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ANSC 313 > Chromosomal inheritance > Flashcards

Chromosomal inheritance Flashcards

1
Q

cytogenetics and somethings we can see within it

A

the study of chromosomes
-multiple malformations
-fertility problems
-phylogeny/evolution
-sexing animals

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2
Q

when does DNA get turned into chromosomes

A

after interphase it gets condensed into chromosomes in prophase I

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3
Q

how are chromosomes packed up

A

-DNA double helix
-DNA and histones
-chromatin fiber
-super coiled DNA
-chromosome

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4
Q

types of chromosomes

A

-depends on centromere placement
-telocentric (no P arm)
-acrocentric (small P arm)
-submetacentric (bigger p arm)
-metacentric (almost equal p and q arm

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5
Q

what are the part of the chromosome

A

-centromere
-p arm (short)
-q arm (long)

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6
Q

karyotype

A

-arranges by size (depending order b-s)
-numbered
-sex chromosomes last
-short arm up (p)
-autosomes
-grouped by centromere placement
-homologous chromosomes, same size, band patterns

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7
Q

how many chromosomes do pigs have

A

38

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8
Q

how many chromosomes to humans have

A

46

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9
Q

how many chromosomes do cows have

A

60

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10
Q

sexing birds

A

-now done with DNA typically
-many chromosomes
-6-9 pairs of macrochromosomes
(including sex chromosomes)

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11
Q

how many chromosomes do dogs have

A

78

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12
Q

how many chromosomes do horses have

A

64

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13
Q

chromosomes nonenclature

A
  1. total # of chromosomes
  2. sex
  3. special findings (e.g. + or -)
    ie. 78, XX, (normal bitch)
    65, XY, +15(abnormal colt fetus)
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14
Q

origin of chromosomal anomalies

A

-many chromosomal anomalies arise “de novo” during meiosis of one of the parents
-arise through mismatching of homologues during meiosis
-also can occur through an error in cell division

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15
Q

how do chromosomes divide

A

-mitosis
-meiosis

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16
Q

mitosis

A

-exact duplication of somatic cells
-DNA replicates
-chromatids separate
-results in 2 diploid cells

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17
Q

stages of mitosis

A

-interphase (DNA replicates)
-prophase (chromosomes become visible as extended double structures)
-metaphase (nucleus is replaced by the spindle, chromosomes become aligned on the equator)
-anaphase (chromosomes pairs split and move towards opposite poles
-telophase (chromosomes reach poles)
cytokinesis (nuclei reform; each daughter cells has complete set of chromosomes, one member of each pair derived from each parent

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18
Q

meiosis

A

-(reduction division-in gametes)
-meiosis I
-DNA replicates
-homologous pair (crossing over)
-chromosomes separate
-result in 2 haploid cells

-meiosis II
-chromatids separate
-result in 4 haploid gametes

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19
Q

meiosis I

A

Prophase I - chromosomes become visible
Metaphase I - bivalents align at the equator
Anaphase I - homolog pairs move to opposite poles
Telophase I - homolog pairs enter separate cells

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20
Q

meiosis II

A

Prophase II - chromosomes re-form
Metaphase II - homologs line up at equator
Anaphase II - homologs move to opposite poles
Telophase II - four gametes each have one copy of each
chromosome

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21
Q

when does meiosis occur

A

gametogenesis

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22
Q

gametogenesis

A
  • a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes
  • Oogenesis, spermatogenesis
    ▪ Timing is different depending on if female or
    male
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23
Q

oogonum

A

immature egg cell

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24
Q

what does the oogonum turn into

A

-primary oocyte (2n)
-gains zona pellucida after puberty
-after meiosis I becomes secondary oocyte + polar body (1n)
-then because of fertilization meiosis II occurs and turns into zygote + second polar body (2n)

