Test 2 Flashcards
How are proteins formed?
Amino acids link head-to-toe (amino group to carboxyl group)
This bond releases water
What are the 4 levels of structure in a protein?
Primary- type of amino acids
Secondary- winding pattern of chain
Tertiary- the way the chain folds and bends 3 dimensionally. Most properties come from this level
Quaternary- uncommon, two or more chains joining together like snakes
What is denaturation?
Loss of secondary, tertiary, or quaternary structure
Caused by heat, acids & bases, enzymes, UV light
What are some key characteristics of proteins?
Large
Can be conjugated with other organic molecules (lipoproteins, glycoproteins, etc)
High specificity- making them immunogenicity and easy to detect
Maintains pH (buffer)
Do proteins dissolve well?
No, they are colloidal because they have a charge as well as a water pocket surrounding them
Solubility can be altered by ph, ionic strength, temperature, and dielectric constant
What are ampholytes?
Compounds with both acid and base (dipolar)
What is an amphoteric compound?
Compounds which behave as an acid and a base concurrently
What is a zwitterion?
Characteristic pH for each AA where positive charge and negative charge are equal
(Occurs at isoelectric point)
What are the implications of zwitterions?
When put in basic solution, charge will be negative
When put in low ph, charge will be positive
What are the main functions of proteins?
Structure, enzymes, hormones,electrolyte/water balance, transport, defence, energy, coagulation. Buffer
What is salts effect on proteins?
High salt concentration- less water avian able for protein, stronger protein-protein bond, weaker protein-water bond (salting out)
Salting in is opposite
How do organic solvents (alcohols etc) affect solubility of proteins?
Alcohols and other organic compounds bind to water, so protein can’t
What is important about protein metabolism?
They are too big for us to use upon eating them , must be broken down
What happens with excess proteins?
Stored in nitrogen pool after being converted into biologically useful molecules
What is the process of protein digestion?
In stomach, pepsinogen (excreted by chief cells) meets HCl and becomes pepsin
Pepsin begins protein breakdown and converting even more pensinogen (autocatalysis)
In small intestine, proteolytic enzymes break down proteins into amino acid
Amino acids absorbed in small bowel to portal vein
What is protein synthesis
Formation of tissue proteins, enzymes, hormones, antibodies, and plasma proteins from amino acid pool
What is decarboxylation
Loss of CO2 from an amino acid
Generates an amine which can be used to form non-protein nitrogen compounds (like nucleic acids)
What is deamination?
Oxidative- splitting off of amino group from amino acid- forming ketone acid and ammonia
Transamination- reversible transfer of amino acid group from amino acid to keto acid
Ammonia from deamination
Product of oxidative
Toxic in high concentrations- CNS disruption
Removed by the ORNITHINE cycle- ammonia to urea (in liver)
Liver damage- difficulty converting ammonia to urea
Normal serum protein level
60-80g/L
Five major serum proteins
Alpha 1 globulins- 1-4 g/L (LIVER)
Alpha 2 globulins-4-8 g/L (LIVER)
Beta globulins- 5-10 g/L (LIVER)
Gamma globulins- 6-13g/L (bone marrow)
Albumin- 35-47g (tiny) (LIVER)
Fibrinogen- only in plasma 2-4.5 g/L (LIVER)
AG ratio
Number obtained when total albumins divided by total globulin
Hypoproteinemia and hyperproteinemia
Hypo- under 60
Hyper- over 80
Are serum proteins positive or negative?
Negative in blood
What are the two types of AA abnormalities?
Overflow(primary)- renal threshold exceeded
Renal type- defects in kidney cause release of AA
Methods of protein measurement
Immunochemical- antibodies
Elecrophoresis- proteins carry charge
Quantitative
Mass Spectrophotometry and ultraviolet absorption
Specimen requirements protein
Non hemolyzed, cell free serum, urine OR CSF
Stored 2-8 for up to 3 days
Biuret method
Under high pH copper binds with nitrogen in proteins, making red colour
550 nm
Needs di peptide structure and three amino acids (no albumin)
Not sensitive enough for CSF or URINE
Lipemia, hemolysis, bilirubin interfere
More peptide bonds= darker colour
Do biuret methods require fasting?
