Lecture A10, A11 Flashcards
fertilization (def.)
sperm meets egg (haploid + haploid = diploid)
sperm is the only human cell type that has ______
a flagellum
sperm evolved specifically for _____
the delivery of DNA
head of sperm contains _______
acrosomal vesicle, haploid nucleus
midpiece of sperm contains _____
a lot mitochondria to propel movement
the flagellum of sperm is _____
the motile part
sperm is produced by _____
spermatogium through meiosis
maturing spermatogonium remains ________ throughout their differentiation
connected by cytoplasmic bridges
in the process of sperm differentiating, this happens?
most of the cytoplasm is discarded as residual bodies
process of sperm production
1) spermatogonium
2) spermatogonia
3) primary spermatocytes
4) secondary spermatocytes
5) spermatids
6) differentiating spermatids
7) mature spermatozoa
unipotent sperm cells
spermatogonium
primary spermatocytes becomes secondary spermatocytes through ______
first meiotic division
secondary spermatocytes becomes spermatids through ______
secondary meiotic division
spermatogonium becomes spermatogonia becomes through ______
mitosis
niche of oocyte is _____
the ovary
cells that creates oocyte niche
granulosa cells
granulosa cells produces ____ which do what?
-steroids (ex. estradiol) and growth factors
-that interact with oocyte during its development
following ovulation, the granulosa cells do what?
changes into luteal cells that produce progesterone
steps of oocyte production
1)primordial follicles
2)primary follicle
3)secondary/antral follicle
4)mature/graafian follicle
5)corpus luteum
6)corpus albicans
primordial follicles comes from _____
oocyte stem cells
corpus luteum & corpus albicans are from _______
granulosa cells
zona pellucida (def.)
specialized extracellular matrix that surrounds the PM of oocyte
corpus luteum & albicans function
hormone signalling that encourage fertilization
generally, how many oocyte finishes differentiation each month from puberty until menopause?
one oocyte
stage of oocyte in primary follicle
-primary oocyte
stage of oocyte in secondary follicle
-primary oocyte
stage of oocyte in mature follicle
-secondary oocyte
how many polar bodies produced in oogenesis?
2 polar bodies
egg and sperm are both derived from _____
primordial germ cells (PGCs)/ stem cells
PGCs are not ______
part of 3 germ layers
lineage of oocyte from PGCs
-PGCs migrate
-oogonia proliferate and germ cell nest form
-nest breakdown
-primordial follicle formation
at week 3, human PGCs are ______
specified early during development
early PGCs in ______ move forming the _______ with ______
-yolk sac
-genital ridge
-migratory/gonadal PGCs
Imprinting (def.)
epigenetic information that controls which allele is expressed (paternal vs maternal)
imprinting is ______ in somatic cell during embryonic development
maintained
imprinting is ______ in PGCs during germ cell development
removed
imprinting is ______ in gametes during gametogenesis
re-established
imprinting is ______ in iPS cell during induced pluripotent stem cell development
maintained
majority of genes are not _______
imprinted
mendelian rules are not followed if ____
genes are imprinted
example of imprinting
DNA methylation
NANOG encodes a ________ that _____ by ______
-homeobox transcription factor
-helps embryonic stem cells (ESCs) maintain pluripotency
-suppressing cell determination factors
signalling that PGC specification
WNT/BMP
genes that program germ line cells (part of PGC circuitry)
PRDM1
PRDM14
TFAP2C
genes that program pluripotency genes (marks stem cells)
OCT4
NANOG
________ (also known as Blimp1) does what ?
-PR domain zinc finger protein 1 (Prdm1)
- is a repressing TF of somatic genes
Loss of Prdm1 blocks _____ in mice
-primordial germ cell formation
PRDM14 does what?
suppresses somatic genes and activates germ cell genes
AP2γ is what?
a HLH protein, encoded by the Tcfap2c gene - Transcription factor ap2 c (c = γ)
AP2y does what?
locks in transcription state
Parthenogenesis (def.)
