Biochemistry Flashcards
Buffer urine
Phosphate & ammonia (secondary)
Buffer blood
Bicarbonate & hemoglobin (CO2 buffering)
Buffer bone
Calcium carbonate
Buffer interstitial fluid
Bicarbonate
Buffer intracellular fluid
Protein & phosphate
ABG normal values
PH 7.35-7.45
pCO2 4.5-6
PO2 10-14
BE -2-+2
Base excess meaning
> +2 = metabolic alkalosis or respiratory acidosis with metabolic compensation
<-2 = metabolic acidosis or respiratory alkalosis with respiratory compensation
When is HCG detected
8 days post-fertilization in blood and 10 days post-fertilization in urine
Mitochondria function
ATP production
Golgi Apparatus
Storing, packaging and modification of proteins
Rough endoplasmic reticulum
Protein assembly, folding & quality control
Smooth endoplasmic reticulum
Folding of proteins and transport in vesicles
Synthesis of lipids & Role in gluconeogensis via G6DP
Nucleus
Contains chromosomes and gene expression
Ribosome
Translation mRNA into protein
DNA Bases
purine bases are adenine and guanine
pyrimidines are thymine and cytosine
RNA bases
purine bases are adenine and guanine pyrimidines are uracil and cytosine
The following shift the oxygen dissociation curve to the right:
Increased temperature
Increased H+ (i.e. acidosis)
Increased 2,3 DPG
Increased pCO2
The following shift the oxygen dissociation curve to the left:
Increasing pCO shifts the curve to the left
Decreased temperature
Decreased [H+] (alkolosis)
Decreased 2,3 DPG
What is Interphase?
G0 Resting Resting state
G1 Interphase Cells increase in size
S Interphase DNA replication
G2 Interphase Cells increase in size
M Mitosis Cells divide in subphases
Prophase
Chromatin condenses to chromosomes (paired as chromatids). Mitotic spindle forms
Metaphase
Chromatids align at the equatorial plane
Anaphase
Chromotids pulled apart into 2 constituent daughter chromosomes
Telophase
New nuclear envelopes form around each daughter chromosome
Cytokinesis
Cells divide
major tumour suppressor?
P53 =
P53 is a protein that is encoded by the TP53 gene in humans. TP53 gene is located on the short arm of chromosome 17.
Glycolysis
Metabolic Pathway that converts Glucose into Pyruvate
Anaerobic - makes 2 ATP
Gluconeogenesis
Metabolic Pathway that generates glucose
Occurs primarily in the Liver and Kidneys
Utilises several precursors such as Lactate, Glycerol and Pyruvate
Glycogenesis
Process of Glycogen synthesis
Glucose is added to glycogen chains for storage
Glycogenolysis
Process of enzymatic breakdown of glycogen producing glucose
Vitamin K
Fat soluble vitamins ADEK
- Essential for clotting 10, 9, 7, 2
- Essential for proteins S, C, Z and osteocalcin GLA proteins
Extracellular cation/anion
Cation = sodium
Anion = chloride
Plasma cation/anion
Cation = sodium
Anion = chloride
Intracellular cation/anion
Cation = Potassium
Anion = Phospahte
In non-excitable cells, what happens
NA/K/ATP-ase pumps push potassium intracellularly in exchange for sodium, while they naturally flow extracellularly (permeability of cell membrane highest to potassium)
Northern blotting
RNA sequences
Western blotting
Protein analysis/ELISA test
Southern Blotting
DNA sequences
Eastern Blotting
Protein modifications (e.g. carbohydrates/lipids)
Southwestern Blotting
DNA binding proteins
Cadherins
calcium ion dependent adhesion molecules.
Bind cells together via adherin junctions which are calcium dependent (
Integrins
Play role in signal transduction between cell and extracellular matrix
Transmembrane receptors
Selectins
E-selectin (in endothelial cells)
L-selectin (in lymphocytes)
P-selectin (in platelets)
Glycoproteins
Bind to leucocytes with catch and slip weak bonds
Play a role in inflammation attracting leucocytes
Inflammatory processes via interleukins increase the amount of selectins present and hence, attract more leucocytes.
What activates fibrinogen (common pathway)?
Thrombin
Accelerin (V) stimulates activation of prothrombin (II) to thrombin (II), which activates fibrinogen (I) to form fibrin clot. This is stabilised by cross linking with the aid of fibrin-stabilising factor (XIII). Remember heparin increases the rate of complex formation of antithrombin III, which inactivates thrombin.
What increases prothrombin time?
Prothrombin time evaluates extrinsic pathway, as does INR
Factor V deficiency
Liver failure
DIC
Warfarin therapy
What ion holds DNA strands together?
Hydrogen
PCR
Amplify very small amounts of DNA (although it can be used for RNA if converted to DNA)
A woman has just undergone a prolonged difficult hysteroscopic operation to resect a fibroid from within the uterine cavity. Three bags of distension medium were utilised during the surgery.
