gametes

t loop which protects it from degradtion

TTAGGG repeats

prevents degaradation

loop prevents enzymes from cleaving the end.

1. obtain a cell

2. phytohemogluttin--> force mitotic div

3. cultur 2

4. add cochicine= prevents spindle formation

5. add hypertonic solution so cell swells and drop on slide-->bursts

6 fixative to prevent enzyme activity

7 trpsin-->digests cell and stain to see banding

8 analyze metaphase chromosome

what produces darker staining

why?

stain

a chromosome further in mitotic cycle

fewer transciprtionally active genes more condesed more at bp

quinacrin

Time phrame for various cells of adults

a blood

b marrow

c fibroblast

a leukocytes 2-3 days wbc

b painful but no culture needed

c 2-3 weeks... skin biopsy

Prenatal cultures

a amniotic

b chorionic villus

a must be taken 16 weeks into pregancy and take 2-3 weeks (low risk)

b higher risk no culture quick result

1 size

2 location of centromere

contain satelite repeats

13-15, 21, 22, and Y

sateliete repateats can be lost

1 of most common reasons for fetus death

more than 2 copies of ALL chromosome

errors in meiosis

condensed even in interphase

less transcriptionally active

on x

turner;s

most common in maternal meiosis

2 sisters to one cell and 0 in other

# of trisomy 21 that die in uterus

Monosomy X?

80%

99%

chromosome with identical arms

occurs in mitosis

one chrom will have 2 p arms and other 2 q

la  la

lb  lb

lc  lc

lc  ld

lb  le

la  lf

RED FLAG

llight space can be seen in ultrasound btwn skin and spine

INVISIBLE NOSE RED FLAG

loss of teleomeres and chromosome forms a ring

no meosis nor mitosis

40% chance of heart problems

symian trace

 hypothroidism

mental rtardation

ears face

early senlity (40)

result of unsuccesful repair of broken chromosome.. pieces attach to diff chrom.

Stable= ok

unstable= loss of dna

Stable= centric for centric

unstable= combo of acentic and centric forms chromosome with 2 centromeres and one with none

proximal q arms attach w/ centromere

satelite p arms attach but are lst

ok cause satelites are found inseveral places

results of reciprocal translocation

a) 46, XX, t(8:18) p21.1;121.1

b) + or-

c unbalanced and balanced robertsonian

a= balanced ok can express genes ok

b mono or tri somy

c. shows tri or mon and bad

balanced ok usually no syptoms

genes on chromosome that causes alzhemeirs. more likely to be expressed if all three are present

may be alleviated with nutrition

percent of DOwnsyndrom due to trisomy 21

due to reciprocol or robertsonian translocation

mosaicism?

95% 47 x? +21 = usually1st maternal meisosis

3-4% translocation mostly roberstonian 46 xy (14:21)+21

1% due to non disjuction at mitosis post zygote

balanced carrier parent very unusual

100% chance of child getting downs mono or tri 21

a Regular person w/ down syndrom chance of child having it

Multiple occurances in one family reason

1/600

14-21 translocation has occured in parents