Medical Biochemistry I-Exam 1

What stabilizes higher order structures in proteins?

  1. electrostatic attraction of charged residues (salt bridges/repulsive effects)
  2. internal H-bonding (specific distance and angle requirements)
  3. short range Van der Waals interactions and London dispersion forces of neutral charged residues
  4. entropy driven hydrophobicity (Gibbs free E change)

Amino Acids that are likely to carry charges on side chains at neutral pH

aspartic acid, glutamic acid, tyrosine, cysteine have negative charges

 

lysine, arginine, and histidine have positive charges

Zinc fingers, kringle domains, and leucine zippers are

Zinc fingers

 

loop of 23 AA resulting from Zn ion being complexed to 4 AA, usually cysteines and histidines

 

Kringle domains

 

conserves seq that fold into large loops that are stabilized by 3 disulfide linkages. Impt in protein-protein interactions with blood coag factors.

 

Leucine Zippers

 

arrangments of leucines along one side of an alpha-helix btwn 2 proteins, so that protein can form dimers leaving basic AA regions to bind DNA

Ways Proteins Can Be Denatured

 

  1. detergents = straightens out protein (Na dodecyl sulfate makes peptide rodlike
  2. chaotropic agents – remove water to unsolubilize protein
  3. high temps (50-60 degrees C or higher)
  4. drastic pH changes
  5. organic solvents

Hydrophobic Effect
when hydrophobic regions of protein in tertiary structure are moved inward and hydrophilic regions outward
In which human organ is myoglobin (Mb) most impt?
heart b/c rapid O2 supply needed
Explain causes and importance of right shift in Hb/O2 binding curve

right shift caused by:

 

decreased pH (increased [H+])

 

increased [CO2]

 

increased [2,3-BPG]

 

increased temperature

 

all factors lead to increased O2 unloading which means that a higher percentage of O2 is delivered to tissues

In Hb, how does binding of first oxygen molecule affect binding of next ones?

Deoxy Hb is usually in taut (T) form where heme groups restricted and hard for O2 to bind

 

When O2 binds to 1st heme group, the Fe of that heme will shift and pull attached his along.

 

Movement breaks salt bridges pushing Hb into relaxed (R) state and allow more O2 binding sites to become available

 

 

What is Bohr effect?

A right shift when pH decreases (increase in H+ conc.)

 

O2 release from Hb will increase when pH is lowered or [CO2] is high

 

Hb has decreased O2 affinity

 

Raising pH or decreasing [CO2]-shift curve to left

Physiological importance of cooperativity in Hb function
Hb has 4 subunits where binding of O2 at one heme group increases the affinity for O2 of the other heme groups in the same molecule
Compare behavior of Mb and Hb with respect to O2, CO2, and H+

Mb has a greater affinity at lower [O2] than Hb

 

Hb can transport more molecules of O2 b/c of cooperative effect of multiple binding sites

 

Hb can’t readily bind 1st O2, but once it does has higher affinity for O2 at other sites

;

Hb-sigmoidal curve

;

Mb-hyperbolic

;

Hb responds more readily to small changes in partial pressures of O2

;

Mb saturated quicker than Hb at low partial pressure of O2 (doesn’t have much flexibility)

How does protein (globin) portion of Mb or Hb affect reactivity of heme?

weaken strength of heme-O2 interaction. Heme binds O2 so strongly it can convert it to a superoxide anion, which can be an unwanted oxidizing agent

 

prevents interaction of oxy-heme groups with other oxy-heme groups

How and where does 2,3-BPG interact with Hb?

2,3-BPG binds to deoxy Hb-makes it more stable and resistant to oxygenation after O2 delivery

 

negative charge allows BPG to bind to a site between two alpha chains

 

causes right shift in O2-dissociation curve (increase O2 release)

Where does 2,3-BPG come from?
product of glycolytic pathway
How does fetal Hb (HbF) differ from HbA?

Fetal Hb has two gamma chains instead of beta chains.

