Lab Technology Microscopy Flashcards

Question

This image was taken with electron microscopy. Which animal cell organelle is this? A. Golgi Apparatus B. Smooth ER C. Nucleus D. Mitochondria E. Rough ER

Answer 1

B. Smooth ER The smooth endoplasmic reticulum (ER) is a membranous network and is free of ribosomes. The smooth ER functions in lipid and steroid biosynthesis and detoxification.

Answer 2

C. Golgi Apparatus The Golgi apparatus is composed of flattened membranous sacs (cisternae). This organelle functions in modifying and packaging products from the endoplasmic reticulum. Vesicles pinch off from the Golgi and carry their products to their specific destinations.

Answer 3

D. TEM creates a 2D image A scanning electron microscope (SEM) bombards a nonliving sample with electrons and produces extremely high-resolution 3D images of the sample’s surface. A transmission electron microscope (TEM) is used to obtain extremely high-resolution 2D images of cells’ internal structures.

Answer 4

A. Confocal Laser Scanning Microscopy Confocal laser scanning and fluorescence microscopy are commonly used together to view thin slices of live tissue. Fluoresce can produce artifacts, or distortions, in the sample. The confocal laser focuses light directly on the substrate and controls the depth of focus, thereby preventing artifacts from occurring.

Answer 5

B. Transmission Electron Microscopy A transmission electron microscope (TEM) is used to obtain extremely high-resolution 2D images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Answer 6

B. Scanning Electron Microscopy A scanning electron microscope bombards a nonliving sample with electrons and produces extremely high-resolution 3D images. The preparation of samples is very expensive and also requires dehydration.

Answer 7

A. Phase-Contrast Microscop A phase-contrast microscope is used to view thin live cells, as well as their internal structures. This kind of microscope creates a phase shift that leads to the high contrast between the sample and the surrounding field. Therefore, the dental plaque will not interfere with viewing the living bacteria.y

Answer 8

B. Dark Field Microscopy A dark field microscope is used to view unstained live cells by creating a high contrast of light between the cells and the background. The high contrast results in the surrounding field appearing extremely dark. A scientist performed electron tomography to form a

Answer 9

A. Transmission Electron Microscopy Electron tomography is an analytical lab technique that stitches together many 2D photos to create a 3D model of a sample. The 2D images are obtained using a transmission electron microscope. This technique cannot be used on living samples. Note: Electron tomography is an analytical lab technique and not a type of microscopy.

Answer 10

B. Can view cell in a more natural form Electron microscopes bombard a nonliving sample with electrons and produce images with extremely high resolution. The conventional scanning electron microscope uses dehydrated samples. When using a Cryo SEM, however, samples are frozen in liquid nitrogen instead of dehydrating them, which keeps them in their more natural forms.

Answer 11

A. Sample is too thick A phase-contrast microscope is used to view thin live cells, as well as their internal structures if the cell is thin enough. This kind of microscope creates a phase shift that leads to a high contrast between the sample and the surrounding field. The sample is generally prepared by freezing or treating it with chemicals.

Answer 12

A. Compound Microscopy A compound microscope is very similar to a light microscope in that it uses visible light to view a sample. The difference is that a compound microscope uses multiple lenses. This kind of microscope allows one to view a single cell layer with its internal structures and usually requires staining to best visualize the sample.

Answer 13

C. Stereomicroscopy Stereomicroscopy, also known as light microscopy, uses visible light to view the surface of an object. Light microscopes have low magnification and resolution.

Answer 14

B. Transmission Electron Microscopy A transmission electron microscope (TEM) is used to obtain extremely high resolution 2D images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Answer 15

C. Homogenization Before differential centrifugation, cells must be lysed in a process known as homogenization, and cellular contents are released. Differential centrifugation is a lab technique that separates macromolecules on the basis of density and shape.

Answer 16

A. Most dense layer in the centrifuge tube

Answer 17

D. Less dense layer in the centrifuge tube

Answer 18

List the order of the cell organelles below from most to least dense. I. ER fragments II. Ribosomes III. Mitochondria/Chloroplast IV. Nuclei A. 4,3,1,2 The nucleus is the most dense component of a cell as it is composed of the nuclear envelope and chromatin. Mitochondria and chloroplasts are similar in density and have greater density than the endoplasmic reticulum. Ribosomes are small and the least dense of these choices.

