Week 3 Ch 3-4 Flashcards
Interphase
Cell grows in preparation for cell division
Chromosomes are duplicated
Mitosis
Chromosome copes are split and moved to opposite ends of the cell
Cytokinesis
Cell divides into two daughter cells, identical
Chromosome structure
DNA is tightly wound around histones to create chromosomes
Centromeres
One on each sister chromatid, point of separation
Primase role
enzyme that synthesizes the RNA primer
RNA primer
Initial nucleotide chain in DNA synthesis
DNA polymerase
Proofreads newly made DNA and replaces any incorrect nucleotides
MIsmatch repair of DNA
repair enzymes replace incorrectly paired nucleotides that have evaded the proofreading process
Flow of proofreading and repairing DNA
(nucleotide excision repair)
- Mismatched nucleotide–>Nuclease cuts out damaged DNA stretches—>DNA polymerase puts correct base pairs on –>DNA ligase reassembles with corrections
Division of a cell occurs in
Mitotic phase
G1 phase:
First gap after mitosis
Metabolic activity and growth
(increase cytoplasm, organelles, mitochondria)
Sphase
Synthesis:
Metabolic activity, growth, DNA synthesis (genome replication)
G2 phase
“second gab” metabolic activity, growth, preparation for cell divsion
M phase includes
Mitosis and Cytokinesis
Cytokinesis
Division of cytoplasm, producing two daughter cells
Mitosis stages:
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Please Pass Me Another Tequila
Prophase
-Chromotin fibers are coiled
-Sister chromatids
-Mitotic spindle begins to form (microtubules)
-Centrosomes have moved away from each other
Prometaphase
-Nuclear envelope fragments
-Microtubules invade nuclear area
-Kinetochore formed at centromere of each chromatid
-microtubles attache to kinetochores
Metaphase
-Centrosomes at opposite boles of the cell
-Line up at metaphase plate
Anaphase
-Shortest stage
-cohesions proteins cleaved at centromere
-sister chromatids part suddenly
Telophase
-Two daughter nuclei form
-Nuclear envelope forms
-Nucleoli reappear
-Chromosomes become less condensed and unwind
-Spindle microtubules move apart (depolymerized)
all cytoplasm and chromatids have separated
Molecular regulation
frequency of cell division varies with the type of cell
Cyclin
concentration of various cyclins tells cell when to divide
Cyclin dependent kinases (Cdks)
reach a tipping point to trigger a cell cycle
rise and fall of Cdks changes with concentration of its cyclin partner
Cyclin and Cdk
Cdks must be attached to a cyclin to be active
Loss of cell cycle in cancer cells
Cell cycle not regulated, they do not stop dividing when growth factors are depleted
Cell transformation
cells that acquire the ability to divide indefinitely (mitosis goes unchecked)
Benign tumor
Abnormal cells remain only at original site
Apoptosis
PROGRAMMED cell death
-no inflammation
-recycling of components
Necrosis
-unplanned cell death
-Unpackaged components
-inflammation
-released enzymes, proteins
-Signals immune reponse