 

2,3-BPG can’t bind to fetal Hb and it has greater affinity fo O2 and takes O2 from maternal Hb

;

HbF is left shifted on O2-dissociation curve compared to maternal Hb

;

;

What does Hill Eqn describe?
importance of cooperativity
How does NO interact w/ Hb and what is physiological significance of that interaction?

Hb binds NO at heme Fe and cys residues in globin chain.

;

NO relaxant for vascular smooth muscle

;

Hb can pick up NO, stiffen vascular tissues, and increase BP

;

NO is strong vasodilator so Hb can be used to mediate vascular tone

What is difference btwn HbS and HbA?
HbA has normal beta chain while HbS has sickle cell hemoglobin. 6th AA for normal beta globin would be a glutamic residue but in HbS that Glu is replaced with a Val. Val is uncharged and allows hydrophobic pockets. The chains bind together and crystallize
Physiochemical/Pathological Basis for All Clinical Manifestations of Sickle Cell Disease

crystallization and stiffening of Hbs causes them to adhere to the endothelium and often obstruct small vessels (capillaries) or cause hemolysis

;

hemolysis can cause anemia and hyperbilirubinemia, causing pallor and jaundice

;

Complete vasocclusion can cause ishemia or infarction resulting in organ damage

;

Stroke, infection and excrutiating pain can result

How is Sickle Cell Disease Inherited?
recessive disorder. Only homozygous HbS cause the disease to become expressed.
What is an enzyme?

a protein catalyst for specific biochem rxns.

;

It will not undergo chem rxn itself and can be reused for other rxns

What does enzyme effect and not effect in rxn?

;

;

Enzymes reduce activation energy.

;

Keq and delta G are not affected by enzymes.

Name and describe 2 models used to describe enzyme specificity and/or catalytic activity

lock and key model

;

describes an enzyme active sites (lock) being specific for binding substrate (key)

describe specificity

;

induced fit model

;

active site will conform to fit substrate

describes specificity and catalytic activity

What is prosthetic group?

non-protein organic molecule that is tightly bound to enzyme active site

;

ex-heme, biotin, or flavin

;

holoenzyme-prosthetic group attached

;

apoenzyme-prosthetic group NOT attached

Name 6 Classes of Enzymes

oxidoreductases-catalyze RED/OX reactions

Ex-H+ donor to substrate


transferases-transfer group from one molecule to another

Ex-phosphorylases


hydrolases-hydrolytic cleavage of bond

Ex-peptide bond cleavage


lyases-cleave bonds w/o water to leave double bond or addition of other groups to double bond

Ex-decarboxylase


isomerases-change geometry of molecule

Ex-cis-trans isomerase


ligases-join 2 molecules together though hydrolysis of high energy bond

Ex-carboxylase

What is Michaelis-Menton Eqn and what do terms mean?

V = Vmax[S]/(Km+[S])

;

V – velocity of rxn

Vmax – max rxn velocity

[S] – substrate concentration

Km – constant value for a specific substrate

;

In a Michaelis-Menton plot, where is Vmax and how do you find Km?

Vmax – when [S] is very high

;

Km – [S] when V = 1/2(Vmax)

A Lineweaver-Burk plot is also called a ———
Double-reciprocal plot
What is plotted on Lineweaker-Burk plot and what are the x- and y-intercepts of the plot?

The LB graph plots the inverse of the Michaelis-Menten plot, which is 1/V on the y-axis and 1/[S] on the x-axis

 

x-intercept – 1/Km

 

y-intercept – 1/Vmax

What are advantages of the Eadie-Hofstee plot?
The E-H plot gives more evenly spaced data points than the  L-B plot.
What characteristics distinguish a competitive inhibitor from the other types of inhibitors?

bind directly to the active site and can be overcome by increased [substrate].

