Lecture 2

Question 0

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

Answer 0

epigenetics inheritence

Question 1

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

Answer 1

epigenetics

Question 2

DNA sequnce changes

Answer 2

genetic inheritence

Question 3

high degree of conservation in a structure indicates

Answer 3

high degree of importance

Question 4

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

Answer 4

heterochromatin

Question 5

heterochromatin

Answer 5

• 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

Question 6

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

Answer 6

position effect.

Question 7

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

Answer 7

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

Question 8

Histone modification

Question 9

histone modification- loosens chromatin sturcutre

Answer 9

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

Question 10

Histone modifications of serines

Answer 10

phosphorlation

Question 11

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

Answer 11

gene regulatory proteins

Question 12

Are histone modifications reversible?

Answer 12

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

Question 13

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

Answer 13

This determines the how when if gene expression takes place

Question 14

What histone hast no variant histones?

Answer 14

H4

Question 15

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

Answer 15

major histones

Question 16

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

Answer 16

variant histones

Question 17

Histone code

Answer 17

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

Question 18

What binds and attracts other components??

Answer 18

code reader complex.. brings onther protein compexes

Question 19

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

Answer 19

code reader-writer

Question 20

IS the chromatin remodeling comlex ATP dependent?

Answer 20

Yes,

Question 21

How is remodeling contained to one area of the chromosome?

Answer 21

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

Question 22

centromeric heterochromatin

Answer 22

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

Question 23

What does centromere sequences in humans consist of?

Answer 23

short repetitive DNA sequences called alpha satellite DNA

Question 24

What is centromerica heterochromatin defined by?

Answer 24

assembly of proteins, not DNA sequences

Question 25

alpha satellite DNA

Answer 25

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

Question 26

What are 2 altering types of chromatin

Answer 26

nucelosomes w CENP-A on the outside fold | Nucleosomes w normal H3 on the inside

Question 27

What does CENP-A do?

Answer 27

binds the kinetochore

Question 28

What does de novo centromere formation require?

Answer 28

a "seeding" event on alpha satellite DNA

Question 29

How are H3-H4 tetramers inherited?

Answer 29

Directly inherited by the daughter strands at the replication fork

Question 30

Centromeres are not randomly placed on

Answer 30

chromosomes

Question 31

structure of interphase chromosomes

Answer 31

extended loops to be more accesible

Question 32

What is assocated with nuclear lamina?

Answer 32

heterochromatin

Question 33

Each chromsomes occupies

Answer 33

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

Question 34

Chromatin structure and location chagnes during

Answer 34

gene expression

Question 35

If a gene is being expressed it goes to?

Answer 35

a chromosomes loop

Question 36

decondensation of chromatin during gene transcription;

Answer 36

chromosomes puffs

Question 37

interior of nucleus very

Answer 37

hertogeneous

Question 38

mitotic chromosomes are

Answer 38

highly condensed, final levle in chromosome packaging

Question 39

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

Answer 39

two sister chromatids

Question 40

What are chromatids held together at?

Answer 40

chromatids

Question 41

What is the purpose of consensation

Answer 41

protection of fragile DNA molecules | allow for separation for cell division

Question 42

Compaction aided by proteins called

Answer 42

condensisns

Question 43

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

Answer 43

homologues... not the same as syntany

Question 44

What is a major clue to gene and prtein function?

Answer 44

recognition of sequnce similarity

Question 45

gene sequences are more tightly conserved than...

Answer 45

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

Question 46

How do genomic changes occur??

Answer 46

mistakes in DNA replication and repair... rare in genetic material

Question 47

types of genetic changes

Answer 47

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

Question 48

elimination of mutations that interfere with improant genetic functions

Answer 48

purifying selection

Question 49

a duplicated gene that has become irreversibly inactivated by multiple mutations

Answer 49

pseudogenes

Question 50

globin genes... duplication and divergence

Answer 50

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

Question 51

SNPs. single-nucleotide

Answer 51

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

Question 52

CNVs- copy number variants

Answer 52

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