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Questions and Answers
The double helix model of DNA consists of three complementary strands twisted together.
True
Adenine (A) pairs with Cytosine (C) in DNA base pairing.
False
The semi-conservative model of DNA replication involves the creation of two new DNA molecules from one old DNA molecule.
True
DNA is only responsible for genetic information storage.
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Plasmid DNA is found in the nucleus of eukaryotic cells.
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Frameshift mutations only involve deletions of nucleotides.
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Study Notes
Structure of DNA
- Double helix model: two complementary strands twisted together
- Each strand composed of nucleotides, which are made up of:
- Sugar molecule (deoxyribose)
- Phosphate group
- Nitrogenous base (A, C, G, or T)
- Hydrogen bonds between nitrogenous bases hold the two strands together
Nitrogenous Bases
- Adenine (A) pairs with Thymine (T)
- Guanine (G) pairs with Cytosine (C)
- Base pairing is complementary and specific
Replication of DNA
- Semi-conservative model: each new DNA molecule contains one old strand and one new strand
- Process involves:
- Unwinding of double helix
- Binding of primers to template strands
- Synthesis of new strands by DNA polymerase
- Proofreading and editing
Functions of DNA
- Genetic information storage
- Template for RNA synthesis
- Regulation of gene expression
Types of DNA
- Nuclear DNA: found in the nucleus of eukaryotic cells
- Mitochondrial DNA: found in the mitochondria of eukaryotic cells
- Plasmid DNA: small, self-replicating circular DNA found in bacteria
Mutations and Variations
- Point mutations: changes in a single nucleotide
- Frameshift mutations: insertions or deletions of nucleotides
- Genetic variations: differences in DNA sequence between individuals
Structure of DNA
- Double helix model consists of two complementary strands twisted together
- Each strand composed of nucleotides, which contain a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (A, C, G, or T)
- Hydrogen bonds between nitrogenous bases hold the two strands together
Nitrogenous Bases
- Adenine (A) pairs specifically with Thymine (T)
- Guanine (G) pairs specifically with Cytosine (C)
- Base pairing is complementary and specific
Replication of DNA
- Semi-conservative model: each new DNA molecule contains one old strand and one new strand
- Replication process involves unwinding of double helix, binding of primers to template strands, synthesis of new strands by DNA polymerase, and proofreading and editing
Functions of DNA
- Stores genetic information
- Acts as template for RNA synthesis
- Regulates gene expression
Types of DNA
- Nuclear DNA: found in the nucleus of eukaryotic cells
- Mitochondrial DNA: found in the mitochondria of eukaryotic cells
- Plasmid DNA: small, self-replicating circular DNA found in bacteria
Mutations and Variations
- Point mutations: changes in a single nucleotide
- Frameshift mutations: insertions or deletions of nucleotides
- Genetic variations: differences in DNA sequence between individuals
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Description
Learn about the double helix model of DNA, its composition, and the process of replication. Discover how nitrogenous bases pair and the importance of complementary base pairing.
