Podcast
Questions and Answers
What is the role of DNA in the formation of proteins?
What is the role of DNA in the formation of proteins?
The structure of enzymes is determined by DNA.
Which one of these statements about proteins and polypeptides is true? (Select all that apply)
Which one of these statements about proteins and polypeptides is true? (Select all that apply)
- All proteins are made up of four polypeptide chains.
- Each polypeptide is made up of one or more proteins.
- A protein may consist of a single polypeptide or more than one polypeptide linked together. (correct)
- All proteins are made up of one polypeptide chain.
Which characteristic of hemoglobin allows it to be considered a protein with quaternary structure?
Which characteristic of hemoglobin allows it to be considered a protein with quaternary structure?
It consists of four polypeptide chains.
What would happen if a single amino acid in a protein consisting of 325 amino acids were changed?
What would happen if a single amino acid in a protein consisting of 325 amino acids were changed?
What is the name given to the level of protein shape for lysozyme, a protein consisting of a single polypeptide?
What is the name given to the level of protein shape for lysozyme, a protein consisting of a single polypeptide?
When comparing the proteome of a yeast cell with that of a human cell, why is the latter more complex?
When comparing the proteome of a yeast cell with that of a human cell, why is the latter more complex?
Which disaccharide is made up of glucose and fructose joined by a glycosidic bond?
Which disaccharide is made up of glucose and fructose joined by a glycosidic bond?
Why is the graph below not an accurate representation of how the rate of reaction of an enzyme-catalyzed reaction changes with temperature?
Why is the graph below not an accurate representation of how the rate of reaction of an enzyme-catalyzed reaction changes with temperature?
What is the name of the DNA structure?
What is the name of the DNA structure?
What is the name of the pentose present in DNA molecules?
What is the name of the pentose present in DNA molecules?
Which statement about RNA is correct?
Which statement about RNA is correct?
Which method was used in the discovery of the DNA double helix?
Which method was used in the discovery of the DNA double helix?
Which is the correct sequence of events for DNA replication?
Which is the correct sequence of events for DNA replication?
Name the enzyme that separates the two strands of the DNA double helix during replication.
Name the enzyme that separates the two strands of the DNA double helix during replication.
What results for the DNA of the last generation showed that replication was semi-conservative in Meselson and Stahl's experiments?
What results for the DNA of the last generation showed that replication was semi-conservative in Meselson and Stahl's experiments?
DNA replication occurs by a:
DNA replication occurs by a:
Which method was used in Meselson and Stahl's experiment to prove their theory about the semi-conservative nature of DNA replication?
Which method was used in Meselson and Stahl's experiment to prove their theory about the semi-conservative nature of DNA replication?
A particular triplet of bases in the template strand of DNA is AGT. What is the corresponding codon for the mRNA transcribed?
A particular triplet of bases in the template strand of DNA is AGT. What is the corresponding codon for the mRNA transcribed?
Which of the following enzymes is responsible for uncoiling and separating the DNA strands during transcription?
Which of the following enzymes is responsible for uncoiling and separating the DNA strands during transcription?
Deduce the DNA base sequence of the antisense strand used to generate the following bases on the mRNA: UAG CCA UCC GGC.
Deduce the DNA base sequence of the antisense strand used to generate the following bases on the mRNA: UAG CCA UCC GGC.
A possible sequence of nucleotides in the mRNA that would code for the polypeptide sequence Phe-Leu-Ile-Val would be:
A possible sequence of nucleotides in the mRNA that would code for the polypeptide sequence Phe-Leu-Ile-Val would be:
What is the role of tRNA in translation?
What is the role of tRNA in translation?
Refer to the table below to deduce the codon for phenylalanine (Phe).
Refer to the table below to deduce the codon for phenylalanine (Phe).
Which components are needed for PCR? (Select all that apply)
Which components are needed for PCR? (Select all that apply)
What is the characteristic feature of Taq polymerase that allows its use in PCR?
What is the characteristic feature of Taq polymerase that allows its use in PCR?
A unicellular organism that carries a specific gene from another organism is called a _____ organism.
A unicellular organism that carries a specific gene from another organism is called a _____ organism.
The production of human insulin in bacteria is possible because of:
The production of human insulin in bacteria is possible because of:
Which organelles are used in transferring genes from one organism to another?
Which organelles are used in transferring genes from one organism to another?
What does the proteome refer to?
What does the proteome refer to?
Which option (A-D) gives the correct classification of rhodopsin, collagen and hemoglobin as globular and fibrous proteins?
Which option (A-D) gives the correct classification of rhodopsin, collagen and hemoglobin as globular and fibrous proteins?
State the name of the protein that catalyses the fixation of CO2 in chloroplasts.
State the name of the protein that catalyses the fixation of CO2 in chloroplasts.
Which of these statements about the denaturation of protein is true?
Which of these statements about the denaturation of protein is true?
What occurs in the induced fit model for enzyme-catalysed reactions?
What occurs in the induced fit model for enzyme-catalysed reactions?
What is an active site?
What is an active site?
