REPRODUCTION (LECTURE 10) Flashcards
What is the definition of sex?
the sum of all structural, functional and behavioral characteristics distinguishing males, females and hermphrodites
What is the definition of gender?
culturally defined term that describes the socially constructed roles of each sex
What is the definition of male?
the sperm-producing form of a bisexual organism
what is the definition of female?
the egg-producing form of a bisexual organism
What is genetic sex determination?
In mammals, sex determined genetically by combination of X/Y chromosomes
XX are female and XY are male
- Y chromosome causes development of male characteristics
- XY system also found in some insects and plants
- BUT a double copy of the sex determining
chromosome does not always lead to a “female” - Birds have Z/W chromosomes: ZZ are male and
ZW are female - W chromosome causes development of female
characteristics - ZW system also found in some fish, crustaceans,
insects like butterflies and moths, and reptiles
What is environmental sex determination?
- sex produced by temperature varies in species
- turtle (cool temps) or warm temps (produce males)
E.g. For some crocodiles and some turtles,
moderate temperatures produce males and
warm/cool temperatures produce females
What is the 3 types of gametes?
- anisogamy
- oogamy
- isogamy
What is the difference between anisogamy, oogamy and isogamy
ANISOGAMY: when there are differences in gamete size or form between sexes of a species
ISOGAMY: when the gametes that fuse together are the same size
OOGAMY: a type of anisogamy with a large non- motile female gamete and a small motile male gamete
What happens in sexual reproduction?
genetic material breaks up and recombines during meiosis. Half of genetic material comes from one parent, and half from the other. Humans have a double copy of each gene, one from our mother and one from our father
What happens in fertilization?
fusion of a sperm and an egg. Fundamental part of sexual reproduction. Can occur inside or outside the body of the female
What happens in external fertilization?
Usually occurs in aquatic environments where both eggs and sperm are released into the water. Happens after sperm reaches egg and mostly occurs during spawning
what is the definition of spawning?
one/several females release eggs and male(s) release sperm in same area at the same time
what happens in external fertilization?
-Spawning triggered by environmental signals like water temperature or the length of daylight
- occurs in both vertebrates and invertebrates
- happens in nearly all fish
what is internal fertilization?
- occurs most often in terrestrial animals but also some aquatic animals
- can occur by male directly depositing sperm in the female during mating
- can occur by male depositing sperm in the environment, in a protective structure
- female picks up sperm and deposits in her reproductive tract
what are 3 ways of internal fertilization?
- oviparity
-ovoviparity
-viviparity
What is the definition of oviparity?
- fertilized eggs are laid outside of female’s body
- eggs receive nourishment from they yolk that is part of the egg
Example is birds
What is the definition of ovoviparity?
- fertilized eggs are kept inside the female until they hatch inside of her, or she lays eggs right before they hatch
- embryo obtains its nourishment from the egg’s yolks
EXAMPLE: Lizards, bony fish, sharks
What is the definition of viviparity?
- young are born alive
- obtain their nourishment from the female and are born in varying states of maturity
Examples: most mammals, some cartilaginous fish
What is the definition of asexual reproduction?
reproduction that does involve the fusion of gametes
What happens in asexual reproduction?
all offspring are genetically identical to parent and to one another. Occurs in prokaryotes (bacteria and archaea). Occurs in many eukaryotic (single/ multicelled organism)
what are the four types of asexual reproduction?
- fission
- budding
- fragmentation
- parthenogenesis
What is the definition of fission?
organism splits itself into 2 parts and regenerates the missing parts of each. Different from binary fission in bacteria. Occurs in some vertebrates, multi celled organisms.
Examples
- E.g. Planarian flatworms separate their bodies
into head/tail regions and then regenerate - E.g. Sea anemones (Cnidaria) divide in 2
halves and regenerate - E.g. sea cucumbers (Echinoderms) divide in 2
halves and regenerate
What is the definition of budding?
- outgrowth of a part of the body leads to a separation of the “bud” from the original organism and the formation of two individuals. One smaller individual is smaller than the other. Occurs in some invertebrates
Examples:* E.g. Hydras: bud forms on the tubular body of an
adult hydra, grows mouth and tentacles, then
detaches from parent
* New hydra finds its own location for attachment
* E.g. coral: bud forms that develops into an adult,
then breaks away from main body
what is the definition of fragmentation?
an individual breaks into parts, which then regenerate. If parts are big enough, new individuals will regrow from each part. Can occur through accidental damage, damage from predators or acts an a natural form of reproduction.
Examples are:
* E.g. sponges, some cnidarians, turbellarians,
echinoderms, and annelids
* E.g. sea stars: a new individual can be
regenerated from a broken arm and pieces of
central disc