Answer 19

B. Ribosome Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The least dense particles will pellet out last. The nucleus is the most dense component of a cell, composed of the nuclear envelope and chromatin. Mitochondria and chloroplasts are similar in density and have greater density than the endoplasmic reticulum. Ribosomes are small and the least dense of these choices.

Answer 20

B. Mitochondria Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The most dense particles will pellet out first. The nucleus is the most dense component of a cell, followed by mitochondria/chloroplasts. If the pellet with the nuclei is discarded, the mitochondria and chloroplasts will then be first to pellet out of the supernatant.

Answer 21

B. ATP Differential centrifugation is a common procedure used to separate organelles and other sub-cellular particles based on their sedimentation rate. Particles of different densities or sizes in a suspension will sediment at different rates, with the larger and denser particles sedimenting faster. The nucleus is the most dense component of a cell, followed by mitochondria/chloroplasts, and the very last components seen would be ribosomes (and other small particles that may be present such as viruses). Given that the tube has gone through two cycles of centrifugation, we would expect to find mitochondria/chloroplast in this pellet layer. Finally, ATP would be produced in significant amounts by mitochondria found in this layer because it is the major ATP-producing organelle in the cell.

Answer 22

A. Insoluble proteins Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. Proteins can also be separated by centrifugation according to their solubility. An insoluble protein will appear in the pellet, and a soluble protein will remain dissolved in the supernatant.

Answer 23

E. Cytosol Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The cytosol is the least dense cellular component and will therefore pellet out last.

Answer 24

Separation of cell contents with multiple spin steps

Answer 25

A. Nuclei During centrifugation, the most dense particles will pellet out of the cell homogenate first. The nucleus is the most dense component of a cell, as it is composed of the nuclear envelope and chromatin, and is, therefore, most likely to appear in the precipitate.

Answer 26

B. Keep the supernatant

Answer 27

B. Centrifuge the tube again Centrifuging the tube again will separate the homogenized supernatant and pellet. The pellet will reform and be separate from the supernatant.

Answer 28

D. Cytosol Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The cytosol is the least dense cellular component and will therefore pellet out last.

Answer 29

C. Differential centrifugation

Answer 30

A. Density centrifugation

Answer 31

A. Spinning cell components at high speeds Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The centrifuge spins test tubes containing cell components at extremely high velocities which force denser components to form a pellet at the bottom of the tube.

Answer 32

B. Laboratory mixer Before centrifugation, cells should be mixed together to form a liquified cell homogenate. A laboratory mixer is the proper piece of lab equipment to homogenize cells.

Answer 33

A. DNA summated from different organisms

Answer 34

B. Bacterial transfection Transfection is a form of horizontal gene transfer in which foreign DNA is introduced into a eukaryotic cell without the use of a virus. Physical and/or chemical methods are employed that enable DNA to easily enter the eukaryotic cell.

Answer 35

A. Restriction endonucleases When DNA from different organisms is combined in vitro, recombinant DNA is formed. Restriction endonucleases are used to cut the DNA at specific palindromic sequences, and the fragments are then ligated together.

Answer 36

A. Sticky ends

Answer 37

C. Protect itself from invading DNA Restriction endonucleases cut DNA at specific palindromic sequences. In bacteria, these enzymes work like an immune system; they recognize and cut foreign DNA to prevent it from integrating into the bacterial genome.

Answer 38

A. Restriction fragment length polymorphisms Different individuals have variations within homologous DNA sequences at the sites recognized by restriction enzymes; these variations are referred to as restriction fragment length polymorphisms. These variations result in differences in DNA fragment length which can be used in identifying individuals utilizing gel electrophoresis in a process known as DNA fingerprinting.

Answer 39

B. Short tandem repeats DNA fingerprinting is a lab technique used to identify individuals based on specific DNA fragments. Restriction fragment length polymorphisms and short tandem repeats are common DNA segments used in DNA fingerprinting.

Answer 40

D. Short tandem repeats are analyzed using probes and PCR amplification Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. Analysis of STRs includes probing and PCR amplification. Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. Restriction enzymes are used for analysis since they will cut RFLPs differently among individuals and produce DNA fragments of varying lengths.

Answer 41

C. Repeats of nucleotides that vary between humans Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. STRs are different among every individual except identical twins.

Answer 42

B. Identical twins Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. STRs are different among every individual except identical twins. Note: Identical twins are monozygotic and result from indeterminate cleavage, and therefore are genetically identical.

