Ch. 4 and 18

1
Ch. 4 and 18

• Cellular Metabolism and Nutrition

2
Metabolism

• Metabolism - Sum total of chemical reactions
  within a cell.
• All of the chemical reactions within your body.

3
2 Types of Metabolic Reactions

• Anabolism - (anabolic metabolism) - Metabolic
  process by which larger molecules are synthesized
  from smaller ones.
• Dehydration synthesis
• Joining monosaccharide to form polysaccharides
  (glycogen).
• Joining glycerol and fatty acids to form fat
  molecules.
• Joining amino acids to form proteins.

4
2 Types of Metabolic Reactions Continued

• Catabolism - (catabolic metabolism) - Metabolic
  process that breaks down large molecules into
  smaller ones.
• Hydrolysis
• Breaking down complex carbohydrates into
  monosaccharides.
• Breaking down fats into glycerol and fatty acids.
• Breaking down proteins into amino acids.

5
Anabolism Molecules made or broken down by these processes Catabolism
Building molecules Glycogen, Fat molecules Proteins Breaking down molecules
EX Dehydration Synthesis Glycogen, Fat molecules Proteins Ex Hydrolysis
Forms molecules while releasing Water Glycogen, Fat molecules Proteins Breaks down molecules while splitting or using water.
6
Metabolism Animation
https//sites.google.com/site/biologymolecules/de
hydration-sythesis-vs-hydrolysis http//www.bcco
nline.com/biol10rs/Pearson-Animations/monomers_and
_polymers.swf
7
(No Transcript)
8
Enzyme Action

• Enzymes are special proteins that catalyze
  chemical reactions in the body.
• They are highly specific.
• The substances that they work on are called
  substrates.
• Substrates bind at the enzymes active site.

9
Enzyme catalysis

• Substrate enzyme ? Enzyme substrate complex ?
  Product (changed substrate) ? Enzyme (unchanged)

10
Enzyme Catalysis

• Speed of the enzyme action depends on the
  concentration of the enzyme and substrate.
• As enzyme concentration increases, substrate
  activity will increase to a point.
• As substrate concentration increases, enzyme
  activity will increase to a point.

11
Metabolic Pathways

• Sequences of enzyme controlled reactions that
  lead to the synthesis or breakdown of particular
  biochemicals.

12
Coenzymes

• Coenzymes are non-protein substances (such as
  vitamins) that either aid in enzyme activity, or
  are required for the enzyme to function properly.

13
Factors that Affect Enzyme Activity

• Excessive temperatures (too hot or too cold)
• Radiation
• Electricity
• Certain Chemicals
• Extreme pH values

14
Factors that Affect Enzyme Activity Continued

• If the enzyme becomes denatured, it will no
  longer work.
• Ex. Frying an egg
• The active site is no longer functional.

15
Lactose Intolerance http//www.dsm.com/le/en_US/m
axilact/html/how_it_works.htm http//www.youtube.
com/watch?vw_KR6k6YIIs
16
(No Transcript)
17
Energy for Metabolic Reactions

• Energy - the capacity for doing work.
• ATP - energy rich molecule in cells that powers
  cellular activities.

18
ATP

• ATP consists of 3 parts
• a sugar (ribose)
• a base (adenine)
• 3 phosphate groups

Energy is stored in the bonds that hold the
phosphates together.
19
ATP

• To release the stored energy, the last
• phosphate is removed and ADP (adenosine
• diphosphate) a phosphate group is formed.

20
ATP

• Energy from cellular respiration is used to
  synthesize more ATP by adding the phosphate group
  back to ADP -
• This is known as phosphorylation.

21
Cellular Respiration

• The process that releases energy from molecules
  of glucose and makes it available for cellular
  use. (In the form of ATP).
• Includes 2 pathways
• Aerobic - requires oxygen.
• Anaerobic - no oxygen required.

22
3 Stages of Cellular Respiration

• Glycolysis - happens in the cytoplasm. (1st stage
  for aerobic and anaerobic reactions.)
• Citric Acid Cycle (Krebs Cycle) - happens in
  mitochondria. (aerobic only)
• Electron Transport chain - happens in the
  mitochondria. (aerobic only)

23
3 Stages of Cellular Respiration

• Glycolysis- happens in the cytoplasm. (1st stage
  for aerobic and anaerobic reactions.)
• The 6-carbon glucose is broken down into 3-carbon
  pyruvic acid molecules.

24
3 Stages of Cellular Respiration

• Citric Acid Cycle (Krebs Cycle)- happens in
  mitochondria. (aerobic only)
• The 3-carbon pyruvic acids enter the mitochondria
  and lose a carbon generating CO2 and is combined
  with a coenzyme to form 2-carbon acetyl coenzyme
  A. Each of those combines with a 4-carbon
  oxaloacetic acid to form a 6-carbon citric acid.

25
3 Stages of Cellular Respiration

• Electron Transport chain- happens in the
  mitochondria. (aerobic only)
• The high energy electrons that were released
  during two previous cycles are carried and
  combined with enzymes that convert most of the
  remaining energy to ATP.

26
Aerobic vs. Anaerobic Respiration
Characteristic Aerobic Respiration Anerobic Respiration
Starting materials Glucose Glucose
1st step Glycolysis Glycolysis
Uses oxygen Yes No
Cell location Cytoplasm then mitochondria Cytoplasm only
Products Water and CO2 Lactic Acid
Number of ATP produced 38 ATP 4 ATP
Net Gain 36 ATP 2 ATP
27
Aerobic vs. Anaerobic Respiration

• http//www.youtube.com/watch?v-Gb2EzF_XqA

28
(No Transcript)
29
Nutritional Requirements

• Carbohydrates
• Energy stored in their chemical bonds used to
  power cellular processes.
• Sources include
• Polysaccharides - grains, vegetables, meat.
• Disaccharides - milk sugar, cane sugar, molasses.
• Monosaccharides - fruit and honey.
• Requirements - at least 125-175 grams daily.
• Will differ based upon activity level.

30
Nutritional Requirements

• Lipids
• Supply energy and help build cellular structures.
• Sources include
• Triglycerides plant and animal based foods.
• Saturated fats - mainly animal origin - meat,
  eggs, milk, lard, (coconut and palm oil)
• Unsaturated fats - plant origin - seeds, nuts,
  and plant oils.
• Requirements - Not more than 30 of daily calorie
  intake should come from fat.

31
Nutritional Requirements

• Proteins
• Amino acids from dietary proteins are used to
  form new proteins such as enzymes.
• Can be used to supply energy.
• Sources include
• Meat, fish, poultry, cheese, nuts, eggs, cereal.
• We cannot synthesize 8 amino acids needed to
  build proteins, therefore we must get these from
  our diet. These are essential amino acids.
• Requirements
• About 0.8 grams per kilogram of body weight.

32
Nutrition Lectures

• http//oyc.yale.edu/psychology/psyc-123/lecture-3
  ch4          lecture 3, part 5
• http//www.thegreatcourses.com/tgc/special/Nutriti
  onFreeLecture.aspx