Mitosis and Meiosis Flashcards
what are the base pairings in DNA?
A–T (2 bonds) and C–G (3 bonds)
3 types of genetic stages (3 C’s) what are they and what stage is each in?
Chromatin - cells not in replication
Chromosomes - during replication
Chromatids - after replication
what is the Q and P arm?
Q = long arm P = short arm
describe the 3 stages of interphase…
G1 - no visible activity, rapid growth, normal metabolic function, new organelles form, protein synthesis of spindle fibre formation
S - DNA doubles through replication, histone proteins double, centrosome replication, finish with double the chromosomes
G2 - chromosomes condense, energy stores accumulate, mitochondria and centrioles double
describe prophase…
the chromatin condenses into chromosomes.
centrosomes nucleate microtubules (several tubulin moleules interact to form a microtubule seed) and move to opposite sides of the nucleus
describe prometaphase…
the nuclear membrane breaks down
microtubules invade nuclear space
chromasomes attach to microtubules that come from the centrosome
cell nucleus no longer there
describe metaphase…
chromosomes line up along equatorial plane
describe anaphase…
sister chromosomes (same as chromatid) separate pulled to opposite ends as spindle fibres contract
describe telophase…
nuclear membrane forms
chromosomes unfold into chromatin
cytokinesis begins
what are the start and stop codons?
start = ATG stop = TAG
describe meiosis 1…
chromosome number is halved
in prophase 1 - crossing over occurs between non-sister chromosomes
in metaphase 1 - random assortment occurs on the metaphase plane
describe meiosis 2…
sister chromosomes separate, 4 haploid cells produced
Sperm production process…
primordial germ cells –> lots of mitoses –> spermatogonia (cell produced at early production stage)
when do spermatogonia undergo meiotic divisions?
during puberty
how long do the spermatogonia take to mature?
60 - 65 days
Ovum production process…
primordial germ cells –> 30 mitoses –> oogonia (immature egg cell, diploid)
when does an oogonia enter prophase 1?
by the 8th month intrauterine life - the process is then suspended until puberty
well does a ovum enter ovulation?
10 - 50 years later
how does the oogonia divide and when do meiosis 1/2 occur?
the oogonia cytoplasm divides evenly into 1 egg and 3 polar bodies that apoptose
Meiosis 1 - completed at ovulation
Meiosis 2 - completed if fertilisation occurs
what is Gonadal mosaicism?
when precursor germline cells to ova or sperm are a mix of 2 or more genetically different cell lines
give examples of conditions caused by gonadal mosaicism?
osteogenesis imperfecta, brittle bones, blue whites of the eyes, duchenne muscular dystrophy
what is somatic mosaicism?
genetic fault present in only some body tissues
