The Cell Flashcards
Nucleus
where almost all genomic information is stored and compacted
2 layer membrane
Heterochromatin
inactive form, appears condensed
Euchromatin
active form, more spread out/relaxed
What is contained in the nucleus?
chromatin, nuclear proteins, RNA, nucleolus
What charge does DNA have?
negatively charged
nucelosome
basic structural unit of chromatin; made up of an octomer of histones
What charge are histones?
negative charge (very basic)
Modification of Histone Proteins
loosening allows for transcription/replication to occur, whereas tightening will shu that process off
How many base pairs are within a nucleosome?
146 bp
transcription
generation of RNA sequence by RNA polymerase
What three types of RNA are made by transcription?
- messenger RNA (mRNA); mainly this
- ribosomal RNA (rRNA)
- transfer RNA (tRNA)
Gene
sequence of DNA that is read to devvelop a particular mRNA encoding a protein
4 Ways Transciption is Regulated
- Transcription factors
- Enhancers
- Repressors
- Epigenetics
Goal of the cell cycle?
to ensure appropriate DNA replication and integrity via checkpoints
What are five proteins that regulate the cell cycle?
- Cyclins
- Cyclin-dependent kinases (CDKs)
- CDK inhibitors
- p53
- Rb
Stages of the Cell Cycle
- G1 (growth)
checkpoint - S (synthesis)
- G2 (growth and prep to divide)
checkpoint - M (mitosis)
Most frequently used DNA repair mechanism?
Nucleotide Excision Repair (NER)
Relationship between Fidelity and DNA Repair
High fidelity = better repair (for small things)
What kinds of things can damage DNA?
radiation, anti-tumor drugs, UV rays, free radicals, etc
Nucleolus
the site at which rRNA is transcribed and ribosomal sub-units are assembled
Relationship between nucleolus size and protein synthesis?
larger nucleolus = more protein synthesis
rRNA as a Diagnostic Tool
sequence the rRNA for fungal and bacterial identification
5 Important Locations in the Cell (inside –> outside)
- Nucleus
- Cytoplasm
- Structural Components
- Plasma Membrane
- Cell Signaling Pathways
Ribosomes
within the cytoplasm, either free floating or on rough ER; synthesize proteins from mRNA via translation
Proteins from free floating ribosomes go where?
cytosol, nucleus, or mitochondria
Proteins from Rough ER can go where?
secretion, membrane, ER, Golgi, or lysosomes
How many amino acids are there?
20
Codon
3 mRNA bases that encodes an AA
Where does translation occur?
in ribosomes
How can translation be regulated in the ribosomes?
repressors or modification of initiation factors
Rough Endoplasmic Reticulum Modifications
- Folds proteins into 3D conformations
- Assembles multi-subunit proteins
- Forms disulfide bonds
- Begins glycosylation
- Adds glycolipid anchors
Functions in the Smooth Endoplasmic Reticulum
site of lipid metabolism and membrane lipid synthesis, including cholesterols and steroid hormones
Smooth ER in Adrenal Cortical Cells
produces sex hormones derived from cholesterol, often appear foamy on histo
Smooth ER in hepatocytes contain what important molecule?
cytochrome p450
Cytochrome p450
inacivates a number of drugs by converting them to water-soluble compounds to be excreted in the urine
What enzyme do cats not have that limits their ability to breakdown acetaminophen?
glucoronyl transferase [via glucuronidation]
Acetaminophen Toxicity in Cats
since it cannot ALL be broken down by sulfation, carried by the blood to liver where cytochrome p450 breaks down acetaminophen which produces toxic NAPQIs and results in hepatocellular necrosis
Golgi apparatus
receives proteins from the ER and packages them to go to lysosomes, plasma membrane, or secretion
Golgi apparatus and plasma cells
golgi creates a perinuclear clear zone within all the antibody
Mott cells
constipated plasma cell, where it makes a lot of Ab but doesn’t secrete it
Russel bodies
dilations of endoplasmic reticulum full of Ab
Lysosomes
membrane-bound vesicles with enzymes to degrade stuff, either from endocytosis and/or autophagy, and can also recycle compnents for new enrgy or proteins by transporting back to the Golgi
Phagocytosis
mainly done by macropahges and neutrophils, eats and digests stuff
Mycobacteria
developed a way to prevent lysosome fusion with the phagosome and therefore avoid the enzymes and don’t breakdown
Mitochondria
powerhouse of the cell
What two processes occur in the mitochondria?
- Citric acid (Kreb’s) Cycle
- Oxidative phosphorylation (electron transport chain)
Possible compoents of Cytoskeleton
- Intermediate filaments
- Microtubules
- Microfilaments
Ways to transport across a cell membrane
passive diffusion, facilitated diffusion, active transport, endocytosis
Intermediate Filaments and Tumor Diagnosis
mesenchymal and epithelial cells will each have a different type of intermediate filament so using different stains can help identify the type of tumor
4 Major Groups of Cell-Adhesion Molecules
- Selectins
- Integrins
- Immunoglobulin superfaimly (IgSF)
- Cadherins
Pemphigus
immune-mediated destruction of desmogelin 1 and 3 (cadherin proteins) so epithelial cells can’t connect, makes acantholytic cells and huge vesicles in your epithelium
Leukocyte Adhesion Deficiency (LAD)
normally leukocytes roll, slow down, and gain entry into the tissue via integrins and selectins BUT in LAD integrin B is missing so the cells won’t slow down so these animals (dogs/cattle) can’t send neutrophils in to kill the bacteria, leading to persistent and recurrent infections
Integrin B
also known as CD11/CD18
crucial in tissue infiltration for leukocytes
2 Cell Signaling Mechanisms
- Cell to Cell Contact (gap jxns or membrane bound ligands)
- Secretion of signaling molecules
Ligand
the term for a signaling molecule (gas like NO, complex protein, etc) when interacting with the receptor on the target cell
Membrane Proteins
often act as target receptors for cell signaling; includes ligand-gated ion chanels, G protein coupled receptors, enzyme linked receptors, cytokine/chemokine receptors, pattern recognition receptors, and cluster differentiation markers
4 Pattern Recognition Receptors
- Toll-Like Receptors (TLR)
- Nucleotide Binding Oligomerization domain-like receptors (NLR)
- C-type leectin receptors (CLR)
- RIG-1 like receptor (RLR)
Largest family of receptors?
G-protein coupled receptors
Kinase
putting on or taking offa phosphate group in order to communicate its signal downstream
Cluster Differentiation Markers (CDs)
used a lot in flow cytology and immunohistochemistry to identify cell types