20 Questions
Which sugar is found in RNA?
Ribose
Which nitrogenous base is a purine?
Adenine
Which component is found in a nucleotide but not in a nucleoside?
Phosphate
What type of bond links the sugars and phosphates in a nucleic acid?
Phosphodiester bond
According to Chargaff's rules, which pair bases are equal in amount?
Adenine and thymine
Which nitrogenous base is found in RNA but not in DNA?
Uracil
What does it mean for DNA replication to be semi-conservative?
Each new DNA molecule contains one original strand and one new strand.
What did the Hershey-Chase experiment conclude about genetic material?
DNA is the genetic material of the bacteriophage
Which base pairs with thymine (T) during DNA replication?
Adenine (A)
What kind of bonds connect adenine (A) to thymine (T) in a DNA molecule?
Two hydrogen bonds
What is the main requirement for the semi-conservative mechanism of DNA replication?
Complementary base pairing
Which form of DNA is most commonly found in solutions?
B-DNA
Which process is illustrated by the creation of new DNA strands from existing ones?
DNA Replication
How many hydrogen bonds connect cytosine (C) to guanine (G) in a DNA molecule?
Three
Which base pairs with guanine (G) during DNA replication?
Cytosine (C)
Which of the following is not a component of DNA?
Phenylalanine
Which of the following statements is true about the new DNA strands formed during replication?
They consist of one original and one new strand.
What did the Meselson-Stahl experiment demonstrate about DNA replication?
DNA replication is semi-conservative
Which form of DNA is characterized by a long, slender, left-handed helix?
Z-DNA
Why are major and minor grooves formed in the DNA helix?
Because the two sugar-phosphate backbones are not exactly aligned
Study Notes
DNA Composition
- Deoxyribose is the sugar found in DNA, while Ribose is found in RNA.
Nitrogenous Bases
- Adenine, Guanine, Cytosine, and Thymine are the nitrogenous bases found in DNA.
- Uracil is found in RNA, replacing Thymine.
- Purines are nitrogen bases containing two rings, including Adenine and Guanine.
- Pyrimidines are nitrogen bases containing one ring, including Cytosine, Thymine, and Uracil.
Phosphate
- The phosphate group is represented by O-P-O- OH.
Nucleosides vs. Nucleotides
- A Nucleoside or Deoxynucleoside is a nitrogenous base bound to a sugar.
- A Nucleotide or Deoxynucleotide is a nitrogenous base bound to a sugar and a phosphate group.
- A Nucleic Acid is a polymer (chain) of nucleotides.
Facts
- Nucleic acids are polymers, and their monomers are called nucleotides.
- Nucleotides consist of a base, sugar, and phosphate group.
- Sugar can be deoxyribose or ribose.
- Phosphate groups link sugar molecules together through phosphodiester bonds.
Famous Experiments
Chargaff's Rules
- The amounts of Adenine (A) and Thymine (T) are equal, and the amounts of Guanine (G) and Cytosine (C) are equal.
- The amounts of A&T and G&C differ between species.
The Hershey-Chase Experiment
- The experiment showed that DNA, not protein, carries genetic information.
- Radioactive phosphorus, which labels DNA, was found in bacteria, while radioactive sulfur, which labels protein, was not.
DNA Composition - Double Helix
- The double helix structure of DNA consists of anti-parallel strands.
- Adenine (A) pairs with Thymine (T) through two hydrogen bonds.
- Cytosine (C) pairs with Guanine (G) through three hydrogen bonds.
- The major and minor grooves are formed due to the alignment of sugar-phosphate backbones.
DNA Conformations
- A-DNA is a short, wide, right-handed helix.
- B-DNA is the most common DNA form in solution, a right-handed helix.
- Z-DNA is a long, slender, left-handed helix.
The Meselson-Stahl Experiment
- The experiment showed that DNA replication is semi-conservative, not conservative or dispersive.
- Each new strand contains one original and one new strand.
DNA Replication
- DNA replication is semi-conservative and depends on complementary base pairing.
- Each new strand contains one original and one new strand, making it a semi-conservative process.
Learn about the components of DNA, including sugars, nitrogenous bases, and phosphate groups, and how they come together to form nucleosides and nucleotides.
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