DNA is made up of nucleotides that form a double helix structure. There are four bases - adenine pairs with thymine and cytosine pairs with guanine. DNA replication involves enzymes that unwind, synthesize new strands, and join the strands. Chromosomes in the cell nucleus contain the genetic material.

1. 1. Genes are made of molecules of DNA which is made of nucleotides that have a phosphate
group, a sugar, and a nitrogenous base. The genetic molecule has a double-helix 3-dimensional
structure.
2. There are four different bases that are used to build a DNA molecule.
3. Adenine is the base that pairs with thymine, cytosine is the base that pairs with guanine, and
guanine is the base that pairs with cytosine in DNA. Therefore, GC and AT are complementary
base pairs.
4. DNA replication is semi conservative.
5. Helicase is the enzyme that unwinds DNA during replication. New strands are made using the
enzyme polymerase, and ligase is the enzyme that connects the short segments of nucleotides in
a newly made DNA strand.
6. The complementary base sequence for TTAG is AATC and the complementary base sequence
for CAATG is GTTAC.
7. Chromosomes are the cell structures in the nucleus that contain the genetic material.
Solution
1. Genes are made of molecules of DNA which is made of nucleotides that have a phosphate
group, a sugar, and a nitrogenous base. The genetic molecule has a double-helix 3-dimensional
structure.
2. There are four different bases that are used to build a DNA molecule.
3. Adenine is the base that pairs with thymine, cytosine is the base that pairs with guanine, and
guanine is the base that pairs with cytosine in DNA. Therefore, GC and AT are complementary
base pairs.
4. DNA replication is semi conservative.
5. Helicase is the enzyme that unwinds DNA during replication. New strands are made using the
enzyme polymerase, and ligase is the enzyme that connects the short segments of nucleotides in
a newly made DNA strand.
6. The complementary base sequence for TTAG is AATC and the complementary base sequence
for CAATG is GTTAC.
7. Chromosomes are the cell structures in the nucleus that contain the genetic material.