Question 1

Which of the following sugar molecules is involved in the structure of DNA?

Accepted Answer

Deoxyribose is a component of deoxyribonucleic acid (DNA), it is a type of sugar molecule that has one less oxygen atom than ribose, the sugar molecule that is a component of ribonucleic acid (RNA).

Question 2

Rosalind Franklin's research contribution was essential in

Accepted Answer

Rosalind Franklin's X-ray crystallography images were used by Francis Crick and James Watson to propose the double helix structure of DNA. Franklin's images provided evidence for the helical shape of DNA and the spacing between the nucleotide units, as well as the presence of a repeating pattern, indicating that the DNA molecule had a regular structure. Without her contribution, the discovery of the double helix structure of DNA would not have been possible.

Question 3

From X-ray diffraction data,which of the following was determined about DNA?

Accepted Answer

X-ray diffraction data showed a helical structure for DNA, indicating it is a double helix. While A and B are true statements regarding the base pair composition of DNA, they were determined through other methods such as chemical analysis. Option C is false; in fact, nitrogen-containing bases are stacked in the interior of the helix with the sugar-phosphate backbone facing outward.

Question 4

In the nucleotide sequence ACTGG,what does C stand for?

Accepted Answer

In the nucleotide sequence ACTGG, the letter C represents cytosine, which is one of the four nitrogenous bases present in DNA molecules. Cytosine always pairs with guanine (G) through hydrogen bonds in the DNA double helix structure.

Question 5

Which of the following terms is NOT related to the other four?

Accepted Answer

Amino acids are the building blocks of proteins, while the other terms are components of nucleic acids (DNA and RNA).

Question 6

DNA varies from species to species in

Accepted Answer

DNA varies from species to species in its sequence of DNA base-pairs. This sequence determines the genetic information that is coded in the DNA, and varies between different organisms. The other options (A, B, C, and D) do not accurately describe the differences in DNA between species.

Question 7

The DNA-histone complex is most analogous to

Accepted Answer

The DNA-histone complex is often referred to as the "beads on a string" structure, where the DNA strand is the string and the histones are the beads. This is analogous to a pearl necklace where the pearls represent the histones and the string represents the DNA strand.

Question 8

If a person had defective centromeres,which of the following would result?

Accepted Answer

Centromeres are responsible for holding sister chromatids together. If a person has defective centromeres, sister chromatids cannot attach to each other, leading to abnormal chromosome segregation, which can result in disorders such as chromosomal abnormalities, Down syndrome, and cancer.

Question 9

The building blocks of nucleic acids are

Accepted Answer

Nucleic acids are made up of units called nucleotides, which consist of a nitrogenous base, a 5-carbon sugar, and a phosphate group. Amino acids are the building blocks of proteins, while fatty acids are the building blocks of lipids. Ribosomes are cellular organelles responsible for protein synthesis.

Question 10

Rosalind Franklin used which techniques to determine many of the physical characteristics of DNA?

Accepted Answer

Rosalind Franklin used X-ray crystallography to determine many of the physical characteristics of DNA. This technique involves analyzing the diffraction patterns of X-rays that have passed through crystallized DNA, which allows the structure and shape of the molecule to be determined.

Question 11

Butterflies are diploid organisms.In these animals,the sex of an individual is determined by Z and W chromosomes.Use this information to answer the following question(s).
-Which chromosomes are carried by a normal female butterfly?

Accepted Answer

A normal female butterfly carries two copies of the W chromosome, making her a ZW genotype.

Question 12

Which of the following is the correct complementary bonding of nitrogen containing bases in DNA?

Accepted Answer

Complementary bonding in DNA occurs between nitrogenous bases, where guanine hydrogen bonds with cytosine and adenine hydrogen bonds with thymine. Therefore, the correct complementary bonding of nitrogen-containing bases in DNA is represented by the pairing of guanine and cytosine (D) and adenine and thymine.

Question 13

Which of the following is NOT true about complementary base pairing in a DNA molecule?

Accepted Answer

Complementary base pairing in a DNA molecule is based on hydrogen bonding between two complementary bases, not covalent bonding. Covalent bonds are formed between the sugar and phosphate groups of adjacent nucleotides in the DNA strand.

Question 14

Which scientist(s)discovered the basis for the base-pair rule,which stated that the amounts of adenine in all DNA are the same,as are the amounts of cytosine and guanine?

Accepted Answer

The base-pair rule was discovered by Erwin Chargaff in 1950, who observed that the amounts of adenine were equal to the amounts of thymine, and the amounts of cytosine were equal to the amounts of guanine, which led to the development of the complementary base-pairing concept in DNA. Watson and Crick are credited with discovering the double helix structure of DNA, Franklin with her work on X-ray crystallography that provided the structural evidence for the double helix, Beadles for his study of genetics in fruit flies, and Pauling for his work on the structure of proteins.

Question 15

Which scientist(s)suggested for the first time that the proportion of adenine and guanine differs from one species to another?

Accepted Answer

Chargaff was the first to suggest that the proportion of adenine and guanine differs from one species to another. This observation, known as Chargaff's rules, was a key factor in Watson and Crick's discovery of the double helix structure of DNA.

Question 16

How many types of nucleotides are found in DNA molecules?

Accepted Answer

There are four types of nucleotides found in DNA molecules: adenine (A), thymine (T), cytosine (C), and guanine (G). Each nucleotide consists of a sugar molecule, a phosphate group, and a nitrogenous base. The nitrogenous base can be one of these four types, which determines the genetic information encoded in the DNA sequence.

Question 17

A nucleotide is made up of

Accepted Answer

A nucleotide consists of a pentose sugar, a nitrogenous base, and one to three phosphate groups. Therefore, the correct option is B, which includes a pentose sugar, three phosphate groups, and a nitrogenous base. Option A is incorrect because it includes three phosphate groups, which is possible but not the general case. Option C and D are incorrect because they include three pentose sugars, which is not true, as a nucleotide has only one pentose sugar. Option E is incorrect because it includes three nitrogenous acids, which is not true.

Question 18

Which of the following nitrogen containing bases is NOT found in molecules of DNA?

Accepted Answer

Uracil is only found in molecules of RNA, not DNA. DNA contains adenine, guanine, cytosine, and thymine.

Question 19

The image of an individual's complement of chromosomes arranged by size,length,shape,and centromere location is called a

Accepted Answer

The image of an individual's complement of chromosomes arranged by size, length, shape, and centromere location is called a karyotype. This is a visual representation of the individual's genetic makeup and can be used for diagnostic and research purposes. Option A (autotype) is not a commonly used term in genetics. Option B (genotype) refers to the genetic makeup of an individual and is not specific to the arrangement of chromosomes. Option C (phenotype) refers to the physical characteristics of an individual and is not related to chromosome arrangement. Option E (chromotype) is not a commonly used term in genetics.

Question 20

What are the length of DNA from a single human cell?

Accepted Answer

The total length of DNA from a single human cell, if stretched out, is approximately 2 meters.

Quiz 6: DNA Structure and Function