Practice quiz questions (all units) Flashcards
The two strands of DNA are held together by hydrogen bonds.
True or False?
True.
The phosphate and deoxyribose molecules form the backbone of the DNA strand.
True or False?
True.
The two DNA strands run antiparallel to each other.
True or False?
True.
The base pairs lie in the exterior of the DNA molecule.
True or False?
False.
The base pairs lie in the interior of the DNA molecule.
Given the following DNA strand:
5’-TAGCAACCGAATC-3’
What is the complementary strand?
5’-GATTCGGTTGCTA-3’
or
3’-ATCGTTGGCTTAG-5’
Prokaryotic mRNA has a Shine-Dalgarno sequence that binds to the ribosomal RNA.
True or False?
True.
In eukaryotes, the Initiator Methionine-tRNA binds the mRNA followed by the small ribosomal subunit.
True or False?
False.
In eukaryotes, the Initiator Methionine-tRNA binds the translation initiation factors and the small ribosomal subunit followed by the the mRNA.
Translation is initiated by the binding of an initiator Methionine-tRNA and translation initiation factors to a small ribosomal subunit.
Next, the 5’-capped end of the mRNA associates with the initiator Met-tRNA- small ribosomal complex
The complex moves along the mRNA until a start codon (AUG) is found
Once the UAC anticodon sequence of the initiator Met-tRNA base pairs with the AUG sequence of the mRNA, the large ribosomal subunit joins the complex to form the initiation complex
In both Prokaryotes and Eukaryotes, the large ribosomal subunit assembles after the mRNA and small ribosomal subunit have assembled.
True or False?
True.
The small and large ribosomal subunits are smaller in Prokaryotes than Eukaryotes.
True or False?
True.
What is the purpose of the 5’-cap in a eukaryotic messenger RNA transcript?
To help the ribosome bind the mRNA
During DNA polymerization, which phosphate group from the nucleotide becomes part of the DNA strand?
Alpha-phosphate
The discovery of the cell and the description of heredity rules by Mendel were two milestones in ‘modern biotechnology’.
True or False?
False.
These are milestones in traditional biotechnology.
The use of fermenting organisms and the discovery of DNA are two milestones in ‘modern biotechnology’.
True or False?
False.
The use of fermenting organisms is a milestone of traditional biotechnology.
The discovery of DNA and the development/use of sequencing technologies are two milestones in ‘modern biotechnology’.
True or False?
True.
Plant breeding for food production and the discovery of DNA were two milestones in ‘modern biotechnology’.
True or False?
False.
Plant breeding for food production is a milestone of traditional biotechnology.
Food diagnostics is an application of ‘Food Biotechnology’.
True or False?
True.
Engineering bacteria for purifying contaminated soils is an application of ‘Food Biotechnology’.
True or False?
False.
This would be better classified as an industrial application of biotechnology.
Fermentation of food is an application of ‘Food biotechnology’.
True or False?
True.
Production of drugs for humans is an application of ‘Food biotechnology’.
True or False?
False.
This is an application in human health.
What is a deoxyribonucleotide?
a DNA base, deoxyribose, and a phosphate group
If an organism has 5.5 billion base pairs of DNA in its nucleus, how would this be abbreviated?
5.5 Gb
Deoxyribonucleotide is used by DNA polymerase for DNA replication.
True or False?
False.
Triphosphate deoxyribonucleotide is used.
Triphosphate deoxyribonucleotide is used by DNA polymerase for DNA replication.
True or False?
True.
Ribonucleotide is used by DNA polymerase for DNA replication.
True or False?
False.
Triphosphate deoxyribonucleotide is used.
Triphosphate ribonucleotide is used by DNA polymerase for DNA replication.
True or False?
False.
Triphosphate deoxyribonucleotide is used.
Given the following DNA strand, what is the complementary strand?
