90 Questions
Who recognized that DNA is a double helix?
Rosallind Franklin
What is the diameter of the DNA molecule?
2nm
Who discovered a double helix structure for DNA?
Watson and Crick
What are the complementary base pairs in DNA?
A-T and G-C
Who discovered four different nitrogenous bases (A, T, C, and G)?
Chargraff
What did Chargraff's ratios of the nitrogenous bases and the phosphate and sugar backbone show?
DNA molecule could only be stable if the strands ran antiparralel
What did the tobacco CEO deny in 1994?
The addictiveness of nicotine
What did the tobacco industry use as a powerful tool to make smoking look cool?
Advertisements
What did the FDA rules (2010) prohibit tobacco companies from doing?
All of the above
What did some tobacco companies do to promote their image in the community?
Helped build/sponsor schools
What was the initial presentation of e-cigarettes to teens?
A way to stop people from smoking
How much did the tobacco industry spend on advertisement and promotion?
12.4 million dollars
What is the function of DNA polymerase during DNA replication?
It synthesizes a product with a base sequence complementary to the template.
What is the role of the primer in DNA replication?
It binds to its complementary sequence in the template DNA.
What contributes significantly to the stability of the DNA double helix?
Base stacking
What is the direction of chain-elongation reaction catalyzed by DNA polymerase during DNA replication?
From 5’ to 3’ of the elongated DNA
What is the function of DNA ligase in DNA replication?
Joins the Okazaki fragments together
What is the orientation of the new strand synthesized by DNA polymerase on the lagging strand during DNA replication?
In the 5’ to 3’ direction using multiple primers
What is the purpose of the 5' cap added to mRNA during processing?
To extend the lifespan of mRNA by protecting it from degradation
What is the central dogma of genetics?
DNA is transcribed into RNA, which is then translated to form proteins
What is the role of introns in eukaryotic mRNA?
Non-coding regions that are spliced out during mRNA processing
What is the function of the Sanger method in DNA sequencing?
Utilizes electrophoresis to determine DNA fragment size and sequence DNA bases
What does the PCR process achieve?
Amplifies a single DNA segment into billions of identical copies using primers and repeating cycles
What is the purpose of a primer in DNA replication?
To initiate replication by providing a starting point for DNA polymerase
What is the function of tRNA in protein synthesis?
Carries an amino acid and has a three-base anticodon to convert mRNA sequences to an amino acid sequence in a protein
What is the consequence of most mutations?
Most changes are repaired quickly, but those that are not result in mutations
What is the primary cause of lung cancer according to the text?
Smoking
How long is the human DNA in one cell?
2 meters
What is the role of ribosomes in protein synthesis?
Convert the sequences of bases in mRNA to an amino acid sequence in a protein via tRNA
What is the redundant nature of the genetic code?
Most amino acids are specified by more than one codon, up to 6
Explain the process of DNA replication and the role of DNA polymerase in synthesizing new DNA strands.
DNA replication is the process of creating a copy of DNA. DNA polymerase is responsible for catalyzing the formation of phosphodiester bonds between nucleotides, adding new nucleotides one at a time, and proofreading the newly synthesized DNA strands for errors.
Describe the structure of a DNA double helix and the significance of antiparallel strands.
A DNA double helix consists of two strands of DNA that run in opposite directions (antiparallel). The antiparallel orientation allows the two strands to form hydrogen bonds between complementary base pairs, contributing to the stability of the double helix.
What are Okazaki fragments and how are they involved in DNA replication?
Okazaki fragments are short, newly synthesized DNA fragments on the lagging strand during DNA replication. They are formed in the 5' to 3' direction and later joined together by DNA ligase to create a continuous strand.
Explain the role of primase and DNA ligase in DNA replication.
Primase is responsible for synthesizing a short segment of RNA, which serves as a primer for DNA polymerase to start synthesizing a new DNA strand. DNA ligase joins the Okazaki fragments on the lagging strand to create a continuous strand.
What is the significance of base stacking in the stability of the DNA double helix?
Base stacking refers to the alignment of adjacent bases in a DNA double helix, which allows their planar rings to stack on top of one another. This stacking contributes significantly to the stability of the DNA double helix.
Describe the semiconservative nature of DNA replication and its implications.
Semiconservative DNA replication results in each new double helix containing one original DNA strand and one new DNA strand. This ensures the preservation of genetic information and allows for error correction during replication.
Explain the process of translocation in protein synthesis, including the movement of the ribosome and tRNA, and the opening of the A site to a new mRNA codon.
Translocation in protein synthesis occurs when the ribosome moves down the mRNA in the 5’ -> 3’ direction, ejecting the empty tRNA, moving the tRNA containing the growing polypeptide into the P site, and opening the A site to a new mRNA codon.
