In tight junction, a series of integral protein molecules (including occluding and claudins) in the plasma membranes of adjacent cells fuse together, forming an impermeable junction that encircles the cell. Tight juctions help prevent molecules from passing through the extracellular space between adjacent cells. For example, tight junctions between epithelial cells lining the digestive tract keep digestive enzymes and microorganisms in the intestine from seeping into the bloodstream.

Junctions among epithelial cells lining the digestive tract.

________ is a water-soluble, complex glycoprotein that is secreted by goblet cells.

Mucin Like mucous cells, goblet cells are unicellular exocrine glands that secrete mucin, a protein that combines with water to form mucus. In goblet cells, the cuplike accumulation of mucin distends the top of the cell, making these cells look like a glass with a stem, thus "goblet" cell. This distortion does not occur in mucous cells.

________ is the tissue that regulates and controls body functions.

Nervous tissue Nervous tissue regulates and controls body functions.

________ is the diffusion of a solvent, such as water, across a selectively permeable membrane.

Osmosis A special name, osmosis, is given to the unassisted diffusion of a solvent, usually water, through a selectively permeable membrane.

Why is the selective permeability of the plasma membrane essential for normal cell function?

Selective permeability allows cells to exclude some substances and allow others to pass into or out of the cell. Selective permeability of the plasma membrane ensures that the continual traffic across the membrane does not include undesirable substances. It also ensures that desirable cell contents are retained within the cell.

Which of the following statements is INCORRECT?

Simple squamous epithelia are associated with filtration and exchange. Simple columnar epithelia are associated with absorption and secretion. *Simple cuboidal epithelia are found in areas that stretch. Stratified squamous epithelia are found in areas subjected to wear and tear. This is incorrect; transitional (not simple cuboidal) epithelia are found in areas that stretch, in particular the ureters and urinary bladder. Simple cuboidal epithelia are designed for absorption and secretion (not stretching).

Which of the following statements is INCORRECT? The cutaneous membrane is a dry membrane exposed to air. Serous membranes line body cavities and organs. The cutaneous membrane is made of a simple columnar epithelium Mucous membranes line exits and entrances to the body.

The cutaneous membrane is made of a simple columnar epithelium The cutaneous membrane, a "dry" membrane exposed to air, consists of a keratinized, stratified squamous epithelium called, the epidermis, and an underlying layer of connective tissue called, the dermis.

What is the primary function of the mitochondria?

They are the main sites of ATP production. Mitochondria are threadlike or lozenge-shaped membranous organelles. In living cells they squirm, elongate, and change shape almost continuously. They are the power plants of a cell, providing most of its ATP supply.

Which of the following is characteristic of cilia?

They are whiplike, motile cellular extensions that occur in large numbers on the exposed surfaces of certain cells. Cilia are whiplike, motile cellular extensions that occur, typically in large numbers, on the exposed surfaces of certain cells. Ciliary action moves substances in one direction across cell surfaces. Centrioles forming the bases of cilia and flagella are commonly referred to as basal bodies.

Each number above molecule B refers to ______.

a codon Note that each number corresponds to a group of three nucleotide bases within the mRNA molecule.

The figure is of which cellular organelle?

a mitochondrion

The mechanism depicted in B would most likely mediate the diffusion of which of the following solutes?

an amino acid Mechanism B depicts the selective transport of a polar molecule such as an amino acid or sugar.

Which is the most atypical connective tissue since it does not connect things or provide structural support?

blood Blood, the fluid connective tissue (CT) within blood vessels, is the most atypical CT. It does not act as a binding or packing material; it does not provide structural support. It is classified as a CT only because it develops from mesenchyme and consists of cells (blood cells) surrounded by an extracellular fluid matrix (blood plasma).

Which tissue is correctly paired with its primary cell type?

bone: osteoblast Osteoblasts/cytes are the primary cell type for bone.

What is a function of the enzyme indicated by structure A?

breaking the bonds between complementary base pairs Structure A is the enzyme helicase, which untwists the DNA helix and breaks bonds between the complementary nucleotides of the two parental ("old") DNA strands.

Which muscle cell type has visible striations but is not under voluntary control?

cardiac Yes, cardiac cells, like skeletal cells, have visible striations but are not under voluntary control.

What process is depicted in the basal layer of the glandular epithelium shown in B?

cell division Cells are regenerated by division in the basal layer and migrate toward the apical surface to replace cells lost by fragmentation. Cell division is indicated by the mitotic phase cells located in the deepest (basal) layer of the glandular epithelium.