5’-GCGACGTGAACAGTGAG-3’
3’-CGCTGCACTTGTCACTC-5’
If an organism is diploid and its karyotype has chromosomes numbered 1 to 25, plus two sex chromosomes, how many total chromosomes does the organism contain in its genome?
25 somatic x 2 each + 2 sex chromosomes
52 total
RNA is generally single stranded whereas DNA is double stranded.
True or False?
True.
The sugar in RNA is ribose whereas the sugar in DNA is deoxyribose.
True or False?
True.
The sugar in RNA is deoxyribose whereas the sugar in DNA is ribose.
True or False?
False.
The sugar in RNA is ribose whereas the sugar in DNA is deoxyribose.
RNA is generally double stranded whereas DNA is single stranded.
True or False?
False.
RNA is generally single stranded whereas DNA is double stranded.
Instead of thymine, the base uracil is found in RNA.
True or False?
True.
Instead of uracil, the base thymine is found in RNA.
True or False?
False.
The base uracil is found in RNA instead of thymine.
In the RNA molecule, adenine pairs with thymine.
True or False?
False.
Adenine pairs with uracil.
In the RNA molecule, adenine pairs with uracil.
True or False?
True.
DNA ligase adds nucleotides to an RNA template.
True or False?
False.
This would be RNA dependent DNA/RNA polymerase.
DNA ligase creates phosphodiester bonds between DNA nucleotides.
True or False?
True.
DNA ligase breaks the phosphodiester bonds that link DNA nucleotides together.
True or False?
False.
Nucleases do this (endo/exo)
DNA ligase generates a primer needed for DNA synthesis.
True or False?
False.
This is primase.
Prokaryotic ribosomal RNA has a Shine-Delgarno sequence that binds to the mRNA.
True or False?
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)
In eukaryotes, the initiator Methionine-tRNA binds the mRNA followed by the small ribosomal unit.
True or False?
False.
The small ribosomal subunit (& bound translation factors) bind the Met-tRNA before interacting with the 5’ cap of the mRNA.
In prokaryotic translation initiation, the fMet-tRNA binds the small ribosomal subunit followed by the mRNA.
True or False?
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.
In prokaryotic translation initiation the small ribosomal subunit binds the mRNA first, followed by the fMet-tRNA.
True or False?
True.
In eukaryotes, the small ribosomal subunit binds the Met-tRNA before interacting with the mRNA.
True or False?
True.
The eukaryotic initiator complex scans along the mRNA until a start codon is identified.
True or False?
True.
The prokaryotic initiator complex scans along the mRNA to identify a start codon.
True or False?
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.
A gene contains a promoter sequence that DNA polymerase binds to.
True or False?
False.
A gene contains a promoter sequence that RNA polymerase binds to.
A gene contains a promoter region that RNA polymerase binds to.
True or False?
True.
A gene is a region of the genome that contains a start codon.
True or False?
True.
The start codon is not part of what defines a gene.
True or False?
False.
A gene is a region of the genome that contains a start codon.
A gene contains exons and introns.
True or False?
True.
Not in prokaryotes!
A gene contains exons but not introns.
True or False?
False.
A gene contains exons and introns.
Only exons in prokaryotes.
A gene has untranslated DNA upstream and downstream.
True or False?
True.
A gene does not have untranslated DNA upstream or downstream.
True or False?
False.
A gene has untranslated regions upstream and downstream.
An anticodon is 3 nucleotides on DNA where transcription begins.
True or False?
False.
Transcription begins at a promoter sequence in the DNA. The anticodon is located in transfer RNA.
An anticodon is 3 nucleotides on mRNA where transcription begins.
True or False?
False.
A codon is 3 nucleotides on mRNA where translation begins.
An anticodon is 3 nucleotides on mRNA where translation begins.
True or False?
False.
A codon is 3 nucleotides on mRNA where translation begins.
An anticodon is 3 nucleotides on tRNA that bind to 3 mRNA nucleotides.
True or False?
True.
Why are sticky-end ligations more efficient than blunt end ligations?