What are the consequences of mutations, and what factors can contribute to the accumulation of mutations over time?
The consequences of mutations include selective advantage, genetic diseases (e.g., sickle cell anemia), and cancers caused by defective DNA repair. Mutations accumulate over time due to age and environment, with smoking being a classic mechanism of lung carcinogenesis and a leading cause of cancer deaths in the US and Canada.
Describe the role of tRNA in protein synthesis, including its structure and function in adding amino acids to the growing protein.
tRNA carries an amino acid and has a three-base anticodon. The amino acid carried by tRNA is added to the growing protein via the formation of a peptide bond, with each amino acid specified by three bases (codon) in mRNA.
Explain the impact of mutations on an organism's DNA sequence and phenotype, and discuss the relationship between mutations and abnormal protein function.
A mutation is any change in an organism’s DNA sequence, affecting the phenotype only when expressed as abnormal protein function. Not all mutations generate a phenotype.
Discuss the process of DNA replication and the factors contributing to the occurrence of mutations during replication.
Most mutations occur during DNA replication, but some occur when DNA is not replicating, with most changes being repaired quickly; those that are not result in mutations. Mutations can come from the incorporation of incorrect bases during DNA replication, with most spontaneous changes in DNA being immediately corrected by DNA repair.
Explain the relationship between tobacco smoke, mutations, and cancer, including the components of tobacco smoke and the preventability of lung cancer.
Tobacco smoke consists of about 60 known components, and lung cancer is almost entirely preventable, with 80% of cases due to smoking. Secondhand smoking can also have severe health consequences, especially for pregnant women and their babies.
Explain the structure and composition of DNA according to the text.
DNA is composed of deoxyribonucleic acid and is made up of two strands of nucleotides. Each nucleotide consists of a phosphate group, a sugar molecule, and a nitrogenous base. The strands are arranged in a double helix structure, with complementary base pairs (A-T and G-C) held together by hydrogen bonds.
What were the contributions of Rosalind Franklin, Watson, and Crick to our understanding of DNA structure?
Rosalind Franklin recognized that DNA is a double helix and provided crucial X-ray diffraction images. Watson and Crick used Franklin's work and other data to propose the double helix structure for DNA, discovering the base pairing rules and the antiparallel nature of the DNA strands.
Describe Chargraff's ratios and their significance in understanding DNA structure.
Chargraff's ratios revealed that the amount of adenine (A) is equal to thymine (T), and the amount of cytosine (C) is equal to guanine (G) in DNA. This finding provided essential clues about the base pairing rules and the structure of DNA.
What is the significance of the phosphate and sugar backbone in the DNA molecule?
The phosphate and sugar backbone provides structural support for the DNA molecule, forming the outer framework to which the nitrogenous bases are attached. This backbone plays a crucial role in maintaining the stability of the DNA double helix.
Explain the role of DNA in the transmission of genetic information.
DNA is responsible for transmitting genetic information from one generation to the next in most forms of life on Earth. It carries the genetic code in the sequence of nucleotides, allowing for the inheritance and expression of traits in organisms.
Discuss the challenges and breakthroughs in understanding the structure of DNA as outlined in the text.
Challenges included understanding the arrangement of nitrogenous bases and the overall three-dimensional structure of DNA. Breakthroughs involved the recognition of the double helix structure by Rosalind Franklin, the discovery of complementary base pairing and antiparallel strands by Watson and Crick, and the establishment of Chargraff's ratios, leading to a deeper understanding of DNA's composition and function.
Explain the significance of Kornberg's work in molecular biology and its implications for DNA replication initiation and strand length variation in DNA.
Kornberg's work highlighted the need for a primer for DNA polymerase to initiate replication and the variation in length of DNA strands, which are crucial aspects of DNA replication.
What tactics did tobacco companies use in the 40s to convince women to smoke, and what quote reflects the ethical implications of their marketing strategies?
Tobacco companies used physiological manipulations to convince women to smoke, and the quote 'If you can market a product that kills people, you can sell anything' reflects the ethical implications of their marketing strategies.
Describe the process and significance of the Sanger method in DNA sequencing, including the use of electrophoresis and its impact on determining DNA fragment size and base sequencing.
The Sanger method utilizes electrophoresis to determine DNA fragment size and enables the sequencing of DNA bases, which has been pivotal in advancing our understanding of genetics and genomics.
What did the tobacco CEO deny in 1994, and what did the tobacco industry use as a powerful tool to make smoking look cool?
The tobacco CEO denied that 'nicotine is not addictive' in 1994, and the tobacco industry used advertisements as a powerful tool to make smoking look cool.
Explain the PCR process and its role in molecular biology, including the utilization of primers and repeating cycles to amplify a single DNA segment into billions of identical copies.
