Week 1 (ch. 1-5)

while small, uncharges molecules can diffuse through the hydrophobic core of a phospholipid bilayer, larger polar molecules such as glucose must enter cells by binding to

carrier proteins that facilitate the passage of specific molecules across membranes

While small, uncharged molecules can diffuse through the hydrophobic core of a phospholipid bilayer, larger polar molecules such as glucose must enter cells by binding to

carrier proteins that facilitate the passage of specific molecules across membranes.

n plants, the molecule that captures energy from sunlight is

chlorophyll

Solid tissues in animals include epithelial tissue, _______ tissue, nervous tissue, and muscle.

connective

In RNA interference, expression of a gene is most effectively inhibited by injection of

dsDNA

The main difference between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) is that

dsDNA has bases that include thymine (T), while ssDNA has bases including uracil (U)

In fluorescence microscopy, the immediate source of the light detected is light that has been _______ the sample.

emitted by

Cholesterol, a membrane lipid in animals, has a chemical structure similar to

estradiol

T/F: Caenorhabditis elegans is an important organism for the study of plant development.

false

T/F: Nucleic acid synthesis occurs by polymerization of nucleotide monophosphates into DNA or RNA.

false

T/F: The amount of free energy released when bonds are broken during a reaction is higher when the molecule has more electronegative atoms.

false

Our fundamental knowledge about mutation, genetic linkage, and the relationships between genes and chromosomes was acquired largely from experiments on the

fruit fly Drosophila

Embryonic stem cells are different from primary cell cultures or permanent cell lines derived from a tissue in that they are capable of

generating many cell types

the Calvin cycle is involved in the synthesis of _______ from _______.

glucose from CO2

Phospholipids consist of a 3-carbon core to which two fatty acids and a phosphate group are linked. The most common 3-carbon core is

glycerol

Which energy-producing process is thought to have come first during cellular evolution?

glycolysis

In polysaccharides, sugars are linked together by means of _______ bonds

glycosidic

Which technique is used to inactivate a gene by altering the DNA that encodes it?

homologous recombination

mutations may be introduced into selected genes of living cells by

homologous recombination with an altered cloned gene

Which method requires the experimental construction of two fusion proteins to assess protein-protein interactions?

immunoprecipitation

The technique by which a particular nucleic acid sequence is localized with labeled probes within a cell, tissue, or isolated chromosome is called _______ hybridization

in situ

The Calvin cycle can occur

in the absence of light

The role of double bonds in the fatty acid tails of membrane phospholipids is to

increase membrane fluidity

Electron transport and oxidative phosphorylation are performed by protein complexes in the mitochondrial

inner membrane

NADH produced in glycolysis yields fewer ATP molecules than that produced in the citric acid cycle because

its electrons are shuttled across the mitochondrial inner membrane to complex II.

What is a common method for testing blood samples of athletes for the presence of performance enhancing drugs?

mass spectrometry

Phospholipids in a membrane commonly

move laterally in the plane of the bilayer and rotate within the bilayer.

Which method would be used to determine if drug treatment of a cell culture led to increased expression of mRNA?

northern blotting

Which of the following cell components will be concentrated in the first pellet produced by differential centrifugation?

nuclei

In the primary structure of a protein, amino acids are joined together by _______ bonds.

peptide

Transgenic plants are easier to produce than transgenic animals because

plants can be grown more easily from single cultured cells into which recombinant DNA has been introduced.

Proteins must have more than one _______ to have a quaternary structure.

polypeptide chain

The unique functions of different membranes are primarily due to their

proteins

Sequencing the genomes of Caenorhabditis elegans and Drosophila melanogaster led to the discovery of many new genes for

proteins for regulating animal development

The interaction of two α and two β subunits to form a functional hemoglobin molecule is an example of _______ structure

quaternary

Sphingomyelin contains two hydrocarbon chains linked to

serine

Epinephrine increases available glucose by binding to a cell surface receptor that activates a G protein, which then activates cAMP-dependent protein kinase, then phosphorylase kinase, and finally glycogen phosphorylase, which breaks down glycogen into glucose-1-phosphate. This is an example of

signaling pathway

What is the term used in cell biology to describe the transmission of information from the environment, such as the presence of a hormone, to targets within the cell?

signaling pathway

The fluid mosaic model of cell membranes was proposed by

singer and nicholson

SDS-polyacrylamide gel electrophoresis (SDS-PAGE) separates proteins by

size

Coenzymes are

small molecules that work with an enzyme to enhance reaction rate.