Because there is transient base pairing between sticky ends
The 5’ cap and the 3’ poly A tail on mRNA are important for: [3]
In eukaryotes
- increasing mRNA stability
- transporting the mRNA out of the nucleus into the cytoplasm
- interaction with the mRNA with the ribosome
What is the purpose of the lacZ gene in the pUC8 cloning plasmid?
To select for insertion of recombinant DNA
Genes are evenly distributed throughout the genome in eukaryotes.
True or False?
False.
They are distributed randomly.
Genes are randomly distributed throughout the eukaryotic genome.
True or False?
True.
Genes are localized mostly in telomeric regions.
True or False?
False.
Genes are always organized in clusters of genes with similar function.
True or False?
False.
Eukaryotic genomes are always circular.
True or False?
False.
They are always linear.
Eukaryotic genomes are always linear.
True or False?
True.
Genes generally constitute the majority of the genome content.
True or False?
False.
Genes constitute only ~1.5% of the genome.
Chromosomes are uniform in number among organisms/species.
True or False?
False.
Duplicated genes are always located in clusters in the same genomic region.
True or False?
False.
Duplicated genes can have the same function.
True or False?
True.
Duplicate genes cannot have the same function.
True or False?
False.
Duplicated genes are also called pseudogenes.
True or False?
False.
Duplicated genes are functional; pseudogenes are not.
Duplicated genes are always expressed in the same tissue and at the same development stage.
True or False?
False.
Duplicated genes can be expressed in different tissues or at different developmental stages.
True or False?
True.
Duplicate genes can have the same function, or different functions.
True or False?
True.
The proteins that bind to DNA in the nucleosome and form a core octamer are called:
Histones
The centromere is the end of a chromosome.
True or False?
False.
It is the constricted region of the chromosome where the two copies are held together.
A centromere is the region that contains most of the functional genes.
True or False?
False.
The centromere is the constricted region of the chromosome where the two copies are held together.
A centromere is the restricted region of the chromosome where the two copies are held together.
True or False?
True.
What have scientists observed regarding the distribution of genes in eukaryotic genomes?
Genes appear to be randomly distributed throughout the genome and their density varies.
A plasmid is a small, usually circular DNA molecule that is independent from the main chromosome.
True or False?
True.
A plasmid is a small, usually circular DNA molecule that contains essential genes.
True or False?
False.
Plasmids contain non-essential genes.
A plasmid is a small, usually circular DNA molecule that contains non-essential genes.
True or False?
True.
A plasmid is a small, usually circular DNA molecule that stabilizes the bacteria chromosome.
True or False?
False.
A plasmid is a small, usually circular DNA molecule that is independent from the main chromosome and contains non-essential genes.
A bacterial operon is a group of genes that have related biochemical functions.
True or False?
False.
A bacterial operon is a group of genes that are involved in a single biochemical pathway and are expressed together.
A bacterial operon is a group of genes that are involved in a single biochemical pathway and are expressed together.
True or False?
True.
In prokaryotes, the number of genes is NOT correlated with genome size.
True or False?
False.
Gene number is correlated with gene size in prokaryotes.
In prokaryotes, the number of genes is correlated with genome size.
True or False?
True.
Plasmids contain the largest portion of genes of the prokaryotic genome.
True or False?
False.
In prokaryotes, gene number is the same among species.
True or False?
False.
Due to factors like horizontal gene transfer and plasmids, strains within a species do not share the exact same gene number.
In prokaryotes, the genome is normally smaller for parasites than for free living species.
True or False?
True.
In prokaryotes, the genome is normally smaller for free living species than for parasites.
True or False?
False.
In prokaryotes, the genome is normally smaller for parasites than for free living species.
Hybridization is based on recombination of alleles through sexual reproduction.
True or False?
False.
Hybridization refers to the recombination of alleles (variants of a gene) through sexual reproduction OR through introgression of genes from another species.
Define: hybridization.
