Practice quiz questions (all units) Flashcards

Question

Triphosphate ribonucleotide is used by DNA polymerase for DNA replication. True or False?

Answer 1

False. Triphosphate deoxyribonucleotide is used.

Answer 2

3'-CGCTGCACTTGTCACTC-5'

Answer 3

25 somatic x 2 each + 2 sex chromosomes 52 total

Answer 4

False. The sugar in RNA is ribose whereas the sugar in DNA is deoxyribose.

Answer 5

False. RNA is generally single stranded whereas DNA is double stranded.

Answer 6

False. The base uracil is found in RNA instead of thymine.

Answer 7

False. Adenine pairs with uracil.

Answer 8

False. This would be RNA dependent DNA/RNA polymerase.

Answer 9

False. Nucleases do this (endo/exo)

Answer 10

False. This is primase.

Answer 11

False. The Shine-Delgarno sequence is found on the mRNA (near the 5' end of the mRNA, a few nucleotides upstream of the start codon)

Answer 12

False. The small ribosomal subunit (& bound translation factors) bind the Met-tRNA before interacting with the 5' cap of the mRNA.

Answer 13

False. The 3' end of the rRNA of the small ribosome unit binds the Shine-Delgarno sequence of the 5' end of the mRNA first, followed by the fMet-tRNA.

Answer 14

False. In prokaryotes, the initiator complex does not scan along the mRNA. Instead, the small ribosomal subunit binds directly to the Shine-Dalgarno sequence near the start codon, positioning it correctly for translation initiation.

Answer 15

False. A gene contains a promoter sequence that **RNA polymerase** binds to.

Answer 16

False. A gene is a region of the genome that contains a start codon.

Answer 17

True. ## Footnote Not in prokaryotes!

Answer 18

False. A gene contains exons and introns. ## Footnote Only exons in prokaryotes.

Answer 19

False. A gene has untranslated regions upstream and downstream.

Answer 20

False. Transcription begins at a promoter sequence in the DNA. The anticodon is located in transfer RNA.

Answer 21

False. A codon is 3 nucleotides on mRNA where **translation** begins.

Answer 22

False. A codon is 3 nucleotides on mRNA where translation begins.

Answer 23

Because there is transient base pairing between sticky ends

Answer 24

* increasing mRNA stability * transporting the mRNA out of the nucleus into the cytoplasm * interaction with the mRNA with the ribosome

Answer 25

To select for insertion of recombinant DNA

Answer 26

False. They are distributed randomly.

Answer 27

False. They are always linear.

Answer 28

False. Genes constitute only ~1.5% of the genome.

Answer 29

False. Duplicated genes are functional; pseudogenes are not.

Answer 30

False. It is the constricted region of the chromosome where the two copies are held together.

Answer 31

False. The centromere is the constricted region of the chromosome where the two copies are held together.

Answer 32

Genes appear to be **randomly distributed** throughout the genome and their **density varies**.

Answer 33

False. Plasmids contain non-essential genes.

Answer 34

False. A plasmid is a small, usually circular DNA molecule that is independent from the main chromosome and contains non-essential genes.

Answer 35

False. A bacterial operon is a group of genes that are involved in a single biochemical pathway and are expressed together.

Answer 36

False. Gene number is correlated with gene size in prokaryotes.

Answer 37

False. Due to factors like horizontal gene transfer and plasmids, strains within a species do not share the exact same gene number.

Answer 38

False. In prokaryotes, the genome is normally smaller for parasites than for free living species.

Answer 39

False. Hybridization refers to the recombination of alleles (variants of a gene) through sexual reproduction OR through introgression of genes from another species.

Answer 40

Hybridization refers to the recombination of alleles (variants of a gene) through sexual reproduction OR through introgression of genes from another species.

Answer 41

False. It does require this.

Answer 42

False. It is.

Answer 43

False. All traits are inherited.

Answer 44

Part of a previously successful fermentation is used for the next fermentation

Answer 45

False. It is LAB, but not for dairy. ## Footnote Dairy LAB include: *Lactobacillus*, *Lactococcus*, *Leuconostoc*, and *Streptococcus*.

Answer 46

False. It is LAB, but not for dairy. ## Footnote Dairy LAB include: *Lactobacillus*, *Lactococcus*, *Leuconostoc*, and *Streptococcus*.

Answer 47

False. They are not LAB, but are sometimes included in dairy as a probiotic.

Answer 48

Because *S. thermophilus* is more aerotolerant than *L. bulgaricus*.

Answer 49

* Positive air pressure * Culture rotation * Use of freeze dried cultures ## Footnote The use of calcium chelator phage inhibitory media would also inhibit LAB because they require calcium for growth.

