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Questions and Answers
What is the role of DNA in an organism?
Which component is NOT part of a nucleotide in DNA?
Who were the first discoverers of the DNA structure model?
In DNA, which of the following base pairs is complementary to adenine?
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What process involves the transcription of genetic information from DNA to mRNA?
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Where does translation occur within the cell?
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What is the primary function of DNA replication?
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What role does DNA polymerase play in DNA replication?
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What does a triplet code, or codon, specify?
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During which phase of the cell cycle does DNA replication occur?
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How many chromosomes are present in a human cell after DNA replication?
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What happens to the old strand of DNA during replication?
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How do complementary base pairings contribute to DNA replication?
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Study Notes
DNA Overview
- DNA (deoxyribonucleic acid) is the primary carrier of genetic information.
- Miescher discovered DNA in 1869; Watson and Crick built the first model in 1953.
DNA Structure
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Nucleotide: The basic building block, composed of:
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Nucleobase (Nitrogenous Base):
- DNA bases: Adenine (A), Guanine (G), Cytosine (C), Thymine (T)
- RNA bases: Adenine (A), Guanine (G), Cytosine (C), Uracil (U)
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Sugar (Pentose):
- DNA: Deoxyribose
- RNA: Ribose
- Phosphate Group: Consists of H3PO4.
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Nucleobase (Nitrogenous Base):
Polynucleotide Chain
- Composed of multiple nucleotides linked together.
- Hydrogen bonds hold nitrogenous bases in pairs.
- DNA strands adhere to complementary base pairing:
- DNA pairs: Cytosine (C) with Guanine (G), Adenine (A) with Thymine (T)
- RNA pairs: Cytosine (C) with Guanine (G), Adenine (A) with Uracil (U).
Functions of DNA and RNA
- DNA: Stores and transmits genetic information.
- RNA: Converts DNA information into proteins.
Transmission of Genetic Information
- Involves three key processes:
- Replication: DNA copy-making in the cell nucleus before mitosis.
- Transcription: Transcribing genetic information from DNA to messenger RNA (mRNA).
- Translation: Protein synthesis from mRNA, occurring in ribosomes and the endoplasmic reticulum.
DNA Replication
- Takes place during the S phase of the cell cycle prior to mitosis.
- Human cells replicate 46 chromosomes to form 92 chromosomes for cell division.
Mechanism of DNA Replication
- The double helix structure "unzips" to separate strands before replication.
- Specialized enzymes break hydrogen bonds between base pairs to create a template for new strand synthesis.
- DNA polymerase enzyme assembles nucleotides to form a new strand guided by the old strand's sequence.
- Complementary base pairing directs the synthesis process, ultimately reforming the double helix.
Genetic Code Essentials
- The genetic code consists of nucleotide sequences that instruct protein synthesis.
- It provides rules for translating DNA or mRNA sequences into amino acid chains.
Properties of the Genetic Code
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Three-Letter (Triplet) Code:
- Comprised of triplets of nucleotides known as codons (e.g., CCA, TGG).
- Each codon specifies the insertion of a particular amino acid in a polypeptide chain during protein synthesis.
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Description
Explore the fascinating world of DNA in this quiz, including its discovery, structure, and functions. Learn about nucleotides, polynucleotide chains, and the genetic information storage and transmission roles of DNA and RNA.
