MCB BABY (chapter 3.3-5)

Proteins, like lipids, are free to move in the membrane. True False

True

Phospholipids: are amphipathic have hydrophobic heads hydrophobic fatty acid tails have heads that can H-bond with water.

are amphipathic hydrophobic fatty acid tails have heads that can H-bond with water.

RNA polymerase makes a mistake in approximately 1 in ____________ nucleotides. 1,000,000 100,000,000 10,000 1,000

10,000

Which of the following correctly matches a cytoskeletal element with one of its functions? A mutation that interferes with intermediate filament formation could result in layers of cells not adhering to one another. Microtubules guide chromosomes during cell division. Cilia and flagella are made up of microfilaments. Microtubules act as tracks for motor proteins like kinesin.

A mutation that interferes with intermediate filament formation could result in layers of cells not adhering to one another. Microtubules guide chromosomes during cell division. Microtubules act as tracks for motor proteins like kinesin.

Why must pH be regulated in various organelles? Because proteins inside organelles can denature (and become nonfunctional) if the pH is not optimal. Because the optimal pH is 7 (neutral) Because the pH needs to be the same throughout the cell. Because the reactions and enzymes in one organelle may be quite different from those of another organelle.

Because proteins inside organelles can denature (and become nonfunctional) if the pH is not optimal. Because the reactions and enzymes in one organelle may be quite different from those of another organelle.

Which of the following statements about DNA are correct? DNA transmits genetic information from one generation to the next. It is differences in the order of the individual subunits/bases (ATCG) that accounts for differences in genes. DNA stores information. The "turning on" of genes is called gene expression.

DNA transmits genetic information from one generation to the next. It is differences in the order of the individual subunits/bases (ATCG) that accounts for differences in genes. DNA stores information. The "turning on" of genes is called gene expression.

All cell types in your body have the same types and numbers of transmembrane or membrane-associated proteins. True False

False

In secondary active transport, the potential energy of an electrochemical gradient is used to drive the movement of molecules against their gradient. ATP plays no role in this. True False

False

What is the difference between a primary RNA transcript and an mRNA (messenger RNA)? In prokaryotes only, the mRNA can include the "recipes" for multiple proteins. In prokaryotes, they are one in the same. In eukaryotes, the primary transcript must be extensively modified-- including the addition of a 5' cap and a 3' poly(A) tail. Pieces of non-coding sequences, called introns, must be removed from eukaryotic primary transcripts: RNA splicing.

In prokaryotes only, the mRNA can include the "recipes" for multiple proteins. In prokaryotes, they are one in the same. In eukaryotes, the primary transcript must be extensively modified-- including the addition of a 5' cap and a 3' poly(A) tail. Pieces of non-coding sequences, called introns, must be removed from eukaryotic primary transcripts: RNA splicing.

RNA polymerase is catalyzing the formation of a phosphodiester bond; it is building a polymer. This is an endergonic (energy-requiring) reaction. Where does the energy come from? It comes from an exergonic (energy-releasing) reaction. Energy is released when the hydrogen bonds between the nucleotides is cleaved. ATP has to be added to every one of these reactions. Energy is captured when two of the phosphates are cleaved from the in-coming nucleoside triphosphate.

It comes from an exergonic (energy-releasing) reaction. Energy is released when the hydrogen bonds between the nucleotides is cleaved. ATP has to be added to every one of these reactions. Energy is captured when two of the phosphates are cleaved from the in-coming nucleoside triphosphate.

A nucleoside (a sugar attached to a base) can have 1, 2, 3 or no phosphate group. True False

True

Various characteristics of the lipids in a membrane contribute to its fluidity-- which in turn determines how easily molecules can diffuse into and out of the cell across the membrane. Which of the following statements about this topic are correct? Longer fatty acid tails of phospholipids make the membrane less fluid, thus slowing diffusion. A higher concentration of saturated fatty acid tails of phospholipids makes the membrane less fluid, thus slowing diffusion. At ambient temperatures (temperatures typically found in a cell), cholesterol stiffens the membrane, reducing fluidity and diffusion. A higher concentration of unsaturated fatty acid tails of phospholipids makes the membrane less fluid, thus slowing diffusion.

