- Large molecules with many functions
- Our bodies contain thousands of different proteins
- Contain carbon, hydrogen, oxygen, and nitrogen
- Made of long strings of amino acids
There are 20 amino acids, 9 of them are essential; our bodies can’t make them and you have to
There are 11 non-essential amino acids; they are still important but our body can make them through transamination. • If there aren’t enough of all the essential AA’sIf there aren’t enough of ALL the essential AAs, your body can’t
• Complete proteins have all the essential AAs
• Incomplete proteins are missing some AAs
• Complementary protein = 2 sources of protein that together contain all the AAs
COMPLETE PROTEINS INCOMPLETE PROTEINS COMPLEMENTARY PROTEINS
Animal: meat, fish, poultry, eggs, milk. Grains: low in isoleucine and lysine Eating beans with grains
Plants: soy, quinoa Beans: low in menthionine and tryptophan provides all the amino acids.
HOW PROTEINS ARE MADE
Your body keeps a “pool” of amino acids; your DNA tells your
body how to string amino acids together to make proteins.
Transcription: RNA message, making a copy of your DNA.
Translation: creating the protein from the RNA message.
During translation, amino acids are attached with peptide
Dipeptide: 2 amino acids
Tripeptide: 3 amino acids
Ogliopeptide: a few
Polypeptide: a lot of amino acids Protein Shape
Different AA’s in the chain are attracted to each other; complex folding of the molecule. Folding determines the shape &
shape determines the function. One protein may contain several polypeptide chains.
Sickle Cell Anemia: genetic mutation that caused proteins that don’t work; one AA difference changes shape, and
function of hemoglobin.
Mouth: mechanical digestion
Stomach: acid denatures protein; pepsin breaks long proteins into smaller chunks and single AA’s; becomes unfolded;
denatured proteins don’t work, so you can’t take hormones/enzymes orally (unless they work before they hit acid, or
have special coating).
Small intestine: proteases break down remaining proteins into oligopeptides, tripeptides, dipeptides and amino acids;
peptidases break ogliopeptides, tripeptides, and dipeptides into amino acids; free amino acids, di- and tripeptides can be
absorbed into the intestinal cells; the cells break di- and tripeptides into AA’s.
A kilocalorie is the amount of energy it would take to increase the temperature of 1 gram of water by 1 degree Celsius
FALSE. Answer: calorie.
Aspartame: it is 200 times sweeter than sugar.
Review serving sizes!
Denatured protein: unfolded protein that doesn’t work anymore; happens in the stomach with the stomach acid; only
acid that can do this, and lemon juice.
October 12 th
WHAT DO PROTEINS DO
1) Cell growth, repair and maintenance:
- Many cell structures contain lots of protein; muscle, skin, bones, organs (liver, pancreas), blood cells; all need to
be replaced; muscles need the most protein; it allows them to contract (us to move).
- We recycle; old cells are broken down and we save the amino acids of the proteins to use again.
2) Act as enzymes and hormones
- Enzymes allow chemical reactions to happen; everything our body does involves chemical reactions
- Hormones send chemical signals in the body; protein hormones include:
Growth hormone, insulin, prolactin (stimulates breast milk production), gastrin (stimulates the
stomach), leptin (role in satiety and weight control).
3) Transport into and out of cells
- Facilitated diffusion
- Active transport
4) Transport in the blood
- Albumin: transports nutrients such as calcium, zinc and vitamin B6
5) Maintain fluid balance – Albumin
- Fluids are attracted to protein (diffusion – when you try to dissolve something in water, all particles will
distribute equally; in the body, fluids in the cell membrane will try to distribute the atoms evenly but the
membranes will not let the atoms move anymore; only water can move them).
- Balanced concentrations of protein are needed between the insides and outsides of cells in the blood - If not, edema (swelling of feet); when there is not a lot of protein in the blood and the water moves towards the
6) Maintains electrolyte balance; needed for muscle
and nerve function
- Main electrolytes: sodium and potassium;
cell have sodium/potassium pumps made of
protein to keep the balance.
7) Acid base balance
- Some proteins are good