Answer 50

* Gene density is higher in yeast than in humans because yeast have very few introns and interspersed repeats, whereas humans have many. * Yeast have a low gene number, plants and humans a higher gene number. ## Footnote The yeast chromosomes have higher gene density, fewer introns, and less interspersed repeats.

Answer 51

Genes that are not functionally active (evolutionary relics) | A non functional gene. ## Footnote May be conventional (i.e., caused by mutations) or processed (i.e., caused by retrotransposition).

Answer 52

1. **Gene disruption** - when transposons or retrotransposons insert themselves into functional genes, they can disrupt the coding sequence, leading to a loss of gene function, loss of enzyme activity, or altered traits/phenotype. 2. **Gene regulation** - if these elements insert near regulatory elements of genes, they can influence gene expression by either up- or down-regulating gene activity, potentially altering traits by changing how much of a particular protein is produced. ## Footnote If when they move, they land on a gene (promoter or coding sequence) they might affect the functionality.

Answer 53

**Loss of UFGT expression:** * Since MybA1 and MybA2code for the MybA transcription factor, which regulates UFGT expression via the MBW complex, non-functional mutations in these genes would prevent the formation of the MBW complex. Without the MBW complex, UFGT would not be expressed. **No anthocyanin biosynthesis:** * UFGT is essential for anthocyanin biosynthesis, so without its expression, the pathway to produce anthocyanins (red pigments) would be blocked, leading to a lack of pigment production. ## Footnote The grapes would be **green/colourless** because the absence of anthocyanin production means no red or purple pigmentation would form during ripening. If MybA1 and MybA2 become non-functional because of mutations there will be no activation of the expression of the gene UFGT, as all the three MybA genes will be codifying for non- functional proteins. The grapes will be green/yellow as there will be no production of anthocyanins if the UFGT gene is not expressed.

Answer 54

False. It is generally accepted.

Answer 55

False. Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.

Answer 56

False. Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.

Answer 57

False. Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.

Answer 58

False. A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.

Answer 59

False. A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.

Answer 60

False. A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.

Answer 61

False. A mutation is a permanent alteration of the nucleotide sequence of an organism's genome.

Answer 62

False. A mutation is a permanent alteration of the nucleotide sequence of an organism's genome.

Answer 63

False. A mutation is a permanent alteration of the nucleotide sequence of an organism's genome.

Answer 64

False. *Agrobacterium tumefaciens* is a bacterium used as a vector to deliver foreign genes into plant genomes.

Answer 65

False. *Agrobacterium tumefaciens* is a bacterium used as a vector to deliver foreign genes into plant genomes.

Answer 66

False. *Agrobacterium tumefaciens* is a bacterium used as a vector to deliver foreign genes into plant genomes.

Answer 67

False. The purpose of a selectable genetic engineering is to identify plant cells that have successfully incorporated the foreign gene.

Answer 68

False. The purpose of a selectable genetic engineering marker is to identify plant cells that have successfully incorporated the foreign gene.

Answer 69

False. The purpose of a selectable genetic engineering marker is to identify plant cells that have successfully incorporated the foreign gene.

Answer 70

Cyanidin Pelargonidin

Answer 71

False. The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.

Answer 72

False. The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.

Answer 73

False. The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.

Answer 74

A variation in a single position in a DNA sequence among individuals. ## Footnote Single nucleotide polymorphism

Answer 75

18-27 degrees Celsius

Answer 76

To protect the plasmid and donor DNA from cell endonucleases and binding to the cell wall

Answer 77

1. **Design** - need sequence diversity – find gene that encodes the enzyme of interest and do a BLAST search to find the natural diversity in other species Try changing the amino acids at certain positions. 2. **Build** - Since the gene that encodes the enzyme you want to express in yeast is not naturally in the yeast genome, find a safe region to CRISPR-Cas9 it into (usually an intergenic space, not into a known gene). You will also need to add a yeast promoter and terminator to each novel gene. You will need to introduce all of the different variations of the gene (with the different amino acid mutations) into separate yeast strains 3. **Test** - Ferment each new yeast strain and test for production of metabolite using HPLC or GCMS.

Answer 78

* **Agrobacterium-mediated transformation**: *Agrobacterium tumefaciens* is a soil bacterium with the natural ability to infect plants and transfer DNA segments into a plant's genome. This makes it an ideal vector, or delivery system, to introduce desirable genes. * **Biolistics**: Also called the gene gun, this method uses a device to shoot tiny particles of coated with DNA into plant cells.

