1. The double helix structure of DNA was discovered by James Watson and Francis Crick in 1953.
2. The two strands of the DNA double helix are held together by hydrogen bonds between complementary nitrogenous bases.
3. The four nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
4. Adenine pairs with thymine, and cytosine pairs with guanine.
5. The sugar-phosphate backbone forms the outer edges of the DNA double helix.
6. The antiparallel nature of DNA means that one strand runs 5' to 3' while the complementary strand runs 3' to 5'.
7. DNA replication is semi-conservative, meaning each new DNA molecule consists of one original strand and one newly synthesized strand.
8. The enzyme helicase unwinds the DNA double helix during replication.
9. DNA polymerase adds nucleotides to the growing DNA strand during replication.
10. The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously in Okazaki fragments.
11. DNA ligase joins the Okazaki fragments on the lagging strand.
12. The genetic code is read in triplets called codons, each specifying a particular amino acid.
13. A gene is a segment of DNA that codes for a specific protein or functional RNA molecule.
14. Mutations are changes in the DNA sequence that can result from errors in replication or environmental factors.
15. DNA fingerprinting uses variations in non-coding regions of DNA to identify individuals.
16. The Human Genome Project aimed to map and sequence all human genes.
17. DNA is found primarily in the nucleus of eukaryotic cells, but also in mitochondria and chloroplasts.
18. In prokaryotes, DNA is located in the nucleoid region of the cell.
19. Chromatin is the complex of DNA and proteins (histones) that makes up chromosomes.
20. The double helix structure allows DNA to be compactly stored and accurately replicated.
Parent Tip: Review the logic above to help your child master the concept of nucleic acids dna the double helix worksheet answers.
