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MD2002 > CELL AND MOLECULAR MEDICINE > Flashcards

CELL AND MOLECULAR MEDICINE Flashcards

1
Q

What is a gene?

A

A length of DNA that encodes for a particular protein

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2
Q

What is meant by “locus”?

A

The precise position of a gene in the linear order of the chromosome

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3
Q

What is an allele?

A

An alternative form of a gene

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4
Q

What term means that 2 chromosomes carry the same alleles? And what is it’s anonym?

A

Homozygous

Heterozygous

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5
Q

Name 4 different forms of DNA mutation?

A

Promoter and splice site sequence change
Base change causing a single amino acid change
Insertion/deletion of bases (can be “in-frame” or “out of frame”)
Trinucleotide repeat expansions

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6
Q

What is the difference between mendelial and non-mendelian inheritance?

A

Mendelian: A change in a single gene, sufficient to cause clinical disease e.g. autosomal dominant/recessive and X linked
Non-mendelian: everything else including common “multifactorial” diseases

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7
Q

What does allelic heterogeneity mean?

A

Different mutations in the same gene can cause the same disease
(different locations in same gene = same disease)

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8
Q

What does locus heterogeneity mean?

A

The same disease might be caused by mutations in one of several genes.
(different genes = same disease)

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9
Q

What dos consanguineous mean?

A

Famillies where the parent’s are cousins hence they have 12.5% of shared genes

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10
Q

In the sex chromosomes, where do the mutations lie.. on the x or y chromosome?

A

X

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11
Q

What is nonpenetrance?

A

Failure of a genotype to manifest

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12
Q

What is variable expression?

A

Different family members may show different features of a disorder

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13
Q

Name two complications that occur in basic pedigree patterns and why they occur?

A

Non-penetrance and variable expression

Due to influence of other genes and environment

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14
Q

Where is your mitochondrial DNA inherited from? and what genes does it contain?

A

Mother

contains important genes for mitochondrial metabolic pathways and ribosomal RNAs

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15
Q

How does G1 differ from G2?

A

G1 involves checking that the cell is nutritionally sufficient to divide. G2 is checking that the DNA replication in S phase is sound

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16
Q

What is the structural difference between activated CDK- cyclin complex vs inactivated?

A

Inactivated: cdk, cyclin, 2 phosphate groups (activating and inhibitory) Phosphorylation via protein kinases
Activated: lacks the inhibitory phosphate

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17
Q

Name 2 protein kinases involved in the phosphorylation of cdk-cyclin complexes?

A

Wee1 and Cak (CDK-activating-kinase)

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18
Q

What is the R point?

A

The point at G1 at which the cell no longer requires growth factors to complete the cell.
This is the point when the cell decides if it’s going to divide or not.

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19
Q

What is the mechanism for ubiquitination?

A
  1. Ubiquitin has to be activated which requires an E1 enzyme
  2. Ubiquitin gets conjugated through an E2 enzyme
  3. Ubiquitin is transferred using an E3 enzyme (E3 ubiquitin ligase). It is the combination of the E2 and E3 that recognises the substrate, this allows the transfer of the ubiquitin onto the substrate
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20
Q

Function of a proteasome?

A

To recognise ubiquitinated cyclin

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21
Q

What is the function of cdk inhibitors? 1 example?

A

Function: controls of the checkpoints.
Transcription of inhibitors can be induced if conditions are not right for cell division (e.g. p21)
They sit on top of cyclin-cdk complex and prevent its activation

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22
Q

Describe how the activation of p16 prevents cell proliferation?

A

When p16 is active the cdk-complex of cdk 4 and cyclin D is inactive. These leads to activation of Rb protein which represses the expression of E2F transcription factor.

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23
Q

What is cdc6?

A

CDC6 (cell division cycle 6): Gene which encodes for a protein which initiates DNA replication. Once it has done its job (initiated DNA replication it is phosphorylated.

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24
Q

What is p53?