Longer fatty acid tails of phospholipids make the membrane less fluid, thus slowing diffusion. A higher concentration of saturated fatty acid tails of phospholipids makes the membrane less fluid, thus slowing diffusion. At ambient temperatures (temperatures typically found in a cell), cholesterol stiffens the membrane, reducing fluidity and diffusion.

The endoplasmic reticulum is comprised of two different subsystems: the rough (RER) and the smooth (SER). Which of the following statements about this topic are correct? Both SER and RER are sites of protein synthesis. Not all proteins are synthesized by the ribosomes on the RER. Both SER and RER are studded with ribosomes. Both SER and RER are sites of lipid synthesis.

Not all proteins are synthesized by the ribosomes on the RER.

In eukaryotic cells, the total surface area of the plasma membrane is about 1/10th that of all the membranes inside the cell. True False

True

Why does it make sense that the enzymes that operate in the lysosome are nonfunctional at normal cellular pH of 7? The function of these enzymes is to degrade macromolecules; if they escaped the lysosome, they could damage things if they were functional at pH 7. These enzymes are free to move around the cell; they are not confined to any one organelle. The function of these enzymes is to synthesize proteins, which cannot fold properly at pH 7.

The function of these enzymes is to degrade macromolecules; if they escaped the lysosome, they could damage things if they were functional at pH 7.

Why does water diffuse across the membrane in the beaker in the manner shown in the figure below? (Figure 5.11) The solute cannot diffuse across the membrane in order re-establish equilibrium. The solutes diffuse with their concentration gradient. Water moves with its concentration gradient, to re-establish equilibrium with the solute. Water moves from a region of lower solute concentration to a region of higher solute concentration.

The solute cannot diffuse across the membrane in order re-establish equilibrium. Water moves with its concentration gradient, to re-establish equilibrium with the solute. Water moves from a region of lower solute concentration to a region of higher solute concentration.

What are the basic characteristics of the shapes of cytoskeleton elements? Microtubules are the thinnest of the cytoskeletal fibers, comprised of a helix formed of two actin polymers. Intermediate filaments form long tubular structures made of tubulin monomers. They are all composed of long protein polymers. Microfilaments form bundles of strong, cable-like structures that provide cells with mechanical strength.

They are all composed of long protein polymers.

What do microfilaments do in the microvilli of intestinal cells? They support the finger-like projections of the microvilli. They link together the intestinal cells. They absorb nutrients from the intestines. Each microvillus is a separate cell that must be linked to other such cells.

They support the finger-like projections of the microvilli.

Frederick Griffith's experiment in the 1920s (Fig 3.1 in the book) with the bacteria that cause pneumonia showed that a bacterium could change its genotype (and thus its physical characteristics) by picking up an unknown molecule from its environment. DNA was the genetic material. the non-virulent strain bacteria were transformed genetically to being virulent, when they picked up some molecule from the killed virulent cells.

a bacterium could change its genotype (and thus its physical characteristics) by picking up an unknown molecule from its environment. the non-virulent strain bacteria were transformed genetically to being virulent, when they picked up some molecule from the killed virulent cells.

A nucleotide consists of: a double or single ring structure called a base a 5-carbon sugar called deoxyribose a phosphate group an amino acid

a double or single ring structure called a base a 5-carbon sugar called deoxyribose a phosphate group

The plasma membrane: actively maintains the homeostasis of the cell (e.g., the narrow range of salt concentration, pH, etc tolerable to the cell) is a passive boundary that allows traffic of molecules and out of the cell consists of phospholipids embedded with proteins is the boundary that defines the space of the cell, and separates it from the outside environment is selectively permeable-- allow some molecule in and out freely, but regulates the movement of other molecules.

actively maintains the homeostasis of the cell (e.g., the narrow range of salt concentration, pH, etc tolerable to the cell) consists of phospholipids embedded with proteins is the boundary that defines the space of the cell, and separates it from the outside environment is selectively permeable-- allow some molecule in and out freely, but regulates the movement of other molecules.

Polycistronic mRNAs: occur in both prokaryotes and eukaryotes. allow for multiple proteins that are needed for a common purpose to be synthesized at the same time. are mRNAs with the 'recipe' for multiple polypeptides.

allow for multiple proteins that are needed for a common purpose to be synthesized at the same time. are mRNAs with the 'recipe' for multiple polypeptides.

