Flashcards in Block 1 - Cytology Deck (54):
What are the layers of the nuclear envelope?
Outer nuclear membrane
Inner nuclear membrane
What is the perinuclear space continuous with?
The lumen of the RER
Are there ribosomes on the outer nuclear membrane?
Yes, this closely resembles the RER membrane and is continuous with it.
Is the inner nuclear membrane continuous with the ER?
No, it is distinct.
What is able to bind to the inner nuclear membrane?
Chromatin and lamins
What supports the inner nuclear membrane?
Rigid network of intermediate filaments.
What is the nuclear lamina?
Thin, dense protein layer continuous with the inner nuclear membrane.
What is the skeleton of the the nucleus made out of?
Lamins (intermediate filament). Cross-linked into an orthogonal lattice (lettuce)
Where is ribosomal RNA processed?
In the nucleolus, what contains DNA loops with rRNA genes?
What is the dense fibrillar component?
In the nucleolus, it contains ribosomal genes that are being translated as well as large amounts of rRNA
What is the granular component?
It is the site for ribosomal assembly and is made of densely packed clusters of pre-ribosomal particles.
What are three major types of filaments in the cytoskeleton?
Actin, microtubles, and intermediate filaments
What are actin's three most important roles in the cytoskeleton?
Cell movement, shape, and organelle transport.
What is G-actin?
Soluble globular protein that can be polymerized into F-actin.
What is F-actin?
Thin filaments, a double stranded helix made out of polymerized head-to-tail g-actin.
What are two thin filaments?
Actin and myosin
What is the cortex of a cell?
cross-lined actin filaments in a thin sheath beneath cytoplasm
What three things to cross-lined actin filaments (cortex) do?
Resist cell deformation
Restrict organelle movements
How does actin interact with myosin (motor)?
Generates force and movement
Which are the only cells that do not contain microtubules in their cytoskeleton?
What are the three vital functions of microtubules?
Organelle and vesicle movement
Mitotic Spindle/chromosome movement
Beating of cilia and flagella
What is the structure of microtubules?
Two polymerized globular proteins, alpha-tubulin and beta-tubulin
Describe the two ends of a microtubule
Plus end, grows faster, toward periphery
Minus end, grows slower, towards nucleus
Which way do dyneins move?
Towards the minus end, in towards nucleus
Which way to kinesins move?
Toward the plus end, out towards periphery
What are 4 high order stuctures of microtubules?
Cilia, flagella, centrioles, and microtubule-organizing centers
What is in the core of cilia and flagella?
Describe the composition and function of an axoneme
9 doublet pairs of microtubules on outside
1 central pair
Dynein arms attach tubules of one pair to the next, causing a walking motion
What is at the base of cilia/flagella?
A centriole (aka basal body) consisting of 9 doublets, no central pair
What two cell types do not contain a microtubule-organizing center (MTOC)?
Erythrocytes and neurons
Where do virtually all cellular microtubules come from?
What type of filament is between thickness of actin filaments and microtubules?
What are the 6 classes of intermediate filaments and where are they found?
Lamins - Inside nuclear envelope (..)
Keratins - epithelial tissue
Vimentin - connective tissue
Desmin - muscle cells
Glial fibrillary acidic protein (glial cells) - support cells of nervous system
Neurofilaments - neurons
What are the 4 main purposes of cytoplasmic intermediate filaments?
Spread tensile forces
Maintain cell structure
Act as a cocoon when cell is damaged
Anchor ion channel proteins
What is the standard color of most tissue?
What is hematoxylin?
A basic dye that stains acid structures blue
What is eosin?
An acid dye that stains basic structures pink
What are the similarities and differences of integral and transmembrane proteins?
All transmembrane proteins are integral membrane proteins, but not all integral proteins are transmembrane proteins.
Both have hydrophobic parts that anchor in the center of the plasma membrane, but transmembrane go all the way through.
Where do peripheral proteins attach?
To integral proteins or hydrophillic heads of membrane lipids
What are three classes of functional membrane proteins?
Transport, receptor, and structural
What is glycocalyx?
The fuzzy coating on external surface of many cells due to large amounts of carbohydrates attached to proteins and lipids on cell surface
What are particles and inclusions used for? What are two main types?
Synthesis and storage
Ribosomes and gylcoproteins
What are 3 ways ribosomes exist in cells?
In mirtochondria, in RER, or free
Where do proteins synthesized in the RER go?
Golgi, lysosome, secretory granules, and plasma membrane
Most proteins are synthesized on what type of ribosome?
What is a polysome?
During ribosome synthesis, string of ribosomes attached to mRNA
What are the 4 main functions of the SER?
Lipid and steroid synthesis
Ca++ storage (only in sarcoplasmic reticulum of muscle cells)
What are 2 main functions of the golgi?
Modifications of proteins
Sorting and packing
What is the principal signal that directs proteins from trans golgi to the lysosome?
What disease is caused when mannose-6-phosphate is mutated? What happens to the proteins?
I-Cell. Proteins intended for lysosomes are secreted into the intercellular space
What do peroxisomes contain? What is their purpose?
Oxidative enzymes (catalase)
Oxidize/break down long chain fatty acids
What is Zellweger syndrome?
Mutations in proteins used for transporting enzymes to peroxisomes.
Affects brain development through improper formation of mylein sheath.
No cure. Patients die before 6 months of age.