Mitosis & Meiosis Flashcards
where cells multiply by dividing
mitosis
asexual reproduction
1 cell (2n) –> 2
2 (2n)
to = two cells
meiosis
sexual reproduction
2n –> 4 cells (n)
sperm, eggs
four vowels = 4 cells
2 rounds of cell division
diploid
2n = 46
n = 23
human
haploid
1
human life cycle
man & woman
- man - meiosis , woman - meiosis
- fertilization - zygote
- zygote - mitosis
- baby (2n) - mitosis
cell cycle
Interphase (90%):
G1, S-phase, G2
M phase(10%): mitosis
G1
first part of interphase
organelles begin to double in number
S phase
2nd part of interphase
replication of DNA
G2
3rd part of interphase
synthesis of proteins, prep for cell division
interphase
centrosomes, chromatin, nuclear envelope, plasma membrane
prophase
DNA condenses like yarn, nucleus disappears
metaphase
‘middle phase’
metaphase plate forms
chromosomes are aligned
at the equator of the spindle
anaphase
separate sister chromatids, they go to the opposite sides of the cell
telophase
opposite of prophase
nuclei form and spindle disappears
cytokinesis
cell moves apart, cleavage furrow, creating two daughter cells
cancer
uncontrolled cell growth
90% of cancers are caused by epithelial cells
- avoids checkpoints in cell cycle
contact dependent
cells will continue to grow until an area is covered, then stop - cancer cells do not have contact dependency
tumor
cancer cells pile up on top of each other creating
(benign is fine)
anchorage dependent
cells will stay attached / grounded to surroundings
cancer - loss of anchorage dependency
metastasis/ metastatic cancer
movement of unanchoraged tumors
apotosis
cell suicide - won’t happen in cancer/ bad cases of cancer
G0 cells
cells that will not regenerate when killed
nerve cells, cardiac, skeletal
stage 1 cancer
loss of contact dependency
benign tumor at this point
take a sample to see if its self contained
stage 2 cancer
cells spread and invade neighboring tissue
typically rough edged
stage 3 cancer
loss of anchorage dependency, can now migrate, has it metatisized?
check lymphatic vessels
stage 4 cancer
small percentage of cancer cells may survive and establish a new tumor in another part of the body
- based on other people who have had this, estimate for how long you will live
chemotheraphy + radiation
kill rapidly dividing cells
nausea
hair loss
2n 46 chromosomes
n 23 pairs
meiosis
two rounds of cell division
1 cell diploid (2n)
–> meiosis –> 4 cells haploid (n) –> sperm + eggs
interphase before meiosis
pair of homologous chromosomes in diploid parent cell (g1) chromosomes duplicate (s phase) duplicated pair of homologous chromosomes (g2)
centromere
holds the two sister chromatids together (forms a chromosome)
meiosis I
homologous chromosomes separate (now they are haploid)
meiosis II
sister chromatids are split (now there are four singular chromatids)
prophase I
homologous pairs come together exchange segments (crossing over - chiasima)
metaphase I
pairs of homologous chromosomes line up
anaphase I
separate the pairs of homologous chromosomes
telophase/cytokinesis I
cells divide (two haploid cells form - chromosomes are still doubled)
prophase II
pairs together
tetrad (two pairs of sisters)
metaphase II
align
anaphase II
separate
telophase / cytokinesis II
creation of four new cells, haploid daughter cells, containing single chromosomes
human gametogenesis
making sex cells
spermatogenesis
making sperm
1 –> 2 –> 4 (spermatids)
spermiation - remodel the spermatid to make sperm
oogenesis
making an egg
excess DNA (polar body)
fertilization
zygote (finish meiosis II)
- fertilized egg (diploid)
mutations of chromosomes
nondisjunction - chromosomes do not split up correctly
23 homologous pairs
1 - 22 autosomes
23rd pair - sex chromosomes
down’s syndrome
2n +1 (trisomy)
cridochat
2n - 1 (monosomy)
Y chromosome
sex determining region of the chromosome
SRY gene
make a male gene
X0
Turner’s syndrome
- no secondary sex characteristics
- infertile
- 1 gonad, not specified, no internal reproductive system
XXY
Klinelfelter’s syndrome
- poor secondary sex characteristics
infertile