The internal membrane compartments (organelles) inside a cell are: are connected, in some cases, by membrane vesicles (sacs) that move substances from one place to another inside the cell. make up the endomembrane system. isolated from one another. are connected, in some cases, by membrane "bridges".

are connected, in some cases, by membrane vesicles (sacs) that move substances from one place to another inside the cell. make up the endomembrane system. are connected, in some cases, by membrane "bridges".

Transcription and translation: are separated in eukaryotic cells (such as our own): transcription takes place in the cytoplasm; translation takes place in the nucleus. are separated in eukaryotic cells (such as our own): transcription takes place in the nucleus; translation takes place in the cytoplasm. both take place in the cytoplasm of prokaryotic cells (such as bacteria). are separated in prokaryotic cells (such as bacteria): transcription takes place in the nucleus; translation takes place in the cytoplasm.

are separated in eukaryotic cells (such as our own): transcription takes place in the nucleus; translation takes place in the cytoplasm. both take place in the cytoplasm of prokaryotic cells (such as bacteria).

Regarding the roles of channels and carrier proteins in diffusion both move substances against their concentration gradients. both are transmembrane proteins (they span the membrane) both allow for substances to move across the membrane from an area of high concentration to an area of low concentration. both bind to the molecules/ions they bring in, and change shape in response to that binding.

both are transmembrane proteins (they span the membrane) both allow for substances to move across the membrane from an area of high concentration to an area of low concentration.

DNA is unique among cellular molecules in that: it is able to specify exact copies of itself. only living cells possess DNA as genetic material. it is the only macromolecule composed of nucleotide monomers. it is the only molecule to store or transmit genetic information.

it is able to specify exact copies of itself

Two broad classes of cells: can be distinguished by those that have genetic information and those that don't. can be distinguished by the presence/absence of membrane-enclosed internal compartments. can be distinguished by those that have a plasma membrane and those that don't. can be distinguished by those that have a nucleus and those that don't.

can be distinguished by the presence/absence of membrane-enclosed internal compartments. can be distinguished by those that have a nucleus and those that don't.

Amino acids: are all water soluble. are identical in one part of their structure: the R-group. come in 20 different kinds. all have an amino group on one end, a carboxyl group on the other end, and an alpha-carbon in the middle.

come in 20 different kinds. all have an amino group on one end, a carboxyl group on the other end, and an alpha-carbon in the middle.

Transcription: ends when RNA polymerase reaches the DNA sequence called the terminator. involves H-bonding (base-pairing) between the nucleotides of the DNA template and the RNA transcript. begins when RNA polymerase and proteins called transcription factors bind to a region of the DNA called the promoter. requires the assembly of a large number of proteins, including RNA polymerase, at the promoter.

ends when RNA polymerase reaches the DNA sequence called the terminator. involves H-bonding (base-pairing) between the nucleotides of the DNA template and the RNA transcript. begins when RNA polymerase and proteins called transcription factors bind to a region of the DNA called the promoter. requires the assembly of a large number of proteins, including RNA polymerase, at the promoter.

Functions of proteins in cells include: enzymes that catalyze reactions. molecular signals that enable cells to coordinate and communicate. stiff filaments that help define a cells shape and hold organelles in place (the cytoskeleton) pores and channels through the plasma membrane through which ions and small molecules can enter and exit the cell.

enzymes that catalyze reactions. molecular signals that enable cells to coordinate and communicate. stiff filaments that help define a cells shape and hold organelles in place (the cytoskeleton) pores and channels through the plasma membrane through which ions and small molecules can enter and exit the cell.

Regarding simple diffusion and facilitated diffusion, examples of substances that can simply diffuse are O2, CO2, and water. simple diffusion is the movement of substances with their concentration gradient across the membrane. in both, substances are moving against their concentration gradients. facilitated diffusion requires a membrane protein to move substances across.

examples of substances that can simply diffuse are O2, CO2, and water. simple diffusion is the movement of substances with their concentration gradient across the membrane. facilitated diffusion requires a membrane protein to move substances across.

