bio exam 2 ch. 9

• interphase
• mitotic stage

• G₁
• S   {interphase
• G₂

M {Mitotic

• is most of the cell cycle
• consists of the cell's normal functions
• varies by cell type

• G₁ phase: cell matures; recovery and growth
• S phase: DNA replication
• G₂ phase: preparation for division

• mitosis:nuclear division
• daughter chromosomes are distributed by the mitotic spindle to two daughter nuclei
• no change in number of chromosomes
• Cytokinesis: division of the cytoplasm
• results: genetically identical daughter cells

cyclin proteins: increase and decrease during cell cycle; control completion of cycle

• programmed cell death
• the nucleus fragments
• the plasma membrane blisters
• the fragments are destroyed
• it is the opposite of mitosis

chromosomes

network of DNA strands associated proteins observed within a nucleus of a cell (ball of twine)

constriction where sister chromatids of a chromosome are held together

following replication, a chromosomes consists of a pair of sister chromatids, held together at the centromere: each chromatid is comprised of a single DNA helix

• microtubule organizing center in animal cells
• organizes mitotic spindle
• replicated in the S phase
• need two before mitosis begins

total number of chromosomes; for humans is 46

half number of chromosomes; for humans is 23

result of fertilization; it is always diploid chromosome (46 in humans)

chromosomes are duplicated and attached by a centromere

• centromeres separate
• sister chromatids separate- daughter chromosomes
• sisters of each type are distributed to opposite daughter nuclei

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

• chromatin condensed: each chromosome with 2 sister chromatids attached centromere
• Nucleolus disappears
• Nuclear envelope disintegrates
• spindle begins to assemble
• two centrosomes move away from each other

• centromere develops two kinetochores
• connect sister chromatids to opposite poles of mother cell with kinetochores
• kinetochores-fish hooks
• spindle fibers-fishing line
• daughter chromosomes- fish

chromosomes (2 sister chromatids each) alighted at metaphase plate

• 1. centromeres dissolve, sister chromatids separate and become daughter chromosomes
• 2. daughter chromosomes begin to move toward opposite poles by the spindle
• A for anaphase, A for Away
• 3. cell membrane begins to pinch in (cleavage furrow)

• spindle disappears
• nuclear envelope forms around chromosomes
• nucleoli appear
• new daughter cells form by furrowing

• division of the cell (NOT nuclear division/mitosis)
• division of cytoplasm (cleavage furrow)
• mother cell cytoplasm equally distributed
• each daughter cell gets own plasma membrane

• Interphase
• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

• cell plate forms:
• vesicles align and fuse (sent by Golgi body)
• one thin vesicle extending across the mother cell
• space between daughter cells become filled and secrete primary cell walls

• multi-cellular: growth and repair
• single celled: reproduction

• they retain their ability to divide
• used in therapeutic cloning- produces tissues
• used in reproductive cloning- produces a new individual

uncontrolled cell division

abnormal growth of cells

not cancerous

cancerous

cancer develops when the delicate balance between promotion and inhibition of cell division is tilted toward uncontrollable cell division

• gradual development
• metastasize- when  cancer moves from one part to another

• no differentiation
• have abnormal nuclei
• do not undergo apoptosis
• (immortal, abnormal, non-specialized)

the growth of new blood vessels in and around tumors

• proto-oncogenes: code for proteins that speed up cell cycle and prevent apoptosis
• tumor suppressor genes: code for proteins that slow down the cell cycle and promote apoptosis

cancer-causing genes that keep promoting cell cycle regardless of circumstances

• the ends of the  chromosome
• mutation causes telomeres to continue to lengthen and allows cancer cells to continually divide

• occurs in prokaryotic cells by binary fission
• only needs 1 parent
• offspring are genetically identical to parent

process by which prokaryotes reproduce asexually. the division (fission) produces 2 (binary) daughter cells that identical to the parent

• attach: chromosome to special plasma membrane
• grow: cell prepares by enlarging overall volume
• replicate: DNA rep produces 2 identical chromosomes
• elongate: as cell elongates, chromosomes pulled apart and cytoplasm distributed
• equally
• divide: new cell wall and plasma membrane has divided the daughter cells

• bacteria and archaea: binary fission
• function: asexual reproduction

• Protists & some fungi: mitosis and cytokinesis
• function: asexual reproduction
• Other fungi, plants and animals: mitosis and cytokinesis
• function: development, growth, and repair