Cellular Energy Review
Mrs. Pittaluga
8th Grade Science
Waynesville Middle School
Types of Cells
▪ Prokaryotes
▪ Simple, single-celled organisms (like bacteria)
▪ No defined organelles
▪ No nucleus
▪ Eukaryotes
▪ Complex organisms - plant and animal cells
▪ Multiple defined organelles; need to perform cellular
respiration to get energy
▪ Have a nucleus
Key Cell Structures and Functions
▪ Cell Membrane
• Forms the outside boundary that separates a cell from its environment;
Controls what enters and leaves a cell; made up of lipids
▪ Ribosomes
• Small cellular structures created in the nucleolus that are the site for
protein production
▪ Mitochondria
• Converts energy in food molecules to energy the cell can use to carry
out its functions; location of cellular respiration
▪Chloroplasts
•
Found only in plant cells; uses chlorophyll to convert the sun’s
energy into glucose through photosynthesis.
Organic Compounds
▪ All organic compounds contain carbon.
▪ Primary organic compounds in cells:
• Carbohydrates – Energy-rich compounds; made up of carbon,
hydrogen, and oxygen in a 1:2:1 ratio; Sugars and starches
• Lipids – Energy-rich compounds; store energy; provide
insulation; fats, oils, and waxes
• Proteins – Large organic compounds composed of amino acids;
made up of carbon, hydrogen, oxygen, and nitrogen; enzymes
are made of proteins; meat, eggs, fish, nuts, and beans
• Nucleic Acids – Contain the genetic information for an
organism; DNA and RNA; building blocks are nucleotides
Photosynthesis
▪ The process by which a plant cell captures energy in
sunlight and uses it to make food.
▪ Stage 1: Chloroplasts in plant cells capture energy
from sunlight
▪ Stage 2: The captured light energy is used to
produce sugars and oxygen from water and carbon
dioxide
▪ The photosynthesis equation:
▪ Sun’s energy + 6 CO2 + 6 H2O → C6H12O6 + 6 O2
Cellular Respiration
▪ The process by which cells, plant and animal, obtain energy from glucose
as long as oxygen is present.
▪ Stage 1: Molecules of glucose are broken down through glycolysis into
smaller molecules in the cells cytoplasm.
▪ Stage 2: Takes place in the mitochondria where the small molecules are
broken down into even smaller molecules and generating ATP (cellular
energy).
▪ Cellular respiration process: glycolysis → Kreb’s cycle → electron
transport chain
▪
The majority of the ATP is generated in the electron transport
chain.
▪ The respiration equation:
▪ C6H12O6 + 6 O2→ 6 CO2 + 6 H2O + energy (ATP)
Photosynthesis vs. Respiration
▪ Opposite processes – products from one reaction are
the reactants in the other.
▪ Autotrophs are organisms that make their own food
using the Sun’s energy through the process of
photosynthesis; plants and some single-celled
organisms
▪ Heterotrophs are organisms that rely on food from
other sources; animals
Types of Respiration
▪ Aerobic respiration uses oxygen
▪ Long-term energy (running a marathon)
▪ Anaerobic respiration does not use oxygen
▪ Short-term energy (running sprints)
▪ Fermentation is respiration that occurs without
oxygen
▪ Alcoholic fermentation – ethyl alcohol is a
byproduct; occurs in yeast
▪ Lactic acid fermentation – lactic acid is a byproduct;
occurs in muscles that haven’t gotten enough oxygen
Digestion
▪ Mechanical Digestion
▪ Breaking up food through chewing, tearing, crushing,
squeezing, etc in order to increase the surface area
▪ Chemical Digestion
▪ Breaking up molecules of food through the use of enzymes
Advanced Science Only
Putting the Pieces Together
1. Using the following key terms, create a concept map
showing how everything we have learned in this unit is
related. Make sure you show where all of the energy starts.
You should also include color and pictures.
Photosynthesis
Carbohydrates
Cytoplasm
Respiration
Proteins
Chloroplasts
Glycolysis
Lipids
Ribosomes
Kreb’s cycle
Nucleic Acids
Mitochondria
Mechanical digestion
Enzymes
Amino acids
Chemical digestion
Lactic Acid
ATP
Glucose
Anaerobic
Aerobic
Carbon dioxide
Oxygen
Water
Advanced Science Only
Putting the Pieces Together
2. Using the concept map you already created, write a onepage story showing the life of a food molecule from it’s
creation in photosynthesis to the point where it used in
cellular respiration.
a) You must include at least 10 of the words from your
concept map.
b) The story should be at least one notebook page in length.
c) The story should be written from the point of view of the
food molecule.
d) BE CREATIVE!!