The force that drives and maintains the formation of bilayer sheets by phospholipids in cell membranes is covalent bonding between the polar heads hydrophobic effects ionic attractions between the fatty acid tails H-bonding between the fatty acid tails

hydrophobic effects

Regarding endocytosis and exocytosis, in endocytosis, a vesicle fuses with the plasma membrane and releases its contents into the extracellular space. in endocytosis, a section of the plasma membrane can bud off into the cytoplasm, bringing substances into the cell. in exocytosis, a section of the plasma membrane can bud off into the cytoplasm, bringing substances into the cell. in exocytosis, a vesicle fuses with the plasma membrane and releases its contents into the extracellular space.

in endocytosis, a section of the plasma membrane can bud off into the cytoplasm, bringing substances into the cell. in exocytosis, a vesicle fuses with the plasma membrane and releases its contents into the extracellular space.

In double-stranded DNA, complementary base-pairing: insures the uniform diameter of the double helix. means that a purine always pairs with a pyrimidine. guanine can only pair with cytosine: three H-bonds and purine-pyrimidine. an adenine can make either two H-bonds with thymine, or three H-bonds with cytosine.

insures the uniform diameter of the double helix. means that a purine always pairs with a pyrimidine. guanine can only pair with cytosine: three H-bonds and purine-pyrimidine.

Functions of the cytoskeleton include: endocrine communication between cells internal structural support of the cell movement of substances within the cell changes in cell shape

internal structural support of the cell movement of substances within the cell changes in cell shape

An unrepaired mistake in DNA replication: is always a bad thing. is called a mutation can result in a change in the "recipe" for a protein. can provide an organisms with a new allele (recipe for a protein)

is called a mutation can result in a change in the "recipe" for a protein. can provide an organisms with a new allele (recipe for a protein)

The nucleus: is the site of transcription (RNA synthesis). stores the genome (DNA) of the cell. has ribosomes that synthesize some proteins. has a double membrane (2 phospholipid bilayers) that regulate which molecules move in and out of the nucleus.

is the site of transcription (RNA synthesis). stores the genome (DNA) of the cell. has a double membrane (2 phospholipid bilayers) that regulate which molecules move in and out of the nucleus.

We can tell how an amino acid will be classified (as polar or non-polar) by looking at it to see whether: it has a charge (- or +) in its amino group; this will make it non-polar. it has a hydrocarbon chain or ring in its R-group; this will make it insoluble in water (and thus non-polar). it has an electronegative atom (like oxygen) in its carboxyl group; this will classify it as polar. it has a charge (- or +) in its R-group; this will make it polar.

it has a hydrocarbon chain or ring in its R-group; this will make it insoluble in water (and thus non-polar). it has a charge (- or +) in its R-group; this will make it polar.

Regarding the types of bonds that maintain the different levels of protein structure, it is weak bonds that maintain the dense, 3-D folding of tertiary struture. it is peptide bonds that establish quaternary structure. it is hydrogen bonds that maintain primary structure. it is weak bonds that maintain alpha-helices and beta pleated sheets.

it is weak bonds that maintain the dense, 3-D folding of tertiary structure. it is weak bonds that maintain alpha-helices and beta pleated sheets.

Regarding the Golgi apparatus, it sorts newly-synthesized proteins and lipids for delivery to their final destinations. it chemically modifies proteins and lipids that have been newly-synthesized. it is the site of synthesis of most of the cell's carbohydrates. it receives proteins and lipids that have been received by the cell via endocytosis.

it sorts newly-synthesized proteins and lipids for delivery to their final destinations. it chemically modifies proteins and lipids that have been newly-synthesized. it is the site of synthesis of most of the cell's carbohydrates.

The different parts of the endomembrane system: keep certain molecules and processes physically separated from one another are so similar to one another that processes and molecules flow unimpeded from one to another. each has a distinct identity and unique properties often have membranes composed of different lipids and proteins

keep certain molecules and processes physically separated from one another each has a distinct identity and unique properties often have membranes composed of different lipids and proteins

DNA is a ________ polymer comprised of _______ different monomers (subunits). circular; many linear; four octagonal; dozens helical; dozens

linear; four

Which of the following is a component of cell membranes? nucleic acids lipids carbohydrates proteins

lipids carbohydrates proteins

The endomembrane system includes: the mitochondria and chloroplasts lysosomes & vesicles the nuclear envelope & the plasma membrane the endoplasmic reticulum & Golgi apparatus

lysosomes & vesicles the nuclear envelope & the plasma membrane the endoplasmic reticulum & Golgi apparatus