Answer 79

There are two answers that are valid: **Answer 1:** A major issue with traditional breeding is that many unwanted traits can be inherited along with the desired one. To eliminate these undesirable traits, backcrossing the new selection with the recurrent, or good, parent is often necessary. **Answer 2:** A major issue with traditional breeding is that the selection of the “good” individuals of the progeny is time consuming (several years to assess the phenotypes, large number of genotypes to assess) and requires space for growing a large number of plants. To reduce these issues, we can use MAS (marker assisted selection) to select the individuals that have the regions of the genome that control the desired trait.

Answer 80

The pH differential method. This method utilizes the change in absorbance of anthocyanins at different pH levels. At a pH of 1, anthocyanins are in their colored form (flavylium cation) and absorb light in the visible spectrum. At a pH of 4.5, anthocyanins shift to their colorless form and do not absorb light in the visible spectrum. Measuring the difference in absorbance between pH 1 and pH 4.5 allows for the determination of the total anthocyanin content. This approach helps eliminate background noise from non-anthocyanin absorbance. The differential absorbance measured is directly proportional to the total amount of anthocyanins present in the sample.

Answer 81

* Marker-assisted breeding uses molecular markers, which are DNA fragments associated with specific locations in the genome, to identify desirable traits in plants. This approach speeds up the breeding process, especially for traits like fruit color that may take years to manifest. * Traditionally, breeders would have to wait until the plant matured and produced fruit to assess its phenotype. * With marker-assisted breeding, plants can be screened for the desired traits at the seedling (small plants that emerge from the seed) stage by analyzing their DNA. * This saves time and resources, allowing breeders to select only those plants that possess the target gene for further development. * For example, in raspberries, breeders are working to map the genes responsible for different red color intensities to develop markers for marker-assisted breeding. * This enables the selection of plants with specific color intensities early on, accelerating the development of new varieties with desired fruit colors.

Answer 82

False. DNA polymerase proofreading activity is removal of incorrect nucleotides in the 3' to 5' direction.

Answer 83

False. DNA polymerase proofreading activity is removal of incorrect nucleotides 3' to 5'. | The joining of Okazaki fragments is done by DNA ligase.

Answer 84

True. DNA polymerase proofreading activity is removal of incorrect nucleotides 3' to 5'.

Answer 85

False. DNA polymerase proofreading activity is removal of incorrect nucleotides 3' to 5'. ## Footnote DNA polymerase is responsible for synthesizing new nucleotides on both the leading and lagging strands during DNA replication.

Answer 86

False. Enzymes that produce the same sticky ends are compatible restriction enzymes.

Answer 87

False. Enzymes that produce the same sticky ends are compatible restriction enzymes.

Answer 88

False. Enzymes that produce the same sticky ends are compatible restriction enzymes.

Answer 89

False. A lower % agarose should be used to separate larger molecular weight DNA fragments.

Answer 90

False. In agarose gel electrophoresis, smaller DNA fragments migrate faster than larger DNA fragments.

Answer 91

False. DNA must be stained (for example with ethidium bromide) to be detected by UV light.

Answer 92

False. DNA moves towards the **positive** electrode in agarose gel electrophoresis.

Answer 93

False. *Streptococcus thermophilus* is **more** aerotolerant than *Lactobacillus bulgaricus*.

Answer 94

False. *Streptococcus thermophilus* produces **less** lactic acid than *Lactobacillus bulgaricus*.

Answer 95

False. *Lactobacillus bulgaricus* ferments hexoses but not pentoses.

Answer 96

False. *Lactobacillus bulgaricus* has good proteolytic activity.

Answer 97

False. The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast. ## Footnote Two-micron allows high copy numbers of plasmid in yeast.

Answer 98

False. The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.

Answer 99

False. The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.

Answer 100

False. Ribosomal RNA is the most abundant type of RNA in the cell.

Answer 101

False. Ribosomal RNA is the most abundant type of RNA in the cell.

Answer 102

False. Ribosomal RNA is the most abundant type of RNA in the cell.

Answer 103

False. They seem to be distributed randomly with varying density.

Answer 104

False. HU proteins pack genomes in prokaryotes. Histones are the DNA binding proteins in eukaryotes.

Answer 105

False. Transposition is the process by which a segment of DNA can move from one position to another in the genome.

Answer 106

False. Transposition is the process by which a segment of DNA can move from one position to another in the genome.

Answer 107

False. Transposition is the process by which a segment of DNA can move from one position to another in the genome.

Answer 108

False. ## Footnote Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.

Answer 109

True. ## Footnote Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.

Answer 110

False. ## Footnote Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.

Answer 111

False. ## Footnote Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.

Answer 112

False. The yeast genome is 0.004 times the size of the human genome and yet contains approximately 0.2 times fewer genes. The explanation for this is that the human genome has more interspersed repeats and more introns than the yeast genome.

