1-5 Nucleic Acids Flashcards
1
Q
What are nucleotides?
A
- Nucleotides consist of pentose which is a 5-carbon sugar, a nitrogen containing base and a phosphate group.
- Can join by phosphodiester bonds formed in a condensation reaction resulting in a dinucleotide which join to form polynucleotides. The bond forms between the deoxyribose sugar of one nucleotide and the phosphate group of another.
2
Q
What is the structure of DNA?
A
- DNA carries genetic information.
- The components of a DNA nucleotide are deoxyribose sugar, a phosphate group and one of the nitrogen containing organic bases, adenine, cytosine, guanine or thymine.
- Double helix, composed of two polynucleotides joined by hydrogen bonds between complementary bases.
3
Q
What is the structure of RNA?
A
- RNA transfers this genetic information from DNA to ribosomes for protein synthesis.
- Ribosomes are formed of ribosomal RNA and proteins.
- The components of an RNA nucleotide are ribose sugar, a phosphate group and one of the nitrogen containing organic bases adenine, cytosine, guanine or uracil.
- Relatively short polynucleotide chain.
4
Q
Why is DNA a stable molecule?
A
- The phosphodiester backbone protects the more chemically reactive nitrogen containing organic bases inside the double helix.
- Hydrogen bond forms bridges between the phosphodiester uprights.
5
Q
What does semi-conservative replication ensure?
A
- Ensures genetic continuity between generations of cells meaning that genetic information is passed on from one generation to the next.
6
Q
What are the steps of semi-conservative replication?
A
- An enzyme, DNA helicase, causes the two strands of DNA to separate breaking the hydrogen bonds between the complementary bases.
- One of the strands is used as the template and complementary base pairing occurs between the template strand and free nucleotides.
- Once activated nucleotides are bound, the enzyme DNA polymerase joins them together by forming phosphodiester bonds. The result is that two identical strands of DNA are formed.
