Chloroplasts and lrlitochondria
Plont cells contoin on orgonelle called the chloroplost. The chloroplost
ollows plants to horvest energy from sunlight. Speciolized pigments in the
chloroplost (including the common green pigment chlorophyll) obsorb
sunlight ond use this energy to complete the chemicol reoction:
6 COz* 6 HzO
+
elergy (from sunlight)
---+ CoHtzOo*
6
Oz
fn this woy, plont cells monufocfure glucose ond other corbohydrotes
thof they con store f or lster use. Photosynthetic cells moy hove
thousonds of chloroplosts. Chloroplosts ore double membrone organelles
with on inner membrone f olded into disc-shoped socs colled thylokoids.
Color and labelthe outer membrone light green. Thylokoids, contoining
chlorophyll ond other occessory pigments, ore in stocks colled gronum
(grono, plurol). Color and labelthe grono dork green in Figure 1. Grano
ore connected to eoch other by structures colled lomelloe, ond they are
surrounded by o gel-like moteriol colled stromo. Color and labelthe
lomelloe brown in figure 7. Color and labelthe stromo light blue in
Figure l. Light-capturing pigments in the grono a?e organized into
photosystems. On Figure 2, color and labelo single thylokoid (stock)
dork green. fn onother stock on figure2, color and labelo gronum red.
Mitochondrio orelhe powerhouses of the cell. Glucose ond other
corbohydrotes mode by plonts during photosynthesis ore broken down by
the process of oerobic cellulor respirotion in the mitochondrio of the
cell. This releases energy (ATP) for the cell. The more octive o cell
(such os o musclecell), the more mitochondrio it will hove. The
mitochondrio ore bout the size of a bocteriol cell ond are oflen peonutshoped. Mitochondrio hove o double rnehbrone like the nucleus ond
chloroplost. The outer membrone is smooth, while the inner membrone
is convoluted into folds colled cristoe. Color and label the outer
membrone pink ond the cristoe red on figure 3. This greatly increoses
the surf oce orea of the membrone so thot corbohydrotes (simpla sugors)
1
con combine with oxygen to produce ATP, odenosine triphosphote (the
energy molecule of lhe cell). The electron tronsport choin tokes ploce
ocross the membrones of Ihe cristoe (cristo, singulor). fnside the folds
or cristoe is a spoce colled the motrix thot contoins enzymes needed f or
the Kreb's Cycle. Color and label the motrix yellow on f igure 3.
Figure 1-Chloroplost
Figure 2-Thylokoid
Mitochondrio
Questions:
1.
Whot is the energy molecule of the cell cqlled?
2. What mqcromolecule mode by plonts is "burned" in the mitochondrio?
3. Where is chlorophyll found in the chloroplost?
\
4. Tn which port of o plont would you expect to f ind the most chloroplosts qnd why?
5. How would the number of mitochondrio in on insect's wing compore to the omount
found in other cells in on insect's body? Exploin your onswer.
6. Whqt arelhe rqw moteriols
for
photosynthesis?
7. What product of photosynthesis is used in cellulqr respirotion?
8. Whot is the odvontoge of having q folded inner membrone in the mitochondrioZ
9. Whot is the ene?gy
for
photosynthesis?
10. Besides chlorophyll, whot other pigments ore found in the chloroplosts?