Unit 2 Review: Biochemistry, Cell Biology, & Genetics Flashcards
The catalytic rate of an enzyme is MOST sensitive to [S] when:
When S is much lower than Km, steep curve
For an enzymatic reaction, If the concentration of substrate is 5mM and the Km is 2mM, what fraction of enzyme is bound to substrate?
5/7
[S] = 5 mM; Km = 2 mM
[S]/([S] + Km) = 5/(5+2) = 5/7
When is Km approximately equal to Kd (the dissociation constant) for the ES complex?
when K2 is much greater than K3
Kd = K2/K1 Km = K2+K3/K1
when K3 is small, both are roughly equal
which enzyme’s activity is more sensitive to the body’s concentration of glucose? Hexokinase, glucokinase, or activity is independant for both enzymes?
Hexokinase becomes saturated and reaches its Vmax at a low concentration.
Glucose is much more sensitive to changes in glucose concentration
The protease of an hiv strain that is highly resistant to a protease inhibitor will show what combinations of properties?
High Ki indicates that the protease is highly resistant to a particular inhibitor because that inhibitor does not bind tightly to it
A high kcat/Km (or at least a kcat/Km that is approximately equal to wild type) means that the protease is highly effective at catalyzing the reaction and producing product
The most resistant HIV strains have proteases that are resistant to inhibitors but still efficient at doing their job
Which aspect of the body’s response to blood vessel injury is affected by warfarin?
Localization of the clotting proteins to the site of injury
Warfarin inhibits a vit K-dependent enzyme that allows clotting proteins (factors II, VII, IX, X) to adhere to membranes at the injury site
two requirements for a coupled enzyme reaction
substrate in excess. the reaction that uses the enzyme in question must be slower. the second reaction must be much faster
Coupled enzyme assays are useful when the products of the reaction catalyzed by the enzyme of interest cannot be quantified easily (either because they’re similar to the substrates or difficult to detect)
You can use the products as substrate for a second reaction for which the products CAN be measured easily
In order for this to work, the second reaction must be very fast and all substrates must be present in excess
ALT
viral hepatitis
amylase
pancreatitis
creatine kinase
muscle disorders/MI
Lipase
pancreatitis
lactate dehydrogenase
liver disorders
acid phosphatase
metastatic prostate carcinoma
alkaline phosphate
bone disorders and obstructive liver disesae
Hydrophobic signaling molecules
Typically bind nuclear/cytoplasmic receptors
Bind cell surface receptors and typically activate gene transcription
Tend to have relatively short half lives
Do NOT need binding proteins to be carried throughout the blood, examples include steroids and thyroid hormones.
typically bind nuclear/cytoplasmic receptors
Carried by binding proteins
Relatively long half lives
Freely pass through cell membranes
Bind nuclear receptors- which activate gene transcription
Steroids, retinoids, thyroid hormones
Exception: eicosinoids which are hydrophobic, but bind surface receptors, short half life, function on inflammatory responses and clotting
eicosinoids
which are hydrophobic, but bind surface receptors, short half life, function on inflammatory responses and clotting
hydrophilic signaling molecules
Peptides, nucleotides, amino acids, growth factors
Do NOT need carrier molecules to transport through blood
Have shorter half lives
Bind cell surface receptors and can act through
Ligand-gated ion channels
Enzyme linked receptors
Catalytic receptors,
Trimeric G-protein-linked receptors
pemphigus results from
autoimmune attack of desmosomal cadherin
adherens junctions allow for the
oriented contraction of actin filaments across cells, which is used to form the neural tube during development
fibronectin
a dimer using disulfide bonds, self-associates into bundles and fibrils. Interacts with integrins. Plays role in loose connective tissue, blood clots, wound healing
laminin
interacts with type IV collagen, integrin and proteoglycans. Major component of the basal lamina
Bad-
BCL2-BCLX -
BAX -
Bad- pro-apoptotic, with no signals for the cell to grow (trophic factors). Bad is free to interact with Bcl2/Bclx
Bcl2/Bclx- anti-apoptotic, normally interact with and inhibits Bax. Interaction with Bad prevents interaction with Bax
Bax- pro-apoptotic, when NOT INHIBITED by Bcl2/Bclx, forms channels and leads to cytochrome c release into cytosol ->apoptosis
describe trophic factors and apoptosis pathway
- No trophic factors -> Bad is free
- Bad interacts with Bcl2/Bclx(located in mitochondrial membrane)
- Bcl2/Bclx can no longer exert their inhibitory effects on Bax
- Bax is free to promote cytochrome c release from mitochondria into the cytosol -> procaspases become caspsases -> APOPTOSIS
eosin does what?
