DNA Replication Review

Which sequence of DNA bases would pair with this partial strand
CAT TCA CTG

• ATG TGA CAG

• TAC ACT GTC

• GTA AGT GAC

• CAT TCA CTG

Answer explanation

The given DNA strand CAT TCA CTG pairs with its complementary bases. The correct pairing is GTA AGT GAC, as A pairs with T and C pairs with G, following base pairing rules.

Which of the following units are repeatedly joined together to form a strand of DNA?

• amino acids

• nucleotides

• fatty acids

• polysaccharides

Answer explanation

DNA strands are formed by linking together nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base. Amino acids, fatty acids, and polysaccharides are not involved in DNA structure.

The enzyme that unwinds the DNA to prepare for replication

• helicase

• replicase

• polymerase

• synthase

Answer explanation

The enzyme helicase is responsible for unwinding the DNA double helix, allowing the replication machinery to access the strands for copying. This makes helicase the correct answer for the enzyme that prepares DNA for replication.

DNA replication results in two DNA molecules,

• each one with two original strands

• each one with two new strands

• each one with one new strand and one original strand

• one with two new strands and the other with two original strands

Answer explanation

During DNA replication, each new DNA molecule consists of one original strand and one newly synthesized strand, making the correct answer 'each one with one new strand and one original strand'.

A process in which DNA has the unique ability to make an exact copy of itself.

• Replication

• Translation

• Transcription

Answer explanation

Replication is the process by which DNA makes an exact copy of itself, ensuring genetic information is passed on during cell division. Translation and transcription are related to protein synthesis and RNA production, respectively.

Tags

NGSS.HS-LS3-2

In what phase of the cell cycle does DNA replication take place?

• G1

• S

• G2

• M

Answer explanation

DNA replication occurs during the S phase of the cell cycle, where the cell synthesizes a complete copy of its DNA, preparing for cell division.

The process of DNA replication is called semi conservative because it results in

• none of these

• Two DNA molecules.  One original molecule and one with two new strands

• two exact copies with new strands

• two identical molecules, each with 1 original strand and one new.

Answer explanation

The process of DNA replication is called semi-conservative because it produces two identical molecules, each containing one original strand and one newly synthesized strand, ensuring genetic continuity.

Which of the following best describes a DNA molecule?

• double helix

• contains ribose

• made of amino acids

• contains Uracil

Answer explanation

A DNA molecule is best described as a double helix, which refers to its twisted ladder structure. The other options are incorrect: DNA contains deoxyribose, is not made of amino acids, and does not contain uracil.

Tags

NGSS.HS-LS1-1

Which of the following units are repeatedly joined together to form a strand of DNA?

• amino acids

• nucleotides

• fatty acids

• polysaccharides

Answer explanation

DNA strands are formed by the repeated joining of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base. Amino acids, fatty acids, and polysaccharides are not involved in DNA structure.

In a molecule of double-stranded DNA, the amount of Adenine present is always equal to the amount of

• cytosine

• guanine

• thymine

• uracil

Answer explanation

In double-stranded DNA, Adenine (A) pairs with Thymine (T) through hydrogen bonds. Therefore, the amount of Adenine is always equal to the amount of Thymine, making Thymine the correct answer.