A

p53 (aka TP53 or tumor protein) is a gene that codes for a protein that regulates the cell cycle and hence functions as a tumor suppression. It is very important to suppress cancer.

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25
Q

What is Chk2?

A

Checkpoint kinase 2, a multifunctional enzyme whose functions are central to the induction of cell cycle arrest and apoptosis by DNA damage.

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26
Q

What are the structures that allow the dense condensation of DNA?

A

Condensins

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27
Q

What is the purpose of seperase?

A

In the transition from metaphase to anaphase once all the chromosomes are in the correct orientation, it destroys the cohesion rings

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28
Q

What is the inhibitor protein of seperase?

A

Securin

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29
Q

What is the APC?

A

Anaphase promoting complex

When activated degrades securin which activates seperase.

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30
Q

WHAT IS THE DIFFERENCE BETWEEN MEIOSIS AND MITOSIS?

A
  • Meiosis results in haploid cells (gametes) whereas mitosis results in diploid cells
  • Meiosis consists of one round of DNA replication and two divisions
  • At the metaphase plate the homologous chromosomes line up independently vs in their pairs as they do in mitosis.
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31
Q

What is a bivalent?

A

Structure formed when chromosomes replicate and align

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32
Q

What are the sources of genetic variability in haploid cells? And when do they occur?

A

Recombination via chiasma
independent assortment
IN PROPHASE 1

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33
Q

Non-disjunction errors in the Meiosis I result in…

A

Uniparental heterodisomy

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34
Q

Non-disjunction errors in the Meiosis II result in…

A

Uniparental isodisomy

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35
Q

What is one of the potential causes for the increased incidence of meiotic error as maternal age increases?

A

There is a long arrest in the prophase of female gametes. Hence the strength of cohesion complexes is vital, as age increases these begin to degrade hence there is an increased chance of non-disjunction occuring

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36
Q

Which chromosomes are acrocenteric?

A

13,14,15,21, 22

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37
Q

Why do chromosomes become acrocenteric?

A

There important genetic information is only contained on the long arm (i.e. the short arm is useless)

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38
Q

What syndrome is caused by trisomy of chromosome 21? How is it written?

A

Down syndrome

written as 47 XY/XX +21

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39
Q

What syndrome is caused by trisomy of chromosome 18? How is it written?

A

Edward syndrome

47 XY/XX +18

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40
Q

What syndrome is caused by trisomy of chromosome 13? How is it written?

A

Patau syndrome

47 XX/XY +13

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41
Q

Why are there no syndromes with just one chromosome (monosomic)

A

They are not compatible with life hence result in miscarriage

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42
Q

What is the karyotype of Turner syndrome?

A

Only 1 X chromosome

45 X

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43
Q

What are 2 chromosome mutations in structure?

A

Chromosomal insertion and translocation

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44
Q

When does robertsonian translocation occur?

A

When two acrocentric chromosomes stick end to end.

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45
Q

How to write out karyotype?

A

(total number of chromosomes), (sex chromosomes), “mutation abbreviation” (of which chromosomes ) (position of break points)
E.g. 46, XX, t(14;21) (p13,p14)

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46
Q

What do these abbreviations mean in karyotypes:
t?
der?

A 
t= translocation
der= derived from parent during pregnancy
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47
Q

In order for a reciprocal translocation to be stable there must be an exchange of…`

A

Two acentric fragments

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48
Q

When is a mutation balanced?

A

When there is an equal quantity of genetic information

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49
Q

Unbalanced products of mutations result in? (2 options)

A

Miscarriage is large segments are affected (either missing or added)
Dysmorphic delayed child (if small segments are effected)

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50
Q

What illness is caused by the presence of a phildelphia chromosome/

A

Common myeloid leukaemia

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51
Q

What are three types of single chromosome mutations?

A

Deletion, duplication and inversion

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52
Q

What disease is found in duplication of ch17 p11.2?

A

Charcot Marie Tooth disease

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53
Q

Describe the formation of mature t cell from bone marrow stem cells.