 

Other inhibitors bind to other sites on enzyme

On the Lineweaver-Burk plots are the vertical or horizontal intercepts the same or different for competitively inhibited rxns?

same y-intercept

 

different x-intercepts

On the Lineweaver-Burk plots are the vertical or horizontal intercepts the same or different for non-competitively inhibited rxns?

different y-intercepts

 

same x-intercepts

On the Lineweaver-Burk plots are the vertical or horizontal intercepts the same or different for uncompetitively inhibited rxns?

different y-intercepts

 

different x-intercepts

What does inhibitor react with for competitive inhibition?
active site of the enzyme
What does inhibitor react with for non-competitive inhibition?
react with enzyme to reduce its effectiveness to bind w/ substrate
What does inhibitor react with for uncompetitive inhibition?

bind with ES complex.

 

irreversible inhibitors.

Sigmoid V versus [S] plot and curved Lineweaver-Burk plots indicate
allostery and positive cooperativity of the enzyme (n = 2)
What factors determine the amount of enzyme activity in serum?

amount of tissue producing enzyme

 

rate of enzyme released

 

rate of enzyme inactivation/elimination from plasma

Define: Standard International Unit (SIU)
1 standard international unit of enzyme activity converts 1 μM of substrate/minute
2 most commonly measured serum aminotransferases and describe rxns they catalyze

Aspartate aminotransferase (AST) – catalyzes exhange of amino group between alpha amino acids (aspartate) and alpha keto acids

 

Alanine aminotransferase (ALT) – catalyzes exchange of amino group between alpha amino acids (alanine) and alpha keto acids

In which pathological states are the two most commonly measured serum aminotransferases elevated?

AST – liver damage and myocardial cells,hemolysed blood

 

ALT – liver damage

Reaction catalyzed by γ-glutamyltranspeptidase and how it is used diagnostically?

Glutathione + amino acids → γ-glutamyl-amino acid + cys-gly

 

γ-glutamyltranspeptidase found in kidney, intestine, liver, and fetal tissue

 

GGT levels are elevated and very sensitive in liver damage

 

2 commonly measured phosphatases and how are they used diagnostically?

Alkaline phosphatase (ALP)

 

Hydrolyzes phosphate groups from organic monophosphate at pH~9

Found in liver, bone, intestine, and placental tissue

Elevation of ALP means damage to liver and bone tissue

Elevated in gowing children, bone fractures, and pregnant women

 

Acid Phosphatase

 

hydrolyzes phosphate groups from organic monophosphates at pH~5

 

found in prostate, platelets, and erythrocytes

Elevation found in metastatic prostate cancer and hemolysed blood samples

 

 

Diagnostic utility of LDH
Used to detect MI and hemolysis
“flipped” LDH

Most common form is LDH2 (HHHM)

 

After MI or hemolysis, LDH1 (HHHH) predominates causing a “flipped” LDH b/c LDH1>LDH2

What reaction does LDH catalyze?

Lactate + NAD → pyruvate + NADH + H

 

interconversion of pyruvate and lactate

Another name for alpha hydroxybutyrate dehydrogenase (HBD)?

 

 

LDH1
What does elevated serum HBD mean?
damage to myocardial cells due to recent MI
Reaction catalyzed by CK (CPK)
creatine phosphate + ADP → Creatine + ATP
Diagnostic meaning of elevated serum CK

has 2 subunits, M and B

 

MB-MI or brief ischemia

 

MM-vigorous exercise, injection, convulsions

 

BB-neural tissue damage

Diagnostic significance of elevated serum amylase

pancreatitis

 

morphine

Reaction catalyzed by serum amylase

starch + H2O → maltose, maltotriose & limit dextrins

 

digest starch

Elevated serum lipase means

pancreatic pathology

 

morphine

Reaction catalyzed by serum lipase

trigylceride + H2O → fatty acids + glycerol

 

fat digestion

What are troponins and how are they used in diagnosis?

proteins that function in the contractile apparatus of the muscle

 

Cardiac troponin I is increased in plasma 3-6 hours after MI

Serum Enzyme Levels in crush injury

mildly elevated alkaline phosphatase (healing bone)

 

elevated creatine kinase MM (skeletal muscle)

Serum Enzyme Levels in vigorous exercise
elevated creatine kinase MM (skeletal muscle)
Serum Enzyme levels in morphine injection
elevation of serum amylase and lipase
Serum Enzyme Levels in pregnancy

mildly elevated alkaline phosphatase (bone growth)

