Questions and Answers
Describe the role of DNA polymerase in DNA replication.
Joins free nucleotides to form a new strand
What does DNA hold?
Genetic information for our features and characteristics.
What is the difference between the DNA of the virus and that of other organisms?
Adenine does not equal Thymine so no base pairing so DNA is not double stranded.
What are histones?
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Explain the significance of DNA to organisms.
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Explain the structure of DNA.
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How is DNA replication on the leading strand different from DNA replication on the lagging strand?
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What is the role of single-stranded DNA binding proteins?
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What is the role of DNA ligase?
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Why did many scientists initially doubt that DNA was the genetic code?
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Explain the importance of base pairing in DNA replication.
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How does DNA polymerase participate in DNA replication?
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Why is DNA replication described as semi-conservative?
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Explain the role of RNA in transferring genetic information.
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Explain the structure of RNA.
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Why are there more than 423 bases in the DNA of the α-polypeptide gene?
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Where are ribosomes formed from?
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Compare and contrast the similarities and differences between DNA and RNA.
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Name the bases in DNA.
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Name the bases in RNA.
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Describe how DNA is replicated.
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How does cytarabine prevent DNA replication?
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Study Notes
DNA and its Role
- DNA polymerase functions to join free nucleotides, forming a new strand during DNA replication.
- DNA is structured as a double helix and contains genetic information essential for the traits and characteristics of organisms.
- In eukaryotic cells, DNA is located in the nucleus and is organized into structures called chromosomes.
Characteristics of Viral DNA
- Viral DNA differs from the DNA of other organisms as adenine does not pair with thymine, leading to a lack of double-stranded structure.
Histones and Chromosome Structure
- Histones are proteins associated with DNA within eukaryotic chromosomes, playing a crucial role in DNA packaging.
Significance of DNA
- Deoxyribonucleic acid (DNA) is vital for life, serving as the repository of genetic information in all living cells.
Structure of DNA
- DNA consists of nucleotides linked by phosphodiester bonds, formed through condensation reactions. Each nucleotide has a deoxyribose sugar, a phosphate group, and a nitrogenous base.
- The DNA structure consists of two strands wound into a double helix, with hydrogen bonds connecting complementary base pairs (A-T and C-G).
DNA Replication Process
- Leading strand replication is continuous, while lagging strand replication occurs discontinuously due to opposite directional movement of DNA polymerase at the replication fork.
- Single-stranded DNA binding proteins prevent reannealing of separated strands during replication.
- DNA ligase joins Okazaki fragments on the lagging strand to complete DNA replication.
Historical Skepticism Regarding DNA
- Early scientists doubted DNA's role as the genetic code, perceiving it as too simplistic compared to proteins, which exhibit greater variability.
Importance of Base Pairing in Replication
- Base pairing is crucial in DNA replication, allowing free nucleotides to bind to exposed strands, ensuring the production of identical DNA copies.
Role of RNA
- RNA transfers genetic information from DNA to ribosomes for protein synthesis and is a key component of ribosomal structure.
Structure of RNA
- RNA is a polymer of nucleotides, each made of ribose sugar, nitrogenous base, and phosphate group, linked by phosphodiester bonds. RNA molecules are typically shorter than DNA.
Gene Structure and Base Count
- A gene coding for an α-polypeptide chain consists of 423 bases coding for amino acids, but the total count of bases exceeds this due to start/stop sequences, non-coding regions, complementary base pairing, and potential mutations.
Ribosome Formation
- Ribosomes are synthesized from a combination of RNA and protein.
Comparison of DNA and RNA
- Both DNA and RNA consist of nucleotides, but differ in structure and function. DNA is double-stranded and contains thymine, while RNA is single-stranded and contains uracil instead of thymine.
DNA Bases
- The bases in DNA include adenine, thymine, cytosine, and guanine.
RNA Bases
- The bases in RNA include adenine, uracil, cytosine, and guanine.
Mechanism of DNA Replication
- DNA replication begins with helicase breaking hydrogen bonds to separate strands, allowing templates for free nucleotides to attach through complementary base pairing. DNA polymerase then connects these nucleotides, reforming hydrogen bonds. This semi-conservative process yields new DNA molecules containing one original and one new strand.
Impact of Cytarabine on DNA Replication
- Cytarabine, a cancer drug, inhibits DNA replication by mimicking the structure of the DNA base cytosine, leading to interruptions in the synthesis of new DNA strands.
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Explore the fundamental concepts of DNA structure, replication, and the role of proteins in gene expression through these flashcards. Test your knowledge on key terms and processes involved in molecular biology, including DNA polymerase and chromosomes.