Which disturbance in serum biochemistry can occur in these circumstances?
Hyponatremia - TURP syndrome
Sodium levels below 120mEq/l cause cardiac depression. Level less than 115mEq/L is associated with bradycardia, widening of QRS complex and T inversion. Level below 105mEq/l is associated with respiratory and cardiac arrest
In a pregnant woman with diabetes mellitus, target levels of HbA1C should be below what level?
6.5 % (48)
Aim for ideal control of 6.1%
Above 10% pregnancy not advised.
A 14-year-old child presents to the adolescent gynaecology clinic. She has a history of virilisation after undergoing pubertal changes. The karyotype reveals 46XY. An ultrasound scan does not show the presence of a uterus and ovaries.
What condition can produce these clinical features?
5-alpha-reductase deficiency (prevents androgen from becoming estrogen).
Which body fat has a major role in gene transcription?
Fatty acids
Eicosanoids
Hormone synthesis
contributes half the osmolarity of the extracellular fluid
Sodium
Chronic renal failure can produce what effect on the parathyroid system?
Secondary hyperparathyroidism (other causes small bowel disease and chronic pancreatitis)
Which biochemical findings are most likely with paget’s disease of bone?
Normal calcium, normal phosphate, raised ALP
Glycated haemoglobin (HbA1C) is a marker of diabetic control over what time period?
8-12 weeks
Which enzyme transcribes DNA to mRNA?
RNA polymerase
What is the primary source of negatively charged ions in the blood?
Bicarbonate and chloride
What is the average haemoglobin concentration in a newborn at term?
17 g/dl
What coagulation factors are reduced in pregnancy?
platelets
protein s
clotting factor 11
clotting factor 13 (up or down)
Where is the chloride shift phenomenon seen?
Red blood cells
What is the major hydrogen ion buffer in blood?
Hemoglobin
Clotting factors decreased in pregnancy
platelets
Factor 11 ( = or down)
Factor 13 (up or down)
protein S
t-PA
Clotting factors increased in pregnancy
Fibrinogen
Von Willebrands
Factors 7, 8, 9, 10, 12
Factor 13 (up or down)
Protein C
Heparin co-factor 2
D-dimer/TAT/F1+F2
ELT/PAI/TAFI
What is the major production mechanism of 2,3 DPG?
Glycolysis
With regard to plasma calcium, what proportion is carried in an ionised form?
45%
With regard to bound plasma calcium, what is the major carrier?
plasma proteins.
Where in the body is the major production of 1,25 (OH) D3 (calcitriol)?
Kidneys (proximal tube of nephrons)
With regard to oral iron absorption, reduction of Fe3+ to Fe2+ is inhibited by what substance?
Tea
What is the action of cytochrome P450 enzymes?
catalyse hydroxylations.
Which cells in the body are dependent upon anaerobic respiration?
Red blood cells
Where in the body is ATP found?
Only intracellular
With regard to Conns syndrome, what are the likely changes in pH, potassium and sodium concentration?
hypernatraemia, hypokalaemia, alkalosis.
Ammonia is made from what amino acid in the kidney?
Glutamine
With regard to transport in the red blood cells, what ion enters the cell to maintain electrical neutrality with the outward movement of bicarbonate?
Chloride
RNA to DNA by
Reverse transcriptase
Which molecule do hepatocytes use to produce primary bile acids?
Cholesterol
- two main types are cholic acid and chenodeoxycholic acid. 75% are conjugated with glycine
Gonorrhea treatment in pregnancy:
Non-pregnant:
ciprofloxacin 500 mg orally as a single dose
When antimicrobial susceptibility is not known prior to treatment, prescribe ceftriaxone 1 g intramuscular (IM) injection as a single dose (also pen allergic).
Dual-therapy = Ceftriaxone + Azithrmycin
Pregnant:
For pregnant or breastfeeding women, prescribe ceftriaxone 1 g IM injection as a single dose.
Azithromycin 2 g as a single oral dose can be used.
homocystinuria due to which vitamin deficiencies?
B12
Folate (B9)
B6
Patient with a drain develops gram negative bacilli infection. Cause?
Pseudomonas aeruginosa
Classified as an opportunistic pathogen
Which conditions can be caused by Robertsonian translocation?
Down’s and Patau
Young female with menorrhagia - after FBC, what is the next test?
Clotting
Post-menopausal bleeding with granulosa cell tumor. What is the effect on the endometrium?
Proliferative
Lancefield grouping of streptococci is based on what?
Antigen on cell wall
Maximum levels of progesterone are found at:
Term
The main stimulus for aldosterone release:
Angiotensin 2
Main precursor for nitrous oxide:
L-arginine
Transcription requires which enzyme?
RNA polymerase
If a male patient has congenital absence of the vas deferens, what is the chance that he has cystic fibrosis?
80%
Patient has body aches and malaise and all investigations are normal other than ALP which is raised. Diagnosis?