The PCR process amplifies a single DNA segment into billions of identical copies using primers and repeating cycles, revolutionizing various fields such as diagnostics, forensics, and research.
What has the tobacco industry been targeting since the 1970s, and what are two things that tobacco companies cannot do under the new FDA rules (2010)?
The tobacco industry has been targeting young children and adolescents since the 1970s. Under the new FDA rules (2010), tobacco companies cannot sponsor sporting events or sell items with tobacco brands’ logos.
Discuss the central dogma of genetics and its fundamental principles, emphasizing the transcription of DNA into RNA and the subsequent translation to form proteins.
The central dogma of genetics emphasizes the flow of genetic information from DNA to RNA to proteins, serving as a cornerstone in understanding gene expression and molecular biology.
What did some tobacco companies do to promote their image in the community, and what was the initial presentation of e-cigarettes to teens?
Some tobacco companies helped build/sponsor schools to promote their image in the community. E-cigarettes were initially presented as a way to stop people from smoking.
Explain the process of transcription, including the synthesis of an RNA transcript using one strand of DNA as the template and the directionality of the synthesis.
Transcription involves the synthesis of an RNA transcript using one strand of DNA as the template, proceeding in the 5'→3' direction, and is a critical step in gene expression.
How much did the tobacco industry spend on advertisement and promotion, and what was the intended purpose of e-cigarettes for teens?
The tobacco industry spent 12.4 million dollars on advertisement and promotion. The intended purpose of e-cigarettes for teens was to stop people from smoking, but it did not work.
Describe the structure of genes, highlighting the coding regions known as exons and the non-coding regions called introns, and explain their significance in eukaryotic mRNA.
Genes consist of coding regions called exons and non-coding regions called introns, and the splicing out of introns in eukaryotic mRNA is a crucial process in generating functional proteins.
What did the FDA rules (2010) prohibit tobacco companies from doing, and what are two things that companies are not allowed to do with tobacco products under these rules?
The FDA rules (2010) prohibited tobacco companies from sponsoring sporting events and selling items with tobacco brands’ logos. Companies are also not allowed to sell tobacco products in vending machines accessible to minors.
Rosalind Franklin recognized that DNA is a double helix, rotating in a clockwise direction
True
Watson and Crick discovered a double helix structure of DNA
True
Chargraff's ratios of the nitrogenous bases and the phosphate and sugar backbone showed that DNA molecule could only be stable if the strands ran parallel
False
DNA molecule has a diameter of 2nm and one turn of the helix was 3.4 nm in length
True
DNA is responsible for the transmission of information from one generation to the next in most forms of life on this planet
True
Enzymes are responsible for cell activity and are found in the cytoplasm
True
DNA strands must have the hydroxyl of the 3’ carbon attached to the deoxyribose sugar at one end and the phosphate attached to the 5’ carbon of the last sugar at the other end
True
The DNA backbone is assembled from repeating deoxyribose sugar unit that are linked through phosphate groups
True
Adjacent bases are aligned so that their planar rings stack on top of one another
True
DNA polymerase catalyzes the formation of a phosphodiester bond only if the base on the incoming nucleotide is complementary to the base on the template strand
True
DNA replication comes largely from studies of E. coli bacteria that are found by the billions in the large intestine
True
DNA is denatured into single strands at near-boiling temperature during DNA replication
False
Nicotine was declared as addictive by the tobacco CEO in 1994
False
The tobacco industry targeted young children and adolescents as part of their marketing policy since the 1970s
True
Under the new FDA rules (2010), tobacco companies can still sponsor sporting events and sell items with tobacco brands’ logos
False
E-cigarettes were initially presented as a way to stop people from smoking and were successful in doing so
False
The tobacco industry spent 12.4 million dollars on advertisement and promotion
True
Tobacco companies can still sell tobacco products in vending machines accessible to minors under the new FDA rules (2010)
False
Genetic code is never redundant, with each amino acid being specified by a unique codon
False
Ribosomes start translating mRNA as soon as it reaches the cytoplasm and progress from 3' to 5' end
False
Mutations are always quickly repaired and have no long-term impact on the organism
False
Point mutations can only result from replication errors and not from exposure to mutagenic toxins
False
Mutations can only lead to silent or missense mutations, but not to nonsense or frameshift mutations
False
Smoking is not a leading cause of cancer and does not contain known carcinogens
False
Kornberg's work emphasized the need for a primer for DNA polymerase to initiate replication
True
The Sanger method utilizes electrophoresis to determine DNA fragment sizes and sequence bases
True
The Central Dogma of genetics involves DNA being transcribed to RNA and then translated into proteins
True
Eukaryotic mRNA undergoes processing, including splicing out introns and adding a cap and tail
True
The genetic code is universal and involves 64 possible codons, but only 20 amino acids
True
Caps and tails added to mRNA extend its lifespan by protecting it from degradation
True
Study Notes
Translation and Translocation in Protein Synthesis
- The genetic code is redundant, with most amino acids specified by more than one codon (up to 6).
