Notatki Danniego part 4 Flashcards
Inversion -
A section of chromosome that has been rotated and replaced in position
- > a loop must be made
- > a chromosome with an inversion will be inherited as a block known as a supergene
translocation
Two nonhomologus chromosomes exchange parts
- > part of the Y chromosome can attack on to the x chromosome
- > gives XXy (x with a bit of y)
- > this makes you a male but you cannot produce sperm
position effect variegation
drosophila white eye gene carried on chromosome
- > gives red or white
- > cam give white eyes with red patterns
- > bit of the X chro0mosome has been translocated to another chromosome
- > shows the way genes are turned on/off sped up/slowed down by other genes
- > gene interaction
cancer
- usually loss of tumor suppressor which codes for the gap in cell division so cell reproduce too quickly
- can also have tumor accelerators
aneuploidy
- > incorrect number of chromosomes
- > malfunction in the formation of gametes can occur where both copies of the chromosome end up in one cell
95% of cases ?! (5% due to translocation)
- > Down’s syndrome an extra chromosome 21 (shortest chromosome)
- > flat face
- > enlarged colon
- > simple singerprints
- > single palmer crease
- >mental retardation - > a piece of 14 shifted on 21
Klinefelter syndrome
XXY - xx egg fertilised by a Y sperm
-> tall stature - slightly feminised physique - osteoporosis
-> female pubic hair, breast development - impaired IQ
1/500 males have Klinefelter
Turner syndrome
XO missing a chromosome
- > short - sterile - skin folds - brawn spots
- > heart issues - characteristic face
gynandromorph
male and female
- > can be split down the middle
- > can have two complete sets of genitalia
- > or a mish mash that is nothing like genitalia at all - > can interact with genes that are associated with sex chromosomes
- > eye colour on X chromosome for drosophila
HAPLODIPLOIDY IN BEES (18 STRONA OD NIEBIESKIEGO)
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Autopolyploidy
spontenous naturally occuring genome doubling
diploid autotetraploid species
AA ———————————————————> AA AA
endoreduplication
Alloploidy
2 species hybridize and double chromosomes
AA \ allotetraploid
diploid = ————————————————->AABB
BB / Hybridization + endoreduplication
In wheat AA hybridized with BB. Then again with DD to give AABBDD hexaploid production wheat
- > Also AABB crossed with Rye (RR) to give tritical
- > An alloploid of emmer wheat and rye
- > productive in cold climates
Triploidy can create sterile organisms
- > seedless watermelons
- > oysters that can’t self-fertilize
Primate chromosomes
- chromosome bands almost identical to Gorrilas, chimps and orangutans
- > humans have slightly less
- > human also have a fusion of chromosome 2 which other primates do not.
- > near identical DNA sequences but split over 2 chromosomes
Asexual species tend to live in environmentally predictable places
- > can rely on inversions of chromosomes
- > don’t need to change genome to adept
More sexual species live in … as they need to ….
environmentally harsh places
change and adapt quicker
Polyploidy could be the reason for dramatic changes in appearance of fish who have much more DNA then us
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… working genes on human genome
23,000
Linkage:
Batson & Punnet
sweet pea 2 character cross
Purple Long pollen X red round pollen
- Expected 9:3:3:1 in f2
215: 71:71:24 - What they got: 284: 21! : 21! :55 f2
- > Parental excess
- > Recombinant deficiency - Linkage
- > Colour and pollen size are on the same chromosome
Morgan’s test cross
?! check dominancy of these genes
+ = wild type
P1: purple vestigial X Red Normal
prpr vgvg pr+pr+ vg+vg+
F1: All red normal prpr+ vgvg+
Take f1 and mate with mutant fathers prpr vgvg
-> This is a TEST CROSS or BACK CROSS
Morgan’s test cross exp
back cross:
sperm: prvg
egg: prvg, pr+vg, prvg+, pr+vg+
Expected:
1 purple vest : 1 red vest : 1 purple normal : 1 red normal
- 1000 flies - 250 of each follows mendels second law
Actual result:
1339 : 151 : 154 : 1195 parental Recombinants parental
Repulsion cross
mutant & wildtype homozygotes in each parent
P1: pr+pr+ vgvg with prpr vg+vg+
F1: All double heterozygotes pr+pr vg+vg
Then Backcross with prprvgvg males
Expect f2 to be 1:1:1:1
But got:
146 : 465 : 1067 : 157
Recombinant Parental Recombinant
- still shortage of recombinants!
MAKE MITOSIS SCHEME
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Meiosis
2n n n
2n -> ->
2n n n
- Synapsis of homologous chromosomes
- usually a crossover per homologous pairs
- centromers do not divide ii anaphase I but do at anaphase II
- Every meiosis in females only makes 1 egg
- > eggs are largest cell in body and too big to split
- > males make 4 cells (sperm) from one cell
Meiosis2
- sister chromatids form tetrad in prophase of the first meiotic division
(ZDJECIE) - this is accompanied by a breakage and rejoining og chromosomal material
-> Cross over
-> Swap, genetic material between parental & maternal chromosomes
Crossing over on the chromosome explains lack of recombinants in Morgans test
Chiasma
- Point where chromosomes crossover