What is the major carbohydrate-storage molecule in plants?

starch

Which character is NOT necessary in a plasmid vector to facilitate successful cloning?

strong bacterial promoter

Which of the following would not necessarily be part of a cellular signaling network?

synthetic genetic toggle switches

Which method would best determine posttranslational modifications to a protein, such as phosphorylation?

tandem mass spectrometry

In tandem mass spectrometry the unique second phase is characterized by

the addition of a collision based fragmentation step to the first phase sample to determine amino acid sequence.

When introduced into living cells, antisense RNA molecules bind

to complementary mRNA sequences and block protein synthesis

The simplicity and clarity of Caenorhabditis elegans allowed researchers to

trace the developmental lineages of all cells in the adult.

T/F: Ammonia is incorporated into organic molecules primarily during the synthesis of the amino acids glutamate and glutamine.

true

T/F: Eukaryotes contain a mixture of genes from eubacteria and archaebacteria.

true

T/F: Hybridization of fluorescent labeled cDNAs to microarrays of thousands of gene sequences allows gene expression to be assayed.

true

T/F: In photosynthesis, energy from sunlight is used to drive the synthesis of ATP and NADPH.

true

T/F: Plastoquinone (PQ) can carry electrons from both photosystems I and II to cytochrome bf.

true

To sequence the human genome, the International Human Genome Sequencing Consortium

used BAC clones as substrates for sequencing.

To identify the protein against which a given sample has an antibody, the best technique to use would be _______ blotting.

western

Which technique would be used to clone intact pieces of human DNA that are 400 kb pairs long?

yeast artificial chromosome

Which fish is proving to be a useful model organism for the study of vertebrate development

zebrafish

Light is captured by _______ different photosystems associated with the thylakoid membranes of chloroplasts.

2

The diffraction limited resolving power of a standard light microscope is approximately

2 Å

Through the oxidation process, fatty acids produce approximately _______ energy per gram compared to carbohydrates.

2.5

An E. coli cell under well-defined laboratory conditions divides about every

20 minutes

What are the energetic consequences of coupling a reaction with a + ΔG to one with a larger - ΔG?

A ΔG that is favorable overall and drives the reaction with a +ΔG in the forward direction

Which of the following is a high-resolution light microscope technique for detecting interactions between proteins?

FRET (fluorescence resonance energy transfer)

Which statement correctly describes the difference between the proton gradient across the inner mitochondrial membrane and the proton gradient across the thylakoid membrane of chloroplasts?

The first creates an electrochemical gradient, while the second produces a mostly chemical gradient.

Organelles such as mitochondria and chloroplasts are thought to have originated in eukaryotic cells via a process called

endosymbiosis

T/F: Glycolysis can act on glucose or fatty acids as initial substrates.

false

T/F: Higher plants and higher animals are similar in that they contain about the same number of different cell types.

false

T/F: Lipids are synthesized from acetyl CoA, which is produced by reversing the citric acid cycle.

false

introducing a double bond into a fatty acid puts a(n) _______ into the conformation of the molecule.

kink

The initial importance of membrane-enclosing, self-replicating RNA molecules and associated proteins was that they

maintained these molecules as a unit capable of reproduction and evolution.

Which of these organisms is not a unicellular eukaryote?

methanococcus

Phospholipid bilayers are permeable only to molecules that are _______ and _______.

small; uncharged

T/F: Some enzymes participate directly in the chemical reactions they catalyze.

true

T/F: Sphingomyelin is a serine-based phospholipid.

true

T/F: The glucose molecules in cellulose are joined by β(1→4) bonds.

true

T/F: The oxidation of NADH via the electron transport chain is a highly efficient process with little or no energy loss to heat.

true

T/F: The sugar groups of glycolipids and glycoproteins are found on the outer surface of the plasma membrane

true

T/F: Viruses can have either RNA or DNA for their genetic material.

true

A common use of green fluorescent protein (GFP) is to

visualize proteins living in cells

Super-resolution light microscopes extend the resolution limits of light microscopy to

20-100 nm

The human body is composed of more than _______ different types of cells.