- Ribosomes convert the sequences of bases in mRNA to an amino acid sequence in a protein via tRNA, which carries an amino acid and has a three-base anticodon.
- The amino acid carried by tRNA is added to the growing protein via the formation of a peptide bond, with each amino acid specified by three bases (codon) in mRNA.
- Translocation occurs when the ribosome moves down the mRNA in the 5’ -> 3’ direction, ejecting the empty tRNA, moving the tRNA containing the growing polypeptide into the P site, and opening the A site to a new mRNA codon.
- As soon as a messenger RNA molecule is transported from the nucleus to the cytoplasm, ribosomes begin to translate the sequence into amino acids, simultaneously translating the mRNA.
- Human DNA in one cell is 2 meters long, and 10^16 cells are produced in a human lifetime, equivalent to 2 x 10^13 km of DNA, which is the length of DNA synthesized by our body.
- Most mutations occur during DNA replication, but some occur when DNA is not replicating, with most changes being repaired quickly; those that are not result in mutations.
- Mutations can come from the incorporation of incorrect bases during DNA replication, with most spontaneous changes in DNA being immediately corrected by DNA repair.
- A mutation is any change in an organism’s DNA sequence, affecting the phenotype only when expressed as abnormal protein function, and not all mutations generate a phenotype.
- The consequences of mutations include selective advantage, genetic diseases (e.g., sickle cell anemia), and cancers caused by defective DNA repair.
- Mutations of genes accumulated over time due to age and environment, with smoking being a classic mechanism of lung carcinogenesis and a leading cause of cancer deaths in the US and Canada.
- Tobacco smoke consists of about 60 known components, and lung cancer is almost entirely preventable, with 80% of cases due to smoking. Secondhand smoking can also have severe health consequences, especially for pregnant women and their babies.
Molecular Biology Fundamentals
- Kornberg's work highlighted the need for a primer for DNA polymerase to initiate replication and that DNA strands vary in length.
- The Sanger method utilizes electrophoresis to determine DNA fragment size, enabling the sequencing of DNA bases.
- The PCR process amplifies a single DNA segment into billions of identical copies using primers and repeating cycles.
- The central dogma of genetics emphasizes that DNA is transcribed into RNA, which is then translated to form proteins.
- Transcription involves the synthesis of an RNA transcript using one strand of DNA as the template, in the 5'→3' direction.
- Genes consist of coding regions called exons and non-coding regions called introns, which are spliced out in eukaryotic mRNA.
- The mRNA undergoes processing, including the addition of a cap to the 5' end, a poly-A tail at the 3' end, and removal of introns.
- The 5' cap and the poly (A) tail extend the lifespan of mRNA by protecting it from degradation.
- Protein synthesis involves converting the information stored in nucleic acid sequences into proteins, mediated by mRNA, ribosomes, and tRNA.
- Amino acids are the building blocks of proteins, and the genetic code uses 64 possible codons to specify 20 amino acids.
- Proteins play key roles in biochemical reactions, gene expression regulation, and cellular structure and function.
- The genetic code is universal and is used in the nuclear genome of most organisms, with each codon linked to a specific amino acid.
DNA Replication, Transcription, and Protein Synthesis
- Kornberg's work emphasized the need for a primer for DNA polymerase to initiate replication
- The Sanger method utilizes electrophoresis to determine DNA fragment sizes and sequence bases
- The Polymerase Chain Reaction (PCR) can amplify a single DNA segment into billions of identical copies
- DNA serves two functional roles: replication for cell division and as an information carrier
- The Central Dogma of genetics involves DNA being transcribed to RNA and then translated into proteins
- Transcription involves copying DNA into RNA, using RNA polymerase and promoter and terminator sites
- Eukaryotic mRNA undergoes processing, including splicing out introns and adding a cap and tail
- Caps and tails added to mRNA extend its lifespan by protecting it from degradation
- Proteins play key roles in cell processes, with major classes including enzymatic, regulatory, and structural
- Translation involves converting the nucleic acid sequence into proteins using mRNA, ribosomes, and tRNA
- The genetic code is universal and involves 64 possible codons, but only 20 amino acids
- Transfer RNA (tRNA) serves as an adapter between codons in mRNA and amino acids, through its complementary anticodon.
Test your knowledge of translation and translocation in protein synthesis with this quiz. Explore concepts such as genetic code redundancy, tRNA function, peptide bond formation, and the process of translocation. Gain insights into the impact of mutations on DNA sequences, their consequences, and factors contributing to genetic diseases and cancer.
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