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25
what happens to spermatogonium
-(2n) can become dormant for later division or active -active undergoes mitosis -16x (2n) primary spermatocytes -meiosis I - two (n) secondary spermatocytes meiosis II -four (n) spermatids -turns into spermatozoa
26
what are the differences in gametogenesis
-female -one ovum + two polar bodies form one primary oogonium cell -male -four sperm form one primary spermatogonium cell -female -no new oocytes during lifetime, so accumulate damage (initiated in fetus) -males -new sperm generated every 60 days
27
different types of chromosome anomalies
-with phenotypic effect: numerical, structural -w/o phenotypic effect: structural
28
chromosome numerical errors
-called aneuploidy (loose or gain) -cause is usually non disjunction -usually results in multiple malformations -risk increases with maternal age
29
non disjunctional
-chromosomes in egg do not separate properly during meiosis I or II -either have too many chromosomes or too little in fertilized eggs
30
risks of downs and chromosomal mutations
-risk increases exponentially in humans at the age of 35 (less then 1 % before) -cows after 9 years of age
31
incidence of chromosomal problems
-~30% of human conceptuses abort -2.5-10% of "late" spontaneous abortions have chromosomal problems/causes -assume a high proportion of early abortions have chromosomal problems -live birth weights with major malformations -many chromosomal
32
type of numerical errors
-aneuploidy which includes: -trisomy -monosomy -mosaicism -chimera
33
aneuploidy
one chromosome pair has the wrong number (i.e. not 2)
34
trisomy
-3 of one chromosome -severe, usually lethal effects
35
klinefelter syndrome
-sex chromosome aneuploidy -61, XXY -infertile
36
monosomy
-1 of one chromosome -severe, usually lethal effects early in gestation -59, XX, -15
37
turner syndrome
-sex chromosome aneuploidy -63, X0 (mare with one X missing) -infertile -note if X is missing in a male, lethal (i.e 63, Y0 is not viable)
38
what are the deaths of the different types of numerical errors like
-monosomies abort earliest -trisomies may abort later -aneuploids of larger chromosomes abort earlier -few survive to term -usually the bigger the chromosome that is affected= abort earlier
39
mosaicism
-> 1 cell type -moderate abmornalities -60, XX/59, XX, -? -likely a mitotic error -some cells normal but not all -if less then 10% of their cells have abnormal chromosome karyotype, individuals may not exhibit symptoms
40
chimera
-own karyotype plus other (twin) -special type of mosaic -> 1 cell type, derived from >1 individual ->10% of cells abnormal leads to problems -60, XX/60, XY -freemartin heifer is sterile and male co-twin has lower sperm count
41
placenta anastomosis
a cross connection between cotyledons
42
chimeric twins in different species
-~99% of cattle -<10% of goats -few sheep (who have the same kind of placenta) -rare in dogs, humans, etc. none of who have this form of placenta
43
implications of a numerical error
-cull affected individual (but they aren't viable) -usually retain parents unless old -recurrence risk ~1% if "young"
44
polyploidy
-triploidy -tetraploidy
45
triploidy
-3 haploid sets -fert egg becomes 3n -dispermy?
46
tetraploidy
-4 haploid sets -chickens die -cattle mosaics live (also have normal cells)
47
types of chromosome anomalies with and with out phenotypic effects
with phenotypic effects: -numerical -structural without phenotypic effects: -structural
48
structural errors (with phenotypic effects)
-deletion -duplication -ring (rarely reported in animals because rarely studied)
49
types of chromosomal structural errors (without phenotypic effect)
-translocation -inversion
50
indications of structural errors with out phenotypic effect
-sub fertility -25% reduced litter size ->10% of cows serviced by bull remain open ->2% spontaneous abortions (or late conception in cows)
51
robertsonian translocation
-2 acrocentric chromosomes fuse -count is off by one (2n-1)
52
reciprocal translocation
-2 chromosomes exchange pieces -number is unchanged (2n)
53
what is the most common translocation in cattle
robertsonian translocation t(1;29) -normal and balanced translocation=live calf -trisomy 1, 29 and monosomy 1,29=aborted calf
54
where is translocation in cattle more commonly seen
10% in some continental breeds not common in british breeds
55
t(14;30)
extremely rare but seen in some simmintals
56
where is translocation testing mandatory in
some breeds: -charolais -simmental some countries: -australia -brazil -england -newzeland -sweden some AI companies
57
implications of robertsonian translocation
-cull unbalanced bulls (usually lethal but in the case they arent) -screen relatives if economic -cull translocation carriers?
58
reciprocal translocation example
part of chromosome 7q exchanged with chromosome 11q
59
implications of reciprocal translocations
-translocation carrier will have low fertility (litter size) -may observe mummified piglets -serious if a boar
60
two kinds of translocations
reciprocal and robertsonian
61
phylogeny evolutionary relationship
-acrocentric= more primitive -fusion of chromosomes=more recent -results in increase metacentric chromosomes -decrease in chromosome number
62
hybrid fertility
-if karyotype is different; both sexes are sterile, (eg. horses have 64, donkey 62, mule 63) -if karyotype is similar; only the heterogametic sex is sterile, increased embryo mortality (eg. bison and domestic cattle, yak and domestic cattle)
63
dogs/wolf/coyote hybrids
-both sexes of canid hybrids are fertile -species or subspecies -canis lupus -canis latrans
64
bos taurus and indicus hybrids
-both sexes oh hybrids are fertile -species or sub species -but when they are crosses with yak and bison (all have 60 chrmosomes) sterile male

ANSC 313 (25 decks)

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