Chapter 6 - DNA & Biotechnology

Question 1

DNA Libraries

Answer 1

large collections of known DNA sequences

Question 2

Genomic Libraries

Answer 2

contain large fragments of DNA and include both coding (exon) and noncoding (intron) regions of the genome

Question 3

cDNA Libraries

Answer 3

constructed by reverse-transcribing processed mRNA, lacks noncoding regions, only includes genes that are expressed in the tissue

Question 4

Hybridization

Answer 4

joining complementary base pair sequences (DNA-DNA or DNA-RNA), uses 2 single strands, vital part of PCR and Southern blot

Question 5

Restriction Enzymes (Restriction Endonucleases)

Answer 5

enzymes that recognize specific palindromic double-stranded DNA sequences, once a sequence is identified, restriction enzyme can cut through the backbones of the double helix

Question 6

Southern Blot

Answer 6

used to detect the presence and quantity of various DNA strands in a sample

Question 7

Transgenic Mice

Answer 7

altered at their germ line by introducing a cloned gene into fertilized ova or into embryonic stem cells

Question 8

Transgene

Answer 8

cloned gene that is introduced into transgenic mice

Question 9

Nucleosides

Answer 9

five-carbon sugar (pentose) bonded to a nitrogenous base and are formed by covalently linking the base to C-1’ of the sugar

Question 10

Ribose vs. Deoxyribose

Answer 10

ribose has —OH at C-2; deoxyribose has —H

Question 11

Pyrimidines

Answer 11

CUT the PYe (cytosine, uracil, thymine)

Question 12

Purines

Answer 12

As Gold (adenine and guanine)

Question 13

Aromaticity

Answer 13

1. compound is cyclic
2. compound is planar
3. compound is conjugated
4. Compound has 4n+2 (where n is any integer) pi * electrons (Huckel’s Rule)

Question 14

Watson-Crick Model of DNA Structure

Answer 14

Two strands of DNA are antiparallel, sugar-phosphate backbone is on outside of helix with nitrogenous bases on inside

Question 15

Chargaff’s Rules

Answer 15

in double-stranded DNA, purines = pyrimidines

%A = %T
%G = %C

Question 16

B-DNA

Answer 16

turn every 3.4 nm and contains about 10 bases within that span, major and minor grooves can be identified between interlocking strands

Question 17

Z-DNA

Answer 17

left-handed helix that has a turn every 4.6 nm and contains about 12 bases within each turn, high GC content or high salt concentration may contribute to its formation

Question 18

Chromatin

Answer 18

a DNA wound histone (small basic protein)

Question 19

Nucleosome

Answer 19

two copies of each histone protein, H2A, H2B, H3, and H4 form a histone core and about 200 base pairs of DNA are wrapped around this protein complex

Question 20

Heterochromatin

Answer 20

small percentage of the chromatin remains compacted during interphase, appears dark under light microscopy, it is transcriptionally silent

Question 21

Euchromatin

Answer 21

dispersed chromatin, appears light under light microscopy, contains genetically active DNA

Question 22

Centromere

Answer 22

a region of DNA found in center of chromosomes, sites of constriction, form indentations, allows two sister chromatids to remain connected at centromere until microtubules separate the chromatids during anaphase

Question 23

Helicase

Answer 23

unwinds DNA, generates two single-stranded template strands ahead of the polymerase

Question 24

Single-stranded DNA-binding Proteins

Answer 24

bind to unraveled strand, prevent both reassociation of the DNA strands and the degradation of DNA by nucleases

Question 25

DNA Polymerases

Answer 25

they read the DNA template, or parental strand, and synthesize the new daughter strand

Question 26

Leading Strand

Answer 26

in each replication fork is the strand that is copied in a continuous fashion, in the same direction as the advancing replication fork

Question 27

Mismatch Repair

Answer 27

cell machinery in G2 phase of cell cycle, these enzymes detect and remove errors introduced in replication that were missed during the S phase of the cell cycle

Question 28

Base Excision Repair

Answer 28

affected base is recognize and removed by a glycosylase enzyme, leaves behind an AP site

Question 29

Apurinic/Apyrimidinic (AP) Site

Answer 29

abasic site, recognized by an AP endonuclease that removes the damaged sequence from DNA