Proteins what are they

4. The word protein comes from the Greek "protos,"
which "reflects protein's top- shelf status in
human nutrition,"
What is protein? | Live Science

5. Proteins are large, complex molecules that play many critical
roles in the body. They do most of the work in cells and are
required for the structure, function, and regulation of the
body’s tissues and organs.
What are proteins and what do they do?:
MedlinePlus Genetics

6. highly complex substance that is present in all living
organisms. Proteins are of great nutritional value and
are directly involved in the chemical processes
essential for life.
Protein | Definition, Structure, & Classification | Britannica

7. Protein is a macronutrient that is essential to
building muscle mass. It is commonly found in
animal products, though is also present in other
sources, such as nuts and legumes.
What is protein? | Live Science

8. Protein is one of three macronutrients, which are
nutrients the body needs in larger amounts. The
other macronutrients are fat and carbohydrates.
Protein: Sources, deficiency, and requirements (medicalnewstoday.com)

12. According to the Dietary Guidelines for Americans 2015–
2020Trusted Source, a healthful eating pattern includes a
variety of foods containing protein. Both animal and plant
foods can be excellent sources of protein.

16. HOW MUCH PROTEIN DO YOU NEED
Anywhere from 10% to 35% of your calories should come from protein.
So if your needs are 2,000 calories, that’s 200–700 calories from
protein, or 50–175 grams. The recommended dietary allowance to
prevent deficiency for an average sedentary adult is 0.8 grams per
kilogram of body weight. For example, a person who weighs 165
pounds, or 75 kilograms, should consume 60 grams of protein per day.

17. Once you reach ages 40–50,
sarcopenia, or losing muscle
mass as you age, begins to set
in. To prevent this and to
maintain independence and
quality of life, your protein
needs increase to about 1–1.2
grams per kilogram or 75–90
grams per day for a 75-
kilogram person.

18. People who exercise regularly also
have higher needs, about 1.1–1.5
grams per kilogram. People who
regularly lift weights, or are training
for a running or cycling event need
1.2–1.7 grams per kilogram.
Excessive protein intake would be
more than 2 grams per kilogram of
body weight each day.

19. If you are overweight,
your weight is adjusted
before calculating your
protein needs to avoid
overestimating. You can
see a dietitian to help
develop a personalized
plan.

20. When is the best time to consume protein?
Spread out protein consumption evenly throughout the
day. On average, people tend to get most of their protein
during evening meals and the least at breakfast. Some
newer studies show moving some protein from supper to
breakfast can help with weight management by decreasing
hunger and cravings throughout the day.
General recommendations are to consume 15–30 grams of
protein at each meal. Studies show higher intakes — those more
than 40 grams — in one sitting are no more beneficial than the
recommended 15–30 grams at one time.

25. What Are Proteins Made Of?
Proteins are polymers, meaning they are large molecules made up of
many smaller molecules. The small molecules that make up proteins
are called amino acids.

27. Proteins fold into stable
three‐dimensional shapes, or
conformations, that are
determined by their amino
acid sequence. The complete
structure of a protein can be
described at four different
levels of complexity: primary,
secondary, tertiary, and
quaternary structure.

28. The most basic type of protein structure is called
the primary structure. A primary protein is a
simple, linear chain of amino acids (AKA a
polypeptide chain).

29. The secondary protein structure is made by folding of
the polypeptide chain. The polypeptide chain folds
up and hydrogen bonds form between the atoms of
the polypeptide chain, holding the secondary structure
in place.

30. A protein isn’t fully functional until it
has a 3D shape. The 3D structure of
a protein is referred to as its tertiary
structure and is made by
further folding of secondary
proteins.

31. Interactions between the side chains
of amino acids lead to the formation
of the tertiary structure, and bonds
form between them as the protein
folds. These include hydrogen
bonds, ionic bonds,
and disulfide bonds.

32. Disulfide bonds are covalent bonds
that form between sulfur-containing
side chains and are much stronger
than other types of bonds. The
disulfide bonds are what hold the
tertiary structure of the protein in
place.

33. Many proteins are made of a
single polypeptide chain and
don’t become any more complex
than their tertiary structure.
However, some proteins are
made up of multiple polypeptide
chains. When several
polypeptide chains
(AKA subunits) come together,
they can form a structure known
as a quaternary protein.

34. Classes of Protein Structure
The function of a protein depends heavily on its final
structure. Tertiary and quaternary proteins are
both functional proteins with a 3D structure. However, the
type of structure can vary significantly between different
proteins.
There are two main classes of 3D protein
structure: globular proteins and fibrous proteins.

35. Globular Proteins
Globular proteins are usually round and ball-
shaped. They usually have metabolic
functions, for example, they may
be enzymes or antibodies. Hemoglobin is an
example of a globular protein.

36. Fibrous Proteins
Fibrous proteins are long and narrow and usually have
a structural function. Examples of fibrous proteins
include collagen (found in bones, muscle, and skin)
and keratin (the material that makes up hair, nails, and
feathers).

37. What is Protein Denaturation?
Proteins are only functional so long as they keep
their 3D structure. If they are unfolded and lose their
shape, they will no longer be functional.
A protein will lose its 3D structure if the hydrogen
bonds that hold it together are broken.