Which type of membrane is a dry membrane exposed to the air?

cutaneous membrane The cutaneous membrane is your skin, an organ consisting of a keratinized stratified squamous epithelium (epidermis) firmly attached to a thick layer of connective tissue (dermis). Unlike other epithelial membranes, the cutaneous membrane is exposed to the air and is a dry membrane.

Which cell component helps to maintain the structural integrity of the cell?

cytoskeleton The cytoskeleton acts as the cell's "bones," "muscles," and "ligaments" by supporting cellular structures and providing the machinery to generate various cell movements.

Which type of gland produces hormones?

endocrine glands Endocrine glands, which are ductless glands, secrete hormones into the interstitial fluid surrounding them. The hormones then diffuse toward and pass through a nearby capillary wall to enter the blood. Circulating throughout the body in the blood stream is how hormones eventually reach their target cells.

Which tissue type consists of a sheet of cells that covers a body surface or lines a body cavity?

epithelial tissue Epithelial tissue is a sheet of cells that covers a body surface or lines a body cavity (epithe = laid on, covering). In addition to coverings and linings, epithelial cells can also form glands, called glandular epithelium.

Which of the following cellular processes is portrayed in A?

exocytosis Merocrine secretion involves the release of materials from intracellular secretory vesicles into the duct by exocytosis.

What process is indicated by C?

exocytosis of secreted proteins. The event indicated by C includes the fusion of a secretory vesiclel with the plasma membrane and the subsequent release of the vesicle contents to the extracelluar space.

Which tissue repair process results in the formation of scar tissue?

fibrosis Fibrosis involves proliferation of fibrous connective tissue, called scar tissue.

After a heart attack, fibrosis occurs at the site of cardiac muscle cell death. This reduces the efficiency of the heart's pumping activity because __________.

fibrous connective tissue is incapable of contracting Cardiac muscle contains sarcomeres, which allow for the tissue to contract when electrically stimulated. Fibrous connective tissue lacks these special contractile units.

What type of protein is indicated by the arrow?

histone Histone proteins are the major structural protein associated with chromatin.

The membrane-bound compartment indicated by structure D contains which of the following?

hydrolytic enzymes Structure D is a lysosome, which stores enzymes that catalyze the hydrolysis (digestion) of organic cellular materials.

Solutions with a higher concentration of solutes than the concentration inside the cells are __________.

hypertonic Hypertonic solutions have a higher concentration of nonpenetrating solutes than seen in the cell (for example, a strong saline solution). Cells immersed in hypertonic solutions lose water and shrink, or crenate.

Where is transitional epithelium found?

in areas subjected to stretching Transitional epithelium is found in the urinary system. It lines the ureters, bladder and proximal part of the urethra-organs that are subjected to distention or stretching as urine passes through or fills them.

The nucleolus ________.

is the site of ribosome assembly in a cell Nucleoli ("little nuclei") are the dark-staining spherical bodies found within the nucleus where ribosomal subunits are assembled. They are not membrane bounded. Typically, there are one or two nucleoli per nucleus, but there may be more. Nucleoli are usually large in growing cells that are making large amounts of tissue proteins.

Smooth muscle ________.

is under involuntary control Smooth and cardiac muscle are under involuntary control. Skeletal muscle is under voluntary control.

What is the specific role of the enzyme indicated by B during the formation of the new DNA strands?

joining the nucleotides that form the new DNA strand DNA polymerase catalyzes formation of bonds between sugar groups and phosphate groups that link the DNA nucleotides together.

Which of the following substances would NOT be found in significant amounts in the extracellular matrix of the illustrated areolar connective tissue?

keratin Keratin is a protein typically found in epithelial tissues, notably the cornified layers of the epidermis. Keratin would therefore not be found in significant quantities in the ECM of connective tissues.

Which of the following epithelial tissue locations is NOT correctly matched to its function?

kidney: secretion kidney: filtration digestive tract: absorption skin: protection *skin: absorption The keratinized stratified squamous epithelium of skin is designed for protection, not absorption from the external environment.

Which of the following does not occur during RNA processing?

mRNA attaches to the small subunit of a ribosome. mRNA attaches to the small subunit of a ribosome at the beginning of translation.

Which of the following is a correct statement about mRNA?

mRNA moves from the nucleus to the cytoplasm following RNA processing. mRNA undergoes RNA processing in the nucleus and then moves to the cytoplasm for translation.