 

elevated GGT

Four Categories of Cell Adhesion Molecules

integrins

 

immunoglobulin superfamily

 

cadherins

 

selectins

Which of the CAM categories would be actively involved in transmitting signals from the inside to the outisde of the cells and vice versa?
integrins
What CAM category is involved in adherens junction between cell?
cadherins
Abbreviations for 3 types of adhesion molecules of Ig suberfamily and tell their origins

NCAM – neural cell adhesion molecule

 

PECAM – platelet-endothelial cell adhesion molecule

 

VCAM – vascular cell adhesion molecule

 

Named for their similarity in structure to the Igs

4 Diseases in which CAMS are involved

Rheumatoid arthritis – overexpression of VCAMs

 

Psoriasis – form of an integrin

 

Pemphigus vulgaris – autoantibodies interacting with desmoglein

 

von Willebrand disease – expression of P-selectin

Describe alpha-helix
tightly coiled, stabilized by H bonding btwn imido groups and oxygen of carbony groups, many helices (3.6 AA/turn)
Beta sheet

regions of same chain or neighboring chains bond to each other w/ H bonds, the H bonds are perependicular to the long axis of the chain

 

most stable conformation – antiparallel sheets (one side N→C other side C→N

Beta turns

H bonding of AA 3 sequences apart in same chain

 

results in U turn bend of chain

What AA usually phosphoylated in proteins?

ser

 

thr

 

tyr

Commonly occurring modification of AA found in some proteins

acetylation of N terminus

 

carboxylation – add COOH

 

hydroylation – add OH

 

glycosylation – add glucose

 

phosphorylation – add phosphate group

 

disulfide linkages

Primary Structure
AA sequence
Secondary Structure

alpha helix

 

beta-pleated sheets

 

beta-turns

 

random coiling

 

results from free roation of bonds besides peptide bonds

Tertiary Structure

secondary structures fold on each other

 

hydrophobic – inside

hydrophilic – outside

Quarternary Structure
multiple polypeptide chains interact by noncovalent bonds to form single structure
General Solubility Prop. of Proteins

fibrous and insoluble

 

globular and soluble

 

firbrous and soluble

Functions of Proteins

structural roles

 

enzymes

 

role in contractile structures

 

transport (Hb)

 

hormones

 

receptors

 

Abs

What are proteins and peptides made of?

peptides – moderate chain length polymers of amino acids joined by peptide bonds

 

proteins – polymeric compounds composed of AA joined by peptide bonds

What is unique about peptide bond?
it is rigid b/c tautomerism
In ABO blood group, where is difference in oligosaccharide located and how sugars different?

due to presence or absence of N-acetyl-galactosamine or galactose linked to penultimate galactose by C1-C3 linkage

 

1 sugar difference

Glycosaminoglycans and 2 Ex

unbranched polysacc w/ repeating disacc – one is AA, other is uronic acid

 

Ex – hyaluronic acid and heparin

3 Impt Disacc and which alpha or beta linked?

maltose – alpha linked

 

sucrose – alpha linked

 

lactose – beta linked

3 Most Impt polysacc and what are linkages? Why is linkage impt?

starch – alpha linked (spiral)

 

glycogen – 2 types – alpha C1-C4 (linear)

                                 alpha C1-C6 (branched)

 

cellulose – beta linked (linear)

 

alpha and beta linkage affects the shape of the compound and humans can’t digest cellulose b/c beta linkages

What is glycoside?

anomeric -OH group of sugar reacts w/ another -OH compound

 

 

aglycone
compound that attaches to anomeric C of sugar
Name and describe 2 commonly found mod. of sugars

amino sugar – -OH group replaced by amino group

Ex – glucosamine, galactosamine

 

deoxy sugar – 1 OH group replaced by H

Ex – 2-deoxyribose

2 conformation of 6-membered rings
boat and chair
What is mutarotation and where does it take place?

