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Questions and Answers
What is the primary function of the enzyme telomerase?
What is the primary function of the enzyme telomerase?
In eukaryotic cells, what is the role of the enzyme primase during DNA replication?
In eukaryotic cells, what is the role of the enzyme primase during DNA replication?
Primase synthesizes RNA primers to initiate DNA synthesis.
During DNA replication, the enzyme __________ unwinds the double helix structure of the DNA.
During DNA replication, the enzyme __________ unwinds the double helix structure of the DNA.
helicase
Match the following terms with their descriptions:
Match the following terms with their descriptions:
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What is the primary role of mRNA in protein synthesis?
What is the primary role of mRNA in protein synthesis?
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Transcription is the process of synthesizing proteins from mRNA templates.
Transcription is the process of synthesizing proteins from mRNA templates.
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What is a codon?
What is a codon?
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The process of building a protein molecule using the information encoded in mRNA is called ______.
The process of building a protein molecule using the information encoded in mRNA is called ______.
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Match the descriptions with the correct term:
Match the descriptions with the correct term:
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Which of the following is a post-transcriptional modification of pre-mRNA?
Which of the following is a post-transcriptional modification of pre-mRNA?
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Introns are coding sequences that are spliced together to form the final mRNA.
Introns are coding sequences that are spliced together to form the final mRNA.
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What enzyme is responsible for the synthesis of mRNA during transcription?
What enzyme is responsible for the synthesis of mRNA during transcription?
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Which of the following events does NOT occur during the prophase stage of mitosis?
Which of the following events does NOT occur during the prophase stage of mitosis?
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The metaphase plate is located near one of the cell poles.
The metaphase plate is located near one of the cell poles.
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What is the name of the structure that pulls apart sister chromatids during mitosis?
What is the name of the structure that pulls apart sister chromatids during mitosis?
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The process of the cytoplasm dividing at the end of mitosis or meiosis is called ________.
The process of the cytoplasm dividing at the end of mitosis or meiosis is called ________.
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At which stage of the cell cycle, do cells spend most of their time?
At which stage of the cell cycle, do cells spend most of their time?
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The cell cycle is an event that continues indefinitely until the cell dies.
The cell cycle is an event that continues indefinitely until the cell dies.
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What is the purpose of the cell cycle checkpoints?
What is the purpose of the cell cycle checkpoints?
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Study Notes
Mendel's Experiments and Heredity
- Genetics is the study of heredity
- Johann Gregor Mendel established the framework for genetics, prior to understanding chromosomes and genes, and before the understanding of meiosis
- Mendel used a simple biological system (pea plants) and methodical, quantitative analyses using large sample sizes to establish fundamental principles of heredity
- Mendel's experiments revealed that traits are transmitted independently from parents to offspring in dominant and recessive patterns
- Mendel's work was initially ignored but later rediscovered and revitalized by scientists
Mendel's Experiments and the Laws of Probability
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Mendel's experimental work was successful because he chose a suitable organism to study
- Pea plants self-fertilize naturally and thus produce highly inbred, "true-breeding" plants (plants that always produce offspring like the parent)
- Pea plants grow to maturity quickly, allowing for multiple generations to be studied
- A large quantity of garden peas could be cultivated simultaneously, enabling Mendel to conclude that his results did not come about by chance, or errors in his experiments
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Mendel performed hybridizations - by manually transferring pollen (carrying the male gametes / sperm) to the stigma (receiving the female gametes / ova) of pea plants to create hybrids
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The initial plants used in the first generation of crosses were called the P generation
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The offspring of these plants were the F1 generation
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The offspring of these plants were called the F2 generation
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Mendel's work examined traits that were inherited in distinct classes, such as violet versus white flowers, as opposed to continuous traits (blending of characteristics which were thought to occur) - such as height.
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Discontinuous variation in plants were more suited for the experiments demonstrating the presence of distinct traits.
Garden Pea Characteristics
- Mendel conducted experiments with pea plants, which demonstrated inheritance patterns for 7 characteristics
- Seven characteristics were: plant height, seed texture, seed color, flower color, pea pod size, pea pod color, flower position.
- Each characteristic had two contrasting traits, which he studied.
- Mendel generated large numbers of F1 and F2 plants
Mendelian Crosses
- Mendel performed hybridizations between true-breeding plants of different genotypes.
- The resulting traits of the F1 and F2 generations formed a 3:1 offspring ratio.
- The F1 generation always expressed one of the two contrasting traits, whereas the F2 generation consistently displayed the recessive trait in a roughly 1:3 ratio.
- Mendel performed similar monohybrid crosses on other characteristics to verify the outcome of the cross-breeding experiment
Probability Rules
- Probabilities are mathematical measures of the likelihood of an event.
- Mendel's experiments used large sample sizes to calculate the probabilities of traits appearing.
- The product rule of probability calculates the likelihood of two independent events occurring together.
- The sum rule of probability calculates the likelihood of either of two mutually exclusive events occurring.
Phenotypes and Genotypes
- The observable traits of an organism are its phenotype.
- The underlying genetic makeup is the genotype.
- Mendel's experiments and monohybrid crosses distinguish between phenotype and genotype in dominant and recessive gene systems.
Dominant and Recessive Alleles
- A dominant trait only needs one allele.
- A recessive trait requires two alleles for its expression
Test Crosses
- Determine whether an organism with a dominant trait is a homozygote or heterozygote.
- In a test cross, the dominant-expressing organism is crossed with an organism that has a homozygous recessive genotype.
- A homozygous trait results in all F1 offspring being heterozygotes expressing the dominant trait
- A heterozygous trait will result in a 1:1 ratio of genotypes in the F1 offspring
Alternatives to Dominance and Recessiveness
- Incomplete dominance occurs in heterozygotes, where the trait is intermediate between the two parents
- Codominance occurs when both alleles for the same characteristic simultaneously express in the heterozygote.
- Example: blood type MN
- Multiple alleles refer to the presence of more than two alleles in a population, although an individual only has two alleles for each gene.
- Example: coat color of rabbits
- X-linked traits are traits carried on the X chromosome, making their expression differ between the sexes. For example, color blindness and hemophilia are X-linked recessive traits.
Laws of Inheritance
- The law of segregation states that paired traits are separated, or segregated, equally into gametes.
- The law of independent assortment states that genes that are on different chromosomes sort independently during gamete formation.
- A dihybrid cross illustrates the inheritance pattern of two characteristics.
- These laws are part of classical genetics.
Epistasis
- Epistasis is where one gene masks the effect of another gene.
- Example: color in summer squash; pigmentation in mice.
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Description
Test your understanding of key concepts in DNA replication and transcription with this quiz focused on the roles of various enzymes such as telomerase and primase. Explore essential processes like mRNA synthesis and post-transcriptional modifications. Perfect for biology students looking to reinforce their knowledge in genetics.