Answer 43

C. Different fragment lengths depending on individual specific differences in DNA Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. When cut by restriction enzymes, fragment lengths will differ among individuals due to these different DNA sequences.

Answer 44

C. Fragments of different lengths Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. When cut by restriction enzymes, fragment lengths will differ among individuals due to the different DNA sequences. The fragments of different lengths are observed due to polymorphisms, which occur when there are multiple phenotypes that exist within a population.

Answer 45

A. Transfer foreign DNA into another cell In order to express a eukaryotic gene in a bacterium, it must be transferred in some way. A vector is an agent used to transfer the foreign DNA into another cell. A vector can be either a plasmid or a bacteriophage.

Answer 46

B. Plasmid In order to express a eukaryotic gene in a bacterium, it must be transferred in some way. A vector is an agent used to transfer foreign DNA into another cell. A vector can be either a plasmid or a bacteriophage.

Answer 47

A. Transformation

Answer 48

D. Expression vectors contain a very active promoter of the restriction site Cloning vectors contain the DNA segments that contain the gene of interest, the origin of replication, and restriction sites. An expression vector consists of the same elements, but also contains a very active promoter and other regulatory sites.

Answer 49

D. Electroporation

Answer 50

B. Heat shock + CaCl2

Answer 51

D. Antibiotic resistance screen Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Answer 52

A. Die Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Answer 53

C. Separate DNA molecules Gel electrophoresis is a laboratory technique that uses an electric current to separate DNA fragments or proteins in agarose gel. DNA fragments or proteins are separated on the basis of size; smaller molecules migrate furthest. DNA is negatively charged due to its phosphate groups. Therefore, DNA is placed by the negatively charged cathode and will migrate toward the positively charged anode.

Answer 54

B. Positive end DNA is negatively charged due to the phosphate groups. Therefore, DNA is placed by the negatively charged cathode and will migrate toward the positively charged anode.

Answer 55

A. Small molecules Gel electrophoresis is a laboratory technique that uses an electric current to separate DNA fragments or proteins in agarose gel on the basis of size. Smaller molecules will migrate the furthest because they can easily fit through the pores in the gel.

Answer 56

B. Negative charge of the phosphate backbone

Answer 57

A. SDS Due to the presence of their R groups, proteins have different charges that will affect their migration patterns during gel electrophoresis. SDS (sodium dodecyl sulfate) is a chemical that denatures proteins and gives them all a uniform negative charge.

Answer 58

B. Adds a negative charge to the protein Due to the presence of their R groups, proteins have different charges that will affect their migration patterns during gel electrophoresis. SDS (sodium dodecyl sulfate) is a chemical that denatures proteins and gives them all a uniform negative charge.

Answer 59

A. Complementarily bind to the gene of interest A DNA probe is a radioactively labeled single-stranded DNA molecule used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Answer 60

A. Identify the specific DNA sequence A DNA probe is a radioactively labeled single-stranded DNA used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Answer 61

C. Nucleic acid hybridization DNA probes have complementary sequences for a sequence of interest. During nucleic acid hybridization, the DNA (or RNA) and DNA probe are denatured and then hybridize with each other. The result is two double-stranded DNA molecules with strands from a different sources.

Answer 62

A. In situ hybridization A nucleic acid probe is a fluorescently labeled single-stranded DNA molecule used to locate and identify specific DNA sequences. Probes have complementary sequences for the sequence of interest. In situ hybridization uses nucleic acid probes to measure gene expression in intact organisms by identifying specific mRNA molecules.

Answer 63

A. Next-generation sequencing Next generation sequencing is the current method used to sequence a DNA molecule and utilizes PCR.

Answer 64

B. Reverse transcriptase Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. This enzyme can be used to create cDNA (complementary DNA). cDNA is extremely useful as it lacks introns and is composed of exons only; this enables the insertion of human DNA into bacteria for experimentation. Reverse transcriptase is also found in retroviruses, such as HIV.

Answer 65

A. Reverse transcriptase Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. HIV is a retrovirus; within the host cell, its RNA genome is transcribed into DNA by reverse transcriptase and then inserted into the host cell’s DNA genome.

Answer 66

B. No introns Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. This enzyme can be used to create cDNA (complementary DNA). cDNA is extremely useful as it lacks introns and is composed of exons only; this enables the insertion of human DNA into bacteria for experimentation.