What does enzyme-substrate specificity mean?
What does enzyme-substrate specificity mean?
Which of the following statements regarding enzymes is true?
Which of the following statements regarding enzymes is true?
The diagram below shows the energy levels of a reaction in the presence or absence of an enzyme. What is the best explanation of the different energy levels labelled I, II and III?
The diagram below shows the energy levels of a reaction in the presence or absence of an enzyme. What is the best explanation of the different energy levels labelled I, II and III?
What can be concluded from the carbonic anhydrase activity of bacterium A and bacterium B at different pH values?
What can be concluded from the carbonic anhydrase activity of bacterium A and bacterium B at different pH values?
What accounts for the slow rate of the reaction in a student experiment involving the hydrolysis of starch to maltose at 10 °C?
What accounts for the slow rate of the reaction in a student experiment involving the hydrolysis of starch to maltose at 10 °C?
Which of the following could cause denaturation of an enzyme?
Which of the following could cause denaturation of an enzyme?
Proteins have four levels of structural organization. Which two of these are more likely to be affected when enzymes are denatured?
Proteins have four levels of structural organization. Which two of these are more likely to be affected when enzymes are denatured?
Yogurt is tolerated better than milk by lactose-intolerant people because:
Yogurt is tolerated better than milk by lactose-intolerant people because:
Why are immobilized enzymes used in industry?
Why are immobilized enzymes used in industry?
In an experiment, a student added 2 ml of milk to 2 ml of 0.1% lipase solution at room temperature. What is the independent variable in this experiment?
In an experiment, a student added 2 ml of milk to 2 ml of 0.1% lipase solution at room temperature. What is the independent variable in this experiment?
In a preliminary experiment involving a student and lipase solution, which of the following changes would not cause a measurable decrease in pH?
In a preliminary experiment involving a student and lipase solution, which of the following changes would not cause a measurable decrease in pH?
Study Notes
DNA and Proteins
- DNA determines the structure of enzymes, crucial for various biological functions.
- Proteins can consist of a single polypeptide or multiple polypeptides linked together, reflecting diversity in structure and function.
- Hemoglobin is classified as a protein with quaternary structure due to its composition of four polypeptide chains.
- Altering one amino acid in a protein of 325 amino acids affects both the primary and tertiary structure, impacting its function.
- Tertiary structure is the level of protein shape exemplified by lysozyme, which consists of a single polypeptide chain.
Genetic Material and Replication
- The DNA structure is known as a double helix and contains deoxyribose as its pentose sugar.
- RNA differs from DNA by containing uracil instead of thymine.
- X-ray crystallography played a key role in discovering the DNA double helix structure.
- DNA replication occurs in a semi-conservative manner, ensuring each new DNA molecule consists of one old and one new strand.
- Meselson and Stahl's experiment showed that DNA replication is semi-conservative by revealing strands containing both 15N and 14N.
Codons and Translation
- The mRNA codon for the DNA triplet AGT is UCA, illustrating the transcription process.
- tRNA is essential in translation, as it brings the corresponding amino acids to the ribosome.
- The codons for phenylalanine (Phe) are UUU and UUC, underscoring the genetic code's redundancy.
Enzymes and Reactions
- PCR requires primers, Taq polymerase, and DNA nucleotides, critical for DNA amplification.
- Taq polymerase is uniquely suited for PCR as it remains stable at high temperatures.
- Transgenic organisms carry specific genes from other organisms, facilitating gene transfer and genetic research.
- The universality of the genetic code allows for the production of human insulin in bacteria through gene transfer.
- Plasmids serve as vectors for transferring genes between organisms.
Protein Structure and Function
- The proteome signifies the unique set of proteins expressed by an organism, influencing its traits and functions.
- Rubisco catalyzes the fixation of CO2 during photosynthesis in chloroplasts.
- Denaturation alters a protein's quaternary, tertiary, and sometimes secondary structures, affecting functionality.
- Enzyme-substrate specificity indicates that enzymes catalyze specific reactions by fitting only certain substrates.
- Carbonic anhydrase activity varies with pH, with one bacterial source showing superior function over another at higher pH levels.
Practical Experimentation
- Factors like temperature can significantly affect enzyme activity, as observed in amylase-catalyzed starch hydrolysis.
- Denaturation of enzymes can occur due to high temperatures, leading to a loss of biological activity.
- Lactase from yogurt improves lactose digestion in lactose-intolerant individuals compared to milk, highlighting the role of enzymes in food processing.
- Immobilized enzymes are preferred in industrial processes for their reusability and efficiency, minimizing waste and cost.
Experimental Variables
- In enzyme experiments assessing pH changes, temperature acts as the independent variable, affecting reaction rates and outcomes.
- Altering experimental conditions (like temperature) impacts enzyme activity and can affect pH measurements, guiding experimental design and interpretation of results.
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Test your knowledge on the role of DNA in protein formation and the structure of proteins and polypeptides. This quiz covers key concepts essential for understanding cellular biology. Challenge yourself with these flashcards and enhance your comprehension.
