Card Set Information
what is asexual reproduction and what sort of offspring does it produce?
non sexual reproduction and results in genetically identical parent to offsprings cell
how many chromosomes are in haploid, diploid? ploidy #
haploid is 1n
: number of chromosomes sets in nucleus
what is cell division and in multicellular organisms, why is it important? (5)
cell division is precisly passed down unless mutation occurs.
it is important because it allows
growth and development from zygote
replacement of damaged or dead cells
production of reproductive cells
cytoplasmic components are roughly divided by daughter cells
genetic material is replicated and divided precisly by daughter cells
what are the functions of cell division? (3)
growth and development
cell cycle order
doubling of cytoplasm
precise replication of DNA
what are somatic cells?
homologus chromosome pairs have same genes produced by miosis
what is cytokinesis
division of cytoplasm
what is binary fission and in what organisms does this happen?
the process gives two compariable cells and cell division reproduces an entire organism.
mitosis order of events
functions of mitosis?
insures that daughter cells are genetically identical to eachother and their parent cell
what does mitosis proceded by?
events of mitosis prophase (5)
nucleoli disappear and chromatin fibers coil into chromosomes
each chromosomes exist as two sister chromatids joined at centromere.
spindle fiber attaches at kinetochore
nuclear envelope disinegrates
mitotic spindles begin to form
events of mitosis metaphase (3)
replication of cromosomes align along the equatorial metephase plate
in animal cells, centrosomes are positioned at opposite poles
mitotic spindles apparatus is fully formed
events of mitosis Anaphase (2)
sister chromatids separate, migrating towards opposite poles in a "V" shape and are considered chrmosomes
at end of anaphase, each pole has a complete and identical set of chromosomes
events of mitosis telophase (4)
daughter nuclei form at poles
new nuclear envelope forms
chromosomes unfold to form chromatin
at end, mitosis is complete and two identical daughter nuclei are formed
functions of cytokenesis (4)
a cell plate forms by fusion of golgi-durived vesicles
plasma membranes arise from vesicle membranes
a cell wall forms from vesicle content
cleavage furrow formed by contractile microfilaments
where are the mitosis checkpoints?
g1 Checkpoint under G1 phase
G2 Checkpoint under G2 phase
what are the checkpoints for mitosis for?
G1 Checkpoint insures that everything is ready for DNA replication
G2 Checkpoint determines whether the cell can enter the M phase
in a cell cycle, what step do plants do differently after telophase?
they do not have a cleavage furrow. they only make cell wall
how many nuclear divisions are there in meiosis?
when is DNA replicated and how many times?
DNA replicates in interphase and is replicated twice
what is the difference between mitosis and meiosis
steps of meiosis
what is crossing over? what does it achieve?
occurs between on sister chromatids during synapsis at chiasmata
what is bivalent and when does this form?
a pair of homologous chromosomes
where genetic material is exchanged
what is independent assortment? does this apply to linked or unlinked genes?
oriantation of bivalents of metaphase I is random.
each homologous pair aligns on metaphase I plate independently of other chromosome pairs.
number of possible combinations is 2^n
Prophase I in miosis (3)
90% of miosis
: homologous chromosomes form bivalents that are attached by a protein complex
crossing over occurs
nuclear envelope disintegrates
centrosomes migrate towards opposite poles and spindle fibers begin to form.
tetrads (bivalents) migrate towards metaphase plate.
metaphase I in miosis (3)
tetrads align on metaphase plate
both kinetochores of a sister chromatid pair face the same pole.
kinetochores of homologous chromosomes face opposite poles.
anaphase I (3)
spindle fibers guide chromosomes towards poles
sister chromatids remain attached to the centromere
homologous chromosomes migrate towards opposite poles
telophase I (3)
homologous chromosome pairs reach opposite poles
each pole contains a haploid set of chromosomes, each chromosomes still composed of two chromatids.
in some species, chromosomes uncoil, nuclear membranes and nucleoli reappear and the cell enters a period of interkenesis
no DNA replication occurs before Meiosis II
Prophase II (3)
if interkenesis occurred, chromosomes condense, nuclear membranes disintegrate and nucleoli disappear
spindle apparti (2) begin to reform
chromosomes migrate toward metephase plate
Metephase II (3)
chroosomes align on metephase plate
metephase plate and spindle ases are at right angle to that of metaphase I
kinetochores of sister chromatids point towards opposite poles.
anaphase II (2)
centromeres of sister chromatids separate
chromosomes migrate towards opposite poles of spindles.
Telophase II (3)
nuclei form at opposite poles of spindles
4 haploid daughter cells are formed.
pic of anaphase
pic of telophase
pic of phophase
pic of metaphase
pic of prophase I
pic of metaphase I
pic of anaphase I
pic of telophase I
pic of prophase II
pic of metaphase II
pic of anaphase II