Answer 67

C. Single-stranded DNA A DNA probe is a radioactively labeled single-stranded DNA molecule used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Answer 68

A. Death Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Answer 69

B. Antibiotic resistance gene present in plasmid Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Answer 70

B. Electroporation A competent cell is one that is capable of taking up exogenous DNA from the environment. There are two main methods of making bacterial cells competent. The first method is electroporation, in which the cell is given a quick electrical pulse that creates pores in the plasma membrane. The other method is to heat shock and treat with CaCl2.

Answer 71

A. Restriction enzymes

Answer 72

D. DNA ligase Restriction enzymes cut DNA at specific sequences and can generate sticky ends (staggered cuts) or blunt ends (straight cuts). DNA ligase is an enzyme that stabilizes the interaction between the plasmid and DNA by catalyzing the covalent bonding between the molecules.

Answer 73

C. Sticky ends have an overhang

Answer 74

A. Effective transcription and translation of gene cDNA (complementary DNA) lacks introns and is composed of exons only. Because there are no introns, splicing is not required and enables effective transcription and translation of genes. cDNA is extremely useful for when we wish to express eukaryotic genes in bacteria which lack splicing activity.

Answer 75

. Polymerase Chain Reaction The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. There are three steps of PCR: (1) denaturation, (2) annealing, and (3) elongation.

Answer 76

C. Denaturation, Annealing, Elongatio The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. During step 1, denaturation, DNA is heated to separate the double-stranded DNA. Step 2, annealing, involves DNA primers annealing the single-stranded DNA. Step 3 is the elongation of the strands in which Taq polymerase adds nucleotides to the 3` ends.

Answer 77

C. Human DNA polymerase The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The reactions reach almost 100 ˚C which requires a heat-resistant enzyme to be used. Unlike human DNA polymerase, Taq polymerase (derived from the thermophilic bacterium Thermus aquaticus) is extremely heat-stable.

Answer 78

B. Heat resistant The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The reactions reach almost 100 ˚C which requires a heat-resistant enzyme to be used. Unlike human DNA polymerase, Taq polymerase (derived from the thermophilic bacterium Thermus aquaticus) is extremely heat-stable.

Answer 79

C. Separate the double-stranded DNA molecule The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. In order for the DNA to be replicated, the strands must first be separated by denaturation. Once denatured, a primer is added and then the strands are elongated using Taq polymerase.

Answer 80

B. DNA strands would all be double-stranded and unable to separate

Answer 81

C. Allow primers to bind to separated strands of DNA During the annealing phase of PCR, the temperature is lowered to 55 ˚C. At this temperature, primers are able to bind to the separated strands of DNA.

Answer 82

B. The polymerases are less likely to denature when the temperature is raised during PCR PCR (shown in the image below) requires thermostable or heat-stable DNA polymerases to carry out synthesis because high temperatures are used to separate the template DNA strands in each cycle during the denaturation step. Because DNA polymerases are (protein) enzymes, they are susceptible to becoming denatured when exposed to these high temperatures. Certain bacteria and archaea are adapted to extremely hot environments, so their enzymes are more resistant to heat destabilization, making these polymerases an ideal fit for PCR.

Answer 83

A. Hydrogen bonds are breaking between the DNA strands

Answer 84

A. Premature stop of DNA separation The denaturation step of PCR is performed at 95 ˚C in order to separate the two strands of double-stranded DNA. If the temperature was not maintained during this step, the separation of the DNA would stop prematurely and the DNA will only be partially denatured.

Answer 85

Hydrogen bond to the separated DNA strands During the annealing phase of PCR, the temperature is lowered to 55 ˚C. At this temperature, primers are able to bind to the separated strands of DNA. Primers are the nucleotides that begin the complementary strand of DNA and they form hydrogen bonds with the template strand.

Answer 86

Allow the primer to bind to the separated DNA strands The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. In order for the DNA to be replicated, the strands must first be separated by denaturation. Once denatured, a primer is added and then the strands are elongated using Taq polymerase.

Answer 87

In multiple cycles The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. During each cycle, the total number of DNA strands doubles as each DNA strand is replicated to give two daughter strands. After one cycle, there are two strands of DNA; after two cycles, there are four strands of DNA, and so on. Multiple cycles are performed during PCR in order to obtain millions of copies.

Answer 88

A. Single nucleotide polymorphisms Different individuals have single-nucleotide variations within homologous DNA sequences; these variations are referred to as single nucleotide polymorphisms (SNPs). For example, at homologous sequences, one person can have the sequence AAAAAA, and another person can have the sequence AAAAAT. SNPs are responsible for many diseases and much of the genetic variation we see.

