lecture 4 germline 1 Flashcards by jillian Bastidas

down syndrome is

trisomy 21

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XXY

klinefelter syndrome

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turner syndrome

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these cells pass genetic information from one generation to the next

germ cells

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__ is made from RNA binding proteins involved in translational control

Germ plasm

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name two types of RNA binding proteins used by germ plasm

VASA, Tudor

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in frogs, germ plasm is found in

the vegetal pole cytoplasm

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in flies, germ plasm is characterized by

polar granules in fertilized eggs

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in mammals, ___ are released by extra-embryonic tissue into the border of the epiblast and stimulate the change of cells into PCG precursor cells

BMP

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BMP stands for

bone morphogenetic protein

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common BMP factors in mice

BMP-4 and BMP-86

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if germ plasm in frogs is irradiated, what happens to germ cells?

germ cells will not be produced

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what are the three steps of PGC specification

repression of somatic programs
re-aquisition of potential pluripotency
genome-wide epigenetic reprogramming

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what are expressed by PGCs

Prdm

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what does Prdm stand for

PR-domain containing transcription factors

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What helps with the last two steps of PGC specifications

re-aquisition of potential pluripotency
genome-wide epigenetic reprogramming

Prdm 14

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What TF helps with all three steps of PGC specifications

Prdm 1

repression of somatic programs
re-aquisition of potential pluripotency
genome-wide epigenetic reprogramming

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what are some non functional markers expressed by PGCs

TNAP- tissue non-specific alkaline phosphate
Fragilis
Stella

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what is the migration of PGCs

border of epiblast
extra-embryonic mesoderm
base of allantois
move around hindgut through dorsal mesentery
genital ridges

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once PGCs express ___ and ___ their fate is ___

Prdm1 and Prdm14

determined- can’t change into other cells

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PGCs proliferate from ___ cells to ___ cells. This happens around day ___ in mice

45
20,000
E 11.5

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Migration of PGCs are helped by ___ such as ___ produced by ___

chemokine factor
Sdf1
surrounding tissues

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Sdf1 is

stromal cell-derived factor 1

___ is a ____ receptor on ___ that attaches to Sdf1

Cxcr4
chemokine
PGC

___ is a receptor for steel factor and is expressed by ____

c-Kit | PGCs

___ is a cell surface molecule on PGCs

beta1 integrin

Steel + W is __ and leads to ___ by interfering with ___

dominant white spotting sterility, anemia and white coat PCG survival, proliferation and migration

Steel factor (SI) is the product of the ___ locus and the ligand for ____

steel | c-Kit

___ is a tyrosine kinase receptor and is a product of the ___ locus

c-kit | W

gonad differentiation occurs at day ___ in mice

E12.5

___ is the sex determining gene from Y. Produced day ___

Sry expression | E10.5-11.5

before day ___ germ cells are bipotential meaning ____

12.5 | they can become male or female

___ is the enzyme that degrades retinoic acid

CYP26B1

In testes. CYP26B1 is ___ then there is ___ RA and Stra8 is ___ which will ___ meiosis.

on decreased off stop

In ovaries. CYP26B1 is ___ then there is ___ RA and Stra8 is ___ which will ___ meiosis.

off increased on start meiosis

if stra8 is on then ___

meiosis starts

__ are mother cells that help spem production

sertoli cells

what are the 4 stages of prophase

leptotene zygotene pachytene diplotene

meiosis steps

``` PMAT 1 and PMAT 2 P- homologous pairs (male and female) match up and cross over happens M- homologous pairs line up A- homologous pairs are pulled apart T- two cells are formed by cytokinesis ``` P- chromosomes condense M- sister chromatids line up in center A- sister chromatids are divided T- 4 haploid (1N, 1 C) unique cells

reciprocal exchange of genetic material between homologous pairs

meiotic recombination

two ways meiosis 1 is different from mitosis

recombination of homologous pairs | segregation of homologous pairs

what happens in leptotene phase and what step is it

chromosomes begin to condense and become visible as long threadlike structures step 1 of prophase 1

what happens in zygotene phase and what step is it

partial synapsis SYCP1 only located on synapsed regions but not on unsynapsed regions step 2 of prophase 1

what happens in pachytene phase and what step is it

cross over between homologous chromosomes, complete synapsis step 3 of prophase 1

what happens in diplotene phase and what step is it

synapsis starts to break away but held together by chiasmata step 4 of prophase 1

site of recombination

chiasmata

what stage is the first meiosis stop in females and when does it stop

Diplotene phase (step 4 of prophase 1) stops before fetus is born

when does meiosis restart for females

before ovulation at puberty increase levels of FSH (follicle stimulating hormone) triggers the completion of meiosis 1 creating a polar body and secondary oocyte (daughter cell). Meiosis 2 is stopped at Metaphase 2

when does the 2nd meiosis restart for females

at fertilization. when sperm enters egg, meiosis 2 restarts and creates polar body and daughter cell.

what phase is a dog oocyte in when ovulated and how is it different then humans

dog oocyte at prophase I when ovulated, humans oocyte ovulated at Metaphase II

what are some differences between oogenesis and spermatogenesis

oogenesis - limited number - meiosis stops twice - only 1 gamete(oocyte produced) - differentiation of gamete occurs before completion of meiosis Spermatogenesis - unlimited number due to spermatogonial stem cells - meiosis starts at puberty and is continuous - 4 sperm produced - differentiation while haploid

___ are cells that produce testosterone

interstitial Leydig cells

___ is where spermatogenesis occurs

seminiferous tubules

briefly explain spermatogenesis

``` PGC + Sry expression CYB26B1 on spermatogonia- mitotic division primary spermatocyte- meiosis I 2- secondary spermatocyte- meiosis II 4- spermatid- (haploid) residual body leaves 4- spermatozoa ```

briefly explain oogenesis

PGC CYB26B1 off OOGONIA- enters meiosis I stops at diplotene prophase- follicle cells become granulosa cells PRIMARY OOCYTE- granulosa cells fatten PRIMARY FOLLICLE- Puberty hits, FSH stimulates many layers of granulosa SECONDARY FOLLICLE- antrum , ZP and cumulus oophorus form TERTIARY FOLLICLE- cell restarts Meiosis I creating daughter and polar body- stops at Metaphase II- cell is ovulated *breaks out of follicle- still within ZP SECONDARY OOCYTE- stays in Metaphase II until fertilization- completes Meiosis II creates oocyte and polar body. That oocyte then ready to combine with sperm and do mitosis.

mules have an odd number of chromosome which means ___ can't happen. this is called ___.

meiosis | hybrid sterility