DNA structure and replication worksheet with student answers.

1. DNA is made up of nucleotides.
2. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
3. The sugar in DNA is deoxyribose.
4. The four nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
5. Adenine pairs with thymine; cytosine pairs with guanine.
6. The two strands of DNA are antiparallel.
7. DNA replication is semi-conservative.
8. The enzyme that unwinds the DNA double helix is helicase.
9. The enzyme that synthesizes new DNA strands is DNA polymerase.
10. The leading strand is synthesized continuously; the lagging strand is synthesized discontinuously in Okazaki fragments.
11. The enzyme that joins Okazaki fragments is DNA ligase.
12. DNA replication occurs during the S phase of the cell cycle.
13. The template strand is used to synthesize a complementary strand.
14. The new strand is synthesized in the 5' to 3' direction.
15. The origin of replication is where DNA replication begins.
16. Telomeres are repetitive sequences at the ends of chromosomes that protect them from degradation.
17. Telomerase is the enzyme that adds telomeric repeats to chromosome ends.
18. Mutations are changes in the DNA sequence.
19. Point mutations involve a change in a single nucleotide.
20. Frameshift mutations result from insertions or deletions of nucleotides not in multiples of three.
21. DNA repair mechanisms correct errors in DNA replication.
22. The genetic code is the set of rules by which information encoded in genetic material is translated into proteins.
23. A codon is a sequence of three nucleotides that codes for a specific amino acid.
24. There are 64 possible codons.
25. Three codons are stop codons: UAA, UAG, UGA.
26. The start codon is AUG, which codes for methionine.
27. Transcription is the process of synthesizing RNA from a DNA template.
28. The enzyme that catalyzes transcription is RNA polymerase.
29. mRNA carries the genetic information from DNA to the ribosome.
30. tRNA brings amino acids to the ribosome during translation.
31. rRNA is a component of ribosomes.
32. Translation is the process of synthesizing proteins from mRNA.
33. The ribosome reads the mRNA codons and matches them with the appropriate tRNA anticodons.
34. Amino acids are linked together by peptide bonds.
35. The central dogma of molecular biology states that DNA is transcribed to RNA, which is translated to protein.
36. Gene expression is the process by which information from a gene is used to synthesize a functional gene product.
37. Epigenetics refers to changes in gene expression that do not involve changes to the underlying DNA sequence.
38. DNA methylation is an epigenetic modification that can silence gene expression.
39. Histone modification can affect chromatin structure and gene expression.
40. CRISPR-Cas9 is a genome editing technology.
41. PCR (Polymerase Chain Reaction) amplifies specific DNA sequences.
42. Gel electrophoresis separates DNA fragments by size.
43. DNA fingerprinting uses variable number tandem repeats (VNTRs) to identify individuals.
44. Recombinant DNA technology involves combining DNA molecules from different sources.
45. Plasmids are small, circular DNA molecules that can replicate independently of chromosomal DNA.
46. Restriction enzymes cut DNA at specific recognition sites.
47. DNA ligase joins DNA fragments together.
48. Vectors are vehicles used to deliver foreign DNA into host cells.
49. Transgenic organisms contain foreign DNA.
50. Genetic engineering has applications in medicine, agriculture, and industry.