configuration changes in molecule by ring opening and closing

 

occurs at anomeric C

Pyran and furan are named after which sugar structures and how many Cs are in each?

pyranose – 6 C ring

 

furanose – 5 C ring

Most Impt Monosacc and Polysacc made up of this monosacc

glucose – most impt monosacc

 

Polysacc made up of glucose – starch

                                             cellulose

                                             glycogen

What are aldoses?
monosaccharides w/ aldehyde group
What are ketoses?
monosaccharides w/ ketone group
What are carbohydrates?
polyhydroxy aldehydes or ketones or compounts that can by hydrolyzed to these
Two Ex of Differences Between Identical Twins that Illustrate that Environment plays a role in development and health

fingerprints are different of two twins – different positions in womb

 

type I diabetes – if one gets, less than 1/2 the time other twin gets

What percentage of live births suffer from a disease causing monogenic defect?

 

1/100 or 1% of libe births suffer from a monogenic defect
What percentage of live births suffer from a disease-causing chromosomal abnormality?
1/1000 or 0.1% of live births suffer from a disease-causing chromosomal abnormality
How many of the chromosomes are X chromosomes?

normal female – 2 X chromosomes

 

normal male – 1 X chromosome

How many chromosomes are Y chromosomes?

normal female – 0 Y chromosomes

 

normal male – 1 Y chromosome

How many of the chromosomes are considered autosomes?
44 (22 from father, 22 from mother)
What is an autosome?
a chromosome that is not a sex chromosome
4 trisomies for which live birth are possible

trisomy 13

 

trisomy 18

 

trisomy 21

 

trisomy X

 

XYY

Which of the 4 trisomies produces mild to undetectable symptoms?

trisomy XYY

 

trisomy XXX

Which trisomy is otherwise known as Down’s syndrome?
trisomy 21
What is XYY syndrome?

tall

 

other mild symptoms

What is Klinefelter’s Syndrome?

male

 

testicular failure

 

can’t conceive

What is Turner’s Syndrome?

X-

 

sexually immature

 

short

 

web neck

 

phenotypically female

How does x-linked disease inheritance differ from inheritance of an autosomal disease?

lack of male to male transmission

 

gender-dependent

 

x-linked gene comes from mother on X chromosome only, but can affect both males and females, through mostly males show disease

 

autosomal come from chromosomes other than sex chromosome

How does inheritance of a mitochondrial disease differ from the inheritance of an autosomal disease?

An autosomal disease passes on one allele from the mother and one allele from the father

 

A mitochrondrial disease has only one allele from the female/mother only and all offspring will show some degree of the disease

Which will probably have greatest number of offspring who suffer from an inherited disease (may be more than one):

 

A. parents both heterozygous for autosomal recessive disease

 

B. parents both heterozygous for an autosomal dominant disease

 

C. a father who suffers from an X-linked recessive disease and a mother who is homozygous wild type (has only well type of disease gene)

 

D. a mother who is heterozygous for an x-linked recessive disease and a father who is wild type hemizygous (has the well form of that disease gene)

 

E. a father who suffers from a mitochondrial disease and a mother who does not at all have it

 

 

B. parents both heterozygous for a dominant disease will have greatest # of offspring

Of these, which will probably have the least number of offspring who suffer from an inherited disease (may be more than one):

 

A. parents both heterozygous for autosomal recessive disease

 

B. parents both heterozygous for an autosomal dominant disease

 

C. a father who suffers from an X-linked recessive disease and a mother who is homozygous wild type (has only well type of disease gene)

 

D. a mother who is heterozygous for an x-linked recessive disease and a father who is wild type hemizygous (has the well form of that disease gene)

 

E. a father who suffers from a mitochondrial disease and a mother who does not have it

 

 

E. a male who suffers from mitochondrial disease and a female who does not

 

C. a father who suffers from an x-linked recessive disease and a mother who is homozygous wild type (has only well type of disease gene)

Explain how penetrance might mean that individuals with disease symptoms might not be observed in a pedigree
Just because genotypically the person has the disease doesn’t mean they express it phenotypically

Genotype?

