Chromosomes (7)

Question 1

Dyads

Answer 1

during S phase chromosomes duplicate forming dyads

Question 2

sister chromatids

Answer 2

attached duplicated chromosomes

Question 3

ploidy

Answer 3

increase the number of sets of chromosomes

Question 4

Diploid

Answer 4

number of chromosomes per somatic cell

Question 5

Haploid

Answer 5

number of chromosomes in gametes

Question 6

karyotype

Answer 6

complete set of chromosomes in the cells of an organism (image)

Question 7

trisomy

Answer 7

one extra c’some

Question 8

monosomy

Answer 8

missing 1 c’some

Question 9

How does aneuploidy arise?

Answer 9

nondisjunction

Question 10

translocations

Answer 10

movement to a new c’some

transfer of a piece of one c’some to a non homologous c’some

Question 11

inversions

Answer 11

portion of c’some is flipped

Question 12

deletions

Answer 12

section of DNA excised

Question 13

insertion

Answer 13

section of DNA inserted

Question 14

What are 4 results of breakage & repair in c’some ?

Answer 14

translocations
inversions
insertions
deletions

Question 15

normal recombination

Answer 15

translocation of a homologous c’some

Question 16

How do translocations cause changes in the phenotype?

Answer 16

breaking a gene –> gene is non-functional
moving a gene to a region where it can be controlled by another regulatory sequence
Creating a hybrid gene –> brand new gene, may contain selectable trait & thrive

Question 17

How does translocation cause CML?

Answer 17

c’abl gene encodes a kinase that regulates cell proliferation during the cell cycle
translocation causes the cable gene to be moved to another gene’s promoter, the bcr promoter
this promoter causes the gene to be promoted constantly & leading to constant division

CANCER

Question 18

what is an ex of a positive outcome of translocation?

Answer 18

apes –> 48 c’somes
humans –> 46 c’some

we share all of our c’somes except 2

telomere of the ape’s c’some is in the middle of 2 of our c’some (seen in banding techniques)

therefore, there was a fusion of 2 of the ape’s c’some leading the humans

Question 19

centromeres

Answer 19

constricted portion of each c’some

DNA contains alpha satellite DNA

Question 20

alpha satellite DNA

Answer 20

made of non transcribed 171 base repetitive sequences

Question 21

what is the role of centromeres?

Answer 21

enables kinetochore attachment

attach to kinetochores during M phase

Question 22

telomeres

Answer 22

non coding regions at the ends of c’some

short repetitive sequences

include specialized PRO

form a capped end structure with a highly conserved sequence TTAGGG

Question 23

what are the functions of telomeres?

Answer 23

protect end of c’some from nucleases (deoxynuclease) by folding over

allow cells to distinguish c’some ends from broken DNA

prevent c’some from fusing with each other

attachment to the nuclear scaffold (centromeres & telomeres)

Question 24

What happens to telomeres in replication?

Answer 24

become progressively shorter

Question 25

DNA polymerase

Answer 25

an enzyme that replicates DNA strands

Question 26

how do telomeres become shorter?

Answer 26

DNA pol requires a primer builds 5'-3' RNA primer is removed leaving a small overhang (on strand that's not replicated) overhang folds over protecting the strand from nucleases

Question 27

what dictates a cell's life span?

Answer 27

the length of the telomeres

Question 28

what end of the DNA is left unreplicated?

Answer 28

3' end

Question 29

cellular senscence

Answer 29

normal diploid cells seize to divide

Question 30

when is cellular senscence triggered?

Answer 30

when telomere are too short to persist any longer

Question 31

what type of cells have functional repair of telomeres?& what enzyme is involved?

Answer 31

stem cells & telomerase

Question 32

telomerase

Answer 32

RNA containing enzyme that adds more nucleotides to the 3’ end of the telomere strand

Question 33

What are the sets in telomerase repairment?

Answer 33

1. telomerase binds to complementary sequence 2. Nucleotides added to DNA 3' terminus 3. Telomerase slides over & its RNA binds to another complementary strand 4. more nucleotides are added to DNA 3' end 5. other strand filled in using DNA pol

Question 34

what type of genes can reactivate their telomerase?

Answer 34

cancer

Question 35

Where is telomerase absent in ?

Answer 35

cultured cells from normal tissues

Question 36

where is telomerase present in?

Answer 36

tumor cells one celled organisms primordial germ cells tissue stem cells

Question 37

what are the factors in cell aging? (4)

Answer 37

telomere shortening accumulated errors chromic risk exposures such as oxidants & UV glycation

Question 38

Who is Dolly?

Answer 38

1st cloned mammal from an adult cell took nucleus from an udder (somatic tissue) & transplanted it into a de-nucleated embryo

Question 39

What conditions did Dolly suffer from?

Answer 39

arthritis | premature aging

Question 40

how do shortened telomeres cause aging?

Answer 40

not anchored properly, c'some moves around not expressing properly

Question 41

why didn't the de-nucleated embryonic cell restore the length of the telomeres in the 6 year old nucleus?

Answer 41

took away source of telomerasenexpression from the removed nucleus

Question 42

what are the types of DNA sequences?

Answer 42

highly repeated sequences moderately repeated sequences non repeated sequences

Question 43

highly repeated sequences

Answer 43

short sequences in clusters mini-satellite & micro satellite (shorter that satellite)

Question 44

what sequences are used in DNA fingerprinting?

Answer 44

highly repeated sequences

Question 45

moderately repeated DNA

Answer 45

few copies to tens of thousands some code for PROs needed in large quantities (ex: ribosomal PROs)

Question 46

non repeated DNA

Answer 46

encodes PROs, build cells etc. | 20% of genome codes for PROS