DNA and RNA Structure

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 consists of two intertwined strands. It does not contain ribose (which is in RNA), is not made of amino acids, and does not contain uracil (which is also in RNA).

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 are the building blocks of DNA. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base, making them essential for DNA structure.

Guanine bonds with ______________.

• Adenine

• Guanine

• Cytosine

• Thymine

Answer explanation

Guanine pairs with Cytosine in DNA through three hydrogen bonds, making them complementary bases. Adenine pairs with Thymine, while Guanine does not bond with itself.

Which 2 molecules form the sides (backbone) of the DNA ladder?

• deoxyribose sugar and adenine

• deoxyribose sugar and a hydrogen bond

• deoxyribose sugar and the nucleus

• deoxyribose sugar and phosphate

Answer explanation

The sides of the DNA ladder are formed by deoxyribose sugar and phosphate. These components create the sugar-phosphate backbone, while the nitrogenous bases, like adenine, form the rungs of the ladder.

What are the three components of a nucleotide?

• sugar, hydrogen, nitrogen base

• sugar, oxygen, nitrogen base

• sugar, phosphate, nitrogen base

• sugar, phosphate, protein

Answer explanation

A nucleotide consists of three components: a sugar molecule, a phosphate group, and a nitrogen base. The correct answer is 'sugar, phosphate, nitrogen base', as the other options include incorrect components.

The following picture must be

• DNA because it's double stranded

• RNA because it's single stranded

• DNA because it's single stranded

• RNA because it's double stranded

Answer explanation

The correct answer is 'RNA because it's single stranded' as RNA typically exists as a single strand, while DNA is double stranded. This distinction is key in identifying the type of nucleic acid depicted.

Tags

NGSS.HS-LS1-1

What four nitrogen base pairs make up RNA?

• Adenine, Thymine, Guanine, Cytosine

• Adenine, Uracil, Guanine, Cytosine

• Adenine, Thymine, Glucose, Cytosine

• Adenine, Thymine, Guanine, Fructose

Answer explanation

RNA is composed of four nitrogen bases: Adenine, Uracil, Guanine, and Cytosine. Unlike DNA, RNA contains Uracil instead of Thymine, making the correct answer 'Adenine, Uracil, Guanine, Cytosine'.

What base pair does Adenine (A) bind with in RNA?

• Guanine

• Cytosine

• Thymine

• Uracil

Answer explanation

In RNA, Adenine (A) pairs with Uracil (U) instead of Thymine (T), which is found in DNA. This is a key difference between RNA and DNA base pairing.

Where inside a cell is DNA found?

• nucleus

• cytoplasm

• endoplasmic reticulum

• Golgi body

Answer explanation

DNA is primarily found in the nucleus of a cell, where it is organized into chromosomes. The other options, such as cytoplasm, endoplasmic reticulum, and Golgi body, do not contain DNA.

Which sequence of DNA bases would pair with this partial strand
ATG TGA CAG

• ATG TGA CAG

• TAC ACT GTC

• GTA AGT GAC

• CAT TCA CTG

Answer explanation

The DNA bases pair according to complementary base pairing rules: A with T and G with C. Therefore, the strand ATG TGA CAG pairs with TAC ACT GTC, making it the correct answer.