is an acidic stain, binds basic structures such as cytoplasmic proteins
metaplasia hypertrophy hyperplasia atrophy dysplasia
change in cell type that can protect against stress hypertrophy - change in size hyperplasia - increase in number atrophy - cell death dysplasia - change in organization
hematoxylin
Hematoxylin is a basic dye and binds nucleic acids
collagen stains
reticular fibers stain
elastic fibers stain
macrophages stain
Collagen: Stains homogenously PINK with eosin
Reticular fibers: Stain BLACK with silver
Elastic fibers: Special stains, pico-orcein & resorcin fuchsin
Macrophages: Stain with trypan blue
CT in the head is derived from
neural crest cells
Ehlers-Danlos syndrome type IV is caused by
deficient type III collagen
Connective tissue in most of the body develops from
embryonic mesoderm
marfan syndrome
defective fibrillin
A morphogen is
a paracrine signaling molecule that produces concentration-dependent responses
Nodal is a
Nodal is a TGFB signaling molecule, it’s a secreted signaling molecule
Left-right asymmetry defects can lead to
melioration and volvulus in addition to congenital heart defects, asplenia, and polysplenia)
CML
characterized by a t(9;22) translocation which results in the over-expression of a tyrosine kinase (proto-oncogene)
Li-Fraumeni syndrome
associated with an inherited mutation of p53
Breast Cancer is associated with
with losses of homologous recombination & DNA repair genes
Which of the following is characteristic of cancer evolution?
Mutations in different cells complement each other and result in tumor development
Both somatic and germline mutations are generally seen in familial cancers
Genes must be lost in a specific sequential order to result in a given cancer
Proto-oncogenes tend to be responsible for DNA repair pathways
B
A - Multiple mutations must occur in a SINGLE cell to result in cancer
B – Most familial cancers are associated with an inherited loss of a tumor suppressor (from the germline) followed by somatic mutation of the second copy
C – The order of mutations is not important, but certain genes may need to be lost
D- Proto-oncogenes promote unregulated growth and proliferation - only one mutation required (gain of function)
Tumor suppressors tend to promote DNA repair, regulate the cell cycle, or inhibit growth. Both genes must be lost for tumorigenesis
Which of the following is NOT an application of FISH for cancer genetics?
Diagnosis of particular syndromes and prognostic information
Identification of successful treatment (remission)
Identification of relapse
All of the above are potential applications of FISH
all
klinefelter
47, XXY
infertility due to hyalninized testituclar tubules
XYY male
dose not effect interlligence or fertility
due to excluisvely paternal nondisjunction error
turner syndrome
45,X shield chest
XXX female
tall phenotype, does not effect intelligence or fertility
A phenotypically normal female presents to your office complaining of infertility. An ultrasound reveals the presence of testicles in the abdomen and pelvic exam reveals a blind vagina.
What underlying disorder does this patient likely have?
What is their genotype?
Androgen insensitivity
=inappropriate corssing over between TDF region and ARM of X chromosome, the Y then loses its Testes determining factor, end up with just one X chromosome because the Y has lost its testes determining factor (happens in male gamete). Y chromosome loses the male (TDF) region, the fetus inherits the Xy where the Y is worthless, = 46, XY
Turner females are at risk for gonadoblastoma
Due to a mutation of the androgen receptor gene on the X chromosome no androgen receptors produced
TDF protein initiates male development, but without the androgen receptor protein, the pathway is blocked and development defaults back to female
Genotype XY
Disease is called androgen insensitivity
Y chromosome – develop testicles, but receptors don’t develop, so evefytinge sel developes in female pathway
What genetic error could result in a Turner female phenotype with a 46, XY karyotype?
A translocation in which the TDF/SRY region on the Y chromosome is replaced by Xp material would yield a Y without the TDF/SRY sequence. If this Y was passed onto an offspring, normal male development would not occur and the patient would default to a female phenotype. Since the patient would only have one functional X chromosome, a Turner phenotype would occur
In order for balanced translocation carriers to generate gametes resulting in a normal child, which type of segregation must occur?
alternate segregation
In alternate, get a full blue and full red, and a full blue and a full red in both. Good situation. In rest you have unequal balance. You want an alternate segregation
robertsonian chromosome results from
centromere to centromete translocation of acrocentric chromosomes
Recombination products of paracentric inversions are
unstable and tend to be lost
A large pericentric inversion tends to
cause fewer duplications and deletions during recombination than a msall pericentric inversion
an interstitial deletion occurs when
an internal region of a chromosome is lost
TF Low AFAFP can be diagnostic of chromosomal abnormalities
False. It is a screening test. The first trimester screen, Quad screen, and cfDNA are all screening tests and require follow-up diagnostic testing.
TF high maternal AFP associated with downs
False- high AFP is associated with neural tube defects, low AFP is associated with Down Syndrome and other chromosomal abnormalities
common reason for high AFAFP is?
incorrectl reported gestational age
CVS samples…
false- placental tissue, meaning that in rare instances of mosaicism there may be a confined placental mutation or confined fetal mutation)
AFAFP may be collected by CVS
false, no amniotic fluid is collected
describe proteoglycans. what gives them their unique characteristics
Remember that those sugars are often sulfated with many carboxyl groups, very hydrophilic. Recruit large number of water molecules. EXAM q. 90 of it is water= creates hydrated gel.
