bio chapter 9

A nucleotide substitution (point mutation) may occur because the repair enzymes cut out and replaced the original nucleotide instead of the incorrect one. a. true b. false

A true

All the cells of a specific organism contain equal amounts of A-A and G B-G and C C- A and C D- T and C

B guanine and cytosine

The two polynucleotide chains in a DNA molecule are attracted to each other by a. covalent bonds between carbon atoms b. hydrogen bonds between bases c. peptide bonds between amino acids d. ionic bonds between "R" groups in amino acids e. covalent bonds between phosphates and sugars

B hydrogen bonds between bases

If amounts of bases in a DNA molecule are measured, we find A- A=C and G=T B- A=G and C=T C- T=A and C=G D- that no two bases would be equal in amount E- that all bases are equal in amount

C

The sequence of subunits in the DNA backbone is a. -base-phosphate-sugar-base- phosphate-sugar- b. -base-phosphate-base-phosphate- base-phosphate- c. -phosphate-sugar-phosphate-sugar- phosphate-sugar- d. -sugar-base-sugar-base-sugar-base- sugar-base- e. -base-sugar-phosphate-base- sugar-phosphate-

C -phosphate-sugar-phosphate-sugar- phosphate-sugar-

Using an analogy of DNA as a twisted ladder, the rungs (steps) of the ladder are a. phosphate groups b. sugar groups c. paired nitrogenous bases d. oxygen-carbon double bond

C paired nitrogenous bases

The DNA of certain organism has Guanine as 30% of its bases. What percentage of its bases would be adenine? A- 0% B-10% C-20% D-30% E-40%

C- 20%

Sometimes large pieces of chromosomes are rearranged. These mutations are called a. inversions b. translocations c. point mutations d. both a and b e. none of the above

D both a and b

Figuratively speaking, a double helix is comparable to a. coiled rope b. stacked up plates c. braided hair d. twisted ladder e. tangled threads

D twisted ladder

Gene are made of molecules of___________________ which is made of ___________ that have a phosphate group, a sugar, and a nitrogenous base.

DNA, Nucleotide

The correct structure of a nucleotide is A- PO4-Ribose-Adenine B-Phosphilipid-5C sugar-base C-phospahate- 5C sugar - phosphate- 5C sugar D- adenine- thymine and guanine-cytosine E-phosphate- 5C sugar- base

E

__________ is the enzyme that unwinds DNA during replication.

Helicase

Predict the complementary base sequence for each of the following short DNA molecules. Also predict which molecule would be more stable at a temperature 15 degrees above normal body temperature. Molecule One: 5'-CGTAGTAGTAGAATATTGCTGCACC-3' Molecule Two: 5'-AGTGCGAAGGCTCCTTGGGAACGTG-3'

Molecule One: 5'-CGTAGTAGTAGAATATTGCTGCACC-3' 3'-GCATCATCATCTTATAACGACGTGG-5 Molecule Two: 5'-AGTGCGAAGGCTCCTTGGGAACGTG-3' 3'-TCACGCTTCCGAGGAACCCTTGCAC-5' The numbers of GC base pairs in Molecule One is 11, while the number of AT base pairs in molecule one is 14. The numbers of GC base pairs in Molecule Two is 15, while the number of AT base pairs in molecule one is 10. Therefore, Molecule Two has more hydrogen bonds holding the two strands together than does Molecule One, and Molecule Two is more stable at a higher temperature (see Question 28).

The double stranded DNA molecule would have the following proportions of nucleotides: one strand: 10%T, 20% A, 30% C, and 40% G second strand: 10%A, 20% T, 30% G, and 40% C You were given percentages, there would be 100% nucleotides per strand, there are two strands. Therefore, you can use as a total, 200 nucleotides. Collectively: 60/200 = 30% A-T and 140/200 = 70% G-C, which means that A = 15%, T = 15%, G = 35%, and C = 35%.

The double stranded DNA molecule would have the following proportions of nucleotides: one strand: 10%T, 20% A, 30% C, and 40% G second strand: 10%A, 20% T, 30% G, and 40% C You were given percentages, there would be 100% nucleotides per strand, there are two strands. Therefore, you can use as a total, 200 nucleotides. Collectively: 60/200 = 30% A-T and 140/200 = 70% G-C, which means that A = 15%, T = 15%, G = 35%, and C = 35%.

. In DNA molecules, when base pairing occurs between adenine and thymine, two hydrogen bonds form between them. However, when base pairing occurs between cytosine and guanine, three hydrogen bonds form between them. Let's say that we compared DNA from two different species. Species A's DNA has 40% A-T base pairs and 60% G-C base pairs, while Species B's DNA has 70% A-T base pairs and 30% G-C base pairs. Which type of DNA would have to be heated to a higher temperature in order to get the double stranded DNA to dissociate into single strands? (Hint: As the number of hydrogen bonds between molecules increases, the bonding is more stable.)

The greater the number of hydrogen bonds attracting different molecules to each other, the greater the energy needed to break all the hydrogen bonds and allow the molecules to separate from each other. Therefore, it takes more heat energy to separate G from C (3 hydrogen bonds involved) than to separate A from T (2 bonds). Thus, the higher the percentage of G-C pairings within a DNA molecule, the higher the DNA must be heated before the double stranded molecule separates into a pair of single stranded entities. It will take more heat to separate double stranded DNA from Species A (with 60% G-C base-pairs) than to separate double stranded DNA from Species B (with 30% G-C base pairs).

_______ is the base that pairs with thymine

adenine

____________ are the cell structures in the nucleus that contain the genetic material.

chromosomes

________is the base that pairs with guanine, and __________ is the base that pairs with cytosine in DNA. Therefore __________ are complementary base pairs

cytosine, guanine, GC and AT

the genetic molecule has a double- ________________ 3 dimensional structure.

double

true/false: A molecule of DNA is single stranded.

double

there are __________ different bases that are used to build a DNA molecule.

four

Change in the DNA base sequence

mutation

True/False: DNA contains four types of sugars

nitrogenous bases

True or False:The building blocks of nucleic acids are amino acids.

nucleotides

True or False:DNA contains deoxyribose, nitrogen containing bases, and sulfur groups.

phosphate

New strands of DNA are made using the enzymes ______, and ________ is the enzyme that connects the short segments of nucleotide in a newly made DNA strand

polymerase, ligase

DNA replication is _________ each double helix has 1 parental DNA strand and 1 newly synthesized DNA strand

semi conservative

True or False:The duplication of DNA is called fully-conservative replication.

semi-conservative

True or False:Adenine pairs with guanine in DNA

thymine

True or False:Equal amounts of A-T and G-C exist in a given species (Chargaff's rule).

true

True/False: The 5-carbon sugar found in DNA is deoxyribose.

true

True/False:DNA is found in cellular chromosomes

true