Loren bio 2
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Loren bio 2
Loren bio 2 "reproduction"
the division and distribution of the cell's DNA to its two daughter cells
each cell gets a complete copy of the original genome
What is Karyokinesis?
the division of the nucleus
What is cytokinesis?
the division of the cell
90% of cells life is interphase
Chromosomes are duplicated
chromosomes are loose (chromatin)
What's the centromere?
the "waist" spot where the chromatids are held together.
the chromosomes condense
the centriole separate and move to opposite ends
the spindle forms
spindle attaches to a chromatid
they align at the metaphase plate
The chromatid sister's separate to opposite ends
nuclear membrane forms around each chromosomes
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Do plants have centrioles?
No, they form a cell plate
the process by which sex cells are produced
it halves the number of chromosomes
the gametes are produced in the gonads
Female gonads are called....
contain functional male and female gonads (hydra and earthworm)
the sperm production
occurs in the seminiferous tubules
the production of female gametes (eggs)
occurs in the ovaries
the union of the egg and sperm nuclei to form a zygote (diploid number of chromosomes)
The pathway of Sperm....
The testes produce what two things?
1. testosterone (for secondary male characteristics)
What cell produces estrogen?
What two things do follicle cells do?
1. produce estrogen
2. contains, nourishes the ovum (egg cell)
Where does the fetus develop?
in the uterus
All the eggs that a female will ovulate during her lifetime are already present in the ovaries
What regulates secretion of estrogens and progesterone?
LH and FSH
What do estrogens do?
they are the steroid necessary for normal female maturation. female sexual characteristics
thicken the endometrium (uterine wall)
What does progesterone do?
progesterone stimulates the development and maintenance of the endometrial wall in preparation for the fetus
Four phases of the menstrual cycle
1. follicular phase
3. Luteal phase
FSH (follicle stimulating hormone) promotes development of the follicle. It grows and begins secreting estrogen
midway through the cycle
mature ovarian follicles burst and release ovum
caused by a surge in LH
LH (luteinizing hormone) induces the ruptured follicle to develop into the corpus luteum (it secretes estrogen and progesterone)
if ovum isn't fertilized the corpus luteum dies (the drop in estrogen/progesterone causes the endometrium (membrane with lots of blood) to slough off
no fertilization takes place.
genetic carbon copies
used in prokaryotes
the cell just divides down the center.
the replication of the nucleus followed by unequal cytokinesis
yeast and hydra
like starfish growing an arm, or a salamander growing a tail
needs the central disk in the limb
occurs by mitosis
the development of an unfertilized egg innto an adult
male bees develop this way. not fertilized
Sexual reproduction in plants
alternate between diploid sporophyte to haploid gametophyte
evolution trends toward dominance of the sporophyte generation
haploid gametophyte produces gamets (1n) by mitosis.
they join and fertilize together (sexual reproduction)
Sporophyte generation (2n)
meiosis goes to 1n, and then to gametophyte (1n)