 

Phenotype?

genotype-genetic makeup

 

phenotype-physical manifestation

How does penetrance affect onset of hereditary hemochromatosis?

used to be thought rare

 

now known as the most common hereditary disease in the USA

What environmental factors affect the onset of hereditary hemochromatosis?

gender – females under 50 not have disease (menstrual cycle expels excess iron)

 

blood donations

 

diet – not enough Fe normally and you make most of Fe intake

 

alcohol consumption

 

environment

Why does an X-linked disease such as Duchenne muscular dystrophy seldom cause symptoms in females?

X-inactivation and that males with the defect do not reproduce.

 

Females need both x’s to be defective in order the x-recessive diseases to show

 

females have two x’s

A newly inherited disease has been discovered in which the disease ocuurs only when the defect is inherited from the father. The disease gene has what pattern of genetic inheritance?
imprinted
Which is meant by “a genetic disease is never inherited”?
A defect that if inherited would prevent the survival of the fetus and/or prevent reproduction of the fetus
What disease is a genetic disease in which the mutations that cause it often occur after birth?
cancer
Tay Sachs inheritance type
autosomal recessive
cystic fibrosis inheritance type
autosomal recessive
sickle cell anemia inheritance type
autosomal recessive
Huntington disease inheritance type
autosomal dominant
hereditary hemochromatosis type of inheritance
autosomal recessive
Duchenne muscular dystropy inheritannce type
x-linked (recessive)
familial hypercholesterolemia inheritance type
autosomal dominant
Leber’s hereditary optic neutopathy type of inheritance
mitochondrial
genetic defect in Huntington disease

a triplet repeat of CAG (glutamines) amino acids that encode for polyglutamine tract.

 

Normally – ≤ 34

 

Have Disease – ≥ 37

most common inherited disease in the USA
hereditary hemochromatosis
Is hereditary hemochromatosis fatal w/o txt?
yes
most common lethal inherited disease
cystic fibrosis
What protein in defective in cystic fibrosis?
CFTR (Cl- transporter)
Is what organ is the defect of cystic fibrosis most problematic?
lungs
What problem generally causes death in cystic fibrosis?

lung infections caused by P. aeroginosa

 

accumulates in lungs and destroys lining

What does the protein involved in cystic fibrosis do to promote the eventually fatal action that happens?

CFTR used to clear out bacteria from lungs

 

dysfunctional in CF and can’t remove bacteria anymore

 

lungs get destoyed by inhaled bacteria (P. aeroginosa)

2 inherited diseases that protect against infectious disease and what they protect against

cystic fibrosis – protect from typhoid fever

 

sickle cell anemia – protects from malaria

Enzyme defective in Tay Sachs disease
hexosaminidase A
What builds up and where does it build up in Tay Sachs?
glycosphinogolipids build up in the brain
What are the symptoms of Tay Sachs?

mental retardation

 

blindness

 

paralysis

 

muscle atrophy

 

cherry red spot on retina

Is hexosaminidase A the only enzyme that is involved in trimming sugars off glycosphinolipids that is defective in disease?
no
What is class of diseases that involve defective enzymes involved in trimming sugars off of glycosphingolipids?
sphinogolipid storage disorders
3 monogenic or polygenic diseases

hypertension

 

cardiovascular disease

 

type 2 diabetes

Only polygenic diseases

anencephaly

 

spina bifida

 

cleft lip/palate

 

alchoholism

 

asthma

 

bipolar disorder

 

inherited epilepsy

 

idiopathic gout

 

obesity

 

schizophrenizia

 

type I diabetes

3 inherited monogenic diseases that cause hypertension

glucocorticoid-remediable aldosteronism

 

apparent mineralocorticoid excess

 

Liddle syndrome

polygenic syndrome that is generally considered cause of most hypertension
essential hypertension
3 genes that have been associated with type 1 diabetes
3 HLA genes
Name genes that have been associated with a monogenic disease that may be though of as type 2 diabetes
MODY 1-7
3 genes that have been associated with polygenic type 2 diabetes

