Developmental Biology Flashcards
Separation of an organism into two new cells (amoeba) [asexual reproduction]
Fission
Occurs when a new individual grows from an existing one and then splits off (hydra) [asexual reproduction]
Budding
When a single parent breaks into parts that regenerate into new individuals (sponge/planaria/starfish) [asexual reproduction]
Fragmentation / Regeneration
Egg develops without fertilization, resulting in an adult that is either haploid or diploid (honeybees, wasps, ants, lizards, hammerhead sharks) [asexual reproduction]
parthenogenesis
Results in the secondary sex characteristics in men, but also closes the epiphyses of long bones
Testosterone
Sperm is stored here
epididymis
Describe oogenesis
Oogenesis
- begins before birth
- oogonia under mitosis –> primary oocytes being meiosis but remain in prophase I until puberty –> one primary oocyte is selected and stimulated by FSH to continue meiosis I during ~28 day menstrual cycle –> follicle develops around oocyte for protection and nourishment –> completes meiosis I and becomes secondary oocyte and polar body –> secondary oocyte remains arrested in metaphase II until ovulation, polar body disintegrates
oogonia –> mitosis –> primary oocyte –> arrest in prophase I –> puberty –> meiosis I –> secondary oocyte and polar body –> arrest in metaphase II –> ovulation –> fertilization or non-fertilization
Ovulation
- secondary oocyte released from follicle via LH surge
- if fertilized, completes meiosis II and polar body disintegrates
How does female and male contraception work?
FEMALE
estradiol and/or progesterone are spiked high –> negative feedback –> suppress LH/FSH surge –> no ovulation –> fertilization impossible
MALE
interfere with LH and FSH to decrease sperm production
complete cleavage
holoblastic
What are the parts of the female reproductive system?
Ovary (2 ) - eggs produced here
Oviduct/ Fallopian Tube/ Uterine Tube (2) - fertilization occurs here, not a direct connection to ovary; fimbrae sweep egg into oviduct
Uterus - embryo development occurs here
Vagina - fetus passes through the cervix
What are the parts of the male reproductive system?
Testis
- seminiferous tubules: sperm production
- Leydig cells: testosterone, androgens
- Sertoli cells: stimulated by FSH to surround and nurture sperm
- scrotum: location of testis
Epididymis: Final maturation and storage of sperm
Vas deferens: transfers sperm epididymis –> urethra
Seminal Vesicles: two glands that secrete during ejaculation
- mucus (liquid) for sperm
- fructose (energy) for sperm
- prostaglandins (stimulate uterine contractions to move sperm in)
Prostate gland: neutralizes urethra with milky alkaline fluid, will also neutralize vagina acidity
Bulbourethral (Cowper’s) Gland: secrete small amount of mucus of unknown function into urethra
Penis: transports semen into vagina
Sperm: male DNA
- Sperm head: contains acrosome at tip with hyaluronidase enzyme to penetrate the egg
- Mid piece: flagellum (9+2 arrangement) with lots of mitochondria
- Tail: remainder of flagellum, sperm propelled like a whip-like motion
Sperm is produced here
testes (seminiferous tubules)
a genome with extra or missing chromosomes, often caused by nondisjunction
aneuploidy
What is the path of sperm?
SEVEN UP
Seminiferous Tubules
Epididymis
Vas Deferens
Ejaculatory Duct
(nothing)
Urethra
Penis
Chromosome segments are repeated on the same chromosome, which can occur from unequal crossing over
duplication
Describe the follicle in female oogenesis
- FSH stimulates growth of granulosa cells around primary oocyte which form the zona pellucida (jelly like structure around egg)
- Theca cells differentiate from interstitial tissue and grow around primary follicle to form secondary follicle
- Upon stimulation from LH, theca cells secrete androgen –> estradiol which inhibits LH secretion just before ovulation
Describe spermatogenesis
- Spermatogonium
spermatogonium –> mitosis –> primary spermatocytes –> meiosis I –> two secondary spermatocytes –> meiosis II –> four spermatids - Sertoli cells - found in seminiferous tubules and nourish sperm
- Semen - spermatozoa + fluids
- Capacitation
- final stage where sperm mature and prepare for egg penetration
Is spermatogenesis continuous? Is oogenesis continuous?