200

How many genes does an E. coli have?

4,200

Fully folded proteins typically have polar side chains on their surfaces, where electrostatic attractions and hydrogen bonds can form between the polar group on the amino acid and the polar molecules in the solvent. In contrast, some proteins have a polar side chain in their hydrophobic interior. Which of the following would NOT occur to help accommodate an internal, polar side chain?

A hydrogen bond forms between a polar side chain and an aromatic side chain.

Which of the following is a key molecule in the electron transport chain in mitochondria?

Cytochrome c

ATP is synthesized in photosynthesis by which of the following means?

Light energy absorbed by photosystems I and II generate energetic electrons that cause the cytochrome bf complex to pump protons across the thylakoid membrane; these protons drive ATP synthase to synthesize ATP.

Organisms that evolved the ability to use H2O as a donor of electrons and hydrogen for the photosynthetic conversion of CO 2 to organic compounds radically changed Earth by producing

O2

The feature that most clearly distinguishes eukaryotes from prokaryotes is the presence of _______ in eukaryotic cells.

a nucelus

T/F: Most proteins interact with other proteins through covalent protein-protein interaction

false

T/F: One conclusion derived from the Singer and Nicolson fluid mosaic model of membrane structure is that integral membrane proteins are freely soluble in water.

false

T/F: Photosynthesis first evolved in the green algae.

false

T/F: The frog Xenopus laevis is useful for studying early development because its eggs are small and clear.

false

T/F: The function of glycogen, starch, and cellulose is to store glucose.

false

T/F: Viruses are complexes of nucleic acid and protein that can replicate on their own.

false

Animal cells can synthesize glucose (gluconeogenesis) from all of the following except

fatty acids

Specific proteins can be localized in the transmission electron microscope by use of

gold-labeled antibodies

In fluorescence photobleaching experiments, recovery time is defined as the amount of time it takes the bleached area to regain its fluorescence. The recovery time for a cell with fluorescently labeled membrane proteins is

longer than the recovery time for a cell with fluorescently labeled lipids because lipids diffuse faster than proteins.

n photosynthesis, all of the following reactions are directly dependent on light except

nitrogen fixation

Polymerization of nucleotides to form nucleic acids involves the formation of _______ bonds.

phosphodiester

In glycolysis, the key control enzyme that is inhibited by excess ATP is

phosphofructokinase.

Under aerobic conditions, the NADH formed during glycolysis

provides additional energy by donating its electrons to the electron transport chain.

Because of the central role that one amino acid plays in the mechanism by which proteins are cleaved by the enzymes trypsin and chymotrypsin, these enzymes are called _______ proteases.

serine

Anfinsen's experiments on denatured ribonuclease showed that

the conformation of the folded protein is determined by its amino acid sequence.

The Rous sarcoma virus (RSV) is

the first cancer causing animal virus to be identified.

Protons are freely permeable across

the outer, but not the inner, mitochondrial membrane.

The most energetically favorable reactions in glycolysis are catalyzed in reverse in gluconeogenesis by

the use of different enzymes coupled with energy from ATP or NADH

Light-dependent generation of ATP in photosynthesis occurs in the

thylakoid membrane

the role of cytochrome c in the electron transport chain is to

transfer electrons from complex III to complex IV.

Passive transport across a membrane refers to

transport in the energetically favorable direction.

Fatty acids are stored in fat droplets in the form of

triacylglycerols

T/F: Christian Anfinsen and colleagues showed in the 1950s that proteins contain all the information to spontaneous fold into an active enzyme. Yet sixty years later, we can still not predict the three-dimension shape of a protein from its amino acid sequence.

true

T/F: Freeze fracture splits lipid bilayers and allows examination of the distribution of proteins that span the bilayer.

true

T/F: Most of the genes of the bacterial symbionts that evolved into mitochondria are now found in the nucleus.

true

T/F: Most proteins interact with other proteins through covalent protein-protein interactions.

true

T/F: Similarities in basic metabolic mechanisms indicate that all present-day cells on Earth descended from a single primordial ancestor.

true

T/F: With appropriate stimulation, mammalian stem cells in culture can give rise to individual mammalian cell types and hence may provide a source of patient-specific replacement cells.

true

Chymotrypsin, trypsin, elastase, and thrombin are all members of the serine protease family because each

uses the same catalytic mechanism involving the same key amino acids.