Hybridization refers to the recombination of alleles (variants of a gene) through sexual reproduction OR through introgression of genes from another species.
Hybridization refers to the recombination of alleles (variants of a gene) through sexual reproduction OR through introgression of genes from another species.
True or False?
True.
Hybridization does NOT require two interfertile organisms.
True or False?
False.
It does require this.
Hybridization requires two interfertile organisms.
True or False?
True.
Hybridization is NOT used to improve crops.
True or False?
False.
It is.
Hybridization is used to improve crops.
True or False?
True.
Only good traits are inherited through hybridization.
True or False?
False.
All traits are inherited.
Both good and bad traits are inherited through hybridization.
True or False?
True.
What is the best description of back-slopping?
Part of a previously successful fermentation is used for the next fermentation
Lactobacillus is a dairy LAB.
True or False?
True.
Pediococcus is a dairy LAB.
True or False?
False.
It is LAB, but not for dairy.
Dairy LAB include: Lactobacillus, Lactococcus, Leuconostoc, and Streptococcus.
Streptococcus is a dairy LAB.
True or False?
True.
Leuconostoc is a dairy LAB.
True or False?
True.
Lactococcus is a dairy LAB.
True or False?
True.
Enterococcus is a dairy LAB.
True or False?
False.
It is LAB, but not for dairy.
Dairy LAB include: Lactobacillus, Lactococcus, Leuconostoc, and Streptococcus.
Bifidobacteria are dairy LAB.
True or False?
False.
They are not LAB, but are sometimes included in dairy as a probiotic.
Why is Streptococcus thermophilus more dominant than Lactobacillus delbrueckii ssp. bulgaricus at the beginning of yogurt fermentation?
Because S. thermophilus is more aerotolerant than L. bulgaricus.
List 3 control measures for bacteriophage for dairy LAB.
- Positive air pressure
- Culture rotation
- Use of freeze dried cultures
The use of calcium chelator phage inhibitory media would also inhibit LAB because they require calcium for growth.
What differences in gene distributions and repetitive DNA content are seen when yeast and human chromosomes are compared?
- 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.
The yeast chromosomes have higher gene density, fewer introns, and less interspersed repeats.
What is pseudogene?
Genes that are not functionally active (evolutionary relics)
A non functional gene.
May be conventional (i.e., caused by mutations) or processed (i.e., caused by retrotransposition).
Describe how transposons or retrotransposons can affect the phenotype of an organism.
- 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.
- 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.
If when they move, they land on a gene (promoter or coding sequence) they might affect the functionality.
What do you expect if mutations of the coding sequence of MybA1 and MybA2 make both genes non-functional?
What color would the grapes be and why?
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.
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.
In hybridization, (traditional) breeding in relation to crop improvement, the random assortment of parental chromosomes/genes often generates unwanted phenotypes in the progeny.
True or False?
True.
Hybridization (traditional) breeding in relation to crop improvement is generally not accepted by consumers.
True or False?
False.
It is generally accepted.
Hybridization is applied only to crops for whom genetic engineering tools are not available.
True or False?
False.
Hybridization applies only to the traits whose genetic control is known, provided that the source of improved trait and the recipient are interfertile.
True or False?
False.
In a traditional breeding program to improve fruit quality, breeders can introduce genes from bacteria if these genes are helpful to improve fruit quality.
True or False?
False.
In a traditional breeding program to improve fruit quality, breeders should assess the quality of the fruits of the progeny during the selection process.
True or False?
True.
In a traditional breeding program to improve fruit quality, breeders do not need to assess the quality of the fruits of the progeny.
True or False?
False.
In a traditional breeding program to improve fruit quality, breeders must know the which genes control fruit quality.
True or False?
False.
Marker assisted selection refers to the use of molecular markers to identify transposons in the genome.
True or False?
False.
Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.
Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.
True or False?
True.
Marker assisted selection refers to the use of molecular markers to induce mutations in a genome.
True or False?
False.
Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.