Which of the following increases the surface area of certain epithelial tissues?

microvilli Microvilli are small finger-like projections that greatly increase the surface area of epithelial cells (thus epithelial tissues), an important attribute of tissues that have a role in absorption and secretion.

Which cell organelle provides the majority of the ATP needed by the cell to carry out its metabolic reactions?

mitochondrion Mitochondria are the site of the majority of ATP production because of the specialized enzymes on their cristae.

Which mechanism requires energy input by the cell in the form of ATP hydrolysis?

none of the mechanisms require energy input All three mechanisms are forms of diffusion. Transport by diffusion of a molecule down its concentration gradient is a spontaneous process that requires no energy input.

The indicated protein interacts with DNA to form the structural unit of chromatin called a ______.

nucleosome The DNA helix wraps around a group of histone proteins to form a structural unit called a nucleosome.

After DNA replication is completed, each DNA double helix consists of ______.

one old parent strand and one new daughter strand. This mechanism is called semiconservative replication and is based on the ability of each strand of the DNA double helix to function as a template for the synthesis of the opposite strand.

Structures A and B are composed primarily of ______.

phospholipids Phospholipids are a major component of all cellular membranes, including the mitochondrial inner (A) and outer (B) membranes.

The plasma membrane is made primarily of ________.

phospholipids The plasma (cell) membrane is a phospholipid bilayer, composed of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads exposed to water on either side of the membrane. Each lollipop-shaped phospholipid molecule has a polar "head" that is charged and is hydrophilic (hydro = water, philic = loving), and an uncharged, nonpolar "tail" that is made of two fatty acid chains and is hydrophobic.

Connective tissues ________.

primarily consist of extracellular matrix All other primary tissues are composed mainly of cells, but connective tissues are largely nonliving extracellular matrix, which separates, often widely, the living cells of the tissue.

In connective tissue, the role of collagen fibers is to ________.

provide tensile strength Collagen fibers are extremely tough and provide high tensile strength (that is, the ability to resist being pulled apart) to the matrix. Stress tests show that collagen fibers are stronger than steel fibers of the same size!

Which of the following processes allows cells to concentrate material that is present only in very small amounts in the extracellular fluid?

receptor-mediated endocytosis Receptor-mediated endocytosis is the main mechanism for the specific endocytosis and transcytosis of most macromolecules by body cells, and it is exquisitely selective. The mechanism also allows cells to concentrate material that is present only in very small amounts in the extracellular fluid.

Molecule B and molecule C are expected to interact within which of the following cellular locations?

ribosome The codons within the mRNA (B) are recognized by corresponding tRNA molecules within cytoplasmic ribosomes during protein translation.

Which organelle is responsible for synthesizing proteins?

ribosomes Proteins are synthesized at ribosomes. Free ribosomes float freely in the cytoplasm and produce soluble proteins that function in the cytosol, as well as those imported into mitochondria and some other organelles. Fixed ribosomes, which stud the rough endoplasmic reticulum, synthesize proteins destined either for incorporation into the cell membrane or lysosomes, or for export from the cell.

The site of translation is

ribosomes in the cell cytoplasm. Translation occurs at ribosomes in the cell cytoplasm.

Which of the following glands might utilize the secretory mechanism and duct structure shown in A?

salivary Merocrine glands, such as that shown in A, produce secretions such as saliva, sweat, digestive enzymes, and so on.

Exocrine glands ________.

secrete substances onto body surfaces Exocrine glands use ducts to secrete substances into the external environment (onto the surfaces of the cutaneous and mucous membranes). Note: "exo" means outside. Endocrine glands are ductless; they secrete hormones into the extracellular fluid of our internal environment. Note: "endo" means inside.

The proximal tubule of the nephron (kidney tubule) in the kidney is composed of which type of epithelium?

simple cuboidal epithelium Yes, the simple cuboidal cells line the kidney tubules (nephrons) so that secretion and absorption can take place.

The wall of the alveolus (air sac) in the lung is composed of which type of epithelium?

simple squamous epithelium Yes, this single layer of squamous cells is ideal for the diffusion of gases in the lungs.

Which of the three muscle cell types has multiple nuclei?

skeletal Yes, skeletal muscle cells are elongated and many can be quite long; therefore, they have multiple nuclei.

Which part of the neuron (a specialized nerve cell) receives signals from other cells and is also the main metabolic region of the neuron?

soma Yes, the soma or cell body receives inputs (signals) from other cells and sends the information to the axon. But unlike a dendrite, it also is the main metabolic and nutritional center of the cell.

