Molecular Biology Chapter 7

Front 1

chromatin

Back 1

a given region of DNA with its associated protens

Front 2

histones

Back 2

associated proteins that are small, basic protens. majority in the chromatin.

Front 3

non-histone proteins

Back 3

associated with the chromosome. includes the numerous DNA-binding proteins that regulate the transcription, replication, repair and recombination of the cellular DNA.

Front 4

nucleosomes

Back 4

structures that form as a result of the regular association of DNA with histones. formation of this is the first step in a process that allows the DNA to be folded into much more compact structures that reduce the linear length.

Front 5

nucleoid

Back 5

structure that is packed witho ne complete copy of their prokaryotic chromosome(s)

Front 6

diploid

Back 6

two copies of each chromosome

Front 7

homologs

Back 7

two copies of a given chromosome. one from each parent.

Front 8

haploid

Back 8

cells that contain a single copy of each chromosome and are involved in secual reproduction

Front 9

reverse transcriptase

Back 9

an RNA-dependent DNA polymerase, which synthesizes a complementary DNA molecule (cDNA) to each mRNA present.some viruses that have RNA genomes use this enzyme to replicate themselves.

Front 10

reverse transcription

Back 10

the copying of an RNA sequence into a DNA sequence.

Front 11

transposition

Back 11

movement in which the elment moves to a new position in the genome, often leaving the original copy behind. these sequences multiply and accumulate throughout the gemome.

Front 12

centromeres

Back 12

required for the correct segregation of the chromosomes after DNA replication

Front 13

kinetochore

Back 13

interacts with the machinery that pulls the daughter chromosomes away from each other.

Front 14

telomeres

Back 14

proteins distinguish the natural ends of the chromosome from sites of chromosome breakage and other DNA breaks in the cell.
second, they act as a specialized origin of replication that allows the cell to replicate the ends of the chromosomes.

Front 15

telomerase

Back 15

DNA polymerase by which telomeres facilitate end replication through recruitment of this unusual dna polymerase.

Front 16

SMC

Back 16

structural maintenance of chromosome proteins are extended proteins that form defined pairs by interacting through lengthy coiled coil domains.

Front 17

linker DNA

Back 17

DNA between each nucleosome "beads on a string"

Front 18

core DNA

Back 18

the DNA most tightly associated with the nucleosome which is wound 1.65 times around the outside of the histone octamer like thread around a spool.

Front 19

micrococcal nuclease or MNase

Back 19

nucleosomes were first purified by treating chromosomes with this sequence nonspecific nuclease. it cleaves protein-free DNA sequences rapidly and protein-associated DNA sequences poorly. A non-specific double strand endonuclease that cleaves preferentially in regions lacking DNA binding proteins, thus cleaves between the nucleosomes.

Front 20

nucleosome core particle

Back 20

147 bp of DNA that is the remaining minimal nucleosome.

Front 21

histones

Back 21

H1, H2A, H2B, H3, H4. small highly basic very abundant proteins and are among the most CONSERVED proteins in evolution. H1 is the linker histone.

has N terminal tail region that is unstructured but can be extensively modified to regulate histone-DNA interactions.

share common structural fold motif.

Front 22

Histone H1

Back 22

binds two DNA helices. changes angles to make more compact.induces tighter DNA wrapping around the nucleosome.

Front 23

30 nm Filament

Back 23

two models. Solenoid and zigzag
both are likely to exist in vivo.

further organized into loops of DNA that associate with a protein scaffold.

Front 24

solenoid form

Back 24

forms a helical structure with a short linker DNA. hole in the middle

Front 25

zigzag form

Back 25

has a longer linker. No hole in middle

Front 26

Nucleosome remodeling proteins

Back 26

uses atp to alter the association of the DNA and nucleosome particle. by sliding, transfer or remodeling.

Front 27

phosphorylation in modification of histone tails

Back 27

introduces a negative charge. weaakens the interaction of the tails with the DNA

Front 28

acetylation in modification of histone tails

Back 28

neutralizes the positive charge of lysine. weakens the interaction of the tails with the DNA.