A

T cells derive from bone marrow stem cells. T cell precursor cells arrive in thymus (to undergo thymic education) and spend up to 7-21 days undergoing differentiation and proliferation into a mature, but antigen naïve, phenotype. After which they are released into your peripheral lymphoid tissue (i.e. lymph nodes, spleen)

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54
Q

Describe the process of educating T cells

A
  1. T cells start as double positive thymocytes (showing both CD4 and CD8)
  2. They have a TcR that on the most part won’t recognize your own MHC so these T cells die of “positive selection”
  3. The cells that do recognize your MHC go on to mature and express high levels of TcR. These then lose either their CD4 or CD8 to become single positive cells.
  4. Negative selection also occurs to eliminate T cells that see your MHC in high affinity. These would become autoreactive.
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55
Q

What is the aim of t cell education?

A

Results in the release of t cells into the periphery that are restricted to recognizing your own MHC

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56
Q

Name 3 similarities between TcR’s and antibodies

A
  1. Both have alpha and beta chain
  2. Both have an antigen binding site at the front and back end of the structure
  3. Extreme variability is generated by splicing of the DNA leads to chromosomal rearrangement
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57
Q

What is the main difference between an antigen binding onto a TcR vs an antibody?

A

Antibodies bind to antigens on it’s own (free in solution/in a membrane). The TcR can only recognize an antigen when it is bounded by an MHC molecule, it is “MHC restricted”

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58
Q

How are MHCs formed?

A

When proteins inside the cell die they breakdown and degrade. This is broken down to peptides by the immune system then presented on the cell surface as MHC molecules.

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59
Q

What are the difference between Class I and Class II MHC molecule structure?

A

Class I has a smaller “peptide binding groove”

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60
Q

What is the difference between cells that express the class I and II MHC molecules?

A

Class I is on almost every cell, Class II expression is limited to specialized antigen presenting cells and immune cells.

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61
Q

MHC Class I molecules are recognized by which t cell?

A

CD8 T cells

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62
Q

MHC Class II molecules are recognized by which t cell?

A

CD4 T cells

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63
Q

Where do MHC Class I pick up peptides?

A

Derived from the internal contents of the cell e.g. cytoplasm, nucleus
Then meets peptides in the ER

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64
Q

Where do MHC class II pick up peptides?

A

Picks up peptides derived from external sources i.e. outside your cells. These MHC molecules then meet peptides in endosomes.

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65
Q

What is HLA?

A

Human Leukocyte Antigen system:A gene complex encoding the MHC proteins in humans

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66
Q

What is the main cause for graft rejection?

A

MHC disparity. Different MHC presentation will induce an immune response.
MHC matching plus administrating immunosuppressants is key to avoid this

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67
Q

What type of cancer originates during B and T cells development?

A

Leukaeumia

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68
Q

What illnesses are caused when bacteria/viruses produce proteins that interfere with the interactions of TcR and MHC, stimulating large numbers of T cells?

A 
Staphlococcal enterotoxin (SEB)
Severe combined immunodeficiency (SCID)
Bare lymphocyte syndrome
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69
Q

What are the 3 mechanisms of communication between immune cells?

A
  1. Cell-cell contact
  2. Receptor-ligand interactions e.g. MHC and TcR
  3. Secretion of soluble factors that bind to receptors to initiate specific responses
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70
Q

What are cytokines?

A

large group of proteins, peptides or glycoproteins that are secreted by specific cells of immune system. Cytokines are a category of signaling molecules that mediate and regulate immunity, inflammation and hematopoiesis.

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71
Q

What is an interleukin?

A

Cytokine secreted by leucocytes (WBCs)

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72
Q

What cell releases IL-2, IL-4, IF-gamma and TNF-alpha?

A

T cells

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73
Q

What is the function of IL-2?

A

Autocrine mechanism to enhance immune response

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74
Q

What is the function of IL-4?

