Week 5 Flashcards
What are the roles of proteins?
- associated with stregnth and muscle
- wound healing
- structural role (matrix in bones) and functional role in cells (immune system)
What can excess meat result in?
high saturated fat intakes, as meat is one of the main sources of saturated fats
Sources of protein?
- milk
- eggs
- legumes
- many whole grains
- vegetables.
- fruit has almost NO protein
emphasis on protein, mainly meat, can be at the expense of other foods
What are proteins that are working molecules?
- enzymes
- antibodies
- transport vehicles (ex. hemoglobin is made up of a cluster of 4 proteins)
- hormones (ex. insulin)
- cellular “pumps” (what goes in and out of cell)
- oxygen carriers
Are all hormones proteins?
no
Where are proteins present for structure?
- tendons
- ligaments
- scars
- fibres of muscles
- cores of bones and teeth
- filaments of hair
- materials of nails
What is in a protein?
- made of carbon, hydrogen, and oxygen
- contain nitrogen
- some amino acids also contain sulphur
like fat and carbohydrates, they are made of carbon and hydrgogen and oxygen, but what differentiates them is that it contains nitrogen (makes different from the energy yielding ones)
What are proteins composed of (general)?
amino acids
How many amino acids make up most of the proteins of living tissue?
20
What is the structure of amino acids (the general one)?
- an amine group at one end -nitrogen containing part
- an acid group at the other end
- a distinctive side chain (side group) attached to the carbon at the center of the backbone (this is what gives the identity and chemical nature of each amino acid)
What are the side chains of amino acids?
- make the amino acids differ in size, shape, electrical charge
- some are negative, positive, some with no cahrge
- the charge will contribute to the shape of the protein
- long strands of amino acids form large protein molecules
- the side chains help to determine the molecules shape and behaviours
What are essential amino acids?
- amino acids that can not be synthesized at all by the body or can not be synthesized in sufficient amounts
- can’t make, comes from the diet
- can only be replenshed from foods
- body can not make proteins it needs to work without the essential amino acids
What are non essential amnio acids?
- can be made by the body
- can make it from fragements derived from carbohydrate or fat to form the backbones
- nitrogen from other sources
What are the essential amino acids?
- histidine
- isoleucine
- leucine
- lysine
- methionine
- phenylananine
- threonine
- trypotophan
- valine
What are conditionally indispensable/essential amino acids?
- amino acid that is normally nonessential
- when the need exceed’s the body’s ability to produce it, must be supplied by the diet
Where is aspertaine made from?
- amino acids
- what makes it differ from sugar is becuase is 200x sweeter than sugar
How does the body recycle amino acids?
- body breaks down proteins to reuse those amino acids
- protein turnover is about 300-400 g/day
- recycling system provides access to amino acids for energy when needed
How can cells use amino acids for energy when needed?
- tissues can break d own their own proteins in times of fuel or glucose deprivation
- working proteins are sacrificed
- most dispensible proteins used first
- structural proteins of certain organs are gaurded until t heir use is forced by dire need
What is a peptide bond?
- connects one amino acid to another
- formed between the amino of one amino acid and thr acid group of the next amino acid
- a condensation reaction
- forms a chain of amino acids with side chains bristling out from the backbone
What is the primary structure of a protein?
the chain of amino acids
what is the secondary structure of a protein?
- determined by weak electrical attractions within the chain
- positively charged hydrogens attracts nearby negatively charged oxygen
- selections of the chain may twist into a helix or fold into a pleated sheet giving proteins strength and stability
What is the tertiary structure of a protein?
- long peptide chains twist and fold into shapes
- side groups may attract or repel each other
- side groups may be hydrophillic or hydrophobic so chains fold accordingly
- hydrophillic: side groups are on the surface near water
- hydrophobic: side groups are hidden in the middle
- disulfide bridges also determine tertiary structure
- shape gives characteristics
What is the quaternary structures of a protein?
- interactions between 2 or more polypeptides
- some polypeptides work together in large complexes
- an example of this is hemoglobin
What is hemoglobin in regards to a polypeptide
- a large globular protein that carries oxygen is made up of four polypeptide chains
What are globular proteins?
water soluble, such as some proteins of blood
what are proteins that form hollow balls?
carry and store materials in their interior
What type of proteins are much longer than they are wide?
proteins of tendons
What is collagen?
- a protein from which connective tissues are made
- acts like glue between cells
- ex. tendons, ligaments, scars, and the foundations of bone and teeth
what is insulin?
helps regulate blood sugar
what is an enzyme?
- protein catalysts
What is sickle cell disease?
- inherited variation in amino acid sequence
- abnormal hemoglobin
- one amino acid in a critical position has been replaced by a different one
- it changes shape, so it changes the function of the protein
- there was an insertion of an amino acid that changes the shape of the protein and the function of it
- alters the protein so it is unable to carry oxygen
- red blood cells collapse from the normal disk shape into crescent shapes resulting in bad stuff
True or False: every human cell nucleus contains the DNA for making every human protein, but cells do not make every protein
true
What is denaturation?
- irreversible change in a protein’s shape
- can be caused by heat, acids, bases, alcohols
- important to the digestion of food protein
What do stomach acids do to a proteins structure?
open up a proteins structure (denaturation), this allows digestive enzymes to make contact with the peptide bonds and cleave them
What happens between digestion and proteins?
- certain acid tolerant proteins (many of which are enzymes), digest proteins from food that have been denatured by acid
- the coating of mucus secreted by the stomach wall proteins its proteins from attack by either acids or enzymes
- we also have pepsin in stomach for protein digestion
what is the usual acidity of the stomach?
2
What role does the stomach play in protein digestion?
- acid helps to uncoil the protein’s tsngled strands so that the stomach’s protein digesting enzyme can attack the peptide bonds
- pepsin works best in an acidic environment
- pepsin cleaves amino acid strands into polypeptides and a few amino acids
- lining is protected from acid and enzymes from mucus coating stomach cells
What is the role of the small intestine in protein digestion?
- recieves small denatured pieces of protein from the stomach
- most are polypeptides
- a few are single amino acids
- alkaline juices from pancreas enutralize the acid delivered by the stomach, pH to 7
- protein digesting enzymes (proteases) from the pancreas and small intestine continue breaking down the protein until nearly all that is left is dipeptides, tripeptides, or single amino acids