Answer 89

C. Single nucleotide polymorphisms Different individuals have single-nucleotide variations within homologous DNA sequences; these variations are referred to as single nucleotide polymorphisms (SNPs). For example, at homologous sequences, one person can have the sequence AAAAAA, and another person can have the sequence AAAAAT. SNPs are responsible for many diseases and much of the genetic variation we see.

Answer 90

C. Restriction fragment length polymorphisms Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. Restriction enzymes are used to discover RFLPs since they will cut the RFLPs differently in each individual and produce DNA fragments of varying lengths. Polymerase chain reaction (PCR) cannot be used to discover RFLPs.

Answer 91

C. DNA microarray assay The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed.

Answer 92

E. DNA microarray assay The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed.

Answer 93

Reverse transcriptase The DNA microarray assay consists of thousands of DNA probes that represent different genes. Reverse transcriptase is an enzyme that synthesizes cDNA from an mRNA template. cDNA is then fluorescently labeled and will hybridize with the DNA probes.

Answer 94

The gene in the DNA microarray is only expressed in the cancerous tissue The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because this well lights up as red fluorescence, the gene contained in the well must be expressed only in cancerous tissue.

Answer 95

E. The gene in the DNA microarray is expressed in both healthy and pathogenic tissue The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because this well lights up as purple fluorescence, the gene contained in the well must be expressed in both healthy (blue) and pathogenic (red) tissue.

Answer 96

D. The gene in the DNA microarray is not expressed in either healthy or malignant tissue The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because there is no fluorescence, the gene contained in the well is not being expressed in any type of tissue.

Answer 97

Cell density Blotting is a laboratory technique that involves the transfer of DNA, RNA, or proteins from an agarose gel onto a blotting membrane for the purposes of identification and diagnostics. Cell density is commonly identified using a spectrophotometer.

Answer 98

Gel electrophoresis Blotting is a laboratory technique that involves the transfer of DNA, RNA, or proteins from an agarose gel onto a blotting membrane for the purposes of identification and diagnostics. The first step of a Southern blot is to run the molecules of interest in gel electrophoresis to separate DNA fragments.

Answer 99

DNA identification The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 100

B. RNA identification The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 101

Protein identification The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 102

Southern Blotting The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 103

Northern Blotting The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 104

A. Western blotting uses antibodies A Western blot is used to identify proteins, and therefore uses tagged antibodies (or antibody-based probes) that will bind to the protein of interest. The tagged antibodies will change color when the blotting paper is treated with a color development solution. A Southern blot is used to identify DNA fragments, and a DNA probe is used to hybridize and mark the DNA. The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 105

B. Western Blot The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 106

A. DNA or RNA probes Southern and Northern blotting use DNA and RNA probes, respectively. Note: The mnemonic to remember the different blotting techniques is SNoW DRoP: S(outhern) – DNA N(orthern) – RNA W(estern) – protein

Answer 107

A. Aggregation of cloned DNA fragments from a genome A genomic library contains a copy of an organism’s complete genome. By screening a genomic library, specific genes can be located within the genome.

Answer 108

E. Genes of interest are inserted into plasmids Genes of interest are plasmids, which are small, circular pieces of DNA that can replicate independently of the genome of the organism that they are taken from. The plasmids containing the inserted genes of interest are then introduced into host cells, where they can be replicated and stored in large numbers. The resulting collection of plasmids containing the genes of interest is known as a gene library.

Answer 109

C. Plasmids are removed from bacterial cells to be used as vectors During gene cloning, a gene is inserted into a plasmid and then replicated. The plasmid must first be removed from the bacterial cells in order to add the gene of interest. After insertion of the gene and replication of the plasmid, it can now serve as a vector to be inserted into bacteria to express the gene.

Answer 110

B. Extraction of the gene of interest from cell During gene cloning, a gene is inserted into a plasmid and then replicated. The plasmid must first be removed from the bacterial cells in order to add the gene of interest. The gene of interest from another cell must then be extracted and inserted into the plasmid. The plasmid is replicated and can now serve as a vector to be inserted into bacteria to express the gene.

Answer 111

DNA ligase DNA ligase is an enzyme that stabilizes the interaction between the plasmid and DNA by catalyzing the covalent bonding between the two DNA molecules.