No, but lipemia may occur
Normal urine protein values
Per day- 50-80mg
24hr- 10-140 mg/l
CSF value is 15-45mg/dL
Scattered light methods
Used for small concentrations
Uses turbidity (based on light scattered by beam)
Must be precipitated before measurement
Not usually done on urine
Advantages and disadvantages of turbidimetric methods
Can detect low levels (250-900mg/L)
Measures turbidity from every source
Refractometry
Protein changes direction of light
Measuring total solids, not just proteins
Not sensitive (only over 35g/l)
Not specific
Used solely for serum
Dye binding
May be sued for serum, urine, and CSF
PH of solution used for albumin makes it positively charged, dye is negatively charged to attach
Urine dipsticks
Most tests adhere to albumin because it’s positive
Can get false positive from other proteins, or chemical interference affecting pH of urime
False negatives if acid has been added to preserve
Identification of specific proteins
Ultracentrifuge- arranges them by size
Immunochemical- specific antibodies
Chromatography-
Salting out- can separate albumin from globulins
Dyes
Electrophoresis- most common
What are proteins
Organic substances only soluble in non-polar substances
Main functions of fat
Energy (9.3 calories/g)
Insulation
Neurological conductor
Steroids
Membrane formation
Can be adipose or working lipids(tissue)
Major lipids of body
Triglycerides, cholesterol, phospholipids, glycolipids
What are the two classifications of lipids?
SIMPLE CHO
Neutral fats and triglyceride
Triglyceride- glycerol and 3 fatty acids
If 3 same- simple trig, if 3 different, mixed trig
COMPOUND CHO and others
phospholipids, glycolipids, etc
Lipoprotein
Hydrophobic core of trig or chol surrounded by phospholipids, chol
B/c can’t be freely in plasma
Chylomicron
Specific lipoprotein that transports from small intestine to tissues (very small)
Atherosclerosis
Yellow plaque buildup of lipids in medium and large arteries
Cholesterol
Essential component in lipid metabolism
We consume this
Triglyceride
Simple lipid made of three fatty acids estrogen into glycerol
Why are lipids important
Necessary for transporting energy around the body
Lipid metabolism
Mostly digested in small intestine
Emulsified in stomach
Mixed in small intestine with bike from liver which emulsifies and activated lipase
Lipase secreted by pancreas
Fats transported as small water soluble fragments liver and tissues via lymph and blood
Lipids can also be formed by carbs and proteins
Livers role in fat digestion
Releases bile for fat emulsification
What are chylomicroms
Responsible for lipemia
Transport fat from gut to adipose, liver, and muscle
Lipid metabolism for energy
Fatty acid spiral- beta oxidation to remove two carbons and produce ATP
Excess ketones
Acidosis can occur if happening too fast
Occurs b/c low carbs
What is cholesterol
Steroid alcohol
70-80% esterified (one fatty acid molecule)
20-30% free
Used to manufacture and rapid membranes, produces bile acids
Transports fats as wax, helps with muscle contraction
How does cholesterol enter body
In animal products
Some absorbed by intestine
Liver synthesizes, estrified, and converts cholesterol into bile acids
Liver damage decreases chol level
Transported around body as lipoprotein
What are the 4 types of lipoproteins
HDL- high dENSITY
LDL- low density
IDL- intermediate density
VLDL- very low density
Cholesterol levels
1-30 years 2.6a5.2 mmol/l
Over 60. Less than 6.2
Newborns- 1/3
What are causes of abnormal serum cholesterol
Familial hyperlipoproteinemia- hereditary
Postmenopausal- low estrogen
Jaundice
Hypothyroidism
Low cholesterol may be due to liver disease, hyperthyroidism
VLDL
Very bad
Right in trig
More fat than protein
LDL
Bad
Contains most cholesterol (50%)
Transports cholesterol from liver to tissues
High association with CHD
HDL
Smallest of lipoproteins
Made by liver and intestine
Takes away excess chol and returns to liver
Types of atherosclerosis
Peripheral vascular disease- arms or legs
Coronary artery disease- heart
Cerebrovascular disease- brain, stroke
How does plaque buildup happen?
Small vessel injuries occur normally, Lola brings cholesterol For repair, cells accumulate below endothelial layers
Primary atherosclerosis causes
Genetics
Hypertension- extra pressure on arteries
Smoking- increases LDL
Elevated total cholesterol
Decreased HDL
Secondary atherosclerosis causes
Lack of exercise
Obesity
Male
Age
Stress
Diabetes mellitus
Gout
Renal failure
Lipid testing method
Measures triglycerides
Cholesterol
Lipoproteins
SHOULD BE FASTING for trig and chol
CALLED LIPID PROFILE (serum)
Can all cholesterol be measured?
No, esterified chol (70%) must be converted to free in order to be measured
Thus, takes 3 enzyme steps
Cholesterol esterase- converts to esters
cholesterol oxidase
Peroxidase- colour
What are fecal samples used for?
Detection of decreased pancreatic function
Steatorrhea- increased fat in feces 2-6g
What is uric acid
Product of breakdown of adenine and guanine
What are two forms of uric acid
Blood- URATE
Below 6.0- URIC ACID
Uric acid can form crystals- kidney stones
What is reabsortbtion of URATE back into blood l
98- 100%
Issue with uric acid
Overproduction- increased cell breakdown
Decreased renal excretions- kidney disease
Congenital enzyme deficiencies
Gout- buildup of crystals in joints
