Chapter 5 book notes Flashcards
What does protein mean?
“of prime importance.”
Proteins help your muscles…
-contract, your blood to clot, and your eyes to see.
What cannot be built without proteins?
-no new living tissue
Without proteins, what would have no structure?
-bones, skin, and hair.
Proteins are chemical compounds that contain what atoms?
-hydrogen, oxygen, carbon , AND nitrogen.
The nitrogen gives what name to the amino acids that form the links in the chain of proteins?
-amino (nitrogen containing).
How many different amino acids appear in proteins?
-20
Amino acid strucure
-chemical backbone consisting of a single carbon atom with an amino group and acid group attached to it.
The linkage of what structure forms the protein?
-backbones
Side group of amino acid
-varies from one amino acid to another
-makes the amino acid differ in size, shape, and electrical charge.
-makes them distinguishable compared to carbs and lipids.
Dipeptide
-two amino acids bonded together
tripeptide
-3 amino acids bonded together
Most proteins contain how many amino acids?
-few dozen to several hundred amino acids long.
What determines a protein shape?
-the amino acid sequence of a protein determines the way the chain will fold.
-each amino acid has special characteristics that attract it to, repel it from, the surrounding fluids and other amino acids.
What determines the function of a protein?
-the different shapes of proteins enable them to perform different tasks in the body.
Protein shape & corresponding function:
-globular protein=
-hollow balls=
-stiff, sturdy, rodlike protein=
-hemoglobin
-carry and store materials within them
-form tendons (more than 10x long as they are wide)
How many highly folded polypeptide chains form globular hemoglobin protein?
-4
Nonessential amino acids
-more than half of amino acids are this.
-body can make these amino acids
-“dispensable”
essential amino acids & name them
-9 amino acids that are not made within the body and need to be given to by food.
-“indispensable”
-HILLMVPTT
EX of a nonessential amino acid becoming essential
-body normally makes tyrosine from the essential amino acid phenylalanine.
-if diet fails to supply phenylalanine or make conversion to tyrosine than it becomes a conditionally essential amino acid.
Do proteins in foods directly become body proteins?
-NO
-food supply’s the amino acids from which the body makes its own proteins.
Digestion of proteins in foods:
-when a person eats food with protein, enzymes break the long polypeptides into tripeptides and dipeptides and finally the tripeptides and dipeptides are broken down to amino acids.
Protein turnover
-the continuous breakdown and synthesis of body proteins involving the recycling of amino acids
Amino acids must be continuously available to build?
-proteins of new tissues
new tissues include:
-an embryo
-in muscles of an athlete in training
-a growing child
-in scar tissue that heals wounds
-new hair & nails
Less obvious building of new tissues include:
-replacing worn out cells and internal cell structure
EX: intestinal tract cells live for 3-5 days and then shed off so they must be replaced AND cells of skin die and rub off, and new ones grow from underneath
What happens when a protein breaksdown? (2 things can happen)
-the amino acids are recycled into other proteins
-the amino acid will be stripped off of its nitrogen and used for energy.
About how much of the body’s available amino acid is broken down & used for energy?
a quarter.
What do researchers use to estimate protein requirements?
-nitrogen balance studies
Nitrogen equilibrium
-when nitrogen intake equals nitrogen output
-“zero nitrogen balance”
Positive nitrogen status
-the body synthesis more than it degrades
-nitrogen intake exceeds nitrogen output
-protein is being retained in new tissues as they add blood, bone, skin, and muscle to their body.
Who is usually nitrogen positive?
-growing infants
-children & adolescents
-pregnant women
-and people recovering from protein deficiency or illness.
Nitrogen negative status:
-body degrades more than it synthesizes
-nitrogen output is greater than input
-body loses nitrogen as it breaks down muscle and other body proteins for energy.
Who is usually nitrogen negative?
-people who are starving
-or suffering other severe stresses such as burns, injuries, infections, and fever.
What distinguishes human beings chemically different from one another?
-minute differences in particular body proteins (enzymes, antibodies, and others).
the minute differences are determined by what?
-our proteins amino acid sequences, which are written into the genes inherited from our parents and ancestors.
What directs the making of all the body’s proteins?
-our genes
How many genes does the human body have?
-more than 20,000 genes
Where is most of the body’s protein found?
-in muscle tissue, which allows the body to move.
-the amino acids of a muscle protein can be released when the need is dire, as in starvation.
Functions of proteins (8)
1)structural components
2)enzymes
3)transporters
4)fluid & electrolyte balance
5)acid-base balance
6)antibodies
7)hormones
8)energy & glucose
Enzymes
-catalysts essential to all life processes.
-facilitates special chemical reaction, but enzyme remains unchanged (LOOK AT FIGURE 5-4)
Proteins as enzymes:.
-proteins facilitate chemical reactions
-enzymes put amino acids together to make needed proteins (proteins make other proteins).
Proteins as transporters:
-large group of proteins specialize in transporting other substances such as lipids, vitamins, and minerals around the body.
Two examples of proteins being transporters:
1)the protein hemoglobin transports oxygen from the lungs to the cells
2)lipoproteins transport lipids in the watery blood
3 major body compartments that contain the body’s fluid:
1)fluid inside blood vessel (intravascular)
2)fluid inside cell (intracellular)
3)fluid in between cells, outside of blood vessels (interstitial or intercellular)