The three-dimensional structure of a protein is analyzed most definitively by

x ray crystallography

The incorporation of each amino acid into a protein is coupled to the hydrolysis of _______ molecule(s).

1 ATP and 2 GTP

Humans have about 20,000 genes that encode proteins. It is estimated that through alternative splicing and protein modifications, these genes can give rise to how many different proteins?

100,000

Fatty acids are broken down in a stepwise process, _______ carbon(s) at a time.

2

A restriction enzyme with a four-base recognition site would cleave DNA with a statistical frequency of once every

256 bp

The human genome contains approximately _______ billion base pairs.

3

The restriction enzyme NotI recognizes a specific DNA sequence of eight base pairs and cleaves at that site. Statistically, in any genome there should be one NotI recognition site for every _______ base pairs.

4^8

You have identified an unknown protein of approximately 1,500 amino acids. The minimum length of its mRNA is approximately

500 nucleotides

Analysis of the first bacterial genome to be sequenced, H. influenzae, revealed _______ rRNA genes, _______ different tRNA genes, and _______ potential protein-coding genes.

6; 54; 1,743

Analysis of the H. influenza and E. coli genomes revealed that _______% of each genome encodes for protein

90

Why can't a digest of human genomic DNA be resolved by gel electrophoresis?

A typical digest of the human genome produces too many fragments to resolve

Which sequence correctly outlines the process of RNA interference, beginning with a double-stranded RNA molecule?

Cleavage by Dicer; association with RISC; unwinding of siRNA; pairing with target mRNA; mRNA cleavage

6-Mercaptopurine is a potent inhibitor of

DNA synthesis

A cDNA molecule is

DNA synthesized from an RNA template using the enzyme reverse transcriptase

In 2010, scientists developed a series of overlapping oligonucleotides that extended a full 1.08 million base pairs and used it to develop the first complete organism using a synthetic genome. The newly created cells had normal growth and morphology. What organism did they generate in these groundbreaking experiments?

E. coli

The most abundant molecules in cells are

H2O

In which of the following organisms is the highest percentage of its genome used to encode protein?

Haemophilus influenzae

in 1995, the first complete genome of _______ was sequenced by Dr. Craig Venter.

Haemophilus influenzae

Together, glycolysis and the citric acid cycle (also known as the Krebs cycle) directly generate two molecules of ATP and two molecules of GTP. Most of the energy derived from the oxidation of glucose comes from the oxidation of the _______ generated from _______.

NADH; the citric acid cycle

Which statement describes the most common relationship of the inhibitor molecule to the allosteric enzyme in feedback inhibition of enzyme activity?

The inhibitor is the final product of the metabolic pathway

In the synthesis of glycogen, glucose-1-phosphate reacts with a nucleotide triphosphate to form _______-glucose.

UDP

Cytoplasmic organelles are

absent in prokaryotic cells and present in eukaryotic cells

The CRISPR/Cas system has revolutionized the efficiency with which scientists can mutate a gene in vivo to investigate the functional role of the protein it encodes. Which component is not essential in the CRISPR/Cas system?

access to target mRNA

Molecules that traverse a membrane against their concentration gradient do so by _______ transport.

active

proteins can be covalently modified by the addition of phosphate groups to all but which of the following amino acids?

all but arginine

passive transport molecules

allow small molecules across membranes

Stanley Miller applied electric sparks to a reducing atmosphere of methane, ammonia, water, and hydrogen, and the resulting products showed that under these conditions,

amino acids can form

A reaction in which the substrate glucose binds to the enzyme hexokinase and the configuration of both molecules changes is an example of

an induced fit mechanism.

Vectors for expressing a eukaryotic protein in a bacterium must contain

an origin of replication

All of the following are ways in which enzyme activity can be regulated except

by modulation of intracellular sucrose concentrations.