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NSCI 1404 Final: Final Study Guide for Biology II

Natural Science
Course Code
NSCI 1404
Mark Botton
Study Guide

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1. The eukaryotic cell cycle
M - Mitosis (all other events are part of interphase)
Gap 1 - cells use copy of genetic material from parent cell, DNA replication, and cell division
S - DNA synthesis
Gap 2 - preparations for mitosis, synthesis of molecules needed for mitosis (e.g. spindle,
Erythropoietin - increases process of cell cycle
Cyclin-dependent Kinases (Cdk) - protein kinase that catalyzes transfer of phosphate group from
ATP to a target protein
2. The eukaryotic chromosome
Two chromatids attached by a centromere
Cohesin holds daughter chromatids together
Kinetochore - protein on chromatids that help it to attach to the spindle during division
Nucleosomes - subunits of chromatids
Chromosomes are made up of DNA; DNA is made up of genes
3. Mitosis
Daughter cells have the same amount of chromosomes as the parent (and are genetically
identical) because the chromosomes duplicate before division.
4. Cytokinesis in animal vs. plant cells
Animals – starts with furrowing of plasma membrane; contractile ring of actin and
myosin (the proteins interact to create a contraction and pinch the cell into two)
Plants – as the spindle breaks down, membranous vesicles from Golgi apparatus appear
along plane of cell division; vesicles are propelled by kinesin and they fuse to form a new
plasma membrane
5. Meiosis
Meiosis I
oProphase I – Chromosomes condense and become visible. Homologous chromosomes
pair up (synapsis).
oPrometaphase I – chromosomes attach to spindle (still in pairs); nuclear envelope breaks
oMetaphase I – Homologous pairs align in the center
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oAnaphase I – Homologous chromosomes separate and move to separate poles. Unlike in
mitosis, centromeres do not split; sister chromatids remain paired
oTelophase I – New nuclear membrane forms around each set of chromosomes,
cytokinesis divides into two daughter cells. Cell proceeds to Meiosis II with
chromosomes still condensed
Meiosis I separates homologous pairs
Meiosis II divides each chromosome into two copies (like mitosis)
Daughter cells have half the amount of chromosomes as parent cells (haploid—h) because the
chromosomes do not duplicate in prophase I like in mitosis
6. Mechanisms of Genetic Diversity
In Prophase I cross-connections form at chiasma with breakage and rejoining of sister
In Anaphase I homologous pairs align in the center on either side of the cell so that there are
differences in genetic distribution among daughter cells (random segregation)
7. Relate the processes of mitosis and meiosis to the life cycle in animals.
1. Asexual Reproduction
Offspring is genetically identical to parent
oBudding – offspring develop as a growth on the body of parent
Jellyfish, echinoderms, some corals, tapeworms, hydra
oFragmentation – certain worms grow to full size and then break up into fragments which
become mature worms
2. Gametogenesis
Egg and sperm are produced in gonads (ovaries and testes) by germ cells
Germ cells proliferate by mitosis, produce diploid spermatogonia and oogonia
oSpermatogonia give rise to primary spermatocytes through mitosis
oPrimary and secondary spermatocytes connected by cytoplasmic bridge
oSecondary spermatocytes (spermatids) mature into actual sperm
oSpermatogenesis is continuous in males starting from puberty
oOogonia make primary oocytes through mitosis
oPrimary oocyte starts to undergo meosis I prenatally but pauses in prophase I
oMeiosis resumes at onset of puberty and primary oocyte completes meiosis I (becomes
secondary oocyte), first polar body forms
oAfter puberty, about 1 egg every 28 days undergoes completion of meiosis I (hormones
wake cell from meiotic rest) until menopause
oSecondary oocyte completes meiosis II when it is fertilized by sperm to produce ova
Spermatogonia divide by mitosis throughout adulthood (steady supply of spermatocytes that
divide by meiosis to make haploid spermatids)
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Oogonia stop dividing in the embryo, remain arrested in Prophase I until they are ovulated. Each
oocyte makes one haploid ootid, which becomes mature ovum.
3. Reproductive Biology and Habitat
Majority of animals are dioecious (separate sexes) but some are monoecious (hermaphroditic –
can be simultaneous or sequential)
External fertilization is common in marine animals
oSpawning – eggs and sperm are released into water
oSpawning aggregation can be temporal or spatial
Internal fertilization is necessary for land animals since sperm need to swim
oOviparity: internal fertilization, egg is laid
oViviparity: internal fertilization, young are nutritionally dependent on mother’s body
through something like a placenta in mammals
oOvoviviparity: internal fertilization, egg is retained inside mother and young feed off
yolk (e.g. snakes, sharks)
Fishes → Amphibians → reptiles→ birds → mammals
Fish reproduction: Diploid Adults (2N) → Meiosis produces sperm and eggs (N) → external
fertilization (2N) zygote → mitosis → larval stage (2N) (dispersal stage)→ metamorphosis →
Diploid Adults (2N)
Amphibian reproduction: same thing but larval stage is called a tadpole
Bird and reptile reproduction
oHard shell amniotic (filled with fluid) egg, protecting development
oInternal fertilization
oIncrease in parental care in comparison to amphibians/fish
oPrototheria (monotremes): developing embryo is retained in female reproductive tract for
some time. These animals lay eggs (platypus)
oMarsupials: e.g. opossum, kangaroo
oPlacental (eutherian): protected embryo by placenta that provides the young with
4. Anatomy of the Human Male and Female Reproductive Systems
Male reproductive system
oSperm is produced in testes, in the pouch of skin called scrotum. It travels through vas
deferens into seminal vesicles.
oSeminal fluid – fructose is used to move it through the reproductive system, mucus is for
oProstate gland – prostate fluid is alkaline, neutralizes acidity in the male/female
reproductive tracts to make a more hospitable environment for sperm
oBulbourethral glands – help neutralize acidity in urethra, lubricates sperm to facilitate
passage of semen
oSpermatogenesis occurs in seminiferous tubules, sertoli cells provide nutrients for
developing sperm, leydig cells produce testosterone
oSperm structure
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