ILA 1 - Molecular Medicine Flashcards
A sickle cell crisis has been precipitate by several factors, including hypoxia.
Which best describes the response of the abnormal HbS to hypoxia?
A. Deforms
B. Dimerises
C. Flips from Levo- to dextro-isomer
D. Polymerises
E. Stays the same
D. Polymerises
DNA replication involves several stages.
Which of the following enzymes causes the double helix to unzip?
A. Amylase
B. DNA polymerase
C. Glycosylase
D. Helicase
E. Topoisomerase
D. Helicase
Pain is a common symptom during a sickle cell crisis.
The pain is typically caused by capillary occlusion in which structure?
A. Skin
B. Bone
C. Brain
D. Cardiac Muscle
E. Spleen
B. Bone
Early presentations can be pain in the hands and feet with severe pain in bones such as femur, humerus, ribs and pelvis occurring in older children. These are due to vaso-occlusive events in the small vessels. Repeated events in the bones can lead to chronic infarcts.
DNA replication is dependent on the action of various enzymes.
Which of the following enzymes unwinds supercoiled DNA?
A. Amylase
B. DNA Polymerase
C. Glycosylase
D. Helicase
E. Topoisomerase
E. Topoisomerase
A. Helicase unzips the double helix
B. DNA polymerase is involved in the synthesis of DNA using deoxyribonucleotides. DNA polymerase reads the existing DNA strands (3’ to 5’) to create two new strands.
C. Topoisomerase unwinds the supercoiled DNA strand to give an uncoiled DNA strand
D. Glycosylases are involved in the repair of damaged bases in DNA
E. Amylase is an enzyme present in saliva which starts the breakdown of starch to sugars
A 20-year-old student is admitted with signs and symptoms of Sickle cell anaemia (HbS).
Which of the following best describes the underlying cause of Sickle cell anaemia?
A. A random genetic mutation in the beta globin chain
B. An autosomal dominant inherited condition substituting an amino acid in the beta globin chain
C. An autosomal dominant inherited condition substituting an amino acid in the alpha globin chain
D. An autosomal recessive inherited condition substituting an amino acid in the beta globin chain
E. An autosomal recessive inherited condition substituting an amino acid in the alpha globin chain
D. An autosomal recessive inherited condition substituting an amino acid in the beta globin chain
Sickle cell anaemia is an autosomal recessive inherited condition which substitutes valine for the normal glutamine in the beta globin chain.
Sickle cell disease can be treated with hydroxyurea.
Which of the following best describes the action of hydoxyurea?
A. Increases the synthesis of HbF (foetal Hb)
B. Increases the synthesis of normal HbA
C. Interferes with the translation of mutant RNA
D. Prevents the transcription of mutated DNA
E. Reverses the hydrophobic site caused by the point
A. Increases the synthesis of HbF (foetal Hb)
Hydroxyurea (hydroxycarbamide) is a myelosuppressive agent and is the only treatment known to reduce the frequency of painful episodes. It causes a shift towards production of red cells with
HbF. Exact mechanism of action is not completely understood.
HbF is composed of 2 alpha chains and 2 gamma (not beta) chains. It also has a greater affinity for oxygen than HbA.
Haemoglobin is vital for transporting oxygen around the body.
Which of the following best describes the structure of a protein that has a number of subunits held together by cross links?
A. Primary structure
B. Quaternary structure
C. Secondary structure
D. Tertiary structure
B. Quaternary structure
During the construction of proteins, amino acids are transported to the ribosome.
Which of the following carries specific amino acids to the ribosome?
A. Double strand DNA
B. Double strand RNA
C. Messenger RNA
D. Single strand DNA
E. Transfer RNA
E. Transfer RNA
tRNA carries specific amino acids to the ribosome and checks they are incorporated in the right location.
During a sickle cell crisis pain is caused by vaso-occlusive events.
Which best describes the latest theory on how capillary occlusion occurs?
A.
Endothelial damage causes multicellular (platelets, white cells) aggregates which occlude the capillary
B. Sickle cells bind together to form a ‘plug’
C. Sickle cells bind with platelets
D. The sickle cells cause capillary spasm
A.Endothelial damage causes multicellular (platelets, white cells) aggregates which occlude the capillary
The most up to date thinking is that the sickle cells cause endothelial damage causing multicellular (platelets, white cells) aggregates which occlude the capillary
Ribosomes play an important part in intracellular protein production.
Concerning ribosomes, which of the following best describes their structure?
A. They are assembled inside the nucleus
B. They are assembled outside the nucleus
C. They are composed of two small subunits
D. They consist of mRNA and amino acids
E.They never attach to the rough endoplasmic
A. They are assembled inside the nucleus
Ribosomes are assembled inside the nucleus and then translocate to the cytoplasm through nuclear pores where they remain free or can be attached to the rough endoplasmic reticulum. They have one large and one small subunit.
During a sickle cell crisis hypoxia causes structural changes to HbS.
Which of the following best describes the structural change caused by the deoxygenated HbS which leads to sickling?
A. It alters nuclear transcription of cytoskeletal proteins
B. It binds to the cytoskeleton
C. It changes the charge across the cell membrane
D. It dehydrates the cell by osmotic action
E. It pulls on the cell membrane
B. It binds to the cytoskeleton
Deoxygentaed HbS polymerises and binds to the cell cytoskeleton which distorts the normal cell shape into the classic sickle shape.
Protein structures rely on several different forces and bonds to hold their structure together.
Which of the following is defined as ‘A weak attractive interaction between two atoms due fluctuating electrical charges’?
A. Disulphide bond
B. Hydrogen bond
C. Hydrophobic force
D. Van der Waals force
D. Van der Waals force
A. Disulphide bond – covalent bond between side chains of cysteine residues
B. Hydrogen bond – A type of Vander Waals force. It is the strongest of them and is the interaction between dipoles, involving an hydrogen and an oxygen/nitrogen/fluorine.
C. Van der Waals force – A weak attractive interaction between two atoms due fluctuating electrical charges’
D. Hydrophobic force - the attraction of hydrophobic protein side chains which form tightly packed cores on the interior of proteins which exclude water molecules
Proteins can form a variety of different structures.
Alpha helixes and beta sheets are examples of which type of protein structure?
A. Primary structure
B. Quaternary structure
C. Secondary structure
D. Tertiary structure
C.
Secondary structure
mRNA plays a key role in protein formation.
Which of the following processes describes how mRNA specifies the amino acids required for protein formation?
A. Telophase
B. Transcription
C. Transference
D. Translation
E. Translocation
D. Translation
A. Transcription – is where DNA is transcribed / copied into mRNA which then leaves the nucleus
B. Translocation – is where genetic material is exchanged between chromosomes
C. Translation – is where mRNA is used to specify the amino acids required to make proteins
D. Transamination – is the reaction in which an amino group is removed from an amino acid during metabolism
E. Telophase – is a phase during cell division