Membranes are dynamic, meaning that lipid molecules in the membrane can move easily (and sometimes quite rapidly) within the plane of the membrane. because the weak van der Waals interactions between the fatty acid tails of lipids are easily broken and reformed. meaning they are constantly moving, forming, and re-forming. because the phospholipids are not covalently bonded to one another.

meaning that lipid molecules in the membrane can move easily (and sometimes quite rapidly) within the plane of the membrane. because the weak van der Waals interactions between the fatty acid tails of lipids are easily broken and reformed. meaning they are constantly moving, forming, and re-forming. because the phospholipids are not covalently bonded to one another.

Which of the following cytoskeleton elements do your cells have? microtubules cellulose fibers microfilaments intermediate filaments

microtubules microfilaments intermediate filaments

Regarding proteins that associate with the cell membrane, most integral proteins are transmembrane proteins that span the membrane integral proteins are permanently integrated into the membrane all peripheral proteins must have some part of their structure that is hydrophobic peripheral proteins associate with the membrane temporarily on the inside or outside of the cell all integral proteins must have some part of their structure that is hydrophobic

most integral proteins are transmembrane proteins that span the membrane integral proteins are permanently integrated into the membrane peripheral proteins associate with the membrane temporarily on the inside or outside of the cell all integral proteins must have some part of their structure that is hydrophobic

Active transport is needed to: move nutrients into the cell (from higher concentration outside the cell) move substances "uphill", against their concentration gradient. remove wastes that are in higher concentration inside the cell. for example, bring something into the cell that is in lower concentration outside the cell than inside.

move substances "uphill", against their concentration gradient. for example, bring something into the cell that is in lower concentration outside the cell than inside.

Which organelle/structures do animal cells have that plant cells do not? none of these answers is correct (plant cells have all of these organelles/structures) mitochondria Golgi apparatus plasma membrane endoplasmic reticulum

none of these answers is correct (plant cells have all of these organelles/structures)

Within a polypeptide (or protein) an amino acid that is: nonpolar will tend to fold to the inside, where it does not encounter water. polar will tend to fold to the inside, where it does not encounter water. polar will tend to fold so that it is on the outside, where it can interact with water nonpolar will tend to fold so that it is on the outside, where it can interact with water.

nonpolar will tend to fold to the inside, where it does not encounter water. polar will tend to fold so that it is on the outside, where it can interact with water

There are two types of bonds that maintain a double-stranded DNA molecule: phosphodiester bonds, which are stable and resistant to breakage, connect nucleotides within a single strand. H-bonds which link the sugar of one nucleotide to the phosphate of another within a single polynucleotide. H-bonds (hydrogen bonds), which are relatively weak bonds, hold the two polynucleotides together in the double helix. phosphodiester bonds, weak bonds that hold the two polynucleotides to one another.

phosphodiester bonds, which are stable and resistant to breakage, connect nucleotides within a single strand. H-bonds (hydrogen bonds), which are relatively weak bonds, hold the two polynucleotides together in the double helix.

In aqueous (water-based) solution, phospholipids spontaneously arrange themselves into various structures such as bilayer sheets, in which the _________ on the outside interact with water, and the __________ come together on the inside, away from water. hydrophobic heads; hydrophilic tails nonpolar heads; nonpolar tails polar heads; nonpolar tails nonpolar heads; polar tails

polar heads; nonpolar tails

Proteins are large molecules called __________ : long chains of repeated units that are called ________. isomers; ions polymers; amino acids polysaccharides; nucleotides monomers; polymers

polymers; amino acids

Prokaryotes (proks) differ from eukaryotes (euks) in that: proks often contain small circular DNA molecules, called plasmids. prok DNA is concentrated in the nucleoid region of the cytoplasm, rather than in a nucleus. most proks lack the complex internal compartments of a euk cell. a typical prok is ~half the volume of a typical euk.

proks often contain small circular DNA molecules, called plasmids. prok DNA is concentrated in the nucleoid region of the cyplasm, rather than in a nucleus. most proks lack the complex internal compartments of a euk cell.

