Bioenergetics
What is Bioenergetics?
- The study of energy in living systems (environments) and the organisms
(plants and animals) that utilize them.
- Energy is needed by all organisms on Earth -
Energy is the Ability to do work.
Types:
◼ Kinetic Energy - →Energy being used to do work. (ex. heat & light)
◼ Potential Energy - → Stored energy available to do work
How Do Organisms Get Energy?
Organisms usually get the chemical energy they need from food
◼ Autotrophs are organisms that make their own food. (producers)
◼ Heterotrophs are organisms that obtain energy from other organisms.
(heterotrophs)
Energy-Giving Molecules
All organisms mainly use two types of energy-giving molecules: glucose and ATP.
Glucose is made during the process of photosynthesis.
- In the human body, glucose is transported by the blood and taken up by
the cells for energy.
- The stored energy in glucose is released in a reverse reaction of
photosynthesis called cellular respiration.
Adenosine triphosphate (ATP) molecules store smaller amounts of energy, but
each molecule releases enough energy to do work within the cell.
ATP is composed of
● ribose
● adenine
● phosphate group
ATP is made during the first half of photosynthesis and is used during the
second half where glucose is made.
Photosynthetic Organelles
Photosynthetic pigments are unique pigments found in all photosynthetic
organisms such as plants and some bacteria.
Plants have two groups of pigments – chlorophylls and carotenoids.
◼ Chlorophyll a and chlorophyll b are green pigments that absorb all
wavelengths of light the red, blue and violet ranges.
◼ Carotenoids are yellow, orange, and red pigment, they absorb light in blue,
green and violet ranges.
◼ The pigment found in red algae, called the phycobilins, which give them their
reddish color, absorb light in blue and green ranges.
● Chloroplasts are cell organelles found in plants and algae.
Photosynthesis
◼ Photosynthesis is the process by which plants, some bacteria and some
protists use the energy from sunlight to produce glucose from carbon dioxide
and water. This glucose can be converted into pyruvate which releases
adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed.
STAGES:
◼ Light-Dependent Reactions
◼ Light-Independent Reactions.
● Light-Dependent Reactions take place in the thylakoid of the
chloroplast.
● Light-Independent Reactions happen in the stroma surrounding the
thylakoids in the chloroplast.
Cellular Respiration
◼ The means by which cells release the stored energy in glucose to make ATP.
◼ Cellular respiration reactions can be grouped into three stages: glycolysis,
Krebs cycle, and electron transport chain.
Glycolysis is the process that breaks down one molecule of 6- glucose into 3-C
pyruvate or pyruvic acids.
Krebs cycle is a cyclical series of enzyme controlled reactions.
Electron transport chain is a series of photon pumps on the inner membrane of
the mitochondrion.
Aerobic & Anaerobic Respiration
◼ Most cells carry out aerobic respiration when oxygen is present.
◼ Aerobic respiration is an efficient process which yields a lot of ATP.
◼ Organisms that can live without oxygen are called anaerobes.
Anaerobic Respiration
◼ Some anaerobes die if exposed to oxygen – obligate anaerobes
◼ Some anaerobes can live with the presence of oxygen but do not use it –
facultative anaerobes
◼ Alcoholic fermentation
→ ethyl alcohol & carbon dioxide
◼ Fermentation is used for various purposes such as the creation of yogurt,
sour cream and kimchi.
