section 1

Question 1

Histones

Answer 1

Small basic proteins containing high proportion of basic amino acids. (Arginine & Lysine) that package DNA in an ordely way in the cell nucleus. H1, H2A, H2B, H3, H4. C

Question 2

Chromatin

Answer 2

Eukaryotic DNA complexed with proteins such as histones and others nonhistones involved in DNA replication and gene expression. Has 2x more protein than DNA. 10nm

Question 3

Arginine and Lysine in histones

Answer 3

Amino acids in Histones that facilitate the binding to the negatively charged DNA molecule

Question 4

Nucleosome

Answer 4

Basic strucutral unit of chromatin. Repeating 200bp units found by Kornberg with partial digestion of chromatin by Micrococcal nuclease. Gives chormatin beaded appearance. Shortens DNA length 6fold

Question 5

Micrococcal nuclease

Answer 5

An enzyme that degrades DNA used to digest chromatin and find nucleosomes. Yields fragments of DNA 200bp long. Yields a continuous smear of randomly sized fragments in naked DNA.

Question 6

Nucleosome core particles

Answer 6

when more extensive digestion of chromatin with Mn is done. Contain 147bp of DNA wrapped 1.67 turns around histone core that has 2 molecules each of H2A,H2B,H3,H4

Question 7

Core histones

Answer 7

The histones in Nucleosome core particles, w/ 2 of each H2A,H2B,H3,H4.

Question 8

H1

Answer 8

Has one molecule of it bound to DNA as it enters each nuclesome core particle

Question 9

Chromatin condensation

Answer 9

Varies during the life cycle of the cell. Plays important role in regulating gene expression. In interphase it is euchromatin

Question 10

Euchromatin

Answer 10

Decondensed chromatin in the nuclease

Question 11

Heterochromatin

Answer 11

Chromatin in a highly condensed state. Transcriptionally inactive, contains highly repeated DNA sequences

Question 12

Interphase

Answer 12

Period in cell cycle were genes are transcribed from Euchromatin and DNA is replicated in preperation for mitosis. 10% of DNA is in heterochromatin stage similar to how it is when it undergoes mitosis. Chromatin organized in loops.

Question 13

Centromeres

Answer 13

Contains highly repeated DNA sequences

Question 14

DNA during Metaphase

Answer 14

The chromatin organized loops in interphase fold upon themselves to form compact metaphase chromosomes. DNA no longer suitable template for RNA synthesis Transcription stops.

Question 15

DNA during metaphase cont.

Answer 15

Chromosomes highly condensed (can be seen w/ light microscopy), Packaging of DNA into metaphase chormosomes, highly ordered and reproducible process.

Question 16

Centromeres

Answer 16

Holds sister chromatids in chromosome together. plays critical role in correct distribution of replicated chromosomes to daughter cells. Site were spindle fibers of microtubles attach to form kinetichore.

Question 17

Centromeres

Answer 17

Holds sister chromatids in chromosome together. plays critical role in correct distribution of replicated chromosomes to daughter cells. Site were spindle fibers of microtubles attach to form kinetichore. Contains highly repeated DNA sequences

Question 18

Kinetochore

Answer 18

formed when specific proteins bind to centromeric DNA Mediates spindle fibers attachment to chromosome.

Question 19

Centromeric Chromatin

Answer 19

Has unique structure, Specially H3 were it is replaced by CENP-A.

Question 20

CENP-A

Answer 20

the protein that replaces H3 in centromere chromatin nucleosomes in all organisms and is needed for assembly of kinetochore

Question 21

Epigenetic inheritance

Answer 21

Transfer of Information from parent to progeny not based in DNA. Information norally carried by histones. Centromeric chromatin and its nucleosomes that contain CENP-A

Question 22

Telomeres

Answer 22

Simple sequence repeat at ends of chromosomes. Plays critical role in replication and maintenance of linear DNA molecules. Contain residues of G on one strand. Sequence TTAGGG. End w/ 3’ single strand overhang. Makes loop at end. Over expressed in Cancer as size means cell death timem left.

Question 23

Telomere loop

Answer 23

Telomeres binds w/ shelterin and protects from degradation of chromosome termini. Prevents DNA poly from extending DNA here.

Question 24

Telomerase

Answer 24

Enzyme that uses reverse transcriptase to replicates telomeric DNA sequences.