Answer 113

False. The yeast genome is 0.004 times the size of the human genome and yet contains approximately 0.2 times fewer genes. The explanation for this is that the human genome has more interspersed repeats and more introns than the yeast genome.

Answer 114

False. The yeast genome is 0.004 times the size of the human genome and yet contains approximately 0.2 times fewer genes. The explanation for this is that the human genome has more interspersed repeats and more introns than the yeast genome.

Answer 115

False. ## Footnote For example, the Lac operon has 3 proteins.

Answer 116

* Improved nutrients * Improved flavour * Higher yields * Extended shelf-life

Answer 117

False. This is a strength/boon of hybridization.

Answer 118

False. This is a strength/boon of hybridization of crops.

Answer 119

False. It is accepted by consumers.

Answer 120

The genetic code refers to codons (i.e., a set of 3 nucleotides) which each code for a specific amino acid (e.g., AUG -> methionine) or a stop codon (UAA; UGA; UAG), which signals the end of translation. Ribosomes translate this code into a protein product. The genetic code is not always universal (e.g., UGA may code for selenocysteine in some organisms with selenocysteine insertion sequence present in the mRNA), but generally it is.

Answer 121

* Precision fermentation is a biotechnological process that uses microorganisms like yeast, bacteria, or fungi to produce specific compounds with high precision. * By modifying the genetic material of these microorganisms, they can be programmed to produce desired molecules, such as proteins, enzymes, or other bioactive compounds, which are often used in food, pharmaceuticals, or industrial applications. * This process is highly efficient, scalable, and sustainable, allowing for the creation of ingredients like animal-free dairy proteins, sweeteners, or vitamins with a reduced environmental footprint compared to traditional production methods.

Answer 122

1. Bacteriophages have contaminated the product, and caused the starter culture to fail. This is because these bacterial viruses will kill the LAB via cell lysis. 2. Presence of residual sanitizers (e.g., quaternary amonium) have killed the LAB which are very sensitive. 3. Contamination with antibodies (e.g., agglutinin) or antibiotics (*S. thermophilus* is very sensitive), which would prevent their growth.

Answer 123

This is fermentation due to the presence of microorganisms that are naturally present in the food (e.g., LAB in dairy). No additional starter cultures are added, fermentation simply occurs because the correct conditions are provided for growth.

Answer 124

1. Very unpredictable results due to no control over which strains are present and in what proportion. Hence, results from natural fermentation will not be consistent. Controlling the organoleptic properties from batch to batch is not possible. 2. Very time consuming due to no control over what other microbial populations are also present that may inhibit LAB from dominating and fermenting the sugars efficiently. 3. Potentially unsafe because there may be pathogenic microbes present in the naturally occuring microbial community that are able to survive, or there may not be sufficient acid development to inhibit their growth. ## Footnote Natural fermentation is unpreditable, time-consuming, gives inconsistent results, potentially unsafe, the right bacteria need to be present.

Answer 125

The microorganism responsible for the fermentation should be able to be isolated and grown as a pure culture, and then when re-introduced into raw material it should cause the same fermentation to occur.

Answer 126

A pseudogene is a non-functional gene (i.e., an evolutionary relic), and it may be conventional or processed. Conventional pseudogenes arise from the accumulation of mutations (e.g., deletions/insertions/SNPs) which render them non-functional. Processed pseudogenes arise from retrotransposition whereby a gene is copied to another location of the genome via an mRNA intermediate, and in this process it loses its promoter and is rendered non-functional.

Answer 127

The two major classes are retrotransposons, which includes LINEs, SINEs, and LTRs, and DNA transposons. The major difference is that retrotransposons are copied via an mRNA intermediate whereas DNA transposons are directly moved (either conservatively or replicatively) as intact DNA elements by transposase.

Answer 128

Transposable elements can affect the phenotype of an organism if they are inserted within an exon of a gene which can disrupt its function **or** if they are inserted within/near a gene's promoter region, which can alter the gene's expression. For instance, it can lead to less of a specific protein being produced, or none at all, and this will lead to a different phenotypic expression.

Answer 129

Assuming MybA1 is still functional, the grapes will be purpose because the MBW complex will still form. Since the transcription factor is produced by MybA1, the UFGT gene will be expressed and the anthocyanins will be produced. It does not matter that MybA2 is a processed pseudogene due to the transposon disrupting its function, nor that MybA3 is a truncated gene that produces a non-functional protein. MybA1 is functional still, and so the MBW complex forms, ét voilà! Purple grapes!

Answer 130

In this case, since all three MybA genes are non-functional, no transcription factor will be produced. Therefore, the MBW complex will not form and the UFGT gene, while functional, will not be expressed. So, no anthocyanins will be synthesized, and the grapes will be green.