A

Activates B cells to become antibody secreting cells. Can help alter which antibody they secrete e.g. release of IgE in an allergic reaction

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75
Q

What is the importance of IF-gamma?

A

Upregulation of gene that are involved in an immune response in immune cells (e.g. upregulating MHC genes)

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76
Q

What is the function of TNF-alpha? What are the risks?

A

Pro-inflammatory cytokine
Is a primary target for antibody therapy to wipe out inflammatory response. If it induces a systemic response it can cause multiple organ failure.

77
Q

What secretes IL-12 and what is its function?

A

Secreted by macrophages and activates natural killer cells by inducing the differentiation from CD4 t cells into Th1 cells

78
Q

What is a chemokine?

A

A class of cytokines that has a chemoattractant property

79
Q

What are the two groups of chemokines?

A

CC and CXC

80
Q 
CC chemokines:
Source?
Target?
Effect?
Mechanism?
A

Source: monocytes, macrophages, fibroblasts, keratinocytes, endothelial cells
Target: neutrophils, naïve t cells
Effect: activates cells and signals them to migrate to site of infection (chemotactic factor)
Mechanism: Neutrophil adhere to infected cell endothelium, roll over it until they find access point (diapedesis) then migrate to infection site.

81
Q

What are the two types of CD4 T cell?

A

TH1 and TH2

82
Q

What is the difference between TH1 and TH2 CD4 t cells?

A

TH1 cells: release cytokines that produce CELL MEDIATED IMMUNITY (macrophages)
TH2: produce cytokines that activate B cells

83
Q

What are dendritic cells?

A

Professional antigen presenting cells that sit at the interface between the innate and adaptive immune response

84
Q

What is the mechanism of dendritic cells?

A

Highly phagocytic, upon stimulation by sampling external environment cease phagocytosis and migrate to lymph nodes. DC in lymph nodes activate T cells and also influence B cells.

85
Q

What are the two types of increased growth?

A

Hypertrophy
Hyperplasia
[both can be combined]

86
Q

Name 3 examples of how hyperplasia is used in tissue repair

A

Angiogenesis
Wound healing
Liver regeneration

87
Q

Name two examples to physiological atrophy?

A

Thymus alteration

Ageing

88
Q

Name 4 examples of proportional alterations in skeletal growth?
(Category of systemic growth disorder)

A

Turner syndrome
Beckwith-weidemann syndrome
Pituitary giantism

89
Q

Name an example of a disproportional alteration in skeletal growth?
(Category of systemic growth disorder)

A

Achondroplasia

90
Q

What is Turner’s syndrome?

A

Genetic abnormality leading to decreased growth due to only 1 sex chromosome being present (X)
Proportionate alteration

91
Q

What is Beckwith-wiedemann syndrome?

A

Genetic abnormality leading to increased growth due to inheriting two copes of the paternal chromosome.
Proportionate alteration

92
Q

What is pituitary giantism?

A

Increased IGF-1 (insulin growth factor) and growth hormone release often due to pituitary tumours
Proportionate alteration

93
Q

What is achondroplasia?

A

Defect in “Fibroblast Growth Factor Receptor 3” leading to disproportionate growth in bone

94
Q

Name 3 disorders of differentiation

A

Metaplasia
Dysplasia
Neoplasia

95
Q

What is metaplasia and where does it often occur?

A

Disorder of differentiation where there is a change in the differentiated cell type

96
Q

What are 3 characteristics of dysplasia?

A

Increased cell proliferation
Decrease differentiation
Often premalignant

97
Q

Name 2 characteristics of neoplasia

A

Abnormal uncoordinated excessive cell proliferation

Persists after initiating stimulus is withdrawn

98
Q

Name 5 anomalies of organogenesis and define

A

Agenesis: failure to develop an organ or structure e.g. renal agenis
Atresia: Failure to develop a lumen. E.g. in the oesophagus, duodenum and anus.
Hypoplasia: Failure of an organ to develop to normal size
Ectopia: Small areas of mature tissue from one organ present in another
Maldifferentiation: Failure of normal differentiation

99
Q

True or false:

A cell can differentiate and proliferate at the same time

A

False

E.g. Wilm’s tumour in the liver contains cartilage, smooth muscle and bone

100
Q

How do the kidney’s control RBC production?

