Reproduction Flashcards
cell division
process by which a cell doubles its organelles & cytoplasm, replicates its DNA, and then divides in two
unicellular organisms cell division
means of reproduction
multicellular organisms cell division
method of growth, development, and replacement of worn-out cells
types of cell division (2)
mitosis & meiosis
mitosis (2)
- division and distribution of cell’s DNA to its daughter cells such that each cell receives a complete copy of the original genome
- preserves diploid number
nuclear division is followed by ______
cytokinesis
interphase
a period of growth and replication of genetic material
sister chromatids are held together at
centromere region
TRUE/FALSE: individual chromosomes are visible during interphase
FALSE; DNA is uncoiled (chromatin)
parts of interphase
G1, S, G2, M
G1 phase
- initiates interphase; cell increases in size & synthesizes proteins
- length determines the length of the entire cell cycle
S phase
DNA synthesis
G2
cell prepares to divide; growth & synthesis of proteins
M
cell (nuclear) division occurs (prophase; metaphase; anaphase; telophase)
Prophase (3)
- chromosome condense
- centrioles separate & move toward to opposite poles of the cell
- nuclear membrane dissolves
Metaphase (2)
- fibers of the spindle apparatus attach to each chromatid at centromere
- chromosomes align at the center of the cell
Anaphase (2)
- centromeres split allowing chromatids to separate
- spindle fibers shorten
Telophase (3)
- spindle apparatus disappears
- nuclear membrane forms around each set of chromosomes
- chromosomes uncoil
cytokinesis
division of cytoplasm
meiosis (2)
- sex cells are produced
- produces haploid cells (halve # of chromosomes)
asexual vs. sexual reproduction
sexual reproduction involves 2 parents
homologous chromosomes
chromosomes that code for the same traits
crossing over
when homologous chromosomes break at corresponding points and exchange equivalent pieces of DNA
recombination among chromosomes results in ______
increases genetic variation
what phase does crossing over occur in meiosis?
prophase
disjunction
- homologous pairs separate and are pulled to opposite poles of the cell
- random distribution to daughter cells
sexual production requires
- production of functional cells (gametes)
- union of these cells to form a zygote
- development of zygote into an adult
male vs female gonads
male: in the testes (sperm)
female: ovaries (oocytes)
gonads
where gametes are produced
spermatogenesis
sperm production in the seminiferous tubules
(1) 2n -> (4) n cells
oogenesis
production of female gametes in the ovaries
(1) 2n -> 1 egg cell+ polar body
fertilization
union of the egg and sperm to form a zygote
internal fertilization (2)
- provides direct route for sperm to reach the egg cell
- increases the chance of fertilization
the amount of parental care is ______ related to the number of eggs produced
directly; species that care for their young produce fewer eggs
scrotum
- external pouch that holds the testes (testosterone production)
- maintains the testes temp at 2-4 degree Celsius lower than body temp
route of sperm
testes-> vas deferens -> ejaculatory ducts -> uretha
process of spermatogenesis
spermatogonia differientiate into primary spermatocytes (2n) -> secondary spermartocytes 2x(n) -> spermatids 4x(n) -> spermatozoa
acrosome
caplike structure that contains enzymes needed to penetrate the tough outer covering of the ovum
ovaries (2)
- found in the abdominal cavity
- consist of thousands of follicles (multilayered sac of cells)
Once a month an immature ____ is released from the ovary into the _________ _______ and drawn into the nearby oviducts (fallopian tubes). Each fallopian tubes opens up into _____, which is the site of fetal development. The lower end is called the _____
ovum; abdominal cavity; uterus; cervix
TRUE/FALSE: at birth all of the immature primary oocytes that a female will produce are already in her ovaries. which are produced by mitosis.
TRUE
TRUE/FALSE: meiosis II occurs right after meiosis I during oogenesis
FALSE; it doesn’t occur until fertilization. its triggered when the layers of the ovum are penetrated
2 layers of the ovum
zona pellucida & corona radiata
the secretion of both estrogen & progesterone are regulated by
LH (luteinizing hormone) & FSH (follicle stimulating hormone) which in turn are regulated by GnRH (gonadotr
what plays an important role in the female reproductive cycle (3)
- hormonal secretion of the ovaries
- hypothalamus
- anterior pituitary
phases of the menstrual cycle (4)
follicular phase, ovulation, luteal phase, menstruation
follicular phase
FSH from the anterior pituitary promotes the development of the follicle, which grows and secretes estrogen
ovulation (2)
- mid way through the cycle a mature ovarian follicle bursts and releases the ovum
- peak in LH
luteal phase
LH induces the ruptured follicle to develop into the corpus luteum (secretes estrogen & progesterone)
menstruation (fertilized vs not fertilized)
- ovum fertilized: placenta produces hCG maintaining the corpus luteum and supply of hormones until placenta takes over production of hormones
- ovum not fertilized: corpus luteum atrophies; endometrium slough off giving rise to menstrual flow
purpose of the fertilization membrane
surrounds the ovum cell membrane and prevents multiple fertilizations
monozygotic twins
identical twins: single zygote splits into 2 embryos
dizygotic twins
fraternal twins: when 2 ova are released in one ovarian cycle and are fertilized by 2 different sperms
