Topic 2 - The chemistry of life
From KstructIB
State the characteristic of DNA replication It is semi-conservative
Outline DNA replication 1. Double helix unwinds 2. Separation of the strands by helicase 3. Formation of the new complementary strands by DNA polymerase
In DNA replication, the 2 chains separate from each other like a zip unfastening as the hydrogen bonds, which link the bases of one chain with the bases of the other, are not very strong. Any free nucleotides then come along and form hydrogen bonds with each of the 2 chains. These nucleotides then join together through their sugar and phosphate groups; and 2 DNA molecules result. The complementary relationship between the bases ensures that each of the DNA molecules is identical to the original one. Because the sequence of the bases in the 2 daughter molecules is exactly the same in the parent molecule (i.e. A to T and C to G), accurate replication occurs. The enzyme that joins the nucleotides together is called DNA polymerase.
Explain the significance of complementary base pairing in the conservation sequence of the base sequence of DNA
Outline DNA Nucleotide structure in terms of sugar (deoxyribose), base and phosphate DNA consists of units called nucleotides. There are four different nucleotides. Each one consists of a deoxyribose 5-carbon sugar, a phosphate group, and a nitrogenous base- adenine, guanine, cytosine, or thymine. The DNA molecule consists of 2 strands twisted together into a double helix, much like a twisted ladder. The phosphate and the sugar molecules make up the sides of the ladder. The phosphate group is joined to the deoxyribose sugar in the nucleotide on the 5' end carbon and to the 3' end carbon of the deoxyribose of the other sugar. The nitrogenous bases make up the steps of the ladder.
State the names of the four bases in DNA
1. Adenine
2. Guanine
3. Cytosine
4. Thymine
Outline how DNA nucleotides are linked together by covalent bonds into a single strand The bases of one chain are attracted to the bases of the other chain by means of hydrogen bonds. "please put your answeres in here"
Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds
Draw a simple diagram of the molecular structure of DNA