A

It monitors the oxygen delivery
By producing erythropoietin it is able to stimulate RBC production in the bone marrow in situations where oxygen delivery is low

101
Q

What is erythropoietin (EPO)?

A

Glycoprotein hormone produced by fibroblasts in the kidney that regulates RBC release

102
Q

What is the change in EPO conc in anaemic patients?

A

Increase due to low Hb

103
Q

What is the change in EPO conc in patients with renal failure?

A

Cannot produce EPO so cannot compensate for low Hb

104
Q

When do IgG anitbodies appear?

A

After exposure to blood transfusion or foeto-maternal transmission

105
Q

When do IgM antibodies occur?

A

Due to components in food that mimic A and B antigens

106
Q

What does the Fc region of an antibody do?

A

Binds to phagocyte and elicits a response

107
Q

What is the purpose of the H antigen?

[in ABO system]

A

Acts a precursor for A and B antigens

108
Q

Which gene and where on it codes for the H antigen?

[in ABO system]

A

FUT1 and FUT2 genes found on chromosome 19

109
Q

How do the H antigens become A and B antigens?

[in ABO system]

A

A and B genes (found on chromosome 9) code for glucosyl transferases which add further sugar groups

110
Q

What are the different antigens in the Rhesus system?

A

c C D e E

111
Q

Which chromosome codes for the rhesus antigens?

A

Chromosome 1 and inherited as a triplet e.g. cDe

112
Q

What are the 4 types of transfusion reaction?

A

Acute haemolytic reaction
Delayed haemolytic reaction
Urticardia/anaphylaxis
Febrile reactions (HLA antibodies)

113
Q

What is agglutination?

A

The visible expression of the aggregation of antigens and antibodies

114
Q

What is HDFN?

A

Haemolytic Disease of Foetus and Newborn

115
Q

What is the cause, reaction and result of HDFN?

A

Cause: Foetal red cells (carrying antigens from the father) transferring to the maternal circulation
Reaction: In response the mother produces IgG antibodies
Result: These antibodies cross the placenta causing anaemia, jaundice, brain damage and foetal death

116
Q

What are prevention strategies for HDFN?

A

Anti-D prophylaxis given to D-neg mothers at 28 weeks and delivery
Kleihauer test looks for foetal cells in maternal circulation
Foetal monitoring by ultrasound

117
Q

Name 4 properties of malignant cells?

A

Disordered proliferation, apoptosis, differentiation and realationship between proliferating cells and the surrounding environment

118
Q

What are the steps in tumour formation?

A
  1. Normally stratified squamous epithelium
  2. Some loss of stratification. Immature cells escape from basal cell layer
  3. Total loss of stratification immature cells throughout. Basement membrane intact
  4. Erosion of BM. Tumour gains access to vascular channels
  5. Cells escape from tumour via lymphatics
  6. Secondary tumour in lymphatics
119
Q

Alteration of which genes is key for tumour formation?

A

Inactivation of tumour suppressor gene

Activation of oncogene

120
Q

What is the difference between a proto-oncogene and an oncogene?

A

Proto-oncogenes code for proteins that help regulate cell growth.
A change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which produces a different protein and interferes with normal cell regulation.

121
Q

What are the 3 ways in which a gene can become oncogenic?

A
  1. Mutation in coding sequence –> Hyperactive protein made in normal amounts
  2. Gene amplification –> Normal protein greatly overproduced
  3. Chromosome rearrangement –> Nearby regulatory DNA sequence causes overproduction of normal protein / fusion to actively transcribed gene produces hyperactive fusion protein.
122
Q

Name 4 examples of the actions of the proteins coded for by oncogenes

A
  1. Act as growth factors
  2. Activate growth factor receptors
  3. Signal transduction: Interference with intracellular signalling
  4. Transcription factors: Direct stimulation of cell cycle dependent transcription
123
Q

Tumour suppressor gene mutation: Recessive/dominant?