Spermatogenesis - yes
Oogensis - no
Explain the female reproductive cycle (ovarian cycle and menstrual cycle)
MENSTRUAL CYCLE
1. Hypothalamus and anterior pituitary initiate
low estrogen + progesterone –> hypothalamus –> GnRH –> anterior pituitary –> FSH, LH
- Follicle develops
FSH –> follicle –> estrogen –> hypothalamus –> GnRH –> anterior pituitary –> FSH, LH –> LH surge - LH surge
LH surge –> ovulation –> follicle –> corpus luteum –> decrease in LH and estrogen decrease –> estrogen and progesterone –> development of endometrium
“No fertilization”
4. Development of endometrium
thickens in preparation for implantation –> no implantation –> negative feedback on anterior pituitary –> estrogen and progesterone terminate production of FSH and LH due to low GnRH
- Corpus luteum disintegrates because LH is low and becomes shed during menstruation
“Fertilization”
4. Development of endometrium
thickens in preparation for implantation –> implantation –> estrogen and progesterone remain high –> HCG replaces progesterone
OVARIAN CYCLE
1. Follicular phase
- development of egg and secretion of estrogen from follicle
2. Ovulation
- mid-cycle release of egg
3. Luteal phase
- secretion of estrogen and progesterone from corpus luteum after ovulation
The follicle that releases the secondary oocyte is called
Graafian follicle
Serves to thicken the endometrium
estrogen
serves to develop and maintain the endometrial wall and inhibit lactation during pregnancy
progesterone
Explain the male reproductive system
GnRH –> FSH, LH –> testosterone, androgen from testes –> FSH and testosterone –> sertoli cells for sperm development –> LH –> Leydig cells –> testosterone, androgen –> spermatogenesis
A fetus can be tested for genetic disorders via
amniocentesis or chorionic villus sampling (CVS)
What occurs during the fast block of polyspermy?
oocyte membrane depolarizes, preventing other sperm from fusing with it
What occurs during the slow block of polyspermy?
depolarization from fast block causes intracellular Ca2+ to be released causing small cortical granules to release their contents making the zona pellucida impermeable (cortical rxn)
Locate the corona radiate and the zona pellucida
partial cleavage
meroblastic
Describe DNA
A, T, C, G
- double stranded
- deoxyribose
What is the order of cell division after fertilization?
Zygote –> cleavage –> morula –> blastula –> gastrula
Cells that are capable of developing into most, but not all, of the body’s cell types
pluripotent
Stem cells with the potential to differentiate into any type of cell
totipotent
What are the three layers of the gastrula?
Ectoderm “attract-o-derm” (things we’re attracted to)- integumentary system (hair, skin, nails, nose, mouth), eye, nervous system
Mesoderm “means” o derm (moving around)- bones, muscle, circulatory system, gonads, kidney
Endoderm linens of “endermal (internal)” organs-linings of digestive and respiratory tracts, liver, lungs, pancreas, thyroid
the center cavity formed by gastrulation that is completely surrounded by endoderm cells and gives rise to the gut
archenteron
opening into the archenteron, becomes the mouth in protostomes or the anus i deuterostomes
blastopore
OUTER MEMBRANE
Birds and reptiles - gas exchange
Mammals - forms the placenta
chorion
Birds and reptiles - stores wastes and allows gas exchange
Mammals - transport wastes and forms umbilical cord
Allantois
amphibians don’t have this
amniotic cavity that cushions developing embryo
Amnion
Birds and reptiles: nutrient transfer
Mammals: aiding formation of RBCs (no yolk for nutrient transfer)
Yolk sac
Cells along the dorsal surface of mesoderm layer form the _____ a stiff cartilaginous rod that provides support in lower chordates
notochord
directly above the notochord in the ectoderm layer, this layer of cells forms a plate and then a groove which forms
neural tube
notochord becomes
nucleus pulposus of intervertebral disc in adults
neural tube becomes
brain and spinal cord
cell with limited potential to develop into many types of differentiated cells
multipotent
Can only become one type of cell
unipotent
control development by turning on/off genes that code for substances that directly affect development of the body
hox (homeotic) genes
An experiment in fruit flies found that mutant ____ genes resulted in wrong body parts in wrong places
hox, homeotic
programmed cell death
apoptosis
What are the three stages of labour?
dilation, expulsion (birth), placental
twins that originate from the fertilization of two eggs at approximately the same time (two zygotes)
fraternal (dizygotic) twins
develop from a single fertilized egg that splits in two, creating two genetically identical organisms
identical (monozygotic) twins
exernal fertilization
ovuliparity
giving birth to live young
viviparity
egg laying
oviparity
eggs are internal and birthed as live young, but the egg is not nourished in any way by the parent
ovoviviparous
What are the three trimesters of pregnancy?
1-3 months: critical development of organs
4-6 months: fetus very active
7-9 months: final growth
Protostomes will undergo what type of cleavage?
determinant, spiral
Deuterostomes (like humans) will undergo what type of cleavage?
indeterminant, radial
