Ch1 The Cell Flashcards by Rachel Dennis

Binding site for transcription factors

Promoter and enhancer regions

How well did you know this?

Not at all

Perfectly

RNAs that are never translated but regulate gene expression through a variety of mechanisms . Includes miRNAs and lncRNAs

Noncoding regulatory RNAs

How well did you know this?

Not at all

Perfectly

Non-protein coding sequence that make up more than a third of the genome. Can move around the genome (“jumping genes”) resulting in a variable copy number and positioning even among closely related species

Mobile genetic elements (e.g. transposons)

How well did you know this?

Not at all

Perfectly

The two most common forms of DNA variation in the human genome

Single nucleotide polymorphisms (SNPs) and copy number variations (CNVs)

How well did you know this?

Not at all

Perfectly

Variants at single nucelotide positions; almost always biallelic (i.e. only 2 choices existing at a given site within the population e.g. A or T)

Single nucleotide polymorphisms (SNPs)

How well did you know this?

Not at all

Perfectly

Form of genetic variation consisting of different numbers of large contiguous stretches of DNA

Copy number variations (CNVs)

How well did you know this?

Not at all

Perfectly

Non-coding RNAs that modulate translation of target messenger RNAs.
Action results in post-transcription silencing by cleavage or translational repression of mRNA

miRNAs

How well did you know this?

Not at all

Perfectly

Non-coding RNA that modulates gene expression by several mechanisms including:
A) facilitating TF binding and promoting gene activation
B) bind TF to inhibit transcription
C) promote chromatin modification
D) act as scaffolds for assembly of protein complexes

Long non-coding RNAs (lncRNAs)

How well did you know this?

Not at all

Perfectly

Nonrandom association of alleles of different loci

(e.g. SNPS may be useful markers if co-inherited with a disease associated polymorphism as a result of physical proximity)

Linkage disequilibrium

How well did you know this?

Not at all

Perfectly

Contain catalase, peroxidase, and other oxidative enzymes. Play a specialised role in the breakdown of very long chain fatty acids, generating hydrogen peroxide in the process

Peroxisomes

How well did you know this?

Not at all

Perfectly

“disposal” complexes that degrade denatured or otherwise “tagged” cytosolic proteins

proteasomes

How well did you know this?

Not at all

Perfectly

intracellular organelles containing degradative enzymes that permit digestion of a wide range of macromolecules

Lysosomes

How well did you know this?

Not at all

Perfectly

3 major classes of cytoskeletal proteins

Actin microfilaments
Intermediate filaments
Microtubules

How well did you know this?

Not at all

Perfectly

5-9nm diameter fibrils formed from the globular protein actin (G-actin)

Actin filaments

How well did you know this?

Not at all

Perfectly

10nm diameter fibrils that comprise a large and heterogeneous family that includes keratin proteins and nuclear lamins
Predominantly form ropelike polymers that do not usually actively reorganise

Intermediate filaments

How well did you know this?

Not at all

Perfectly

25nm thick fibrils composed of noncovalently polymerised alpha and beta tubulin dimers organised into hollow tubes
Extremely dynamic with + and - ends

Microtubules

How well did you know this?

Not at all

Perfectly

Form the core of primary cilia

Microtubules

How well did you know this?

Not at all

Perfectly

Seal adjacent epithelial cells together to create a continuous barrier that restricts the paracellular movement of ions and other molecules

Occluding (tight) junctions

How well did you know this?

Not at all

Perfectly

Mechanically attach cells and their cytoskeletons to others cells or the ECM

Anchoring junctions (adherens junctions and desmosomes)

How well did you know this?

Not at all

Perfectly

In this form of anchoring junction, the transmembrane adhesion molecules are associated with intracellular actin microfilaments through which they can also influence cell shape and/or motility

Adherens junctions

How well did you know this?

Not at all

Perfectly

In this form of anchoring junction, the cadherins are linked to intracellular intermediate filaments, allowing extracellular forces to be mechanically communicated (and dissipated) over multiple cells

Desmosomes

How well did you know this?

Not at all

Perfectly

In this form of anchoring junction, integrins are the transmembrane connector proteins which attach to intermediate filaments and link the cytoskeleton to the ECM

Hemidesmosomes

How well did you know this?

