Cellular mechanics and Communication Flashcards
Two processes involving manufacturing
a) respiration and expiration
b) active and passive breathing
c) transcription and translation
d) DNA and RNA
Transcription and translation
What is the first step of DNA based gene expression?
Transcription
Define transcription
A segment of DNA copied into RNA (mRNA) by enzyme RNA polymerase
During transcription a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a ______ _______
primary transcript
Adenine (A) bonds to ____________________ by 2 hydrogen bonds
Thymine (T)
Guanine (G) bones to ________________ by 3 hydrogen bones
Cytosine (C)
Steps of transcription
1) RNA polymerase binds to promoter DNA
2) RNA polymerase creates bubble, separating the two strands of the DNA helix
3) RNA polymerase adds RNA nucleotides
4) RNA sugar-phosphate backbone forms an RNA strand
5) RNA further processed (polyadenylation, capping, and splicing)
6) RNA remains in nucleus or leaves cytoplasm through nuclear pore complex
Gene splicing
Introns removed - review
Stages of Translation
1) mRNA is decoded in the ribosome decoding center to produce a specific amino acid chain, or polypeptide
2) polypeptide later folds into an active protein and performs its functions in the cell
3) ribosome facilitates decoding by inducing the binding of complementary tRNA anticodon sequences to mRNA codons
4) tRNAs carry specific amino acids that are chained together into a polypeptide as the mRNA passes through and is read by the ribosome
Codons
hidden messages within nucleotides sequencues that tell a particular amino acid signal to start or stop
Step 1 of Translation: Initiation
ribosome assessmbles around target mRNA
- first tRNA attached at the start codon
Step 2 of Translation: Elongation
tRNA transfers amino acid to tRNA corresponding to next codon
- ribosome then translocates to next mRNA codon to continue process, creating amino acid chain
Step 3 of Translation: Termination
when a peptidyl tRNA encounters stop codon
- ribosome folds the polypeptide into final structure
Cell division
process by which parent cell divides into 2 of more daughter cells
In eukaryotes, there are two distinct types of ______________
cell division
Types of cell division in eukaryotes
Mitosis and meiosis
Each daughter cell is genetically identical to the parent cell
mitosis (vegetative division)
Number of chromosomes in daughter cells is reduced by 1/2 to produce haploid gametes
Meiosis
__________ accounts for a small part of the duration of a cell cycle
Mitosis
Prophase
chromosomes condense and become visible
- centrosomes move toward opposite poles
Prometaphase
Kinetochores appear at centromeres
- mitotic spindle microtubules attach to kinetochores
Metaphase
chromosomes meet at middle
- each sister chromatid is attached to spindle fiber from opposite poke
Anaphase
centromeres split in two
- chromosomes are pulled toward opposite poles
Telophase
chromosomes arrive at opposite poles & decodense
- nuclear envelope surround each set of chromosomes
- mitotic spindle breaks down
- spindle fibers continue to push poles apart
Cytokinesis
2 separate entities
Types of signaling molecules
a) proteins
b) small peptides
c) amino acids
d) nucleotides
e) steroids/retinoids
f) dissolved gases
g) all of the above
All of the above
What are the types of signaling?
a) embryonic signaling
b) paracrine signaling
c) endocrine signaling
d) synaptic signaling
e) A, B, and C
f) B, C, and D
Paracrine signaling, endocrine signaling, and synaptic signaling
Paracrine signaling
local action only
fast acting
growth factors, clotting factors
Endocrine signaling
secreted in blood stream for widespread or distant targeting
very slow acting
pineal, pituitary, thyroid, pancreas, etc.
recognized by receptors
Synaptic signaling
secretion at specialized cell to cell contacts (synapses)
very fast acting
used only by electrically excitable cells
(neurons and muscle cells)
In almost all forms of signaling, the signal molecule is ___________ from the secreting cell via a process known as ____________
released; exocytosis
Long term connections can be classified into functional groups such as:
a) inhibitory junctions
b) tight junctions
c) desmosomes/hemidesmosomes
d) gap junctions
B, C, and D
Impermeable junctions preventing molecules from passing through the intercellular space
tight junctions / occluding junctions
binding adjacent cells together like a molecular “velcro” and help form an internal tension-reducing network of fibers
desmosomes / anchoring junctions
allowing ions & small molecules to pass for intercellular communication
gap junctions / communicating junctions
roles of tight/occluding junctions
1) form leak-proof seals
2) create cell polarizations along membranes
which junction(s) are most prominent in tissues subject to mechanical stress
desmosomes/hemidesmosomes and adherents junctions / anchoring junctions
which junction is comprised of an intracellular plaque that is anchored to IF or actin and cadherin
desmosomes junctions / anchoring junctions
What is the difference between desmosomes and hemidesmosomes
hemidesmosomes are comprised to an intracellular
plaque which is anchored to an ECM protein
How are desmosomes and hemidesmosomes similar
Anchored intracellularly to actin or IF cytoskeleton
What do gap junctions comprise of
junctional complex (connexon)
T/F Permeability of communicating junctions is affected by environmental influences.
True
Extracellular matrix is a network of _______________
macromolecules
The extracellular matrix is a network of _______________
macromolecules
What do the macromolecules include?
1) glycosaminoglycans (hydrated gels)
2) fibrous proteins (structural and adhesive)
What are some basic tissues
epithelium
connective tissue
muscle tissue
nerve tissue
What determines the classification of epithelium
1) shape
2) # of layers
3) cell specializations
Flat and one layered
simple squamous
Square and one layered
Simple cuboidal
Tall and one layered
Simple columnar
Skin
Stratified squamous
An epithelium that is not common
stratified cuboidal
In some parts of the respiratory system
stratified columnar
What are some connective tissues
a) fibroblast
b) collagen fiber
c) macrophage
d) elastic fiber
What is the simplest and most widely distributed connective tissue found in the body ?
areolar tissue
What are the principle cell precursor that are always present and give the matrix its gel-like qualities
fibroblasts
What is the principle cell that has differentiated fibroblasts that maintain fibers
fibrocytes
What cells found in connective tissues hold fat storage
adipocytes
What cells found in connective tissues are stem cells of fibroblasts, macrophages, etc?
mesenchymal cells
What cells found in connective tissues are fixed or free scavengers
macrophages
What cells found in connective tissues contain histamine and heparin to enhance immune response
mast cells
Skeletal muscles has a ___________ apperance
striped
Cardiac muscles has a _______________ apperance
looser
Smooth muscles have a _______________ apperance
wavy
Nervous muscles have _______________
many -cytes that relate to synapses
