DNA Structure and Function Quiz

DNA Structure and Function

• DNA is the hereditary material found in chromosomes.
• Watson and Crick determined DNA's structure as a double helix based on X-ray diffraction data.
• DNA consists of long strands of nucleotides.
• Each nucleotide has a sugar, a phosphate, and a nitrogenous base.
• The sugar and phosphate molecules form the DNA backbone.
• The nitrogenous base attaches to the sugar.

Nitrogenous Bases

• Nitrogenous bases are categorized into purines and pyrimidines.
• Purines include adenine and guanine.
• Pyrimidines include cytosine and thymine.
• Base pairs (A-T and C-G) are held together by hydrogen bonds.
• Base pairing is specific (complementary).

DNA Replication

• During replication, the DNA double helix unwinds.
• Enzymes break the hydrogen bonds between base pairs, separating the strands.
• New DNA strands are assembled using free-floating nucleotides.
• DNA polymerase matches nucleotides to the existing template strands.
• The result is two identical DNA double helix molecules.

DNA and Protein Synthesis

• DNA controls all cellular activities.
• Protein synthesis occurs at ribosomes.
• Instructions for protein synthesis are carried from DNA to RNA.
• RNA has uracil instead of thymine.
• There are three types of RNA:
  • Messenger RNA (mRNA) carries instructions from DNA.
  • Transfer RNA (tRNA) carries amino acids to ribosomes.
  • Ribosomal RNA (rRNA) makes up ribosome structure.