Marker assisted selection refers to the use of molecular markers to select genes for plant transformation.
True or False?
False.
Marker assisted selection refers to the use of molecular markers to help select the progeny in breeding programs.
Mutation breeding requires knowledge on the genetic control of the trait that has to be improved.
True or False?
False.
Mutation breeding can generate new alleles that are not present in nature for the plant species.
True or False?
True.
Mutation breeding maintains the general genetic background of a genotype.
True or False?
True.
Mutations are random/non-targeted.
True or False?
True.
A disarmed Ti plasmid is a plasmid with the virulence genes removed.
True or False?
False.
A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.
A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.
True or False?
True.
A disarmed Ti plasmid is a plasmid with the left and right borders of the plasmid removed.
True or False?
False.
A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.
A disarmed Ti plasmid is a plasmid with the foreign DNA removed.
True or False?
False.
A disarmed Ti plasmid is a plasmid with the tumor producing genes removed.
The Ti plasmids used for the genetic transformation of plants are NOT circular.
True or False?
False.
The Ti plasmids used for genetic transformation of plants MUST contain genes of the same plant species that is going to be transformed.
True or False?
False.
In the Ti plamids used for genetic transformation of plants, the virulence (vir) genes ARE required for the T-DNA movement into the plant genome.
True or False?
True.
The Ti plamids used for genetic transformation of plants MUST NOT contain a selectable marker gene in the T DNA region.
True or False?
False.
Molecular biology tools cannot be used for traditional breeding.
True or False?
False.
Missense mutations can be useful for plant breeding.
True or False?
True.
The selection in progenies can only be done for a single trait.
True or False?
False.
Silent mutations can be useful for plant breeding.
True or False?
False.
A mutation is a change in a plant’s physical appearance caused by environmental factors.
True or False?
False.
A mutation is a permanent alteration of the nucleotide sequence of an organism’s genome.
A mutation is the introduction of foreign genes into a plant using biotechnology techniques.
True or False?
False.
A mutation is a permanent alteration of the nucleotide sequence of an organism’s genome.
A mutation is the process of combining genetic material from two parent plants to create offspring with desired traits.
True or False?
False.
A mutation is a permanent alteration of the nucleotide sequence of an organism’s genome.
A mutation is a permanent alteration of the nucleotide sequence of an organism’s genome.
True or False?
True.
In nature, spontaneous mutations are rare, while induced mutations are common.
True or False?
False.
Spontaneous mutations are beneficial, while induced mutations are harmful.
True or False?
False.
Spontaneous mutations occur naturally, while induced mutations are caused by external factors.
True or False?
True.
Spontaneous mutations occur in all organisms, while induced mutations only occur in plants.
True or False?
False.
Genetic engineering is always a faster and more efficient method for developing new crop varieties compared to traditional breeding, which always requires several generations of plants.
True or False?
False.
Genetic engineering can introduce genes from unrelated organisms, while traditional breeding is limited to gene transfer between interfertile species/organisms.
True or False?
True.
Genetic engineering only focuses on improving agronomical traits, while traditional breeding also addresses food quality and environmental traits.
True or False?
False.
Genetic engineering involves manipulating plant genes in a laboratory setting, while traditional breeding relies on spontaneous cross-pollination occurring in nature.
True or False?
False.
Agrobacterium tumefaciens is a bacterium used as a vector to deliver foreign genes into plant genomes.
True or False?
True.
Agrobacterium tumefaciens is a source of bacterial genes that can be transferred into plants.
True or False?
False.
Agrobacterium tumefaciens is a bacterium used as a vector to deliver foreign genes into plant genomes.
Agrobacterium tumefaciens is a type of fungus that enhances the growth of genetically modified plants.
True or False?
False.
Agrobacterium tumefaciens is a bacterium used as a vector to deliver foreign genes into plant genomes.
Agrobacterium tumefaciens is a pest that attacks genetically modified crops.
True or False?
False.
Agrobacterium tumefaciens is a bacterium used as a vector to deliver foreign genes into plant genomes.
