1.
_________________________ - Copying DNA in a cell
Correct Answer
C. DNA Replication
Explanation
DNA replication is the correct answer because it is the process by which a cell makes an identical copy of its DNA. During DNA replication, the DNA double helix unwinds and separates into two strands. Each strand serves as a template for the synthesis of a new complementary strand, resulting in two identical DNA molecules. This process is essential for cell division and the transmission of genetic information from one generation to the next. RNA replication is not a valid term, as RNA is usually synthesized from a DNA template through a process called transcription, not replication. BNA replication is not a recognized biological process.
2.
The ______________ nitrogen bases found in DNA nucleotides are _______________(a), _______________(G), _____________ (C), and _______________(T).
Correct Answer
four, Adenine, Guanine, Cytosine, and Thymine
Explanation
DNA is made up of nucleotides, which consist of a sugar molecule, a phosphate group, and a nitrogenous base. The four nitrogenous bases found in DNA nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). These bases pair up in specific combinations, with adenine always pairing with thymine and guanine always pairing with cytosine. Together, these four bases form the genetic code that determines the characteristics and functions of living organisms.
3.
A DNA nucleotide has three parts: a ____________ called ___________, a _____________groupwhich consists of P and O atoms), and a ________________________.
Correct Answer
Sugar molecule, Deoxyribose, Phosphate, Nitrogen base
Explanation
A DNA nucleotide consists of a sugar molecule called deoxyribose, a phosphate group (which consists of P and O atoms), and a nitrogen base. These three components form the building blocks of DNA, with the sugar molecule and phosphate group forming the backbone of the DNA strand, and the nitrogen base determining the genetic information encoded in the DNA sequence.
4.
A and G called _____________ (two rings of carbon).
Correct Answer
B. Purines
Explanation
Purines are two-ringed structures made up of carbon and nitrogen atoms. The statement suggests that A and G called something that consists of two rings of carbon. Since purines fit this description, they are the most suitable answer. Pyrimidines are single-ringed structures, and helicases are enzymes involved in DNA replication, so they do not match the given description.
5.
C and T are called _________________ (one ring of carbon).
Correct Answer
A. Pyrimidines
Explanation
C and T are called pyrimidines because pyrimidines are one of the two types of nitrogenous bases found in DNA. Pyrimidines consist of a single ring of carbon atoms and include the bases cytosine (C) and thymine (T). Purines, on the other hand, consist of a double ring of carbon atoms and include the bases adenine (A) and guanine (G). Helicases, on the other hand, are enzymes that are involved in the unwinding of DNA during replication.
6.
In 1953, James ____________ and Francis _________ suggested a model for the structure of DNA that looked like a spiral staircase: ______________.
Correct Answer
D. Watson, Crick, Doublex Helix
Explanation
James Watson and Francis Crick are the scientists who suggested a model for the structure of DNA that looked like a spiral staircase. This model is known as the Double Helix.
7.
Two nucleotide chains separate by unwinding; each chain serves as a template for a new nucleotide chain.Nuceotides are held together wih a _____________backbone.
Correct Answer
B. Sugar-phosphate
Explanation
During DNA replication, the two nucleotide chains separate by unwinding. Each chain then serves as a template for the synthesis of a new nucleotide chain. The nucleotides in the new chain are held together by a sugar-phosphate backbone. This backbone consists of alternating sugar molecules (deoxyribose) and phosphate groups that form a strong covalent bond. The hydrogen bonds between the nitrogenous bases (adenine, thymine, cytosine, and guanine) are responsible for holding the two chains together temporarily, but it is the sugar-phosphate backbone that provides the stability and structure to the DNA molecule.
8.
Two chains separate at the ______________ by enzymes (_____________).
Correct Answer
Replacation Fork, Helicases
Explanation
The replication fork is the point where the two chains of DNA separate during DNA replication. This separation is facilitated by enzymes called helicases, which unwind the double helix structure of DNA by breaking the hydrogen bonds between the base pairs. The helicases move along the DNA strands, separating them and creating the replication fork. This allows the DNA polymerase to access the single strands and synthesize new DNA strands by adding complementary nucleotides.
9.
As the helicase enzymes move along the DNA molecule, they break _______________between the bases, and the chains separate.