Injured cartilage might heal more quickly if a treatment were discovered that would __________.

stimulate blood vessels to develop within cartilage Cartilage is normally avascular, so nutrients required for healing must diffuse from distant blood vessels, which delays the healing process.

The epithelium of the esophagus is composed of which type of epithelial tissue?

stratified squamous epithelium Yes, this epithelium protects underlying tissues from the wear and tear of constant swallowing in the esophagus.

Which of the following is NOT a role of connective tissue?

support protection *absorption insulation Absorption, the movement of substances into the body, is a role of epithelial tissue. Roles of connective tissue include: binding and support, protection, insulation, and transportation of substances, via blood, within the body.

What major function occurs on the specific membranes indicated by A?

synthesis of secreted proteins Structure A is the rough endoplasmic reticulum (ER). The figure illustrates how proteins are synthesized on ribosomes bound to the rough ER, sorted in the Golgi, and delivered to the plasma membrane for secretion or packaged into lysosomes.

________ is a molecular "ferry" that brings amino acids to the ribosome to build a protein.

t-RNA t-RNA serves as an adapter molecule; it ferries amino acids to the ribosome and participates in translation (the process by which amino acids are assembled into proteins).

__________ is a molecule that brings amino acids to the ribosome during translation.

t-RNA t-RNA serves as an adapter molecule; it ferries amino acids to the ribosome and participates in translation (the process by which amino acids are assembled into proteins).

The structure indicated by B is __

the Golgi apparatus Note how the location of the Golgi apparatus within the endomembrane system is consistent with its functions of sorting and modifying proteins being transported to various cellular locations.

In a patient with severely burned skin, the damaged cells that have lost fluid cannot be properly rehydrated because_________.

the absence of selective permeability allows water molecules that enter these damaged cells to also leave the cytoplasm. Skin is an organ made up of tissues, and tissues are made up of cells. Selective permeability requires an intact cell membrane.

Which of the following events might the solid arrow at the bottom of B represent?

the activation of specific cytoplasmic enzymes Once activated by the binding of a specific chemical messenger, such as a hormone, the receptor initiates cellular responses by activating specific signal transduction pathways. These pathways include the activation of enzymes, such as kinases, that lead to specific cellular responses.

What is the most obvious structural feature of areolar connective tissue?

the loose arrangement of its fibers The most obvious structural feature of this tissue is the loose arrangement of its fibers. The rest of the matrix, occupied by ground substance, appears to be empty space when viewed through the microscope. Note: the Latin term areola means "a small open space."

This figure illustrates which of the following descriptions?

the use of a sodium concentration gradient to power the pumping of glucose into the cell. The sodium ion feel gradient is generated by the Na+-K+ pump at the left. Diffusion of sodium ions through the Na+-glucose symport (shown at the right) provides the energy necessary to actively transport glucose into the cell. Such a mechanism is used by intestinal cells (to absorb nutrients) and kidney cells (to recover glucose from urine prior to excretion).

How is the energy from ATP used most directly in the illustrated processes?

to generate a sodium concentration gradient. The energy from ATP hydrolysis is used to transport sodium and potassium ions across the membrane and thereby establish concentration gradients for each of those ions.

What process allows for the production of molecule B from a template consisting of molecule A?

transcription Transcription is the synthesis of RNA using DNA as a template.

What are the two basic steps of polypeptide synthesis?

transcription and translation Polypeptide synthesis involves two major steps: (1) transcription, in which DNA's information is encoded into mRNA, and (2) translation, in which the information carried by the mRNA is decoded and used to assemble polypeptides.

What are the two basic steps of polypeptide synthesis?

transcription and translation Polypeptide synthesis involves two major steps: (1) transcription, in which DNA's information is encoded into mRNA, and (2) translation, in which the information carried by the mRNA is decoded and used to assemble polypeptides.

Which type of epithelium lines the interior of the urinary bladder?

transitional epithelium Transitional epithelium forms the lining of hollow urinary organs, which stretch as they fill with urine. The ability of transitional cells to change their shape (undergo "transitions") allows a greater volume of urine to flow through the tube-like ureters and allows more urine to be stored in the urinary bladder.

Mucous cells are ________.

unicellular exocrine glands Mucous cells are unicellular exocrine glands that secrete mucin, a protein that combines with water to form mucus.

Cells 3 and 6 are both classified as ______.

white blood cells Cell 3 (a lymphocyte) and cell 6 (a neutrophil) are two types of white blood cell.