Not at all

Perfectly

Junctions that permit the diffusion of chemical or electrical signals from one cell to another

Communicating (gap) junctions

How well did you know this?

Not at all

Perfectly

Proteins and lipids destined for other organelles or extracellular transport are shuttled here from the RER

Golgi apparatus

How well did you know this?

Not at all

Perfectly

Relatively sparse in most cells and primarily exists as the transition zone extending from RER to generate transport vesicles that carry newly synthesised proteins to the Golgi apparatus More conspicuous in cells synthesising steroid hormone (e.g adrenals) or that catabolise lipid soluble molecules (e.g hepatocytes)

Smooth endoplasmic reticulum

Responsible for sequestering intracellular calcium

Smooth endoplasmic reticulum

These enzymes are initially synthesised in the ER lumen and then tagged with mannose-6-phosphate (M6P) within the Golgi apparatus

Lysosomal enzymes

Degrade cytosolic proteins such as denatured or misfolded proteins as well as any other macromolecule whose lifespan needs to be regulated (may proteins are labelled for destruction by ubiquitin)

Proteasomes

Phenomenon of rapidly dividing cells increasing their uptake of glucose and glutamine and switching to aerobic glycolysis

Warburg effect

Growth factor produced by activated macrophages, salivary glands, keratinocytes... Mitogenic for many cell types' stimulates epithelial cell migration; stimulates formation of granulation tissue

EGF

Produced by activated macrophages; keratinocytes... Stimulates proliferation of hepatocytes and many other epithelial cells

Transformation growth factor alpha (TGF-a)

Enhances proliferation of hepatocytes and other epithelial cells; increases cell motility Produced by fibroblasts and most mesenchymal cells, endothelial cells, non-hepatocyte liver cells

HGF

Produced by mesenchymal cells Increases vascular permeability Stimulates proliferation of endothelial cells Maintenance of normal epithelium (highest expression in epithelial cells adjacent to fenestrated epithelium)

VEGF

Induces fibroblast; endothelial and SMC proliferation and also chemotactic for these cells

PDGF

Produced by macrophages, mast cells, endothelial cells.. Chemotactic and mitogenic for fibroblasts; stimulates angiogenesis and ECM protein synthesis

Fibroblast growth factors (FGFs)

Multiple and often opposing effects depending on tissue "pleiotropic" Stimulates production of collagen, fibronectin, proteoglycans . Inhibits collagen degradation by decreasing MMP activity and increasing TIMP activity (drives scar formation) Anti-imflammatory cytokine

TGF-beta

occupies the spaces between stromal cells within connective tissue and between parenchymal epithelium and the underlying supportive vascular and smooth muscle structures in some organs

Interstitial matrix

2 major constituents of basement membrane

Type 4 collagen Laminin

Collagen types I, II, III and V that form linear fibrils stabilised by interchain hydrogen bonding

Fibrillar collagens

Enzyme responsible for cross-linking of fibrillar collagens and providing tensile strength. Dependent on vitamin C

lysyl hydroxylase

Collagen that contributes to structures of planar BM; help regular collagen-collagen interactions; provide anchoring fibrils that maintain structure of stratified squamous epithelium

Nonfibrillar collagens

confers the ability of tissues to elastically recoil and return to a baseline structure after physical stress

Elastin

Form highly hydrated compressible gels that confer resistance to compressible forces Consist of long polysaccharides called glycosaminoglycans (e.g keratan sulfate and chondroitin sulfate)

Proteoglycans

Function to enforce the cell cycle checkpoints

CDK inhibitors

stem cells that give rise to the full range of differentiated tissues

totipotent stem cells

stem cells that only have the capacity to replace damaged cells and maintain cell populations within the tissues where they reside

adult stem cells

2 types of cell division used by stem cells for self renewal

- asymmetric division (cell replication in which one daughter cells enters differentiation pathway while the other remains undifferentiated) - symmetric division (both daughter cells retain self renewal capacity)

2 main types of stem cells

- Embryonic stem cells (totipotent) - Tissue stem cells (adult stem cells)

Cell cycle phases? (starting with G0 and G1)

G0, G1, S, G2, M

When does the restriction point occur in the cell cycle?

