Cytology Flashcards
What are the 4 basic tissues?
Epithelium
Connective Tissue
Muscle
Nerve
Exocrine glands and endocrine glands are formed from what type of tissue?
Epithelial
What are the 3 shapes of epithelial cells?
Squamous
Cuboidal
Columnar
Select the functions of epithelial cells -
Absorption
protection
secretion
excretion
gas exchange
All of the above
Connective tissue is - non-vascular/vascular?
Vascular
List some of the functions of Connective Tissue -
- Serves as a medium in which blood vessesl distribute nutrients and take up metabolic waste
- Involved in immune & inflammatory responses
- Involved in tissue repair following injury
What type of tissue is responsible for movement and changes in size and shape of body organs?
Muscle
What are the myofilaments that occupy most of the muscle cytoplasm?
Actin and myosin
What are the 2 main nervous system cells?
neuron and supportin cells
T/F
Tissue cells can be membrane bound and non-membrane bound
True
What are the 3 major components of the Nucleus?
Nuclear Envelope
Chromatin
Nucleolus
What are the main components of the Nuclear Envelope?
Outer membrane
Inner membrane
Niclear pores
Nuclear lamina
List the morphology of a nucleus in “normal cells”
Shape
Size
Number per cell
Location
- Shape: round, ellipsoid, infolded, lobulated
- Size: varies
- Number Per Cell: none to multie
- Location: central, basal, eccentric
How much space seperates the 2 unit membrane of the nucleus?
10-30nm
What other organelle is the outer membrane of the nuclear envelope continuous with?
Why are tehre no ribosomes on the outer membrane?
rER
Psyche - the outer membrane can have ribosomes on it.
T/F
The inner membrane of the nucleus is associated with the nuclear lamina and is supported by chromatin…
- False
- The inner membrane is supported by the lamina and can be associated with chromatin
What are the uni-directional gates of the nucleus?
- There are none
- Nuclear pores are the bidirectional gates of the nucleus
What are the two methods that molecules can pass through the Nuclear Pores?
- Small molecules (<40-60 kd) can diffuse through
- Any size proteins with a nuclear localization amino acid sequence can be transported in via active transport
What is required of a protein to be facilitatively transported into the nucleus?
- Nuclear localization amino acid sequence
- Also - it is not transported through facilitated transports - it is thorugh active transport.
What is another name for nuclear pores?
Nucleoporins
Functions of the Nuclear Lamina:
- Gives [] and [] to the nuclear envelope
- Organizes the [] nuclues (mitotic phase)
- Structural link between [] and the nuclear envelope
- Responsible for the dissolution and [] of the nuclear envelope during [] []
- Positions [] [] complexes within the nuclear evnelope
- shape and stability
- interphase
- chromatin
- reformation, cell division
- nuclear pore
Where is the nuclear lamina generally located?
Between the inner nuclear membrane and the peripheral heterochromatin
What type of proteins make up the Nuclear Lamina?
intermediate filament proteins called lamins
What activity causes the lamina to break apart during mitosis?
lamin phosphorylation
What is the difference between heterochromatin and euchromatin?
- Heterochromatin - condensed, readily visible through microscopy. Not really being transcribed at the moment
- appears as basophilic clump
- Euchromatin - uncoiled. This chromatin is being transcribed and used.
What is a “nucleosome?”
What are its component parts?
- A nucleosome is the “beads-on-a-string” model of packaged DNA in the nucleus
-
The Beads = histones
- Histones are pairs of 4 types of proteins (8 total)
- The string - DNA wrapped around the histone (1.75 time
- Linker DNA - DNA connecting each histone.
How do histones coil eachother even further to a size of 30 nm?
- They form chromtain fibril
- The chromatin coils consectuve nucleosomes and connects everything with another type of histone
What is a rough hierarchy of the size of coiling chromatin?
Nucleosome (11 nm) < Chromatin Fibril (30 nm) < 300 nm loops held together by specific protein-DNA complexes < 700 nm helical loops of chromosomes during metaphase.
Definitions:
- Number of chromosomes in somatic cells
- Standard map of the banding pattern of each chromosome, or what the chromosome looks like during metaphase
- Autosomes….
- Barr Body…
- Genome
- Karyotype
- Chromosomes that are NOT sex chromosomes (humans have 22)
- An inactive X chromosome in females. It can be seen on a light microscope as heterochromatin
- it’ll be a small drumstick or as a clump usually adjacent to the nuclear envelope
This is the site of rRNA transcription and rRNA synthesis in the Nucleus?
Nucleolus
Does the nucleolus have a membrane?
How many nucleoli will you find per cell?
No
Normally 1-2
What is the Nucleolar Organizing Region?
