Chapter 6 pt 2 Flashcards by evan kang

In ________ Females are rock-dwelling marine worms and males live inside the female uterus

echiuroid worm
- bonellia viridis

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in the echiuroid worm, larva that land on the sea floor become _______ while larva that land in the female’s mouth differentiate into _______

1) females
2) males
- example of locational sex determination

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In slipper snails, individuals pile up on each other and the young snails are always _______

male
- older=flexible sex cuz male system degenerates

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In slipper snails, if attached to a female the snail will become _______

male

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In slipper snails, if removed from the pile, or presence of lots of males, the snail will become _______

female
- once female it will not revert to male

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Many _______ species are able to change their sex based on social interactions. These involve the ________ system

fish
neuroendocrine

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in many fish, _______ induces aromatase

cortisol

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In gobies a school typically contains _______ male(s) and _______ female(s)

one
many
- if male is removed, dominant, aggressive female becomes new male in a week

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Newly formed primordial germ cells enter the _______ then migrate forward into the ________

hindgut
bipotential gonad
- traveling niche

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During their migration, PGC’s are surrounded by supporting cells, which secrete _______ which is necessary for PGC motility and survival

stem cell factor (SCF)

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Primordial Germ cells (PGC’s) are ________ becoming either egg or sperm and initially form in the _______ portion of the embryo before migrating

bipotential
posterior

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What are the 5 proteins that repress PGC’s as they travel?

1) VASA
2) Nanos
3) Pumilio
4) Tudor
5) Piwi

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_______ - required for germ cells in all animals. It is a RNA binding protein that activates germ-cell specific mRNA

VASA

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_______ form repressive dimers with _______. Blocks mRNA translation by binding to the 3-UTR

Nanos
Pumilio
- prevents cell from becoming germ layer and prevents cell cycle

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_______ proteins interact with _______ proteins to transcriptionally silence portions of the genome especially active transposons

Tudor
Piwi
- Drosophila females carrying extra Tudor are sterile

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The transcription factor _______ is the gatekeeper of meiosis for PGC’s

Stra8

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In females meiosis of PGC’s begins in the _______ gonads

embryonic

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In females, Stra8 is upregulated by _______ and _______ produced by adjacent kidneys

Wnt4
Retinoic acid

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In Males, meiosis of PGC’s does not begin until after _______

puberty

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In males, Stra8 is down regulated by _______, and retinoic acid produced by kidneys is degraded by _______ enzyme

Fgf9
RA degrading enzyme

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Where is the retinoic acid degrading enzyme produced?

testis

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During puberty, RA is again synthesized by _______ and induces Stra8 expression for sperm stem cells to undergo meiosis

Sertoli cells

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What are the 3 major phases of spermatogenesis?

1) proliferation
2) meiotic phase
3) shaping (spermiogenesis)

_______: Sperm stem cells (spermatogonia) increase by mitosis

phase 1, proliferation

_______: cell go through both meiotic division producing haploid cells

phase 2, meiotic phase

_______: post-miotic shaping. Round spermatids eject most of the cytoplasm and take on the typical streamlined sperm shape

phase 3, shaping - spermiogenesis

PGC's (Gonocytes) arrive at the _______ and become undifferentiated _______

genital ridge - niche near Sertoli cells, Leydig cells, and testicular blood vessels spermatogonia

Spermatogenesis 1: Mitotic proliferation of undifferentiated spermatogonia amplify these cells into population of differentiating _______

Type-A spermatogonia

Spermatogenesis 1: Type-A spermatogonia respond to Stra8 and become _______

Type-B spermatogonia

Spermatogenesis 1: Type-B spermatogonia divide by _______ to produce _______

mitosis primary spermatocytes

Spermatogenesis 2: Primary spermatocytes divide by _______ to produce _______

meiosis (first division) secondary spermatocytes

Spermatogenesis 2: Secondary spermatocytes then complete _______ to produce _______

meiosis (second division) Spermatids (haploid)

Spermatogenesis: Everything is connected by _______ throughout this process, which is eventually lost as sperm differentiates into _______

cytoplasmic bridges spermatozoa

Spermiogenesis: the acrosomal vesicle is constructed by the _______

golgi

Spermiogenesis: A _______ begins to form opposite the acrosomal vesicle

single flagella

Spermiogenesis: Histones are replaced with _______ which completely shuts down transcription and DNA assumes an almost **crystalline** structure

protamines

Spermiogenesis: DNA _______ to **paternal** patterns is established

methylation

Spermiogenesis: Almost all _______ is shed, and forming sperm are exported to the _______ for storage

cytoplasm epididymis - exosomes (contain ncRNA) activate repress genes

Where does final differentiation of sperm occur?

female uterus

_______: PGC's reaching the developing ovary divide rapidly between the 2-7th months of gestation. Produce 7 million oogonia

Proliferation - most die

Surviving oogonia undergo the _______ to become primary oocytes

first meiotic division

Primary oocytes remain in _______ stage of meiosis

diplotene - first stage of prophase 1

_______ from the pituitary gland removes the division block on primary oocytes and meiosis resumes

Leuteneizing hormone (LH)

LH causes oocyte maturation, which synthesizes proteins that make it _______ to fuse with a sperm and divide after fusion

competent

Secondary oocytes remain in _______ stage of meiosis until fertilization

metaphase II

Asymmetric cytokinesis at meiosis I/II generate _______ containing a nucleus but essentially no cytoplasm

polar bodies

A large proportion of oocytes have chromosomal abnormalities, primarily _______

aneuploidy - incorrect number of chromosomes

Maternal age correlates with an _______ risk

increased - @ age 20 = 2-3% - @ age 40+ = 35%

What are two causes of aneuploidy in aging oocytes?

1) degeneration of cohesin 2) instability of linkage between the kinetochore and meiotic spindle

_______ forms rings around sister chromatids at the kinetochore and around the chromatin arms that unite sister chromatids

cohesin

In the first meiotic division, activated _______ in turn activates _______, which seperates unprotected non-sister chromatin

APC/C separase

In meiosis I, _______ is bound and protects the cohesin binding sister chromatids, preventing separase from digesting the cohesin holding them together

Sgo2

As anaphase I ends, _______ is replaced, and sister chromatids can now be separated in meiosis II division

Sgo2

The _______ forms during prophase I of meiosis

synaptonemal complex

The synaptonemal complex is held together by interlocking units of _______

SYCP1

The ___-terminus of SYCP1 binds to DNA

The ___-terminus of SYCP1 binds to other units of itself