A

Recessive

124
Q

Mutations in the tumour suppressor gene lead to…

A

Cell survival and proliferation.

“Divide” signal

125
Q

What is the function of gatekeepers?

A

Inhibit proliferation

Promote cell death, especially those with DNA damage

126
Q

What is the main function of caretakers? and how do they carry it out?

A

To maintain integrity of the genome by promoting DNA repair

by. ..
- nucleotide excision repair
- mismatch repair
- DNA double strand break repair

127
Q

What genes acts both as a gatekeeper and caretaker?

A

p53

128
Q

How do mutated cells prevent shortening of their telomeric DNA?

A

Express telomerase –> immortalization

129
Q

Describe the angiogenesis signaling cascade

A

Cancer cell secretes VEGF (Vascular Endothelial Growth factor) which stimulates endothelial cells to secrete proteins. These stimulate new endothelial cell growth. These activated endothelial cells go onto secrete MMPs (matrix metalloproteinase) which signal for the degradation and turnover of ECM

130
Q

What are the 4 stages of metastasis?

A
  1. Tumor cells detach from one another due to reduced adhesiveness
  2. Cells attach to BM due to laminin receptors
  3. Proteolytic enzymes are secreted (including type 4 collagenase and plasminogen activator)
  4. Degradation of BM and tumor cell migration flow
131
Q

What are the 7 key features in order for a tumour to metastasize?

A 
Self-sufficiency in growth signals
Insensitivity to growth-inhibitory signals
Evasion of apoptosis 
Defects in DNA repair
Limitless replicative potential
Sustained angiogenesis 
Ability to invade and metastasise?
132
Q

How are RBC’s formed? (4 steps)

A
  1. Stem cells differentiate to form CFU-GEMM (colony forming unit- granulocyte, erythroid, megakaryocyte, macrophage) then differentiate again to form CFU- erythroid committed cells
  2. CFU-E’s cluster around macrophages. The kidneys release erythropoietin which stimulates CFU-E to make Hb
  3. The nucleus is then extruded from the cell and released into venous sinusoid
  4. RBC need 7 days to mature in the bone marrow before they are released as reticulocytes
133
Q

Causes of inherited anaemia?

A

Hb problem
membrane problem
RBC enzyme problem

134
Q

Causes of acquired anaemia?

A 
Nutritional deficiency (B12, folate, iron)
Haemolysis (autoimmune disease
Renal failure (decrease in erythropoietin)
Chronic disease associated (cytokine effect from infection/inflammation)
Aplastic anaemia (problem in hematopoiesis)
135
Q

What is the cause of chronic myeloid leukaemia?

A

Translocation of genes between chromosomes 9 and 22, resulting the chromosome 22 forming a shorter “Philadelphia chromosome”

136
Q

What is the course of treatment for acute myeloid leukaemia?

A
  1. Diverse cytogenetic changes so there is the no single target for chemotherapy
  2. Chemotherapy results in marrow aplasia
  3. Marrow regenerates from residual cells
137
Q

What are the three mechanisms of epigenetic gene silencing?

A

DNA methylation
Nucleosome remodeling
Histone modification

138
Q

What is epigenetics?

A

Heritable modifications of DNA that do not alter the primary sequence. Results in altered gene expression

139
Q

How does DNA methylation inhibit gene expression?

A

Methyl groups are bound to cytosine bases in GC rich areas of promotors
Methylation prevents the binding of transcription factors to the promoter and inhibits transcription by converting chromatin from an open to closed conformation

140
Q

What two conditions are caused by DNA methylation on chromosome 15?

A

Prader-willi syndrome

Angelwan syndrome

141
Q

What is the main difference between euchromatin and heterochromatin?

A

Heterochromatin is transcriptionally inactive, euchromatin in transcriptionally active.

