1. All proteins consist of ________. 1.DNA molecules 2.RNA molecules 3.triglyceride chains 4.polypeptide chains 12345

2. The two steps that lead from genes to proteins are ________ and ________. 1.inversion, deletion 2.mitosis, meiosis 3.transcription, translation 4.transmission, translocation 12345

3. Which class of RNA is required for DNA transcription? 1.mRNA 2.tRNA 3.rRNA 4.all of the choices 12345

4. Which nucleotide is found in RNA but not in DNA? 1.adenine 2.thymine 3.cytosine 4.uracil 12345

5. Ribonucleic acid (RNA) differs from deoxyribonucleic acid (DNA) in the structure of its ________. 1.sugar 2.phosphate 3.bases 4.bonds 12345

6. A coding region of DNA, found between a start signal and a stop signal, is also known as a/an ________. 1.mRNA 2.gene 3.protein 4.ribosome 12345

7. In eukaryotic genes, protein-coding sequences are ________, and noncoding sequences are ________. 1.introns, exons 2.exons, introns 3.DNA, RNA 4.RNA, DNA 12345

8. Genetic code consists of ________ that specify different ________. 1.nuclei, DNA 2.proteins, genes 3.base triplets, amino acids 4.polypeptides, proteins 12345

9. The first amino acid in every polypeptide chain is ________. 1.methionine 2.glucose 3.ribose 4.transcriptase 12345

10. Which class of nucleic acid delivers amino acids to ribosomes? 1.mRNA 2.tRNA 3.rRNA 4.DNA 12345

11. Each tRNA molecule binds with one specific ________. 1.amino acid 2.polypeptide 3.ribosome 4.rRNA 12345

12. Ribosomes are made up of which kind of nucleic acid? 1.mRNA 2.tRNA 3.rRNA 4.DNA 12345

13. Translation occurs in ________. 1.the nucleus 2.a DNA molecule 3.a ribosome 4.a tRNA molecule 12345

14. In translation, ________ are translated into ________. 1.genes, a ribosome 2.mRNA codons, a polypeptide chain 3.tRNA codons, a DNA molecule 4.rRNA, amino acids 12345

15. The "start" codon of mRNA binds only to ________. 1.DNA 2.small ribosomal subunits 3.initiator tRNA 4.polypeptides 12345

16. During the elongation stage of translation, ________ are formed. 1.amino acids 2.ribosomes 3.mRNA chains 4.polypeptide chains 12345

17. If one base-pair is substituted for another in a DNA molecule, a ________ has occurred. 1.gene replication 2.gene mutation 3.transcription 4.translation 12345

18. Which of the following is not a type of gene mutation? 1.deletion 2.base-pair substitution 3.insertion 4.replication 12345

19. Which of the following is not a cause of genetic mutations? 1.alkylating agents 2.RNA transcriptase 3.ionizing radiation 4.nonionizing radiation 12345

20. Cigarette smoke contains ________ that ________. 1.alkylating agents, accelerate gene mutations 2.carcinogens, cause cancer 3.harmful chemicals, mutate DNA 4.all of the choices 12345