Molecular Structure of chromosomes & tranposition

Question 1

Chromosomes

Answer 1

Structure in living cells that contain the genetic material

Question 2

Introns

Answer 2

Noncoding intervering sequences

Question 3

Centromeres

Answer 3

Play a role in the seperation (segregation) of chromosomes during meiosis & mitosis

Question 4

Human diploid has _____ chromosomes

Answer 4

46

Question 5

DNA compaction is composed of ______ & ________

Answer 5

DNA & proteins

Question 6

Nucleosomes (“beads on a string”)

Answer 6

Contain 8 histone (4 types but two of each ones) ( Also have a 146 bp DNA)

Question 7

Why does histone have a positive charged “tail”?

Answer 7

Beacuse the phosphate backbone in DNA is negatively charged

Question 8

What are the 4 types of core histones that make up the nucleosome?

Answer 8

H2A, H2B, H3, H4

Question 9

Linker Histone (binds linker DNA & nucleosomes)

Answer 9

H1

Question 10

Roger Kornberg

Answer 10

Made a model for nucleosomes & observed chromatins by x-ray diffraction & e-microscopy

Question 11

Describe Kornberg Model

Answer 11

Tested the “beads on string” model by using DNase-1 enzyme which digest DNA & also cuts the linker DNA to make it accesbile

Nucleosomes interact with each other through linker histone H1 & becomes more condesned (compact) to form a 30nm fiber called Chromatine

Question 12

Nucleosomes become closely associated to form a 30nm fiber, when nucleosome interact with each other to form a more compacy structure (30nm fiber) it shortens the DNA (chromatin) by nearly ______

Answer 12

50x (50 folds)

Question 13

Chromosomes are further compacted by anchoring of the 30nm fiber into _______________ domains along the nuclear matrix

Answer 13

Radical Loop

Question 14

Radical Loop domain

Answer 14

Formed by 30nm fiber & internal nuclear matrix & the protein bounded to them

Question 15

Euchromatin

Answer 15

Less condensed radical loops (will have active transcription)

Question 16

Heterochromatin

Answer 16

More compact radical loop & more condensed area on chromosome where no transcription takes place (genes are silenced)

Question 17

Teleomers

Answer 17

Condensed radical loops (heterochromatins) at the ends of a chromosome

Question 18

Describe the formation of chromosomes

Answer 18

DNA

then DNA wraps around histone proteinsto form nucleosomes

then those nucleosomes become more compacted & form 30nm fiber

then 30nm fiber interacts with internal nuclear matrix & its proteins to form a radical loop

then the radical loop mostly becomes heterochromatin (highly compacted(condensed) & then chromsomes are formed from the highly compacted heterochromatin