Regarding the movement of various substances across the plasma membrane, protein transporters (transmembrane proteins) allow the import and export of some molecules that cannot get across on their own many macromolecules (e.g., proteins, polysaccharides) are too large to cross the plasma membrane on their own gases, lipids, and small uncharged polar molecules are blocked from diffusing across the plasma membrane the hydrophobic lipid interior prevents free diffusion of ions, charged, and polar molecules

protein transporters (transmembrane proteins) allow the import and export of some molecules that cannot get across on their own many macromolecules (e.g., proteins, polysaccharides) are too large to cross the plasma membrane on their own the hydrophobic lipid interior prevents free diffusion of ions, charged, and polar molecules

The so-called "nitrogenous" bases of DNA normally come in two forms: adenine and thymine, which are purines. cytosine and guanine, which are pyrimidines. purines, which consist of double rings. pyrimidines, which consist of single rings.

purines, which consist of double rings. pyrimidines, which consist of single rings.

tRNA: recognizes a sequence of mRNA nucleotides, and brings a specific amino acid. is made of DNA. is made of protein. is the adapter molecule that connects the message of the genetic code to the language of proteins.

recognizes a sequence of mRNA nucleotides, and brings a specific amino acid. is the adapter molecule that connects the message of the genetic code to the language of proteins.

Ribosomes: release the mRNA when they encounter the release factor bound to a stop codon. couple the formation of peptide bonds to the hydrolysis of GTP (a close cousin to ATP). are molecular machines that synthesize polypeptides. allows for a tRNA to pair-bond (H-bond) with its complement in the mRNA.

release the mRNA when they encounter the release factor bound to a stop codon. couple the formation of peptide bonds to the hydrolysis of GTP (a close cousin to ATP). are molecular machines that synthesize polypeptides. allows for a tRNA to pair-bond (H-bond) with its complement in the mRNA.

In the mid-2oth century, scientists had finally determined that the genetic material in cells was made of DNA. In order to serve as the genetic material, DNA would need to be able to replicate the mutations as faithfully as the original DNA replicate itself direct the synthesis of other macromolecules in the cell. undergo rare mutations

replicate the mutations as faithfully as the original DNA replicate itself direct the synthesis of other macromolecules in the cell. undergo rare mutations

RNA polymerase has structural features that: separate the double-stranded DNA allow RNA nucleotides to pair-bond with the DNA template nucleotides elongate the transcript by adding nucleotides restore the double-stranded DNA

separate the double-stranded DNA allow RNA nucleotides to pair-bond with the DNA template nucleotides elongate the transcript by adding nucleotides restore the double-stranded DNA

The key role that membranes play in cells include: separating a cell from the external environment defining structural spaces within cells blocking the diffusion of all substances in and out of the cell defining functional spaces within cells

separating a cell from the external environment defining structural spaces within cells defining functional spaces within cells

Not all primary transcripts are processed into mRNAs. Some are processed into: snRNAs, which play roles in the nucleus, involved in RNA splicing, and the addition of poly(A) tails. rRNAs, which are part of the structure of ribosomes-- the molecular machines that synthesize proteins. siRNAs, which can inhibit translation or mark mRNAs for destruction. tRNAs, which bring individual amino acids to the ribosomes during translation.

snRNAs, which play roles in the nucleus, involved in RNA splicing, and the addition of poly(A) tails. rRNAs, which are part of the structure of ribosomes-- the molecular machines that synthesize proteins. siRNAs, which can inhibit translation or mark mRNAs for destruction. tRNAs, which bring individual amino acids to the ribosomes during translation.

Regarding Fig 5.14 in the text the cell in the very hypotonic solution has taken in too many solutes and will lyse (burst). solutes cannot diffuse across the membrane with their concentration gradients; it is always the water that moves. the cell in the hypertonic solution is surrounded by a high concentration of solutes. cell placed in pure water will lose their solutes and shrivel up.

solutes cannot diffuse across the membrane with their concentration gradients; it is always the water that moves. the cell in the hypertonic solution is surrounded by a high concentration of solutes.

Signal sequences: that are located internally (in the middle of the polypeptide) are usually on proteins targeted to the nucleus. are usually attached to the amino end of polypeptides destined for the chloroplasts or mitochondria. are amino acid sequences that allow proteins to be recognized and sorted. do not exist on proteins that are to remain in the cytosol.

that are located internally (in the middle of the polypeptide) are usually on proteins targeted to the nucleus. are usually attached to the amino end of polypeptides destined for the chloroplasts or mitochondria. are amino acid sequences that allow proteins to be recognized and sorted. do not exist on proteins that are to remain in the cytosol.