142
Q

What is the position effect?

A

Spreading of heterochromatin into euchromatic regions causes cell-to-cell variations in gene expression

143
Q

What is Rett syndrome?

A

Dominant X-linked, neurodegenerative disorder

Caused by a mutation in the gene coding for methyl CpG binding protein 2 leading to loss of gene silencing

144
Q

What is uniparental disomy?

A

When both copies of a chromosome are inherited from the same parent. Resulting in the expression of imprinted genes on the affected (absent) chromosome being altered.

145
Q

What syndrome is caused by trisomy of this chromosome:
21?
18?
13?

A 
21= Down syndrome
18= Edwards syndrome 
13= Patau syndrome
146
Q

What does the liability threshold model represent?

A

As the number of multifactorial genes for the disease increase, the liability for the disease increases. When it reaches the threshold the liability is so great that it results in disease.

147
Q

What is a mutation?

A

A gene change that directly causes a genetic disorder

148
Q

What is a polymorphism?

A

Any variation in the human genome that does not cause a disease in its own right. It may however, predispose to a common disease i.e. is a risk factor.

149
Q

The children of an affected female are more at risk of inheriting the condition. Why?

A
  • Males are more prone to getting the condition (i.e. have a lower liability threshold)
  • For a female to be affected, she must be at the high end of the curve (i.e. have more contributing factors)
150
Q

What makes a polymorphism a risk factor?

A

When the number of polymorphisms in affected > number in unaffected

151
Q

Problems with association studies?

A
  1. Pinpointing gene:
  2. Pinpointing polymorphism:
  3. False results: When you are testing many polymorphisms, some will give a significant result by chance.
  4. Control matching: Your control group has to match your affected group
  5. Replication
  6. Consequent affect on protein
  7. Clinical relevance
152
Q

If the condition is early onset it is likely to be caused by a [ ], if it occurs later on it is likely to be due to a [ ]

A

mutation

polymorphism

153
Q

What is epigenesist?

A

Process by which an organism develops from a single cell through a sequence of steps in which cells differentiate and organs form

154
Q

What does totipotent mean? Example.

A

Identical and unrestricted cells, can give rise to any cell of the body
E.g Cells of the very early mammalian embryo

155
Q

What does pluripotent mean? Example.

A

Less potent cells vs totipotent, can give rise to many cell types but not all
E.g. Inner cells of the blastocyst

156
Q

What does multipotent mean? Example.

A

Can give rise to cells of a particular system

E.g. blood stem cells

157
Q

What are the two stages of cell commitment?

A

Stage 1: Specification

Stage 2: Determination

158
Q

What are the differences between the 2 stages of cell commitment?

A

Stage 1: The cell is capable of differentiating autonomously in isolation but can be respecified if exposed to alternate signals
Stage 2: Cells will differentiate autonomously despite being exposed to alternate signals (e.g. being in a different part of the embryo)

159
Q

What is competence? How is it lost?

A

Competence: Ability of a cell to respond to the chemical stimuli. A cell can lose competence by change in surface receptor or intracellular molecules.

160
Q

What two key pieces of information are needed for a naïve cell to become specified?

A 
Intrinsic (cytoplasmic determinants) to tell the cell who it is
Extrinsic signal (induction) to tell the cell where is it.
161
Q

Patterning of bone and tissue regulated by expression of gene of the…..

A

HOX clusters

162
Q

Removal of which two HOX clusters results in the abrogation of limb development?

A

HOX A

HOX D

163
Q

HOX clusters with a higher number code for more [ ]phenotypes

A

Distal

Hence removal of lower numbered clusters results in a more severe phenotype

164
Q

What is colonization?

A

presence of a microbe in the human body that does not cause infection or a specific immune response

165
Q

What is an infection?

A

occurrence of inflammation due to the presence of a microbe

166
Q

What is bacteraemia?

A

presence of viable bacteria in the blood

167
Q

What does SIRS stand for?

