mitosis Flashcards
what is mitosis and its function?
eukaryotes depend on mitosis, development from a fertilized cell, growth, repair
what is the product of mitosis?
results in duaghter cells that are identical with genetic information as parents DNA, 2 diploid
what is a genome?
all the DNA in a cell
what are chromosomes?
a single DNA molecule common in prokaryotes or many DNA molecules which are common in eukaryotes
what is chromatin?
a complex of DNA and histones that condense during cell division
what are somatic cells?
non reproductive cells that have two sets of chromosomes, diploid
what are gametes?
reproductive cells that have as many chromosomes as somatic cells haploid
how many chromosomes are in drosophila and humans?
Drosophila has 8 and humans have 46
what is a karyotype?
an image that reveals an orderly arrangement of chromosomes
what are homologous chromosomes?
matching pairs of chromosomes one from each parent, that can possess different versions of the same genes
what is the total condensation of chromosomes?
10000 chromosomes
what are sister chromatids?
each duplicated chromosome has two sister chromatids which are joined copies of the original chromosome. they are attached along their lengths by cohesions
what is a centromere?
a narrow waist of the duplicated chromosome, where the two chromatids are most closely attached
what is the kinetochore?
its the centromere + protein attachment
how do chromatids separate?
separase separates chromatids by hydrolyzing cohesin
what does the mitotic phase consist of?
mitosis and cytokinesis
what are the three phases of interphase?
G1 phase, S phase, and G2 phase
how many nucleosomes are present?
6x, and nucleosomes around a 30nm fiber are 1000x
what is the microtubule organizing center?
structure with microtubules emerge, it organizes cilia and flagella, and organizes mitotic and meiotic spindles
what is mitotic spindle?
a structure made of microtubules that control chromosome movement during mitosis
what is a centrosome?
assembly of spindle microtubles begins in the centrosome in animal cells and during interphase forming two centrioles that migrate to the opposite end of the cell
what is considered a centriole?
9 triplets of microtubules
what are kineotochore fibers?
during prometaphase some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes
what are non-kinetochore microtubules?
not connected to centromeres
what happens in metaphase?
the chromosomes line up at the metaphase plate, a plane midway between the spindles two poles
what happens during anaphase?
the cohesins are cleaved by an enzyme called separase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell, microtubules shorten by depolymerizing at their kinetochore ends
what happens in telophase?
genetically identical daughter nuclei form at opposite ends of the cell
what do non-kinetochore microtubules do?
non-kinetochore microtubules from opposite poles overlap and push against each other elongating the cell
what happens in cytokinesis?
begins during anaphase or telophase and the spindle eventually disassembles
what is the eukaryotic cell cycle regulated by?
the molecular control system
what is the molecular control system?
bacteria= 20 min
drosophila= 8 min
mouse= 3 hours
mammalian= 24 hours
frog= 30 min
what do not divide after maturity, how are liver cells different?
heart, rbc, and nerve cells, liver cells retain ability to divide
what does kinases do?
phosphorylates proteins
what is the cell cycle control?
the sequential events of the cell cycle are directed by a distinct cell cycle control system which is like a clock
what is the maturation promotion factor?
a cyclin complex that triggers cells passage past the G2 checkpoint into M phase, phosphorylates proteins, promotes spindle formation, promotes condensation of chromosomes, contributes to degradation of nuclear envelop, ER and Golgi
what is the G1 checkpoint?
checks cell size, growth factors, proteins, organelles and mRNAs
what is G2 growth?
chromosome duplication and DNA is not damaged before entering cell division
what is the M division?
ensures attachment of each kinetochore to a spindle fiber before entering irreversible anaphase, this ensures daughter cells have the correct number of chromosomes
what are external factors?
specific growth factors
what is necrosis?
low oxygen, toxins, ATP depletion, random fragmentation, ingested by phagocytes, inflammation
what happens in density dependent inhibition?
crowded cells will stop dividing by cell- cell contact, cancer cells lose this
what are growth factors?
released by certain cells and stimulate other cells to divide
what is apoptosis?
natural cell death, chromatin condensation, membrane blebbing, ingested by neighboring cells, no inflammation, vitamin D dependent
what happens at G1 checkpoint what does it do?
makes proteins and organelles needed for DNA synthesis, check for nutrients, longest most important, decides whether or not to divide,
what is the G2 checkpoint?
checks for DNA damage, DNA replication, cell proteins and organelles, cell stress, prevents cells from entering mitosis if DNA is damaged, pause repair preventing proliferation of cells