End of G1

2 checkpoints of the cell cycle?

G1/S G2/M

Tissues where cells may cycle continuously

Labile tissues e.g epidermis and GI tract

Cells that are quiescent but can enter the cell cycle

Stable cells e.g. Hepatocytes

Cells that do have the capacity to proliferate

Permanent cells e.g. neurons and cardiac myocytes

Cells that have the dual property of being able to self renew and give rise to differentiated cells and tissues

Stem cells

Result from introduction of selected genes into differentiated stem cells which reprogram somatic cells to achieve the "stem-ness" of ES cells

Induced pluripotent stem cells

2 key growth factors involved in the second phase of liver regeneration

Hepatocyte growth factors (HGF) TGF-alpha (these are produced by many cell types and act on hepatocytes to stimulate cell metabolism and entry of the cells into the cell cycle)

EGFR1 mutations and/or amplification frequently occur in a number of cancers including..

lung head and neck breast brain

These 2 growth factors are produced by macrophages and epithelial cells, are mitogenic for hepatocytes, fibroblasts and a host of epithelial cell types

Epidermal growth factor (EGF) Transforming growth factor alpha (TGF-alpha)

Receptor for this growth factor is MET which has intrinsic tyrosine kinase activity MET is frequently overexpressed or mutated in tumours, particularly renal and thyroid papillary carcinomas

HGF

Major angiogenic factor after injury and in tumours

VEGF

Most important inducer of VEGF production

Hypoxia

Antibodies against this growth factor are approved the treatment of tumours such as renal and colon cancers

VEGF

Increased levels of soluble forms of this growth factor receptor in pregnant women may cause preeclampsia

VEGFR-1 (also known as s-FLT-1)

This growth factor may interact with CD20 affecting Rituxumab therapy

Fibroblast Growth Factor (FGF)

Pleiotropic GF with a key role in neoplasia, chronic inflammation and keloids

TGF-beta

What is steatosis?

Abnormal accumulations of triglycerides within parenchymal cells

Pathological processes involving accumulation of cholesterol or cholesterol esters (name 4)

- Atherosclerosis - Xanthomas - Cholesterolosis (focal accumulations of cholesterol-laden macrophages in the lamina propria of the gallbladder) - Niemann-Pick disease Type C

What is Niemann-Pick disease type C?

Lysosomal storage diseases caused by mutations affecting an enzyme involved in cholesterol trafficking, resulting in cholesterol accumulation in many organs

Intracellular accumulations of these usually appear as rounded, eosinophilic droplets, vacuoles, or aggregates in the cytoplasm

Protein

Excessive production of immunoglobulins by plasma cells can cause the ER to become hugely distended with large homogenous eosinophilic inclusions called...

Russell bodies

alpha1-antitrypsin deficiency involves defective transport and secretion of critical...

proteins

Eosinophilic cytoplasmc inclusion in liver cells that is characteristic of alcoholic liver disease and is composed predominantly of keratin intermediate filaments

Alcoholic hyaline

What is meant by the term Hyaline

Alteration within cells or in the extracellular space that gives a homogenous glassy, pink appearance in routine histologic sections stained with H&E

In this disease, glycogen is found in renal tubular epithelial cells, as well as within liver cells, B cells of the islet of Langerhan in the pancreas, and heart muscle cells

Diabetes mellitus

Excessive intracellular deposits of glycogen are seen in patients with an abnormality in either...

glucose or glycogen metabolism

The most common exogenous pigment

Carbon

Accumulation of this pigment blackens the tissues of the lungs (anthracosis) and the involved lymph nodes

Carbon

What is a lipofuscin

An insoluble pigment composed of polymers of lipids and phospholipids in complex with protein. Not injurious to the cell or functions Sign of free radical injury and lipid peroxidation

Endogenous pigment seen in cells undergoing slow, regressive changes. Seen in the liver and heart of ageing patients or those with severe malnutrition and cancer cachexia

Lipofuscin

Enzyme involved in formation of melanin

Tyrosinase

Haemoglobin derived, golden yellow to brown, granular or crystalline pigment; one of the major storage forms of iron

Haemosiderin

What are the 2 types of stem cells and the difference between them?

