Cell Modifications Flashcards
a process that occurs after cell division where the newly formed cells are structurally modified so that they can perform their function efficiently and effectively.
Cell modification
type of cell modification that is found on the apical surface of the cell
Apical Modifications
Functions may include secretion, absorption, movement of luminal contents, locomotion, sensing, and in some organisms, ingestion
Apical Modifications
a. Villi/Microvilli
b. Pseudopods
c. Cilia
d. Flagella
e. Root hair
Apical Modifications
Function for intercellular connections with the adjacent/neighboring cells
Lateral Modifications
a. Tight Junctions
b. Adherens/Adhering Junction
c. Gap Junction
Lateral Modifications
Found on the basal surface of the cell for anchorage and/or attachment
Basal Modifications
a. Desmosomes
b. Hemidesmosomes
c. Basal infoldings
Basal Modifications
Structure:
- Finger-like cytoplasmic extensions
- Each villus has lacteal (tiny lymphatic vessels that absorb
fatty acids and glycerol)
- One-cell thick to increase the diffusion rate
- Has blood capillary that absorbs glucose and amino acids
- Cells on the villi are packed with microvilli
villi
Present in:
- Apical surface of epithelial cells like in small intestine
villi
Functions:
- Provides a short distance for the diffusion of food molecules in the blood
- Increases surface area for absorption
villi
Structure:
- Elongated, motile structures on the surface of some epithelial cells; short hair-like projections
- Made up of microtubules (axoneme: central core)
- Each cilium is connected to a basal body and extends from the free surface
- Exhibits rapid back-and-forth movement
cilia
Present in:
- Ciliates like Paramecium and Balantidium, mammalian oviduct (respiratory tract: lungs, trachea, paranasal sinus mucosa, primary bronchus)
cilia
Functions:
- move mammalian ova through oviducts
- clean debris from the respiratory systems of mammals
- locomotion (for protozoa)
cilia
Structure:
- Tail-like projections that protrude from the cell body
- Bundle of nine pairs of microtubules surrounding two
central microtubules
- Same axial structure with cilia but much longer
flagella
Present in:
- Sperm cell (spermatozoa- only flagellated cell in human
body)
- Mastigophora: Trypanosoma, Trichomonas, Giardia leishmania
- also occur on the gametes of algae, fungi, mosses and
slime molds
flagella
Function:
- locomotion
flagella
Structure:
- Long tubular-shaped outgrowths from root epidermal cells
- about 10 micrometers in diameter
root hair
Present in:
- Plant roots
root hair
Function:
- Aid in plant nutrient acquisition, anchorage, and microbe
interaction
- increase the root’s surface area.
root hair
Structure:
- intercellular adhesion complexes (predominantly two proteins called claudins and occludins) in epithelia and endothelia
tight junctions
Present in:
- organs (such as skin), blood vessels, and cavities.
- Bladder and intestine
tight junctions
Function:
- Form the border between the apical and basolateral cell
surface domains
- establish a barrier that prevents extracellular fluid across a
layer of epithelial cells.
- Prevents leakage of the contents
tight junctions
Structure:
- Has cadherin receptors that bridge the neighboring plasma
membranes
adherens junction
Present in:
- Just below tight junctions; epithelial tissues
adherens junction
Function:
- maintain the physical association between cells
- Preserve tissue integrity by linking cells and connecting to
actin filaments
adherens junction
Structure:
- composed of two connexons, also known as hemichannels
that line up across the intercellular space.
gap junction
Present in:
- epithelia, nerves, cardiac (heart) muscle, and smooth
muscle (such as that of the intestines).
gap junction
Functions:
- allow for electrical communication between cells, and also allow the passage of small second messengers.
- when heart cells need to beat in unison, it allows for the transmission of electrical signals between the cells.
gap junction
Structure:
- cadherins in the plasma membrane connect to
intermediate filaments
desmosomes
Present in:
- skin epidermis lymphatic endothelial cells
desmosomes
Functions:
- anchoring sites for ropelike intermediate filaments, which
form a structural framework of great tensile strength
- act like spot welds between adjacent epithelial cells,
connecting them
- maintain the cells in a sheet-like formation in organs and
tissues that stretch, such as the skin, heart, and muscles.
- Offer a little bit of space for stress release.
desmosomes
- supports the epithelium and also functions as a passive molecular sieve or ultrafilter.
- These increase surface area for ion transport.
- Present in mitochondria
basal infoldings
- Functions similarly to desmosomes but it specifically
attaches the cell to the basement membrane - Consists of integrin
hemidesmosomes
- cell extensions used for movement and feeding
- They also help in sensing targets which can then be engulfed made up of actin filaments, microtubules and intermediate filaments.
- Commonly present in amoeba
pseudopods
