Chapter 4: DNA- The Molecular Basis of Life Flashcards Preview

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Flashcards in Chapter 4: DNA- The Molecular Basis of Life Deck (117)
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1

Deoxyribonucleic Acid (DNA)

A double-stranded polymer of nucleotides (each consisting of a deoxyribose sugar, a phosphate, and four nitrogenous bases) that carries the genetic information of an organism.

2

Bacteriophage

Any bacteria-infecting virus

3

Isotope

Different atoms of the same element containing the same number of protons but a different number of neutrons.

4

Radioisotopes

Unstable isotopes that decay spontaneously by emitting radiation.

5

Deoxyribose Sugar

Sugar molecule containing five carbons that as lost the -OH (hydroxyl group) on its 2' (2 prime) carbon.

6

Phosphate Group

Group of four oxygen atoms surrounding a central phosphorous atom found in the backbone of DNA.

7

Nucleotides

Molecules that consist of a five-carbon sugar (deoxyribose or ribose) with a nitrogenous base attached to their 1' carbon and a phosphate group attached to their 5' carbon.

8

Nitrogenous Base

An alkaline, cyclic molecule containing nitrogen.

9

Glycosyl Bond

A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom.

10

Antiparallel

Parallel but running in opposite directions; the 5' end of one strand of DNA aligns with the 3' end of the other strand in a double helix.

11

Complementary Base Pairing

The pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).

12

Mitosis

Division of the nucleus of a eukaryotic cell into two daughter nuclei with identical sets of chromosomes.

13

Cytokinesis

Division of cytoplasm and organelles of a cell into two daughter cells.

14

Template

a single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand.

15

Semiconservative

The process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand.

16

DNA Helicase

The enzyme that unwinds double- helical DNA by disrupting hydrogen bonds.

17

Anneal

The pairing of complementary strands of DNA through hydrogen bonding.

18

Single- stranded binding proteins (SSBs)

A protein that keeps separated strands of DNA apart.

19

DNA Gyrase

The bacterial enzyme that relieves the tension produced by the unwinding of DNA during replication.

20

Replication Fork

The region where the enzymes replicating a DNA molecule are bound to untwisted, single stranded DNA.

21

Replication Bubble

The region where two replication forks are in close proximity to each other, producing a bubble in the replicating DNA.

22

DNA Polymerase III

The enzyme responsible for synthesizing complementary strands of DNA during DNA replication.

23

Deoxyribonucleoside Triphosphates

Molecules composed of a deoxyribose bonded to three phosphate groups and a nitrogenous base.

24

RNA (ribonucleic acid) Primer

A sequence of 10 to 60 RNA bases that is annealed to a region of single-stranded ............... not done

25

Adenine and guanine are pyrimidines

False; Adenine and guanine are purines.

26

The DNA double helix makes a complete turn every 3.4 nm along its length.

True

27

DNA’s backbone is held together by hydrogen bonds while the complementary bases are held together by phosphodiester bonds.

Flase; Phosphodiester bonds hold DNA’s backbone together while the complementary bases are held together by hydrogen bonds.

28

If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5'–CTGGAT–3', then the complementary sequence in the opposite strand is 3'–GACCTG–5'.

False; If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5'–CTGGAT–3', then the complementary sequence in the opposite strand is 3'–GACCTA–5'.

29


DNA helicase is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.

False; DNA polymerase III is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.

30

DNA replication is conservative.

False; DNA replication is semi- conservative.