Terms
zygote |
cell that develops into offspring |
embryo |
unprotected or unhatched off spring |
genetic diversity |
inherited genetic differences in a species |
sustainability |
ability of environment to keep supporting its organisms into future |
reproduction |
ensures life exists beyond its present gen. and species exist in future |
DNA
Chromatin |
Condensed form of DNA |
Nitrogen bases |
"steps of DNA"; a with t, c with g |
Chromosomes |
condensed chromatin for reproduction |
Homolog pairs |
chromes that are the same shape, size, have same genetic info in same spot; one from ea. parent |
DNA replication
During late interphase, Dna unwinds with enzyme and bases are paired with new bases. |
Asexual Reproduction
binary fission |
mitosis in prokaryotes |
budding |
buds in multicelluar can detach through repeated mitosis and form separate org. |
frag. |
part of multicelluar breaks off due to injury and becomes separate org. |
vegetative. |
stems, leaves, or roots are used to asex. repro. |
spore |
spores grow into new org. |
Cancer (from mutations in cell cycle)
Cancer cells have large nuclei, no use, they attract blood vessels and become tumours, and can metastasize |
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MITOSIS
prophase |
nuclear membrane disappears, fibres attach to centromeres |
metaphase |
chromes align on equator |
anaphase |
fibers pull sister chromatids to poles |
telophase |
fibres disappear and membrane reforms around each set |
(cytokinesis) |
cell contents are divided into 2 cells |
cleavage furrow or cell plate |
Embryo Develop (first 8 wks)
morula |
end of week one |
ball of cells |
blastula |
end of week two |
hollow ball of cells, cell can develop to any kind |
gastrula |
3 distinct layers of cells (DIFFERENTIATION) |
ecto: skin/ nerves, mes: muscles/bones, end: lungs/liver/digestive system lining |
Asexual v. Sexual
lots of offspring quickly, large colonies can form to out-compete, lots=many may survive if conditions change, less energy |
disease/mute=death, compete for food and space, bad condition=wiped out |
genetic diversity, ext: little energy to mate, more offspring can exist after disaster, int: more protect and care |
int: more energy/risk to mate, fewer produced, ext: gams,embryos, offs are unprotect |
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Fertilization: Pros and Cons
external |
very little energy mate, lots of offspring, spread widely in evrionment (less comp.) |
many gametes die, many eggs aren't fertilized, offspring are unprotected |
internal |
embryo protected, offspring's parents will protect |
more energy, fewer zygotes, more energy to raise |
Fetal Devlopment
differentiation |
formation of organs/tissue from gastrula |
1st tri |
0-12 wks |
development of all organ systems |
2nd tri |
12-24 |
rapid growth (12-16); fetal movements felt |
3rd tri |
24-38 |
continued growth (brain) |
MEIOSIS
prophase |
spindle fibres form and push centris. to poles, homolo chromosomes are paired |
cross over |
metaphase |
homolo chromosomes align on 2 sides of equator |
anaphase |
homolo chromosome pairs separate to opposite poles |
assort |
telophase |
2 nuclei form, after 2 cells form |
Stages of Sexual Repro.
mating |
egg and sperm come together at same time and place |
fertilization |
gametes fuse to make zygote |
development |
embryo develops |
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