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0
Q

No change in actual structure of the gene, no nucleotide change… change in chromatin structure which turns gene off or on… chromatin change acures in germ cells

A

epigenetics inheritence

1
Q

a form of inheritance that is superimposed on the genetic inhertance based on DNA

A

epigenetics

2
Q

DNA sequnce changes

A

genetic inheritence

3
Q

high degree of conservation in a structure indicates

A

high degree of importance

4
Q

one form of chromatin silences the genes it packages without regard to sequence and is directly inherited by daughter cells

A

heterochromatin

5
Q

heterochromatin

A
  • heavily conserved
  • thought to be late replicating and genetically inactive
  • highly conserved at centromeres and telomeres
  • contains very few genes; resistant to gene expression
  • all the rest is less condensed and known as euchromatin
6
Q

activity a gene depends on position on chromosome… will be silenced if relocated near heterochromatin

A

position effect.

7
Q

breakage events that bring heterochromatin near active genes tends to silence them

A

position effect variegation…. zone of inactivation spreads a different distance in different cells

8
Q

Histone modification

A
9
Q

histone modification- loosens chromatin sturcutre

A

Acetylation of lysines… added by histone acetyl transferases (HATs); removed by histone deacetylase complexes (HDACs)

10
Q

Histone modifications of serines

A

phosphorlation

11
Q

What does recruitment of enzymes that cause histone modification depend on?

A

gene regulatory proteins

12
Q

Are histone modifications reversible?

A

All are reversible, but can persist long after regulatory protieins have disappeared

13
Q

What is important consequences for the types of proteins the modified DNA attract?

A

This determines the how when if gene expression takes place

14
Q

What histone hast no variant histones?

A

H4

15
Q

synthesized during S phase and assembled into nucleosomes on duaghter DNA helices just behind replication fork

A

major histones

16
Q

synthesized during interphase and inserted into already formed chromatin. requires histone exchange process catalyzed by chromatin remodeling complex

A

variant histones

17
Q

Histone code

A

thouseand of combinations of modifications (methylation, acetylation, etc)… ready by code reader complex

18
Q

What binds and attracts other components??

A

code reader complex.. brings onther protein compexes

19
Q

gene regulatory proteins has a histone modyfing enzyme “ writer”, the code-reader protein tells the other DNA about the change

A

code reader-writer

20
Q

IS the chromatin remodeling comlex ATP dependent?

A

Yes,

21
Q

How is remodeling contained to one area of the chromosome?

A

physical barriers… nuclear 4 complex, code reader complexes cannot go through
enzymatic barriers- HS4 region- protects the Beta globin locus from silencing, contains a cluster of histone actylase binding sites prevening writers from continuing

22
Q

centromeric heterochromatin

A

centromere specific H3 histon, CENP-A, pack the nucleosoomes into dense arrangements to for the kinetochore

23
Q

What does centromere sequences in humans consist of?

A

short repetitive DNA sequences called alpha satellite DNA

24
Q

What is centromerica heterochromatin defined by?

A

assembly of proteins, not DNA sequences

25
Q

alpha satellite DNA

A

at most centromeres, but not all. and at some areas that are not contromeres, the proteins that form to create the centromere is the MOST important aspect of centromere formation

26
Q

What are 2 altering types of chromatin

A

nucelosomes w CENP-A on the outside fold

Nucleosomes w normal H3 on the inside

27
Q

What does CENP-A do?

A

binds the kinetochore

28
Q

What does de novo centromere formation require?

A

a “seeding” event on alpha satellite DNA

29
Q

How are H3-H4 tetramers inherited?

A

Directly inherited by the daughter strands at the replication fork

30
Q

Centromeres are not randomly placed on

A

chromosomes

31
Q

structure of interphase chromosomes

A

extended loops to be more accesible

32
Q

What is assocated with nuclear lamina?

A

heterochromatin

33
Q

Each chromsomes occupies

A

its own areas of the nucleus, not each pair is next to one another

34
Q

Chromatin structure and location chagnes during

A

gene expression

35
Q

If a gene is being expressed it goes to?

A

a chromosomes loop

36
Q

decondensation of chromatin during gene transcription;

A

chromosomes puffs

37
Q

interior of nucleus very

A

hertogeneous

38
Q

mitotic chromosomes are

A

highly condensed, final levle in chromosome packaging

39
Q

two daughter DNA molecules replicated in interphase are speartely folded to produce

A

two sister chromatids

40
Q

What are chromatids held together at?

A

chromatids

41
Q

What is the purpose of consensation

A

protection of fragile DNA molecules

allow for separation for cell division

42
Q

Compaction aided by proteins called

A

condensisns

43
Q

genes that are similar in both sequence and fucntion due to common ancestry***

A

homologues… not the same as syntany

44
Q

What is a major clue to gene and prtein function?

A

recognition of sequnce similarity

45
Q

gene sequences are more tightly conserved than…

A

genome structure…. size of genome, number of genes, size of introns, abundance of repetitive sequences can be quite different

46
Q

How do genomic changes occur??

A

mistakes in DNA replication and repair… rare in genetic material

47
Q

types of genetic changes

A

base pair substitutions…
more lg scale=
duplications, deletions, inversinos, translocations

48
Q

elimination of mutations that interfere with improant genetic functions

A

purifying selection

49
Q

a duplicated gene that has become irreversibly inactivated by multiple mutations

A

pseudogenes

50
Q

globin genes… duplication and divergence

A

intially there was one hemoglobin genes and now it has four.

51
Q

SNPs. single-nucleotide

A

points in the gneome where one group has one nucleotide and another group as another
variation occurs at a high rate (1% or more)

52
Q

CNVs- copy number variants

A

presence of many duplications and deletions of lg blocks of DNA
some blocks are common and others rare