The purpose of a selectable genetic engineering is to make the modified plant resistant to pests.
True or False?
False.
The purpose of a selectable genetic engineering is to identify plant cells that have successfully incorporated the foreign gene.
The purpose of a selectable genetic engineering is to identify plant cells that have successfully incorporated the foreign gene.
True or False?
True.
The purpose of a selectable genetic engineering marker is to improve the yield and growth rate of the modified plant.
True or False?
False.
The purpose of a selectable genetic engineering marker is to identify plant cells that have successfully incorporated the foreign gene.
The purpose of a selectable genetic engineering marker is to enhance the nutritional content of the modified plant.
True or False?
False.
The purpose of a selectable genetic engineering marker is to identify plant cells that have successfully incorporated the foreign gene.
What are the most abundant anthocyanidins in red raspberries?
Cyanidin
Pelargonidin
The process of developing new molecular markers requires performing mutagenesis, extracting the DNA, and sequencing.
True or False?
False.
The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.
The process of developing new molecular markers requires a mapping population, phenotyping, hybridization, and mapping.
True or False?
False.
The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.
The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.
True or False?
True.
The process of developing new molecular markers requires phenotyping and genotyping.
True or False?
False.
The process of developing new molecular markers requires a mapping population, phenotyping, genotyping, and mapping.
What is an SNP?
A variation in a single position in a DNA sequence among individuals.
Single nucleotide polymorphism
What is the fermenting temperature range of ale yeast?
18-27 degrees Celsius
When transforming the donor DNA and CRISPR-Cas9 plasmid into yeast cells, what is the purpose of
adding salmon sperm DNA?
To protect the plasmid and donor DNA from cell endonucleases and binding to the cell wall
In yeast synthetic biology, explain how an enzyme is chosen for a metabolic pathway to produce a
desired metabolic product that yeast does not typically produce. More specifically, you need to
mention how the enzyme is:
1. Designed
2. Built into the yeast genome
3. Tested for production of the metabolite
-
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. - 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
- Test - Ferment each new yeast strain and test for production of metabolite using HPLC or GCMS.
Name two methods for introducing foreign genes into plants
- 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.
Name one main problems with traditional breeding, and what process can be used to correct the
issue.
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.
What method is commonly used to determine total anthocyanin content in fruit, and on what
principle is this method based?
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.
How does marker-assisted breeding accelerate and enhance the process of developing new fruit
varieties with desirable traits, such as improved color in raspberries?
- 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.
DNA polymerase proofreading activity is the addition of primers for DNA replication.
True or False?
False.
DNA polymerase proofreading activity is removal of incorrect nucleotides in the 3’ to 5’ direction.
DNA polymerase activity is the joining of Okazaki fragments.
True or False?
False.
DNA polymerase proofreading activity is removal of incorrect nucleotides 3’ to 5’.
The joining of Okazaki fragments is done by DNA ligase.
DNA Polymerase activity is the removal of incorrect nucleotides.
True or False?
True.
DNA polymerase proofreading activity is removal of incorrect nucleotides 3’ to 5’.
DNA polyerase proofreading activity is the leading strand of DNA replication.
True or False?
False.
DNA polymerase proofreading activity is removal of incorrect nucleotides 3’ to 5’.
DNA polymerase is responsible for synthesizing new nucleotides on both the leading and lagging strands during DNA replication.
Target DNA is added to a PCR reaction.
True or False?
True.
Primers are added to a PCR reaction.
True or False?
True.
DNA ligase is added to a PCR reaction.
True or False?
False.
Taq polymerase is added to a PCR reaction.
True or False?
True.
Enzymes that both produce 5’ overhangs are compatible restriction enzymes.
True or False?
False.
Enzymes that produce the same sticky ends are compatible restriction enzymes.
Enzymes that both produce 3’ overhangs are compatible enzymes.
True or False?
False.
