Reproduction Flashcards
asexual reproduction
genetically identical offspring (no genetic diversity)
sexual reproduction
mixing of genetic material provides genetic diversity
gametogenesis
diploid individual (2n) produces haploid sex cells (n)
fertilization
haploid gametes unite to form a new diploid zygote
budding
new individual arises from an outgrowth of an older one
ex) sponges
fission
one individual separates into 2 or more individuals of about equal size
fragmentation/regeneration
individual breaks into small pieces, each piece can form a new individual
parthenogenesis
development of an individual from an unfertilized egg
diploid - females
haploid - males
some invertebrates alternate ___
between asexual and sexual reproduction
simultaneous hermaphroditism
have both ovaries and testes
sequential hermaphroditism
change sex
protogynous
changes from female to male
protoandrous
changes from male to female
gametogenesis
haploid gametes produced by germ cells in primary sex organs
oogenesis
ovaries produce eggs (ova)
1 egg produced in ovarian cycle
spermatogenesis
testes produce sperm
1 diploid parent produces 4 sperm cells
progesterone
prepares uterus for receiving the embryo
mating
anatomical and behavioral adaptations to bring gametes into close proximity for fertilization
ovum
eggs - have a jelly like outer layer
sperm
have head and tail
contain mitochondria
fertilization mechanism
jelly coat dissolves > sperm head binds to ovum > sperm nucleus enters the ovum > fertilization membrane forms > fusion of two haploid nucleus to form a diploid nucleus
external fertilization
animals broadcast eggs and sperm
more vulnerable - release many
in watery environments
requires less energy
internal fertilization
more protection
oviparous
lay eggs, no support from parents
viviparous
live young, nutrients from parents
ovoviviparous
young develop in an egg inside parent - live birth but little maternal support
cleavage
mitotic cell division into blastomeres - no increase in size or mass
gastrulation
gastrula with primary tissue layers, forms primordial germ cells
organogenesis
major tissue and organ system development
metamorphosis
adult characteristic develop
morula
has animal and vegetal pole
animal pole
forms the embryo
vegetal pole
forms yolk
blastocoel
forms body cavity
meroblastic
incomplete cleavage
holoblastic
complete cleavage
three germ layers
ectoderm, mesoderm, endoderm
archenteron
cells at vegetal pole pushed toward roof of blastocoel, creates folding inside embryo
neurulation
forming of neural tube from neural plate
neural plate formation
thickening of ectoderm over notochord
formation of neural tube
infolding and pinching off of the neural plate
somite formation
notochord becomes segmented into somites > forms repeated structures like ribs
apoptosis
genetically programmed to die when no longer needed