A

Systemic Inflammatory Response Syndrome

168
Q

What parameters are used to confirm SIRS?

A

Temp: 38
HP: 100bpm20
Normal leukocyte count 4,000/mm3-16,000/mm3

169
Q

What conditions result in Sepsis?

A

SIRS + a documented infection site

170
Q

What is Severe Sepsis?

A

Sepsis associated with:

  • Organ dysfunction
  • Hypoperfusion abnormalities
  • Hypotension
171
Q

What is septic shock?

A

Sepsis induced hypoperfusion despite fluid resuscitation PLUS hypoperfusion abnormalities

172
Q

What is perfusion?

A

The process of the body delivering blood to a capillary bed

173
Q

Name 4 risk factors for sepsis?

A

Diabetes
Immunosuppresion
Asplenic (dysfunction or lack of spleen)
Cancer

174
Q

Name 2 common pathogens for sepsis?

A

S. aureus (inc MRSA)

Streptococcus

175
Q

What is the sepsis 6?

A

A set of interventions:

  1. Administer high flow oxygen
  2. Take blood cultures (important to take before administering antibiotics)
  3. Give broad spectrum antibiotics
  4. Give IV fluids (perfusion of endothelial means giving orally isn’t as effective)
  5. Measure serum lactate and haemoglobin
  6. Measure hourly urine output
176
Q

What would a blood test show in a septic patient?

A

WCC, CRP (C reactive protein, inflammatory marker), platelets, clotting

177
Q

When dealing with a septic patient, what are the steps taken?

A

ABC –> Sepsis six –> Start antibiotic treatment –> Notify infection control  Patient isolation –> Notify public health –> Public health with arrange contact tracing

178
Q

Name 4 infections of the skin

A

Cellulitis
Erysipelas
Necrotising fasciitis
Impetigo

179
Q

Why is deep infection more likely in bites injuries to the hand/foot?

A
  • Poor blood supply in several structures
  • Little subcutaneous fat
  • Superficial signs of deep infection is minimal/absent
180
Q

What is the most common gram film appearance of bacteria causing SSTIs?
Name 2 examples

A

Gram positive cocci

181
Q

What is a very rare cause of SSTI?

A

Coagulase negative staphylococci

182
Q

What is prophylaxis?

A

Measures taken to prevent the spread of disease

183
Q

What drug treatment should NEVER be given to treat an animal bite?

A

Clindamycin monotherapy

184
Q

List the follow infections in order of duration of treatment from lowest to highest:

  • Tenosynovitis
  • Osteomyelitis
  • Cellulitis
  • Septic arthritis
A

Cellulitis (1 week)
Tenosynovitis (3 weeks)
Septic arthritis (4 weeks)
Osteomyelitis (6 weeks)

185
Q

What are the two functions of antibodies?

A

Bind to pathogen that elicited its production

Recruits other cells and molecules that will lead to clearance/destruction of the pathogen

186
Q

Describe the structure of an antibody

A

Made up of 4 polypeptide chains: 2 identical heavy and 2 identical light
The heavy chains are disulphide bonded to eachother
Each heavy chain is disulphide bonded to a light chain
The light chains can either be lamda or kappa. Not a mixture of both

187
Q

What are the two functional regions on an antiobody? and what do they bind to?

A 
Fab= binds to antigen
Fc= binds to receptor
188
Q

ANTIGENS ENTER LYMPH NODES THROUGH [ ] NOT [ ]

A

ANTIGENS ENTER LYMPH NODES THROUGH THE BLOOD NOT LYMPH

189
Q

What 4 methods are used to produce hypervariability in antibodies?

A
  1. Rearrangment of V gene segments
  2. Junctional diversity: N-nucleotides are added to gene sequency
  3. Different combinations of H and L chains
    (above happens during B cell development)
  4. Somatic hypermutation: After development mutationsc an lead to better binding to antigen. These cells are selected to expand. This is a process affinity mutation

MD2002 (7 decks)

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