- **Embryonic stem cells**: present in the inner cell mass of the blastocyst. Totipotent (can give rise to every cell in the body) - **Tissue stem cells (adult stem cells**): found in intimate association with the differentiated cells of a given tissue. Normally protected within specialised tissue microenvironments called stem cell niches. Limited lineage potential.

Where are stem cell niches located?

* Bone marrow * Intestines * Bulge region of hair follicles * Limbus of the cornea * Subventricular zone in the brain

What type of stem cells are found in the bone marrow?

* Haematopoeitic stem cells * Mesenchymal stem cells (can differentiate into a variety of stromal cells including chondrocytes, osteocytes, adipocytes, myocytes)

Which organs are tissue stem cells (Adult stem cells) located in?

* Bone marrow * Liver * Brain * Skin * Intestine

What is the role of stem cells in the repair of damaged tissues?

Regeneration. In tissues such as the skin and intestines, tissue stem cells and their progenitors contribute to the restoration of damaged tissues

What is expressed by stem cells and germ cells that makes them resistant to mitotic crisis, and also to avoid the genetic alterations that trigger senescence?

Telomerase

What are the 2 types of cell division of stem cells?

* Symmetric - both daughter cells remain stem cells (occurs in embyrogenesis or during times of stress) * Asymmetric - only one daughter remains a stem cell; the non-stem cell daughter proceeds along some differentiation pathway

List five non-coding components of the genome.

* Promoter/enhancer regions * binding sites for factors that organise higher order chromatin structures * non-coding regulatory RNA (miRNAs, lncRNAs) * Mobile genetic elements (eg. transposons) * specialised structure regions e.g. centromeres

What is epigenetics?

Heritable changes in gene expression that are not caused by variations in DNA sequence

Difference between heterochromatin and euchromatin?

**Heterochromatin**: cytochemically dense and transcriptionally **inactive** **Euchromatin**: disperse and transcriptionally **active**

What is a histone?

Protein that DNA wraps around

What is the usual effect of histone acetylation, what is the enzyme involved and how is it reversed?

* Histone acetyltransferases (HATs) * tend to open the chromatin and increased transcription * can be reversed by histone deacetylases (HDACs)

What is the role of miRNAs?

Modulate translation of target messenger RNAs Post-transcriptional gene silencing

What is the complex that miRNAs associate with to perform post-transcriptional gene silencing?

RISC (RNA-induced silencing complex)

Roles of proteoglycans in addition to providing compressibility to tissues

* reservoir for growth factors secreted into the ECM * some are integral cell membrane proteins that have roles in cell proliferation, migration and adhesion (e.g. by binding and concentrating growth factors and chemokines)

Large disulfide linked heterodimer that exists in tissue and plasma forms Provides the scaffolding for subsequent ECM deposition, angiogenesis and re-epithelialisation in wound healing

Fibronectin

Most abundant glycoprotein in basement membrane. Connects to underlying ECM components such as type IV collagen and heparan sulfate

Laminin

Family of transmembrane heterodimeric glycoproteins composed of alpha and beta subunits. Provide focal attachment to underlying substrates. Binding elements can also trigger signaling cascades that regulate cell locomotion, proliferation, shape and differentiation

Integrins

Protein ligands that bind to a distinct family of GPCRs - Frizzled family receptors. Regulars intracellular levels of Beta- catenin

Wnt

What is the difference between a cadherin and integrin?

cadherin is a cell adhesion molecule that is mainly important in cell to cell adhesion, while integrin is a cell adhesion molecule that is mainly important in cell to extracellular matrix adhesion

What is the sarcoplasmic reticulum?

Specialised smooth endoplasmic reticulum in muscle that is responsible for the cyclic release and sequestration of calcium ions that regular muscle contraction and relaxation, respectively

What is the role of ubiquitin in proteasomes?

Covalent binding of ubiquitin identifies proteins for destruction by proteasomes

Which growth factor may be involved in pathogenesis of pre-eclampsia?

VEGF

Ch1 The Cell Flashcards

(105 cards)