PPAR-gamma

 

glucokinase

 

calpain 10

Are all individuals with a defect in one of the genes associated with polygenic type 2 diabetes going to develop the disease?
no
Which of these genes associated with type 2 diabetes has been found in 85% of the world population?
PPAR-gamma

Which of the following infectious diseases is NOT thought to be protected against by an inherited genetic mutation or deletion (may be more than one):

 

A. HIV

B. typhoid fever

C. anthrax

D. malaria

E. leprosy

anthrax

 

leprosy

What is a “snip” and with what frequency are SNPs encountered in human DNA?

single nucleotide polymorphisms

 

1:300 bps

A patient has the form of the gene that cause Huntington’s (20 repeats). The patient asks about a “gray area” in testing and whether the result in certain.

 

What do you say?

some people have an intermediate number of repeats (mid-30s) but for someone with 20 repeats the test is certain.

You are treating a case of erythroblastosis fetalis, a disease of the fetus in pregnancy. This is most often caused by isoimmune reaction to the D antigen, which is one of the antigens responsible for the Rh blood group. Abs developed by the Rh- mother “attack” an Rh+ fetus’s RBCs leading to hemolysis. You want to quickly counsel the expecting couple about the likelihood the offspring will have another Rh+ fetus. The antigen is inherited in autosomal domianant fashion so you know the mother is

homozygous for the genes that make her Rh-. The father knows he is Rh+ so you able to advise them that on avg?

 

AND

 

You ask the father if he has previously fathered an Rh- child and he says YES you are able to advise that on avg?

 

AND

 

if the father says that has  has fathered an Rh- child and he instead says NO you are able to advise that on avg?

the info given you can’t determine the likelihood of the disease for their future offspring

 

the info given you can’t determine the likelihood of the disease for their future offspring

 

50% of their offspring will suffer from the disease

 

autosomal recessive homozygote

 

male and female

 

which get disease?

female and male

autosomal recessive heterozygote

 

male and female

 

which get disease?

neither

autosomal dominant homozygote

 

male and female

 

which get disease?

both

autosomal dominant heterozygote

 

male and female

 

which get disease?

both
x-linked recessive hemizygous

male

 

x-linked recessive heterozygote

 

male and female

 

which get disease?

neither

x-linked recessive homozygote

 

male and female

 

which get disease?

female

Mitochondrial, only father has disease

 

male and female

 

which get disease?

neither

Mitochondrial, only mother has disease

 

male and female

 

which get disease?

Both
What are some ways DNA is obtained from children and adults?

blood

 

saliva

 

cheek swabs

3 forms of prenatal diagnosis of inherited disease that utilized together cover most of period between 10 weeks of gestation through birth and rate of fetal loss associated w/ each?

chorionic villus sampling (CVS) – 0.5-1.0% loss

 

ultrasound – 0% loss

 

cordocentesis- 1-2% loss

What does preimplantation diagnosis of in vitro eggs allow?
embryo selection

How many inherited diseases does FL screen for?

 

What do these diseases have in common that makes them a good idea to screen for?

 

What instrument made possible the recent expansion in the number of diseases screened in FL and does it analyze sequences or metabolites?

35 diseases screened in FL

 

cause early damage and effective txt exists

 

tandem mass spectrometry-analyzes metabolites

Advantages of screening for genetic diseases by DNA sequencing

may catch a patient gives a false – by another method

 

easier, less expensive to do in quantity than biochem assays

 

heritage and fam history of person gives info about what diseases and mutations to look for

 

it is predictive (before symptom onset)

Disadvantages of screening by DNA sequencing

false negatives due to gene mutation being in unexpected location in gene

 

limited coverage of test – only test for specific disease, might miss others

 

may have added expenses due to patented genes

% frequency of two most often occuring mutations in CTFR genes

 

Any high frequency mutations in familial hypercholesterimia genes?

70% and 2.5%

 

no, high freq mutations in FH genes

Gene defect that resulted in fava beans causing health problems in Greece and primaquine causing health problems in WW2
hemolytic anemia

Knowledge of person’s VKORC1 and CYP2C9 seq can help you decide what about a patient?