- The region where 10 expanded interphase chromosomes contribute rRNA-producing DNA loops to the nucleolus
What helps to reorganze the nucleoli following cell division?
The Nucleolar Organizing Region
What is the specific composition of ribosomes and their function in creating proteins?
- Large Subunit
- 5S, 28S, 5.8S
- Catalyzes peptide bond formation
- Small Subunit
- 18S
- binds mRNA and tRNA together
Which rRNA is not formed in the nucleolus?
5S
Formation of Ribosome in Nucleolus:
- transcription of [] to form pre-[]
- Association of pre-rRNA with [] proteins to form []
- Cleavage of pre- [] into the []S, [] S, and [] S found in ribosomes
- rDNA; pre-rRNA
- ribosomal; ribonucleoprotiens
- pre-rRNA; 5.8S, 18S, 28S
Formation of Ribosome in nucleus
- 28S and 5.8S rRNA combine with []S rRNA to form the [] subunit
- Where is the [] S rRNA transcribed?
- [] transport of ribosomal subunits to the cytoplasm through [] []
Formation of Ribosome in Cytoplasm
- Assembly of ribosomal subunits into [] and [] in the presence of mRNA
- 5S; Large Subunit
- Nucleus….not nucleolus
- Active; nuclear pores
- ribosomes and polysomes
T/F
Does the underlying cytoskeleton partly determine the shape of the surface of a membrane?
True
What are the 4 concepts to remember regarding membranes?
- They are not homogenous
- Membrane components are in a constant dynamic flux
- They are asymmetric
- The shape of the membrane is partly determined by the underlying cytoskeleton
What are all membranes composed of?
- Lipids - membranes form and permeability properties
- Proteins - responsible for the membranes specific functions
- Carbohydrates - confined to membranes surface
Membrane Lipids
- [] are the most abundant tyope of lipid in membranes
- Phospholipids are [] - containing a hydrophilic and hydrophobic region
- [] is the second major lipid of membranes
- Why?
- [] are the third most abundant membrane lipids
- where are these found?
- Phospholipids
- amphipathic
-
Cholesterol
- It freezes at a lower temperature so it helps maintain the structural integrity of the membrane
-
Glycolipids
- outer leaflet
Membrane Proteins
- Can be [] or []
- Where are these types of proteins associated with the membrane?
- Membrane protiens perform [] of the membrane’s functions
- the [] [] technique indicates the prescence of membrane proteins
- integral or peripheral
- Integral: The protein is buried into the lipid bilayer and can sometimes go all the way through to be a transmembrane protein.
- Peripheral - associated with the hydrophilic heads of the membrane through ionic interactions
- Most
- Freeze Fracture
Where are carboyhydrates located in membranes?
What is the function of these carbs on the membrane?
- Carbs are attached to proteins sticking out of the outer layer of the membrane - creating the glycocalyx
- The glycogalyx is a “fuzzy” area outside the sell that performs…
- cell to cell interactions
- also it can start to breakdown molecules before it reaches the cell
What is the highly dynamic, complex network of protein filaments taht organize the cytoplasm and determine cell shape?
The cytoskeleton
Functions of the cytoskeleton:
- [] motility
- organelle and [] transport
- [] contraction
- cell []
- endocytosis/[]
- providing [] strength
- cell motility
- organelle and vesicle transport
- muscle contraction
- cell division
- phagocytosis
- providing mechanical strength
What are the 3 size groups of the cytoskeleton components? How thick is each component?
- Microfilaments (7 nm thick)
- Intermediate filaments (10 nm)
- Microtubules (25 nm in diameter
Microfilaments:
- composed of [], which acounts for [] - [] % of cytoskeletal proteins
- Specifically composed of []-[] that bind head to tail to form the polarized [] [].
- Requires the hydrolyzation of [] –> [] during polymerization
- Actin; 5-10%
- G-actin; acting protofilament
- ATP –> ADP
Describe the composition of a Microfilament
- 2 protofilaments twist around each other to form a helical F-actin filament
- F-actin is polarized with a plus end (barbed) and a minus end (pointed)
- Filament grows at the + end.
What complex is responsible for the nucleation of F-actin filaments?
ARP
Consists of: Arp3 Arp2 + other proteins + actin monomers
What general class of actin-binding protein allows for microfilaments to branch, giving off almost a web-like appearance?
Arp proteins
“Actin-Related Proteins”
What are the 2 types of “Actin Cross-linking Proteins” (these are actin-binding proteins) and what are some examples of each?
-
Bundling Proteins - cross-link actin into a parallel array
- Ex: fimbrin, a-actin, villin
-
Gel-Forming proteins - 3D meshworks that can form semi-solid gels
- Ex: spectrin, filamin