ILA1 Sickle cell Flashcards
What are characteristics of sickle cell anaemia?
Low RBC count
Episodes of pain
Repeated infections
When do signs and symptoms of SCA usually begin?
Childhood
How does SCA lead to shortness of breath and fatigue?
Sickle RBC break down prematurely, which leads to anaemia and so fatigue
How does SCA cause jaundice?
Rapid breakdown of RBC and heamoglobin
How does SCA cause the painful episodes (vaso-occlusive crisis)?
When sickled RBC (stiff and inflexible) get stuck in small blood vessels, which deprives tissues of oxygenated blood. Can lead to organ damage
Where has the highest rates if SCA?
Africa, Mediterranean, Central America and Carribean
Mutation in which gene causes sickled Hb?
HBB gene
What are the sub-units of normal Hb?
2 alpha and 2 beta globin chains
How is sickle RBC different to normal?
HbS units replace both beta chains
What is the change in amino acid sequence in HbS?
Glutamic acid replaced by valine at position 6
What causes the sickle shape?
Abnormal Hb stick together leading to long rigid molecules
What is Hbc and HbE
Replacing of one beta subunit.
HbC is caused by lysine replacing glutamic acid at position 6
HbE by lysine replacing glutamic acid at position 26
What is beta thalassemia?
Lack of beta subchains
What is the difference between SC disease and SC anaemia?
SCD is a group of collected conditions, the most common being SCA
What is the inheritance pattern shown by SCA?
Autosomal recessive, both beta subunits need to have the mutation
What is a single nucleotide polymorphism (SNP)?
Most common type of genetic variation. Occur once in every 300 nucleotides. It is a variation in a single nucleotide at a specific position.
What is the SNP that causes SCA?
CTC to CAC causing glutamic acid to valine
How does sickling reduce affinity for oxygen?
It causes a change in shape which makes it harder for the oxygen to bind
What are potential complications of SCA in pregnancy?
Anaemia could worsen Pain worsen (keep heat pads to reduce vasoconstriction and so pain)
What direction does polymerase read?
Reads 3’-5’ meaning template is produced in 5’-3’
Why does replacement of glutamic acid with valine lead to change in shape?
Glu is hydrophilic and val is hydrophobic. In deox HbS valine associates with another hydrophobic area on another molecule causing long mols and change in shape
Mitosis: Chromosomes are moving towards opposite poles of the cell and there are no nuclear membranes. Which phase?
Anaphase
What is the last stage of mitosis?
Cytokinesis
What are the microtubules that chromosomes attach to in mitosis made out of?
Tubulin
What stain turns granules in mast cells purple?
Toludine blue
Brown pigment in liver cells. Possible haemochromatosis. What stain turns iron containing pigments blue?
Perl’s stain
Pedigree: male to male, every gen. what type?
Autosomal dominant
Which substance splits two DNA strands apart during DNA replication?
Helicase
A gene sequence is coded in?
SINGLE STRAND DNA
A promotor sequence is coded in
Single strand DNA
What do specific amino acids bind to?
tRNA
The transcriptome of a whole cell is composed of?
mRNA
Alternative splicing of codon regions producing different products of a gene occurs in?
mRNA
A protein composed of two or more peptide chains held together by non-covalent cross links has what structure?
Quaternary
In the cytoplasm the structure that is created by covalent bonds is (Proteins)?
Primary
Alpha helixes and beta sheets are examples of what structure of protein?
Secondary
Which of these cells kill bacteria using respiratory burst?
Neutrophil
Dihydrogen oxide is also known as…?
Water
Which enzyme catalyses 1,3 bisphosphoglycerate to 3-phosphoglycerate?
PHOSPHOGLYCERATE KINASE
The average 70kg man has a store of approximately 350g of what energy source?
Glycogen
How are steroid hormones transported in the blood?
Bound to plasma proteins
How does HbS cause sickling?
In hypoxia the abnormal HbS crystallises and the mutated valines join to normal valine
How does capillary occlusion occur in SCA?
Sickle cells bind to and activate endothelial cells causing inflammation