Correct Answer
hydrogen bonds
Explanation
Helicase enzymes are responsible for unwinding the DNA double helix during DNA replication. As they move along the DNA molecule, they break the hydrogen bonds between the bases (adenine, thymine, guanine, and cytosine), which hold the two strands of the helix together. This breaking of hydrogen bonds allows the two strands to separate, providing access for DNA polymerase and other enzymes involved in DNA replication to replicate each strand.
10.
Enzymes________________ bind to the separated chains of DNA; one nucleotide s time, it constructs a new complementary chain of nucleotides.* Product._______________________________________________________
Correct Answer
(DNA Polymerases)
two identical copies of the original DNA..
Explanation
DNA polymerases are enzymes that are responsible for the replication of DNA. They bind to the separated chains of DNA and construct a new complementary chain of nucleotides by adding one nucleotide at a time. This process results in the formation of two identical copies of the original DNA molecule.
11.
Suppose that the sequence of nucleotides in one chain of the original DNA molecule is A-T-T-C-C- G. DNA polymerases would produce a new nucleotide chain with the sequence of ____________________.
Correct Answer
T-A-A-G-G-C
Explanation
DNA polymerases are enzymes responsible for synthesizing new DNA strands during replication. They do this by adding complementary nucleotides to each original strand. In this case, since the original strand has the sequence A-T-T-C-C-G, the complementary nucleotides would be T-A-A-G-G-C. Therefore, DNA polymerases would produce a new nucleotide chain with the sequence T-A-A-G-G-C.
12.
The process of DNA replication occurs with one error in every 10,000 paired nucleotides. A change in the nucleotide sequence at even one location, (_____________), may have serious effects on new cells.
Correct Answer
mutation
Explanation
A mutation refers to a change in the nucleotide sequence of DNA. Even a single change in the nucleotide sequence, known as a mutation, can have serious effects on new cells. This is because mutations can alter the instructions encoded in DNA, leading to changes in protein structure or function. These changes can disrupt normal cellular processes and potentially result in genetic disorders or diseases. Given that DNA replication occurs with one error in every 10,000 paired nucleotides, the occurrence of mutations is a common and significant factor in genetic variation and evolution.
13.
Sickle Cell Anemia: caused by a __________________ that substitutes adenine for thymine; results in defective hemoglobin/sickle shaped red blood cells (RBCs)
Correct Answer
point mutation
Explanation
Sickle Cell Anemia is caused by a point mutation, which is a specific type of genetic mutation. In this case, the mutation substitutes adenine for thymine in the DNA sequence. This alteration in the genetic code leads to the production of defective hemoglobin and the characteristic sickle-shaped red blood cells (RBCs) seen in individuals with this condition.
14.
_____________________ is the loss of a chromosome segment.ABCDEF --------------> ABEFG CD (lost)
Correct Answer
B. Deletion
Explanation
Deletion is the loss of a chromosome segment. In the given example, the chromosome segment CD is lost, resulting in the remaining segments ABEFG. This loss of a segment is known as deletion.
15.
__________________________ result when homologous chromosomes break at different points.. and swap segmentsABCDEFG ABEFG ----------->ABCDEFG ABCDODEFG
Correct Answer
D. Duplication and deletion
Explanation
When homologous chromosomes break at different points and swap segments, a duplication and deletion event occurs. This means that a segment of the chromosome is duplicated and another segment is deleted. In the given example, the segment "ODE" is duplicated, resulting in "ODODE", and the segment "C" is deleted, resulting in "ABDEFG". Therefore, the correct answer is "Duplication and deletion".
16.
_______________________ results when nonhomologous chromosomes exchange segments.ABCDEFG ABEDCFG ---------->HIJKLMNO HIJKCDEFG
Correct Answer
C. Reciprocal transiocation
Explanation
Reciprocal translocation is the correct answer because it involves the exchange of segments between nonhomologous chromosomes. In the given example, the segments AB and HIJK are exchanged, resulting in the rearrangement of the chromosomes. This type of translocation can lead to genetic disorders or abnormalities as it alters the normal gene sequence and can disrupt gene function.
17.
__________________ results when a broken segment is inserted in reverse order. ----- _----- ABCDEFG -----------> ABEDCFG
Correct Answer
A. Inversion
Explanation
Inversion is the correct answer because it refers to the act of reversing the order of a segment. In this case, the broken segment "EDC" is inserted in reverse order, resulting in the final sequence "ABEDCFG".