A form of reproduction where the egg develops into an embryo without being fertilized by a sperm. Derived from the Greek words for “virgin birth”
Embryoid bodies are _____ that can ______
-3D aggregates of pluripotent stem cells
-differentiate into cells of all three germ layers
There appears to be significant functional differences between_______ with males having _____ and females having ______
-human adult germinal stem cells in each sex
-constantly regenerating stem cell population (spermatogonia)
-a limited number of partially differentiated oocytes (follicles)
methods for studying human cell diversity
-flat (2D) cell culture
-lab animals
-organoids (3D)
types of lab animals
-simple (flies)
-complex (mouse)
easiest human cell to culture in lab
fibroblasts
passage number of cell culture (def.)
the number of times it has been subcultured (creating multiple daughter cell culture flask)
immortalization (def.)
cells from multicellular organisms which won’t normally not proliferate indefinitely but due to mutations, they have lost senescence and keep undergoing division
primary cells (general def.)
normal cells directly from humans or animals
immortalized cell lines (general def.)
cancer (transformed) cells derived from humans or animals
immortalized cell lines are comprised of _____
a single cell type (homogenous) that can divide indefinitely
immortalized cell lines are usually ____ and maintain _____
-diploid
-some degree of differentiation
transformed cell lines have almost ____ but the disadvantage is that _____
-availability
-it retains less of the in vivo characteristics
primary cell lines are derived from ______
excised tissue
primary cultures are initially _____ by eventually become dominated by ______
-heterozygous
-fibroblasts
primary culture lifespan
limited
primary cells usually retain _____
many differentiated characteristics that the cells had in vivo
stem cells are more difficult to _____
culture
stem cells have the unique ability to ______
self-renew or to differentiate into various cell types in response to appropriate signals
working with human cell cultures requires ______
aseptic environment
primary cells will require growth on _____ to promote ______
-special matrixes such as collagen
-cell attachment, differentiation or cell growth
passaging cells
-cells should be split more than 1:10 so seeding density will not be too low
increasing passage number = ____
genetic drift and other variations
anything inside biosafety cabinet must be _____
sanitized
inorganic salts in culture medium do what?
maintain osmotic balance of cells and regulate membrane potential
buffering systems in culture medium do what?
-main pH conditions in 7.2 - 7.4 (indicated by phenol red colour)
carbohydrates in culture medium do what?
main source of energy generally in form of sugars
vitamins in culture medium?
-riboflavin, thiamine and biotin
trace elements in culture medium?
-zinc, copper and selenium
FBS stands for ____
Fetal bovine serum
FBS is used for ____
in-vitro cell culture of eukaryotic cells
FBS is complex mix of ____
albumins, growth factors and growth inhibitors
Normal cells stop proliferating once _____ but cancer cells do what?
-they have proliferated into a single layer
-often disregard these restraints and continue to pile on each other
proliferation depends on contact with dish and is inhibited by _____
contacts with other cells
confluency (def.)
the percentage of the surface of a culture dish covered by cells
confluency is important because _____
cells change their behaviour with changing densities
low-density cells usually grow _____
slower than 50% confluent cells
If plate is completely confluent, cells ___
tend to grow slower
changes of growth rate will influence _____
their genetic programming and behaviour in experiments
steps to establish primary cell culture
1) tissue acquisition
2) dissection (remove dead + fatty tissue)
3) disaggregation (break ECM)
4) incubation & growth
5) separation & purification by selective media, immunomagnetic beads
Hayflick limit (def.)
represents the number of times a normal human cell pop’n will divide before cell division stops (senescence)
telomere length is considered ____
the molecular timer for the number of times a human cell can divide
hayflick limit of stem cells vs. cancer cells
-stem cells: 50-70
-cancer cells: avoid telomere shortening
telomere length is a key contributor to _____
the deleterious effects of aging process in humans
ways to overcome Hayflick limit
-tumor derived cells (inefficient)
-viral gene simian virus 40 T-antigen infected cells (ex. Hek293T)
-human Telomerase reverse transcriptase (hTERT) protein: makes telomeres longer
advantages of hTERT immortalization
-normal cell cycle controls
-contact inhibited
-interact with substrates
-retain normal growth responses to serum & mitogens
-normal karyotype
source of human embryonic stem cells (hESCs)
-fertilized human embryos
use of hESCs are dropped in recent years with _____
increased availability of iPSCs
3D cell culture niche
ECM, cell-cell contact, O2 and nutrients
3D cell culture is often performed in ____
suspension rather than in plastic dishes
3D cell organization happens using ____
molecular scaffolds (natural biomaterials or synthetic polymers)
organoids can be made from _____
adult SC, or PSC
organoids (def.)
small organ-like structures from human cells
KSR
-knockout serum replacements
matrigel (def.)
a 3D scaffold
activin A (def.)
part of the TGFB protein family but acts to promote proliferation instead of inhibits
minimal media (def.)
salts, nutrients only no serum
the diffusion limit (def.)
organoids do not have a vasculature so cells in the center become starved for O2 and nutrients
guided differentiation
provision of signalling molecules at correct time and place to mirror what happens during normal development
organizers (def.)
local sources of morphogens