Vitamin D deficiency
Alkaline phosphatase (ALP) is usually elevated in response to the effect of PTH on calcium absorption from bone
ECG of patient complaining of numbness and body aches with little exposure to the sun.
Hypocalcaemia
Pregnancy with history of DVT in precious pregnancy needs:
Antenatal LMWH
What becomes caput medusa?
Umbilical vein
What marks the beginning of gastrulation?
Primitive streak
Amount of sperm production per day:
300 million
Picture of tall man (Kleinfelter), what will be the lab results?
Low testosterone
High SHBG
High FSH
High LH
37 weeks with obstetric cholestasis - management is:
Induction of labour
Mismatch repair is associated with which tumor?
Clear cell carcinoma
Most common endometrial sarcoma:
Uterine leiomyosarcoma
What is the karotype of male Edward’s syndrome?
47XY
Peptide transport is via what mode?
Active diffusion
Demarcation of indirect and direct inguinal hernias:
Inferior epigastric vessels
replication of HIV depends on which enzyme?
Reverse transcriptase
The Kreb’s cycle occurs where?
Mitochondria
Complement synthesis occurs where?
Liver
Which study design to compare shoulder dystocia with neonatal birth weight?
Retrospective cohort
Standard deviation =
Square root of variance
Calculate interquartile range:
Order the data from least to greatest.
Find the median.
Calculate the median of both the lower and upper half of the data.
The IQR is the difference between the upper and lower medians.
Closure of neural groove complete at which gestational age?
25 weeks
Which hormone is responsible for epiphyseal fusion?
Estradiol
Which cells have a role in phagocytosis and account for 2.5% of WBCs?
Mast cells
Lymphocyte production occurs in:
Bone marrow
Which cell type lyses cells that have been infected with virus:
CD8+T cells
CD4 cells belong to which group of cells?
T cells
Lower part of vagina is derived from:
Urogenital sinus
Topical estrogen acts on which area of the bladder to treat incontinence?
Bladder trigone
which cells are not effected by radiotherapy?
Cerebral cortex
Transport of glucose to the fetus is by:
Facilitated diffusion
What rate does atypical hyperplasia become malignant?
12% in 10 years + 28% in 20 years
Which test has high negative predictive value to detect pre-term pre-labour rupture of membranes?
Fetal fibronectin
The greater momentum is derived from which embryonic structure?
Dorsal mesogastrium
Suxamethonium does not readily cross the placenta because of:
High degree of ionization
What is the smallest human chromosome?
Chromosome 21
What is the origin of the falciform ligament?
Ventral mesentery
What are the biological markers of Kleinfelter’s syndrome?
Low testosterone
High FSH/LH
High SHBG
What is alert line + action line on partogram?
Alert line = starts at 4 cm of cervical dilatation and it travels diagonally upwards to the point of expected full dilatation (10 cm) at the rate of 1 cm per hour
Action line = parallel to the Alert line, and 4 hours to the right of the Alert line.
Vincristine MOA
Microtubule inhibition
Most common mutation in high grade serous adenoca
p53
What is the tubal factor infertility rate following a single episode of Pelvic Inflammatory disease?
Tubal infertility rate following 1 episode PID 12%
Tubal infertility rate following 3 episodes PID 50%
The conditions associated with increased risk of pheochromocytoma are:
MEN type 2
Paraganglioma syndromes types 1,3 and 4
VHL
Neurofibromatosis type 1
potent stimulator of Aldosterone
Hyperkalaemia is arguably the most potent stimulator of Aldosterone.
Juxtaglomerular cells will also secrete Renin (that will ultimately stimulate aldosterone production) in response to Hyponatreamia and hypotension.
Cremasteric artery branch of:
Inferior hypogastric
Artery to Vas Deferens branch of
Internal iliac
According to the Green-top guidelines CVS should NOT be performed before what gestational age?
It should be performed from 11+0 weeks as it is technically difficult before then (and some suggest risk of limb and mandibular defects increased)
It should NOT be performed before 10+weeks
You are asked to prescribe a course of antenatal steroids for a patient undergoing planned C-section at 37+0 weeks. Which of the following is the most appropriate regime according to RCOG guidelines?
Dexamethasone 6 mg given IM x 4 doses or Betamethasone 12 mg IM x 2 doses
Normal semen analysis values:
pH: Greater than or equal to 7.2
Sperm morphology (percentage of normal forms): 4% or more
Vitality: 58% or more live spermatozoa
total motility (% of progressive motility and nonprogressive motility): 40% or more motile or 32% or more with progressive motility
Total sperm number: 39 million spermatozoa per ejaculate or more
DNA Helicase
Unwinds DNA
DNA polymerase
Catalyses the synthesis of DNA molecules from free nucleotides. After DNA helicase unwinds the DNA molecule, DNA polymerase reads the existing DNA strands and incorporates complementary nucleotides one by one to assemble a chain.