Enzymes that produce the same sticky ends are compatible restriction enzymes.
BamHI and PstI are compatible restriction enzymes.
True or False?
False.
Enzymes that produce the same sticky ends are compatible restriction enzymes.
Enzymes that produce the same sticky ends are compatible restriction enzymes.
True or False?
True.
To separate larger molecular weight DNA fragments, a higher % agarose should be used.
True or False?
False.
A lower % agarose should be used to separate larger molecular weight DNA fragments.
A lower % agarose should be used to separate larger molecular weight DNA fragments.
True or False?
True.
In agarose gel electrophoresis, smaller DNA fragments migrate faster than larger DNA fragments.
True or False?
True.
In agarose gel electrophoresis, larger DNA fragments migrate faster than larger DNA fragments.
True or False?
False.
In agarose gel electrophoresis, smaller DNA fragments migrate faster than larger DNA fragments.
Unstained DNA can be detected by UV light.
True or False?
False.
DNA must be stained (for example with ethidium bromide) to be detected by UV light.
DNA stained with ethidium bromide can be detected by UV light.
True or False?
True.
DNA moves towards the negative electrode in agarose gel electrophoresis.
True or False?
False.
DNA moves towards the positive electrode in agarose gel electrophoresis.
DNA moves towards the positive electrode in agarose gel electrophoresis.
True or False?
True.
Streptococcus thermophilus is more aerotolerant than Lactobacillus bulgaricus.
True or False?
True.
Streptococcus thermophilus is less aerotolerant than Lactobacillus bulgaricus.
True or False?
False.
Streptococcus thermophilus is more aerotolerant than Lactobacillus bulgaricus.
Streptococcus thermophilus produces more lactic acid than Lactobacillus bulgaricus.
True or False?
False.
Streptococcus thermophilus produces less lactic acid than Lactobacillus bulgaricus.
Streptococcus thermophilus produces less lactic acid than Lactobacillus bulgaricus.
True or False?
True.
Lactobacillus bulgaricus ferments hexoses but not pentoses.
True or False?
True.
Lactobacillus bulgaricus ferments pentoses but not hexoses.
True or False?
False.
Lactobacillus bulgaricus ferments hexoses but not pentoses.
Lactobacillus bulgaricus has good proteolytic activity.
True or False?
True.
Lactobacillus bulgaricus has low proteolytic activity.
True or False?
False.
Lactobacillus bulgaricus has good proteolytic activity.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in E. coli..
True or False?
False.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.
Two-micron allows high copy numbers of plasmid in yeast.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.
True or False?
True.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to select for E. coli that have transformed the plasmid.
True or False?
False.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to select for yeast that have transformed the plasmid.
True or False?
False.
The purpose of the two-micron gene on the yeast chymosin expression plasmid is to allow replication of the plasmid in yeast.
Messenger RNA is the most abundant type of RNA in the cell.
True or False?
False.
Ribosomal RNA is the most abundant type of RNA in the cell.
Ribosomal RNA is the most abundant type of RNA in the cell.
True or False?
True.
Transfer RNA is the most abundant type of RNA in the cell.
True or False?
False.
Ribosomal RNA is the most abundant type of RNA in the cell.
PolyA RNA is the most abundant type of RNA in the cell.
True or False?
False.
Ribosomal RNA is the most abundant type of RNA in the cell.
In eukaryotic genomes, genes are evenly distributed throughout the genome.
True or False?
False.
They seem to be distributed randomly with varying density.
In eukaryotic genomes, the genome is packed by DNA binding proteins called histones.
True or False?
True.
In eukaryotic genomes, the genome is packed by DNA binding proteins called HU proteins.
True or False?
False.
HU proteins pack genomes in prokaryotes. Histones are the DNA binding proteins in eukaryotes.
In prokaryotic genomes, the genome is packed by DNA binding proteins called HU proteins.
True or False?
True.
Transposition is the process by which a segment of DNA can move from one position to another in the genome.
True or False?
True.
