BIOB50H3 Chapter Notes - Chapter L #5: Chlorophyll, Xylem, Vascular Bundle
CHAPTER 5: COPING WITH ENVIRONMENTAL VARIATION – ENERGY (LECTURE #5)
Pages 110-129
SOURCES OF ENERGY (5.1)
- We get light from the sun radiant energy // cold/warm objects have different
amounts of kinetic energy // grasshopper eating a leaf represents a transfer of chemical
energy
oRadiant and chemical are most use forms of energy for animals, while kinetic
is used to influence the rate of chemical reactions and metabolic energy
demands eg. Endotherm needs to warm self burns chemical energy to
warm self-up (chemical energy to do so came from eating plants who
converted radiant energy into chemical energy)
-Autotrophs: org. that assimilate energy from sunlight (photosynthetic org) or inorganic
chemical compounds in the env. (chemosynthetic archaea and bacteria) convert
sunlight into organic compounds (typically carbohydrates)
-Heterotrophs: include org. that eat non-living matter (detritivores eg. Worms, fungi),
org. that feed off other animals/plants but don’t necessarily kill them (parasites and
herbivores), and consumers that kill their prey (predators eat prey)
-Not all plants are autotrophs plants that have lost ability for photosynthesis gain
nutrients by leeching of another org. (parasitism) = holoparasites (“whole parasites”)
are heterotrophs
Eg. Dodder (a plant parasite)
Also have hemiparasites: plants that are photosynthetic, but obtain some of their
nutrients, energy and water, from host plants
- Animals can also act as autotrophs, but their “photosynthetic capacity” is acquired by
consuming a photosynthetic org. that lives in a close relationship with them, called
symbiosis
EG. Sea slugs have chloroplasts (ingested from algae) that supply it with carbs
AUTOTROPHY (5.2)
- Majority of autotrophic production comes from
photosynthesis // chemosynthesis (or chemolithotrophy)
uses energy from inorganic compounds to produce carbs
important for org. near hydrothermal vents
Chemosynthesis harvest energy from inorganic compounds
-Earliest autotrophs were likely chemosynthetic
bacteria/archaea when atmosphere was rich in hydrogen,
low in oxygen, and with lots of carbon dioxide and
methane
find more resources at oneclass.com
find more resources at oneclass.com
During chemosynthesis, obtain e- from inorganic compound (oxidize) use e- to
create ATP and NADPH use them to take up carbon from CO2 (carbon fixation)
fixed carbon is used to synthesize carbs and other org. molecules
oFixing is done in the Calvin Cycle
- Nitrifying bacteria
Found in both aquatic and terrestrial ecosystems
Convert NH4+ (ammonium) into nitrite (NO2-), and then oxidize into nitrate (NO3-)
very important for nutrient cycling and plant nutrition
-Sulfur bacteria
Associated w/ volcanic deposits, hot-springs, acidic mine waste use higher-energy
forms of sulfur (H2S and HS-) produce elemental sulfur (S) exhausted H2S and HS-,
use S to create SO42-
Photosynthesis is the powerhouse for life on Earth
- Majority of biologically available energy on Earth comes from photosynthesis process of
converting sunglight into organic carbon
- Photosynthetic org. are: archaea, bacteria, protists, most algae and plants
- Leaves are main photosynthetic organ in plants process into organic carbon molecules
involves fixing it
a) Light-Driven And Carbon Reactions
- 2 major steps in photosynthesis: light-driven reaction (harvest energy from sunlight
splits water to provide e- for making ATP and NADPH) and carbon reaction/dark
reactions (fix carbon and synthesize carbs + sugars)
- sunlight is harvested by chlorophyll (a pigment) doesn’t absorb green wavelength
(Reflects it)
other pigments called carotenoids reflect orange/red/yellow
all pigments are in chloroplast membrane and arranged like antennae absorb
energy from photons energy is used to split water and provide e- splitting water
prod. Oxygen (and release that into the atmosphere) release of O2 was likely
reason for changing Earth’s atmosphere (and for also producing Ozone in the
atmosphere that protects org. from UV rays)
- in dark reaction CO2 is taken from atmosphere by stomates of vascular plants (or
diffuses across membranes on non-vascular plants) key enzyme used is Rubisco
catalyzes synthesis of CO2 into a 3-carbon compound called phosphoglyceraldehyde
(PGA) PGA is converted into a 6-carbon sugar (glucose)
b) Environmental Constraints And Solutions
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Chapter 5: coping with environmental variation energy (lecture #5) Autotrophs: org. that assimilate energy from sunlight (photosynthetic org) or inorganic chemical compounds in the env. (chemosynthetic archaea and bacteria) convert sunlight into organic compounds (typically carbohydrates) Heterotrophs: include org. that eat non-living matter (detritivores eg. worms, fungi), org. that feed off other animals/plants but don"t necessarily kill them (parasites and herbivores), and consumers that kill their prey (predators eat prey) Not all plants are autotrophs plants that have lost ability for photosynthesis gain nutrients by leeching of another org. (parasitism) = holoparasites ( whole parasites ) are heterotrophs. Also have hemiparasites: plants that are photosynthetic, but obtain some of their nutrients, energy and water, from host plants. Animals can also act as autotrophs, but their photosynthetic capacity is acquired by consuming a photosynthetic org. that lives in a close relationship with them, called symbiosis. Sea slugs have chloroplasts (ingested from algae) that supply it with carbs.
