Chapter 7 Protein Flashcards
What elements are protein made of?
Carbon, hydrogen, and oxygen. Some contains nitrogen and mineral sulfur.
What is the building block of protein?
Amino acid.
The structure of amino acid
A central carbon bonded with 4 groups of elements.
What are the four groups elements bond with the carbon?
Nitrogen(amino) group, acid (carboxyl) group, hydrogen, and a side chain(R)
How many amino acids does body need?
20 different animo acids.
Nonessential amino acids
11 amino acids that we do not need to get from food, because our bodies can produce them by other amino acids we consume.
Essential amino acids
The amino acid that body cannot produce, and we can only get from food.
Why body cannot synthesize essential acids?
Because body cannot make carbon skeleton, cannot attach the group to the carbon skeleton, or cannot do the whole process fast enough to reach the need.
Conditional Essential amino acid
Some nonessential amino acid will be classified as conditional essential amino acid during the infancy, disease, or trauma.
Transamination
The process of body synthesizing nonessential amino acids.
Transamination involves
One amino acid lose an amino group and form another amino acid. Eg. One acid donates an acid group to another amino group’s carbon skeleton to becomes a nonessential acid.
Deamination
One amino acid lose an amino group but does not transfer it to another amino acid.
The transportation of animo acids
The amino acids incorporated in the urea of liver, and transported in the bloodstream, and go into the kidney, and excreted in the urine.
When the amino acid breaks down
To amino-free carbon skeleton, it is used as energy or synthesized into other compounds, such as glucose.
Difference between animal protein and plant protein
Animal protein contains all 9 essential amino acids, but plant protein doesn’t.
Classification of dietary protein
Animal protein is complete protein. Plant protein is incomplete protein, because it contains amount limited 1 or more amino acids.
Limiting amino acid
The essential amino acid in smallest supply in a food or diet in relation to body needs is called the limiting amino acid. 木桶原理中的短板
Complementary protein
Two or more plant proteins combine together to compensate the deficiency of each protein.
Do complementary proteins eat in one meal?
No, but the protein should be balanced over a day to provide sufficient amino acid to body. For non vegetarians, it is better to have small amount of animal protein.
Peptide bond
—CO—NH— 肽键
Joining the body of peptide can form
dipeptide, tripeptide, oligopeptides(4-9 peptides), and polypeptides(10 or more)
What kind of protein is most in body?
Polypeptides, ranging from 50 to 2000 animo acids. Body can synthesize many proteins by joining different combinations of of amino acids with peptide bond.
Gene expression
The process determine the synthesis of protein in body.
When does gene expression begin?
It begins when the DNA replicate.
What is gene served as?
It is served as a template to guide the duplication of genetic info carried by DNA.
Structure of DNA
DNA is a double-stranded, helical form. Each strand contains four nucleotides核苷酸.
4 nucleotides
A (adenine), G(guanine), C(cytosine), T(thymine)
Relation between 4 nucleotides
They are bind to each other, A and T, C and G.
Codons
Sequence of 3 nucleotides per unit of instruction which dictate where the amino acids should be placed in a protein and in which order. These nucleotides units are called codons.(密码子)
How many codons do amino acids have?
Some amino acids have only one codon, whereas most of the amino acids have 6 codons.
What is the result of mistake order or type of amino acids?
Profound health consequences.
Where is the protein synthesis?
Ribosomes in cytosol of cells.