Answer 112

In vitro mutagenesis If a mutation occurs within a gene, its function can be altered. In vitro mutagenesis takes advantage of this by introducing mutations into a cloned gene. Phenotypic changes are observed and can be used to determine the function of the gene of interest.

Answer 113

E. Introduction of mutations to a cloned gene If a mutation occurs within a gene, its function can be altered. In vitro mutagenesis takes advantage of this by introducing mutations into a cloned gene. Phenotypic changes are observed and can be used to determine the function of the gene of interest.

Answer 114

In vitro mutagenesis In vitro mutagenesis is a procedure in which mutations are introduced into a cloned gene which will result in phenotypic changes. These changes can be used to determine the function of the gene of interest. In knockout mice, the gene of interest is “knocked out” (i.e. inactivated) and phenotypic changes are observed.

Answer 115

Primer specific PCR The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The presence of a gene sequence in an individual’s genome can be identified by using a specific primer that will hybridize to the sequence of interest.

Answer 116

Transgenic mice Oncomice are transgenic because they have a gene from a different species introduced into their genome. Transgenic animals are often studied to understand the function of a gene.

Answer 117

Knockout mice are more specifically targeted In transgenic mice, the gene of interest is removed and replaced with a gene from another organism. In knockout mice, the gene of interest is “knocked out” (i.e. inactivated). The method used in knockout mice specifically targets the gene of interest and inactivates it, whereas by transgenic mice, the gene that is removed may be randomly selected.

Answer 118

Examination of the genome and its interdisciplinary function Genomics is the branch of biology concerned with the study and examination of the entire genome and its interdisciplinary function.

Answer 119

Genomics looks at the whole genetic data of an organism Genomics is the branch of biology concerned with the study and examination of the entire genome and its interdisciplinary function. Genetics only looks at specific genes and heredity.

Answer 120

Spontaneous development of organisms is not possible without life already present Louis Pasteur’s swan neck flask experiment proved that organisms cannot develop spontaneously without life already being present. In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. When he tilted the flask to allow dust to mix with the broth, growth occurred. Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Answer 121

Bacteria formed in the broth In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. When he tilted the flask to allow dust to mix with the broth, growth occurred. Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Answer 122

Microorganisms could not form In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. Growth was only able to occur once he tilted the flask to allow dust to mix with the broth. Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Answer 123

Prevent the entry of microorganisms In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The curved neck of the flask prevented dust particles containing microorganisms from reaching the broth and therefore no microbial growth occurred.

Answer 124

List the steps of Pasteur’s swan neck flask experiment in a logical order. 1. Bacteria formed 2. Flask was left to sit 3. Bacteria did not form 4. Heat applied to the flask with curved neck 5. The curved neck was removed A. 4,2,5,1 In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The flasks were left to sit initially. One of the flask’s necks was then broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth. The other flask’s neck was kept intact and no growth occurred as microorganisms could not reach the broth.

Answer 125

. Kill off all existing microorganisms in broth In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The curved neck of the flask prevented dust particles containing microorganisms from reaching the broth.

Answer 126

Pneumonia strains Griffith’s transformation experiment showed that bacteria can transfer genetic traits to each other by transformation. In his experiment, Griffith mixed living non-virulent pneumoniae with inactivated virulent pneumoniae. Some of the non-virulent bacteria became virulent after being mixed with the virulent strain. The non-virulent bacteria was the rough (R) strain, and the virulent bacteria was the smooth (S) strain.

Answer 127

Genetic traits can be transferred using bacterial transformation Griffith’s transformation experiment showed that bacteria can transfer genetic traits to each other by transformation. In his experiment, Griffith mixed living non-virulent S. pneumoniae with inactivated virulent S. pneumoniae. Some of the non-virulent bacteria became virulent after being mixed with the virulent strain. The non-virulent bacteria was the rough (R) strain, and the virulent bacteria was the smooth (S) strain.

Answer 128

Smooth strain has a protective capsule

Answer 129

. Protect it from the immune system

Answer 130

B. Mouse lives

Answer 131

A. Mouse lives

Answer 132

Mouse dies

Answer 133

The smooth strain DNA was transferred to the rough strain

Answer 134

The rough strain and heat-killed smooth strain injection killed the mouse

Answer 135

DNA is heritable in bacterial transformation The Avery-MacLeod-McCarty experiment was conducted to discover what was the cause of bacterial transformation in Griffith’s experiment. They revealed that DNA was the heritable material that causing the bacterial transformation.