Transposition is the process by which a protein can move from one position to another in the genome.
True or False?
False.
Transposition is the process by which a segment of DNA can move from one position to another in the genome.
Transposition is the process by which a chromosome can move from one position to another in the genome.
True or False?
False.
Transposition is the process by which a segment of DNA can move from one position to another in the genome.
Transposition is the process by which a gene is moved from one organism to another.
True or False?
False.
Transposition is the process by which a segment of DNA can move from one position to another in the genome.
Interspersed repeat sequences are localized in a specific region of the genome.
True or False?
False.
Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.
Interspersed repeat sequences recur at many places in the genome.
True or False?
True.
Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.
Interspersed repeat elements are localized in the centromere.
True or False?
False.
Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.
Interspersed repeat elements are absent in eukaryotic genomes.
True or False?
False.
Interspersed repeat elements include LINEs, SINEs, LTRs, and DNA transposons.
Plasmids are usually larger in size than chromosomes.
True or False?
False.
Plasmids are usually present in eukaryotic cells.
True or False?
False.
Plasmids carry genes that are not usually present in the chromosome.
True or False?
True.
Plasmids carry only pseudogenes.
True or False?
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 histones are more frequent in yeasts.
True or False?
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.
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 yeast genes contain no start codon and terminator sequence so space is saved.
True or False?
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.
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 yeast genome contains many overlapping genes, similar to the E. coli genome.
True or False?
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.
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.
True or False?
True.
A typical bacterial operon has genes that codify for a single protein.
True or False?
False.
For example, the Lac operon has 3 proteins.
In a typical bacterial operon the expression of the operon genes occur at the same time.
True or False?
True.
In a typical bacterial operon, the genes encode proteins that are involved in a single biochemical pathway/function.
True or False?
True.
In a typical bacterial operon, the genes are under the control of a single promoter.
True or False?
True.
What are the major traits that have been/are being improved in food crops? [4]
- Improved nutrients
- Improved flavour
- Higher yields
- Extended shelf-life
In the hybridization of crops, it is a limitation that the parental genotype and phenotype cannot be easily recovered in filial generations.
True or False?
True.
In the hybridization of crops, it is a limitation that no knowledge is required on the genetic control of the trait.
True or False?
False.
This is a strength/boon of hybridization.
In the hybridization of crops, it is a limitation that it applies to all traits, provided that the source of the improved trait and recipient are interfertile.
True or False?
False.
This is a strength/boon of hybridization of crops.
Hybridization of crops is not accepted by consumers.
True or False?
False.
It is accepted by consumers.
Explain what the genetic code is.
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.
Give a definition of precision fermentation.
- 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.
You are making yogurt and have added all the necessary ingredients (milk and starter culture) and your equipment is functional. However, after incubating at the appropriate temperatures, you find that the yogurt gel has not formed.
List three ideas for what could have stopped the gel from forming.
- 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.
- Presence of residual sanitizers (e.g., quaternary amonium) have killed the LAB which are very sensitive.
- Contamination with antibodies (e.g., agglutinin) or antibiotics (S. thermophilus is very sensitive), which would prevent their growth.
Give a definition of natural fermentation.
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.
What are three potential problems with using natural fermentation.
- 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.
- 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.
- 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.
Natural fermentation is unpreditable, time-consuming, gives inconsistent results, potentially unsafe, the right bacteria need to be present.
Give the definition of Koch’s postulates with regards to fermentation science.
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.
What is a psuedogene? List two ways that a pseudogene can be generated.
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.
What are the two major classes of transposable elements in eukaryotic genomes? What is the major difference between these two classes?
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.
Describe how transposable elements can affect the phenotype of an organism.
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.
What would you expect if a transposon ‘jumps’ from another region of the genome into the promoter region of MybA2, disrupting its expression? What colour would the grapes be?
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!
What would you expect if mutations of the coding sequence of MybA1 and MybA2 make both genes non-functional? What colour would the grapes be?
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.