 

What other seq can be screened?

drug dosage and type

 

P450 screened also

 

 

Pharmacogenomics
use sequence info to make decisions about a drug
A 27 y/o patient’s father has been diagnosed with Huntington disease. It would be important to:
tell the patient there is a test involving DNA seq to show if he will suffer from Huntington disease later in life
Is Cushing syndrome characterized as a cancer b/c it involves overgrowth of cells (a tumor) in the adrenal gland that produces cortisol?
No, it is not metastatic
What can be involved in genesis of cancer and which always involved?

bacteria

 

viruses

 

inherited predispositions

 

gene defects – always involved

 

enviro causes

 

cell cycle genes
Rb and p53
growth signal transduction genes
ras, HER2, PDGF, EGF
DNA repair genes

hMLH1

 

hMSH2

BRCA-1
anti-oncogene
Why can hEGFR be considered a protooncogene and how might become an oncogene?

protooncogene b/c it is a growth-stimulating gene

 

can become oncogene if its activity starts to result in uncontrolled growth

 

 

Gene A loses activity w/ certain mutation.

 

Is the normal gene a tumor suppressor, oncogne, anti-oncogne, or proto-oncogene?

tumor suppressor and anti-oncogene for both normal and mutant genes
characteristics of matrix metalloproteinases and involved in what cancerous process

protein/enzymes that require a metal (Zn or Ca) ion to break down proteins in ECM of cell

 

involved in metastasis

Tumorigenic cells for cancer therapy

only some cells in tumor can generate new tumor

 

if can treat or cut out those cells, then localize tumor and control metastasis

Unique Characteristic of PARs
proteolytically remove N-terminus of receptor itself and new N-terminus is the ligand that activates receptor
Kd

[ligand] for 1/2 max occupancy of receptors

 

measure affinity of ligand for receptor

EC50

[ligand] for 1/2 max response

 

effectiveness in eliciting cellular response

largest superfamily of receptors
GPCRs
What family of receptors facilitates addiction to tobacco?
ionotropic nicotinic Ach-R
Differences and Similarities in Intracellular Receptors

some reside in cytoplasm until encounter ligands-glucocorticoid and aldosterone-Rs

 

most reside full time in nucleus

 

receptor ligand complex acts on nucleus by binds to DNA and affecting expression (turn on/off expression)

concentration of albumin in serum
4 g/dL
4 functions of plasma albumin

fatty acid transport

 

bilirubin transport

 

transport of steroid hormones

 

transport of sulta drugs, penicillin, aspirin

Plasma protein degraded randomly at a rate of 100%/day. What is biological half life?
0.693 days

most abundant alpha-1 globulin?

 

Function?

 

Clinical result of its absence?

alpha-1 antiprotease

 

protease inhibitor on compounds such as elastase and collagenase

 

prevents proteolysis in lungs

 

lung loses ability to recoil after inspiration leading to emphysema and respiratory failure

organ albumin is synthesized in
liver
major class of proteins NOT synthesized in liver
immunoglobulins
most abundant of plasma proteins
albumin
how are fatty acids transported in plasma
bound to albumin
major fetal plasma protein
alpha-1 fetoglobulin
plasma protein that binds and transports iron
transferrin
plasma protein that binds and transports cortisol

cortisol-binding globulin (alpha-1 globulin)

 

 

plasma protein that binds and transports vitamin A derivitives
retinol-binding protein (alpha-1 globulin)
plasma protein that binds and transports testosterone

sex hormone binding globulin (SHBG)

 

beta-globulin

plasma protein that binds and transports bilirubin
albumin
What ahppens to free hemoglobin in plasma?
degraded by reticulothelial cells
What would happen to hemoglobin in plasma if haptoglobin were absent?

iron would be lost due to Hb breakdown.

 

Hb is lost through the kidney and excreted in urine.

blue protein and what is its function

ceruloplasmin

 

blue b/c of copper

 

oxidize Fe 2+ Fe 3+ in plasma

 

low levels found in Wilson’s disease

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