Genetics Yr1 sem1final

What is cytogenetics?
A study of chromosome structure, inheritance and their abnormalities.
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What does DNA contain?
Genetic info on genes (base sequence)
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How much is Human genome?
3x10^9 bps(20,000-25,000genes)
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What is chromatin?
1.complex DNA and proteins. 2. Observable in non-dividing stage.
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what is chromosome?
1.condensed form of chromatin. 2.observable in dividing stage.
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Structure of chromatin?
1.double helix 2.nucleosome fibre=bead on string, DNA wrapping around histone octamer. 3.solenoid=nucleosome wrap around itself to form solenoid. (FUNDAMENTAL STRUCTURE),TopoisomerseII cause it to be lope and attach to non-histone protein.
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What is component of histone octamer?
1.2 H2A, 2H2B, 2 H3, 2 H4. but H1 is not in octamer, facilitating packing.
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How many base pairs in one bead ?
140 bp.
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what is fundamental unit of chromatin fibre?
Solenoid= superhelix, 6 nucleosomes per turn.
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What enzyme give a rise to loop domain structure?
Topoisomerase II allowing attaching to non-histone protein. 60-100kb/loop.
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what locate in short arm of acrocentric chromosome?
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what is the name of terminal of chromosome?
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what are functions of telomere?
contain tandem repeat(telomeric DNA) "TTAGGG" sealing the end of chromosome and maintain structural integrity.
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what is telomerase enzyme?
Telomerase enzyme decrease activity as age incrase. if level is too high causing cancer while the reverse is telomeric disease.
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what i s Quiescene?
G0 phase= non-division or differentiation phase. Liver cell sometimes can move from G0 to G1 phase.
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which phase in interphase does take the longest?
G1 phase. At G1 chromosome still have 1 sis chromatids. but after S phase - all have 2 sis chromatids.
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Properties of G1 phase?
1. longest 2.most variable in length 3. some cells may differentiate and leave cell cycle.
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Which phase is histone proteins produced?
S phase.
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which cells permanently arrest during G1?
Neurone, RBC, muscle cell.
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Which cell can move back to G1?
Liver cells.
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What is Restriction checkpoint? (exam)
G1/s check point. Size,environmental favorable and whether DNA is intact.
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What is function of checkpoin?
1.Determine timimg of each step 2. control cell cycle. 3. rely on CDK.
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what happen in prophase?
1. chromosome start to condense. 2. formation of bipolar spindle fibre. 3. can see sister chromatids.
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what happen in prometaphase?
1. spindle fibre attach to kinetochore 2.nuclear membrane degenerate
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which phase chromosome maximally condensed?
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what happen in telophase?
chromosome decondensation, nuclear membrane reformation.
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In meiosis, which stage daughter cell become haploid?
since meiosis 1.
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How meiosis I cause genetic variation?
There are synapsis, genetic recombination "crossing over".
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what happen between meiosis I and II?
there is interphase without S-phase.
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what is sub-division of prophase I?
1. Leptotene 2.Zygotene 3. Early pachytene 4. Late pachytene 5. Diplotene 6.Diakinesis.
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what happen in Leptotene?
Replicated chromosome condense.
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what happen in Zygotene?
Synapsis forming, synaptonemal complex.
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what happen in pachytene?
Synapsis complete forming bivalent/ tetrad. crossing over ocuur betwenn homologous chro(non-sister chromatids). DNA at this point =ladder structure.
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what happen in Diplotene?
synaptonemal complex disintegrate; chiasmata
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what happen in Diakinesis?
nuclear membrane disintegrate.
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which cells undergo mitosis?
somatic ells and inital stage of germ line cells
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which cell undergo meiosis?
only germ line cells
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Describe spermatogenesis.
see answer outside.
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How many sperm produced from 1 spermatogonium?
4 sperms
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how long does a cycle of spermatogenesis take?
60-65 days and can occur for whole life.
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when oogonium start mitosis?
it start at embryonic and fetal period producing primary oocyte stopping at prophase I.
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Describe oogenesis
answer is outside.
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How many ovum arise from 1 oogonium?
1 ovum + 3 polar body.
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when does vesicular follicle form?
when there is secondary oocyte.
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Other cards in this set

Card 2


What does DNA contain?


Genetic info on genes (base sequence)

Card 3


How much is Human genome?


Preview of the front of card 3

Card 4


What is chromatin?


Preview of the front of card 4

Card 5


what is chromosome?


Preview of the front of card 5
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