Which of the following organelles plays some role in the synthesis or processing of proteins the cell? the peroxisomes the Golgi apparatus the endoplasmic reticulum the mitochondria

the Golgi apparatus the endoplasmic reticulum the mitochondria

In transcription: the RNA is synthesized in the 3' to 5' direction. the RNA polymerase enzyme builds phosphodiester bonds between RNA nucleotides. the RNA that is synthesized is an exact copy of the DNA template. the RNA that is synthesized is complementary to (in a sense, opposite of) the DNA template.

the RNA polymerase enzyme builds phosphodiester bonds between RNA nucleotides. the RNA that is synthesized is complementary to (in a sense, opposite of) the DNA template.

Regarding Fig 5.13 in the text, the build-up of high concentration of protons on one side of the plasma membrane is a form of potential energy. the potential energy in a concentration gradient (a high concentration) of the protons can be used to drive the movement of other molecule against its gradient. protons are initially pumped out of the cell against their gradient, and then flow back in passively. using an antiporter, as protons are pumped in and molecules of another substance (the brown diamonds) are pumped out.

the build-up of high concentration of protons on one side of the plasma membrane is a form of potential energy. the potential energy in a concentration gradient (a high concentration) of the protons can be used to drive the movement of other molecule against its gradient. protons are initially pumped out of the cell against their gradient, and then flow back in passively.

Cell theory states that the cell is the smallest unit of life. some cells come from pre-existing cells, but others today arise from non-living matter. the cell is the fundamental unit of life. most, but not all, organisms are made of cells.

the cell is the smallest unit of life. the cell is the fundamental unit of life.

In alternative splicing of RNA, the change in the sequence of nucleotides in the mRNA results in a change in the specified amino acids in the encoded protein. only some of the introns are removed from the primary transcript. allows for the production of multiple proteins from a single gene. in addition to all of the introns, one or more exons is removed.

the change in the sequence of nucleotides in the mRNA results in a change in the specified amino acids in the encoded protein. allows for the production of multiple proteins from a single gene. in addition to all of the introns, one or more exons is removed.

In translation, the first tRNA does not enter the ribosome until after the large subunit has joined the small subunit. synthesis of the polypeptide begins with the very first mRNA nucleotide on the 5' end. the first step is when the small ribosomal subunit binds to the ribosome recognition site on the mRNA. the first amino acid of any newly-synthesized polypeptide is methionine, because methionine is specified by the 'start' codon in the mRNA.

the first step is when the small ribosomal subunit binds to the ribosome recognition site on the mRNA. the first amino acid of any newly-synthesized polypeptide is methionine, because methionine is specified by the 'start' codon in the mRNA.

The fluid mosaic model of the cell membrane refers to the fact that: the membrane is fluid in the sense that phospholipids can flip from fatty acid tails facing into the interior of the bilayer, or outward to the exterior of the bilayer. the membrane is fluid in the sense that all of its components can move laterally within the membrane the membrane is a mosaic, in the sense that it is made two types of molecules: lipids and proteins the membrane is fluid in the sense that all of its components can easily flip from one side of the membrane bilayer to the other

the membrane is fluid in the sense that all of its components can move laterally within the membrane the membrane is a mosaic, in the sense that it is made two types of molecules: lipids and proteins

To form a DNA polynucleotide (a single strand): the phosphate of one nucleotide is covalently linked to the 3' carbon of another nucleotide's sugar. nucleotides are linked by phosphodiester bonds. the base of one nucleotide is covalently bonded to the base of another nucleotide the phosphate of one nucleotide is covalently linked to the 5' carbon of another nucleotide's sugar.

the phosphate of one nucleotide is covalently linked to the 3' carbon of another nucleotide's sugar. nucleotides are linked by phosphodiester bonds.

