Unit 6 Review

What is the 3-D structure of DNA?

• Triple Helix

• Single Helix

• Double Helix

Answer explanation

The 3-D structure of DNA is known as the Double Helix, which consists of two intertwined strands. This structure is crucial for its function in storing and transmitting genetic information.

The _________ provide the instructions for amino acids that form proteins.

• Nitrogenous bases

• Phosphate

• Deoxyribose sugar

• Hydrogen bonds

Answer explanation

The nitrogenous bases in DNA and RNA provide the specific sequences that code for amino acids, which are the building blocks of proteins. Therefore, they are essential for protein synthesis.

Tags

NGSS.HS-LS1-1

NGSS.HS-LS3-1

What was the first image of DNA called?

• Photograph 2

• Photograph 51

• Rosalind Franklin

• Watson

Answer explanation

The first image of DNA, known as Photograph 51, was taken by Rosalind Franklin. This crucial X-ray diffraction image provided key insights into the helical structure of DNA, leading to its discovery.

Scientists build upon each other's work to make new discoveries.

• False

• True

Answer explanation

The statement is True because scientific progress relies on collaboration and building upon previous research. Each discovery often leads to new questions and further exploration, demonstrating the interconnected nature of scientific work.

Tags

NGSS.HS-LS3-1

What is the first step of DNA replication?

• DNA polymerase adds to the template strand.

• Enzymes rewind the two identical DNA strands.

• Helicase unzips the DNA.

• DNA is checked for mistakes and repaired.

Answer explanation

The first step of DNA replication is when helicase unzips the DNA, separating the two strands. This unwinding is essential for the replication process to begin, allowing other enzymes to access the template strands.

What amino acid does this codon code for? UCC

• Threonine

• STOP

• Serine

• Proline

Answer explanation

The codon UCC codes for the amino acid Serine. Codons are sequences of three nucleotides that correspond to specific amino acids, and UCC is one of the codons that specifies Serine.

Which answer correctly describes the steps of protein synthesis?

• mRNA is transcribed in the cytoplasm, mRNA goes to the ribosome. mRNA is translated into amino acids. The amino acids form a polypeptide.

• DNA is translated in the nucleus, mRNA goes to the mitochondria. mRNA is transcribed into amino acids. The amino acids form a polypeptide.

• mRNA is transcribed in the nucleus, mRNA goes to the ribosome. mRNA is translated into amino acids. The amino acids form a polypeptide.

Answer explanation

The correct choice outlines the accurate steps of protein synthesis: mRNA is transcribed in the nucleus, then transported to the ribosome where it is translated into amino acids, which subsequently form a polypeptide.

Tags

NGSS.HS-LS1-1

What type of bond holds the two DNA strands together?

• Covalent

• Hydrogen

Answer explanation

The two DNA strands are held together by hydrogen bonds, which form between the complementary nitrogenous bases. Covalent bonds are present within the sugar-phosphate backbone, but hydrogen bonds are responsible for the base pairing.

What type of bond holds the sugar-phosphate backbone together?

• Covalent

• Hydrogen

Answer explanation

The sugar-phosphate backbone of DNA is held together by covalent bonds, specifically phosphodiester bonds, which link the sugar of one nucleotide to the phosphate group of the next. Hydrogen bonds, on the other hand, connect base pairs.

What is the anticodon for AUU?

• UAC

• UGG

• UAA

Answer explanation

The anticodon is complementary to the codon. For AUU, the complementary bases are UAA, making UAA the correct anticodon. The other options, UAC and UGG, do not match the required pairing.