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Pathology BPS exam > Section 1 Cells > Flashcards

Section 1 Cells Flashcards

1
Q

Define SNPs

A

Single nucleotide polymporphisms
A form of DNA variation
Always biallelic

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2
Q

What portion of SNPs occurs in the coding regions?

A

1%

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3
Q

What is linkage disequilibrium in the context of SNPs?

A

Neutral SNPs are coinherited with a disease-associated polymorphism as a result of proximity

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4
Q

Is the effect of SNPs on disease susceptibility weak or strong?

A

Weak

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5
Q

Define CNVs

A

Copy number variations
Form of DNA variation consisting of large contiguous stretches of DNA

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6
Q

What portion of CNVs is in the coding regions?

A

50%

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7
Q

Do CNVs underlie a large portion of phenotypic diversity?

A

Likely, 50% of CNVs are in coding regions

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8
Q

Define histones

A

Central core structure of highly conserved low molecular weight proteins around which DNA wraps to form nucleosomes

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9
Q

Define nucleosomes

A

DNA segments wrapped around histones

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10
Q

How long are DNA segments in a nucleosome?

A

147bp

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11
Q

How does chromatic structure regulate gene activity?

A

Densely packed heterochromatic is not available for transcription
Dispersed euchromatic is available for transcription

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12
Q

What is the effect of histone methylation?

A

Methylation of histone lysine residues can lead to transcription activation of repression, depending on which histone residue is marked

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13
Q

What part of histones can be methylated?

A

Lysines and arginines

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14
Q

What is the effect of histone acetylation?

A

Increased transcription

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15
Q

How does histone acetylation occur?

A

Histone acetyltransferases (HATs) acetylate lysine residues, which opens chromatin

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16
Q

What is the effect of histone deacetylases (HDACs)?

A

Reversal of histone acetylation

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17
Q

What is the effect of histone phosphorylation?

A

DNA may be opened for transcription or condensed depending on which serine residue is phosphorylated

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18
Q

What part of histones gets phosphorylates?

A

Setine residues

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19
Q

What is the effect of DNA methylation?

A

Typically transcriptional silencing

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20
Q

What is the role of chromatic organising factors?

A

Bind to non-coding regions and control long-range looping of DNA, regulating the spacial relationships between enhancers and promoters.

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21
Q

What is the structure of histones?

A

Octamers of histone proteins, the subunits are positively charged

22
Q

Are microRNA and lncRNA transcribed or translated?

A

Transcribed by not translated

23
Q

What is the role of microRNA?

A

Post-transcriptional silencing of gene expression

24
Q

Does each microRNA regulate one or multiple protein-coding genes?

A

Multiple

25
Q

How is microRNA produced?

A

miRNA genes are first transcribed into a primary transcript. The pri-miRNA is then processed into progressively smaller segments, for example, trimmed by Dicer

26
Q

How does miRNA work?

A

miRNA is associated with RISC. When miRNA binds to target mRNA, RISC either induced mRNA cleavage or represses translation to post-transcriptionally silence mRNA.

27
Q

What is the overall effect of miRNA, Dicer and RISK on gene expression?

A

Post-transcriptional gene silencing

28
Q

What is the role of lncRNA?

A

Modulation via a variety of mechanisms

29
Q

Give an example of how lncRNA modulates gene expression

A

Bind to chromatin to restrict RMA polymerase reaching coding genes
Help ribosone binds and gene activation
Promote chromatic modification
Assemble protein complexes to alter chromatin structure

30
Q

What is XIST?

A

As example of lncRNA that silences the X chromosone in females.

31
Q

List three different sites of molecule breakdown within the cell

A

Proteasome, lysosome and peroxizome

32
Q

What is the function of a proteasome?

A

Breakdown of denatured or tagged cytosolic proteins

33
Q

Give an example of proteasome function

A

Proteases in antigen presenting cells produce peptides displayed on MHC molecules

34
Q

What is the function of a lysosome?

A

Contain degrading enzymes for digestion of a wide range of molecules (proteins, polysaccharides, lipids, nucleic acids)
Intracellular organelle breakdown (autophagy)
Killing and catalysis of phagocytosed microbes

35
Q

What is the function of peroxisomes?

A

Contain catalase, peroxidase, oxidative enzymes
Breakdown of very long-chain fatty acis
Generating hydrogen peroxide

36
Q

Which cellular structure allows movements of structures within the cell and the cell itself?

A

Cytoskeleton

37
Q

What is the cytoskeleton made up of?

A

Actin (microfilaments)
Keratin (intermediate filaments)
Microtubules

38
Q

On which surface of the plasma membrane is phosphatidylinositol located?

A

Both

39
Q

On which surface of the plasma membrane is phosphatidylserine located?

A

Inner surface
Can be flipped to outer surface to become an “eat me” signal

40
Q

On which surface of the plasma membrane are glycolipids and sphignomyelin located?

A

Extracellular

41
Q

How can components of the membrane be confined to discrete domains?

A

Localisation to lipid rafts or intercellular protein-protein interactions (e.g. tight-junctions)

42
Q

What is a common function of actin filaments?

A

With actin nucleating, binding and regulatory proteins, control cell shape and movement
Muscle contraction

43
Q

What is a common function of intermediate filaments?

A

Tensile strength

44
Q

What is a clinical application of intermediate filaments?

A

Have tissue-specific patterns of expression (useful for cancer indentification)

45
Q

What is a common function of microtubules?

A

Lines for molecular motor proteins (kinesins and dyneins) to move components
Sister chromatid separation in mitosis
Form the core of primary cilia, motile cilia (bronchial epithelium), or flagella (sperm)

46
Q

List the three basic types of cell-cell junctions

A

Tight/occluding junctions
Anchoring junctions (adherins junctions and desmosomes)
Communicating junctions

47
Q

What is the clinical significance of Adherins junctions (type of anchoring junctions)?

A

Loss of E-canherin explains the discohesive invasion pattern of some gastric cancers and breast carcinomas

48
Q

Which cells have higher concentrations of SER or in which cells SER have an important function?

A

Cells that synthesise steroid hormones (gonads, adrenals), catabolise lipid-soluble molecules (hepatocytes) or store calcium (sarcoplasmic reticulum in muscle cells)

49
Q

What are the functions of mitochondria?

A

ATP generation
Intermediate metabolism
Regulation of apoptosis

50
Q

List the four types of cell signalling

A

Paracrine
Autocrine
Synaptic
Endocrine

51
Q

How can endothelial cells regulate regulate vasomotor tone?

A

NO produced by endothelial cells diffuses into smooth muscle cells to reach an intracellular receptor.
Activates cGMP, which causes smooth muscle relaxation.

Pathology BPS exam (3 decks)

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