Regarding the levels of proteins structure: the primary structure is the sequence of amino acids. the quaternary structure is the folding of a polypeptide into a 3-dimensional shape. the secondary structure is the twisting of the polypeptide into alpha helices or folding back on itself into beta sheets. the tertiary structure is the assembly of multiple polypeptide units into a protein.

the primary structure is the sequence of amino acids. the secondary structure is the twisting of the polypeptide into alpha helices or folding back on itself into beta sheets.

Regarding Fig. 5.12 in the text, the pump is an example of secondary active transport. the purpose is to keep a high concentration of Na+ outside the cell and a low concentration of K+ inside the cell. the pump requires the expenditure of energy, in the form of ATP. the pump moves two ions against their concentration gradients.

the pump requires the expenditure of energy, in the form of ATP. the pump moves two ions against their concentration gradients.

RNA and DNA are very similar, but there are some differences, including which of the following?: RNA is more stable than DNA. DNA is usually single-stranded and RNA is usually double-stranded. the ribose sugar has one more oxygen than the deoxyribose. the base thymine in DNA is replaced by uracil in RNA.

the ribose sugar has one more oxygen than the deoxyribose. the base thymine in DNA is replaced by uracil in RNA.

Regarding mitochondria and chloroplasts: they are part of the endomembrane system. they are both semi-autonomous: they grow and divide independently of the other organelles, and they have their own genomes. they are both specialized to harness energy for the cell. both are thought to have evolved from bacteria that were captured by a eukaryotic cell. only animal cells have mitochondria; only plant cells have chloroplasts.

they are both semi-autonomous: they grow and divide independently of the other organelles, and they have their own genomes. they are both specialized to harness energy for the cell. both are thought to have evolved from bacteria that were captured by a eukaryotic cell.

The two polynucleotides that make up double-stranded DNA are said to be antiparallel. This means that: one strand is composed of purines; the other strand is composed of pyrimidines. one strand has major grooves; the other has minor grooves. they run in opposite directions: the 3' end of one is across from the 5' end of the other. the nucleotides of one strand are oriented differently-- they are "upside-down" relative to the nucleotides in the other strand.

they run in opposite directions: the 3' end of one is across from the 5' end of the other. the nucleotides of one strand are oriented differently-- they are "upside-down" relative to the nucleotides in the other strand.

Which of the following definitions is/are correct about transcription and translation? transcription is about making an mRNA strand complementary to a DNA template. translation is about synthesizing a polynucleotide from an mRNA template. transcription is about making a new DNA strand from a template. translation is about synthesizing a polypeptide from an mRNA template.

transcription is about making an mRNA strand complementary to a DNA template. translation is about synthesizing a polypeptide from an mRNA template.

Regarding the Central Dogma of molecular biology: translation refers to the synthesis of a protein (a sequence of amino acids) from an RNA template. transcription refers to the synthesis of an RNA, using a DNA template. transcription and translation of every gene occurs in all cells at all times. translation refers to the synthesis of a protein (a sequence of amino acids) from a DNA template.

translation refers to the synthesis of a protein (a sequence of amino acids) from an RNA template. transcription refers to the synthesis of an RNA, using a DNA template

Proteins that are embedded in membranes act as transporters that move ions and molecules across the membrane enzymes that catalyze reactions anchor that attach to other proteins and help to maintain cell structure and shape signal receptors

transporters that move ions and molecules across the membrane enzymes that catalyze reactions anchor that attach to other proteins and help to maintain cell structure and shape signal receptors

What structures does a typical plant cell possess that a typical animal does not? vacuole cell wall chloroplasts plasmodesmata

vacuole cell wall chloroplasts plasmodesmata

We can think of proteins as analogous to words in English, with amino acids as the letters. with nucleotides as the letters. and the order of the letters in the word (or the amino acids in the protein) can change the meaning of the word (or the structure of the protein).

with amino acids as the letters. and the order of the letters in the word (or the amino acids in the protein) can change the meaning of the word (or the structure of the protein).

Imagine a section of the membrane that is comprised of phospholipids with long tails, saturated tails, and lots of cholesterol. This localized area of membrane, called a lipid raft, would be more fluid than the surrounding membrane. would be less fluid than the surrounding membrane. if it had proteins embedded in it, would facilitate the ability of those proteins to move around. if it had proteins embedded in it, would reduce the ability of those proteins to move around.

would be less fluid than the surrounding membrane. if it had proteins embedded in it, would reduce the ability of those proteins to move around.