Medicinal Plants 2 and Mitosis

Plant meristems

the site of cell growth in plants where cell division, enlargement, and differentiation (specialization) occur

Cell division

the process by which one cell divides into two, has 2 parts

Mitosis

division of the nucleus/the process of nuclear division; consists of 4 stages

Cytokinesis

division of the cytoplasm that separates two daughter nuclei into two cells

begins in late anaphase & is completed by late telophase

Phragmoplast (vesiles, microtubules, and ER) accumulates across the center of the dividing cell

Cell plate forms in the middle of the cell

Cell plate

becomes the the cell wall that separates two new daughter cells and begins to form in early telophase

M (mitotic phase)

dividing phase

Interphase

the non dividing metabolically active stage in which a cell spends 90% of its time in and the stage where preparation for cell division occurs; has three phases

G1 (gap 1) phase

period of intense biological activity: cell is actively growing, organelles increase i size, protein synthesis occurs, respiration occurs

S (synthesis) phase

DNA is duplicated (other sister chromatid is formed)

G2 (gap 2) phase

increase in protein synthesis & final preparations for cell division are completed

Prophase

-Chromatin begins to condense and thicken, forming chromosomes

-Nuclear membrane & nucleolus disappear

-Chromosomes are free in the cytopasm

-Spindle starts to form

Spindle

a framework of microtubules that pull the chromosomes from the center of the cells to the poles

Microtubules

fibers that act like muscles

Metaphase

-Chromosomes line up on the cell’s equator

-Each centromere is attached to a spindle fiber

-Cell has two poles

-At the end of this phase, centromeres divide

Anaphase

-sister chromatids are pulled to opposite ends of the cell by contraction of the spindle fibers

-each chromatid is now considered one chromosome

-genetic material is divided in 2 identical sets

Teleophase

-Nuclear membrane reforms

-Chromatids unwind and lengthen: become indistinct

-Nucleolus reappears

-Cell plate egins to appear

Chromatin

DNA & proteins

Chromatids

condensed duplicated strands of DNA

Homologous chromosomes

chromosome pairs of the same size & shape that carry genes for the same traits

Madagascar Periwinkle

(Catheranthus roseus) has alkaloids that are used as chemotherapuetic agents for treating cancer and childhood leukemia

the alkaloids act on microtubules to interfere w/ spindle formation & prevent mitosis

Vincristine and vinblastine

useful chemotherapuetuc agents that interfere w/ spindle formation, preventing mitosis from happening

Pacific yew (Taxus brevifolia)

the source of taxol

a conifer tree located in forests in the Northwest US

needs shade to grow, is found under canopy layers in forests, and grows slowly

Taxol

an anticancer drug discovered in the 1960s that is an alkaloid that has anti-tumor properties that may help treat women w/ ovarian and breast cancer

it works by biding to and inhibiting the break down of microtubules

Happy Tree

(Camptotheca acuminata) a tree native to Southern China

Contains camtothecin in the bark, an alkaloid w/ anticancer properties for colon & rectal cancers

Chinese skullcap

(Scutellaria baicalensis) used for centuries in traditional Chinese medicine

flavons in roots may halt tumors, kill cancer cells, and lave normal cells intact. It has the potential for treating cancer & liver diseases

Mandrake

(Mandragora officinarum) has been used for its anesthetic properties

it looks like a two leg like branches & a protuberance that suggests male genitals

the doctrine of signatures said it made men virile, but it does not

Belladonna (atropa belladonna(

used by Italian and Spanish women to enlarge their pupils and achieve a seductive look (done by rubbing their eyes with this plant)

now used by ophthalmologists b/c it dilates pupils

also stimulates circulation and the sympathetic nervous system