Answer 136

DNase The Avery-MacLeod-McCarty experiment revealed that DNA was the heritable material that caused the bacterial transformation. In their experiment, they treated cell lysate from heat-killed S strains (virulent) with various enzymes. The mixtures were then mixed with R strains (nonvirulent). The mixture with DNase was the only one that did not result in R strains becoming transformed into S strains because DNase digested the virulent S strain DNA.

Answer 137

DNase digested the virulent DNA from the smooth strain of pneumonia The Avery-MacLeod-McCarty experiment revealed that DNA was the heritable material that caused the bacterial transformation. In their experiment, they treated cell lysate from heat-killed S strains (virulent) with various enzymes. The mixtures were then mixed with R strains (nonvirulent). The mixture with DNase was the only one that did not result in R strains becoming transformed into S strains because DNase digested the virulent S strain DNA.

Answer 138

DNA is the genetic material The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively.

Answer 139

Virus that infects bacteria

Answer 140

Phosphorus and sulfur The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively.

Answer 141

DNA of the virus The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus to track DNA as it contains phosphorus in its phosphate groups. They used radioactive sulfur to track proteins as sulfur is contained in two of the amino acids (methionine and cysteine).

Answer 142

Protein of the virus The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus to track DNA as it contains phosphorus in its phosphate groups. They used radioactive sulfur to track proteins as sulfur is contained in two of the amino acids (methionine and cysteine).

Answer 143

Radioactively labeled phosphorus appeared inside the bacteria The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively. The radioactively labeled phosphorus (contained in DNA) appeared inside the bacteria after the phage infected it, proving that DNA is the genetic material that is being transferred. The radioactively labeled sulfur (contained in proteins) was not found to be transferred to the bacteria.

Answer 144

Rosalind Franklin Rosalind Franklin used X-ray diffraction to capture a photo of DNA. This photo assisted Watson and Crick in discovering that DNA has a double helical structure.

Answer 145

Meselson-Stahl experiment

Answer 146

Semiconservative

Answer 147

Parental strand serves as the template for the formation of a daughter DNA with one newly synthesized and one original parental strand

Answer 148

Johann Friedrich Miescher Johann Friedrich Miescher was the first to isolate DNA along with its associated proteins in 1869. He referred to this isolated product as nuclein.

Answer 149

Differentiated cells have altered gene expression Gurdon transplanted the nuclei of frog embryos (undifferentiated) and tadpoles (fully differentiated) into enucleated eggs. He discovered that the less differentiated the cell was, the more likely it was to develop into a tadpole. This experiment revealed that differentiated cells have altered gene expression since they cannot differentiate into other cell types.

Answer 150

The altered egg cell formed into a tadpole Gurdon transplanted the nuclei of frog embryos (undifferentiated) and tadpoles (fully differentiated) into enucleated eggs. He discovered that the less differentiated the cell was, the more likely it was to develop into a tadpole.

Answer 151

Reproductive cloning The first successful reproductive cloning of a mammal produced Dolly the sheep in 1996. A mammary cell and an enucleated egg cell from two separate sheep were fused and grown in culture. Once it was at the early embryo stage, it was placed into a surrogate. The embryo (Dolly) was genetically identical to the mammary cell donor sheep.

Answer 152

To track protein movement in a cell The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and are incorporated into proteins.

Answer 153

Size exclusion chromatography

Answer 154

D. Radioactive amino acids are incorporated into the cell’s protein The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and incorporated into proteins.

Answer 155

Nonradioactive amino acids are added to the cell The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and incorporated into proteins.

Answer 156

Chromatography separates a mixture of liquid Chromatography separates a mixture of liquid in a column in which components migrate at different speeds. Centrifugation is a lab technique that separates liquids of different densities or solids from liquids. Centrifugation uses a tube that rotates at extremely high velocities to separate components.

Answer 157

Fluorescence recovery after photobleaching Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Answer 158

B. The whole cell Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Answer 159

Photobleaching Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Answer 160

Fluorescence recovery after photobleaching Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching. A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility. Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Answer 161

High percent recovery and fast mobility Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility. Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Answer 162

The light return relative to the light present before photobleaching Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching. Note: A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility.

Answer 163

Low percent recovery and slow mobility Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility. Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Answer 164

Somatic cell nucleus donor

Answer 165

Enucleated egg

Answer 166

Electric pulse