DNA Structure

Question 1

Rett Syndrome

Answer 1

• X chromosome
• neurodevelopmental affects only females
• defect in methyl-CpG-binding protein 2 in chromatin conformation
• problem in way DNA is packaged in cells, effects epigenetics

Question 2

Primary structure

Answer 2

Covalent makeup and base pair sequence

Question 3

Secondary structure

Answer 3

Stable structure taken up by some or all of the nucleotides

Question 4

Tertiary structure

Answer 4

Complex folding of chromatin to form chromosomes

Question 5

B-DNA

Answer 5

Right handed, Watson crick, 10 bp/turn

Question 6

Z-DNA

Answer 6

Left handed, GC rich

Question 7

A form

Answer 7

Dehydrated B form, 11 bp/turn. Planes tilted 20 degrees away from perpendicular to helixes.
-DNA-RNA hybrids and RNA-RNA double strands

Question 8

Denaturation

Answer 8

Disruption of the non-covalent interactions holding the duplex together
Lowers viscosity and absorbs more UV (hyperchromic effect)

Question 9

Viruses

Answer 9

Protein coat surrounding genome

Question 10

Bacteria

Answer 10

Single Circular chromosome in nucleoidand smaller circular DNA’s called plasmids

Question 11

Eukaryotes

Answer 11

Package DNA into chromatin

Question 12

Euchromatin

Answer 12

Loosely packaged and transcriptionally active

Question 13

Hterochromatin

Answer 13

Tightly package and transcriptionally inactive

Question 14

Histones

Answer 14

Contain large amounts of basic Aminos (Lys and Arg) that are positively charged to attract neg charged DNA

Question 15

Topoisomerases

Answer 15

Relax supercoiling and maintain neg supercoiling by nicking and resealing

Question 16

DNA methylation

Answer 16

• Inhibit binding of trans acting factors, repressing transcription if at promoter sequences but can affect binding of repressive factors and activate transcription
• Also serve as recognition motif

Question 17

DNA methyltransferases

Answer 17

Catalyze methylation using S-adenosyl methionine (SAMe) as donor.

Question 18

Ten-eleven translocation

Answer 18

Enzymes that catalyze remove of DNA methylation involving multiple intermediates. Followed by base excision repair

Question 19

Thymine-DNA glycoylase (TDG)

Answer 19

Removes thymine moieties from G/T mismatches by hydrolyzing the C-N bond between the sugar-phosphate backbone of DNA and mismatched thymine

Question 20

Acetylation

Answer 20

Most commoner his tone modification, transfer of acetyl group from acetyl coenzyme A to the epsilon-amino of lysine
-causes naturalization of positive charged histones, decreasing affinity for DNA