Questions and Answers
What is meant by the term base pairing and how is base pairing involved in DNA replication?
Base pairing is the pairing of nucleotide bases in DNA where Adenine pairs with Thymine and Cytosine pairs with Guanine. During DNA replication, the DNA molecule splits and DNA polymerase adds the matching bases to form new strands.
Describe the appearance of DNA in a typical prokaryotic cell.
Prokaryotic cells are generally smaller and simpler than eukaryotic cells and have genetic material that is not contained in a nucleus. They may also contain internal membranes.
Explain the process of DNA replication. When a DNA molecule is replicated, how do the new molecules compare to the original?
The new molecule is complementary to the original.
Describe the similarities between DNA replication in prokaryotic cells and eukaryotic cells.
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What is the difference between transcription and translation?
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What is the role of rRNA during translation?
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What is the sugar, number of strands, and bases in DNA and RNA?
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What are the building blocks of DNA?
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What are the nucleotides in DNA made of?
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In DNA, ___ can be joined in any order.
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The nucleotides in DNA are joined by ___ bonds.
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What did Erwin Chargaff, Rosalind Franklin, and Watson and Crick contribute to DNA research?
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What are the functions of a DNA molecule and how does it perform each essential function?
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Why are the strands of DNA said to be complementary?
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What is the first step in eukaryotic DNA replication?
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What enzyme joins individual nucleotides to produce the new strand of DNA?
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What enzyme makes it less likely that DNA will be lost from telomeres during replication?
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How does telomerase work?
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What is a replication fork?
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Does DNA replication take place in the same direction along both strands of the DNA molecule that is being replicated?
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Where is the location, amount, and starting points of DNA replication in prokaryotes and eukaryotes?
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Study Notes
Base Pairing and DNA Replication
- Base pairing involves specific pairing of nitrogenous bases: Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).
- A and T are connected by two hydrogen bonds; C and G are connected by three hydrogen bonds.
- During DNA replication, the DNA molecule splits, exposing base pairs for replication.
- DNA polymerase adds matching nucleotides to form new complementary strands.
Characteristics of Prokaryotic Cells
- Prokaryotic cells are smaller and simpler compared to eukaryotic cells.
- Genetic material is not enclosed in a nucleus; may have internal membranes.
- They contain DNA and ribosomes, but lack membrane-bound organelles.
DNA Replication Process
- Newly replicated DNA molecules are complementary to the original strand.
- Replication includes unwinding of the double helix and synthesis of new strands.
Similarities in DNA Replication
- Both prokaryotic and eukaryotic cells undergo DNA replication.
- Prokaryotic cells have a single point of origin for replication, while eukaryotic cells have multiple origins.
Transcription vs. Translation
- Transcription involves converting DNA code into mRNA code for protein synthesis.
- Translation occurs when ribosomes synthesize proteins by interpreting mRNA sequences.
Role of rRNA in Translation
- Ribosomal RNA (rRNA) is an integral component of ribosomes, aiding in decoding mRNA into amino acids.
Nucleotides Structure in DNA and RNA
- DNA nucleotides consist of deoxyribose sugar, a phosphate group, and nitrogenous bases (A, T, C, G).
- RNA nucleotides contain ribose sugar, one strand, and uracil (U) instead of thymine.
Building Blocks of DNA
- Nucleotides are the fundamental building blocks of DNA.
- They are linked together by covalent bonds.
Key Scientists in DNA Discovery
- Erwin Chargaff identified the base pairing rule (A=T, C=G).
- Rosalind Franklin utilized X-ray diffraction to reveal the double helix structure of DNA.
- James Watson and Francis Crick created a model that explained the structure of DNA.
Functions of DNA
- DNA stores genetic information through sequences of bases.
- It copies genetic information by breaking hydrogen bonds and synthesizing new strands.
- DNA transmits genetic information during cell replication.
Complementarity of DNA Strands
- DNA strands are complementary, allowing each strand to serve as a template for synthesizing a new strand.
Steps in Eukaryotic DNA Replication
- The initial step involves the two DNA strands separating to create a template for replication.
Enzymes in DNA Replication
- DNA polymerase is responsible for joining individual nucleotides to form new DNA strands.
- Telomerase helps prevent loss of DNA from telomeres during replication by adding repetitive sequences.
Replication Forks
- The replication fork is created at the point where the double helix separates during DNA replication.
Direction of DNA Replication
- DNA replication occurs in opposite directions along the two strands of the helix.
Replication Location and Characteristics
- In prokaryotes, DNA replication occurs in the cytoplasm with a single starting point.
- In eukaryotes, replication takes place in the nucleus, has multiple starting points, and involves more DNA.
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Description
Explore the concept of base pairing in DNA, focusing on the relationships between the four base pairs: Adenine, Thymine, Cytosine, and Guanine. Understand how these pairings play a critical role in the process of DNA replication.
