Cytology of Cells Flashcards
Network (biology)
a method of representing systems as complex sets of binary interactions or relations between various biological entities
Amino acids (biology)
- an organic molecule that is made up of a basic amino group (−NH2), an acidic carboxyl group (−COOH), and an organic R group (or side chain) that is unique to each.
- Building block of proteins
Protein (biology)
- catalyze the vast majority of chemical reactions that occur in the cell.
- They provide many of the structural elements of a cell
- they help to bind cells together into tissues.
- Some act as contractile elements to make movement possible.
- Some are responsible for the transport of vital materials from the outside of the cell (“extracellular”) to its inside (“intracellular”).
- Controls gene expression
- And more!
Filaments (biology)
a long chain comprised of protein subunits.
Protein subunits can either be single protein molecules or polypeptide chains that join to form a protein complex
Plasma membrane (description)
Lipid bilayer with embedded proteins
The cell membrane is
a phospholipid bilayer
Cell Nucleus
- contains the cell’s genome and serves as control center.
- Contains the nucleolus and chromosomes necessary for production of proteins within the cell
Humans have __ genes
~20,000
TRUE OR FALSE: Number of genes in a genome does not correlate with cellular or organismal complexity.
TRUE
Much genetic activity is dependent on…
Transcription factors that regulate when and to what degree a given gene is expressed.
The nucleolus…
…produces Ribosomes
Genes (biology)
- Subunit of a chromosome
- Induce production of mRNA upon activation
Messenger RNA (mRNA)
- A duplicate of the information contained in the gene that can encode proteins
Transcription (cell biology)
the process of copying a segment of DNA into RNA
Occurs in the cell’s nucleus
mRNA translation
- After mRNA leaves the nucleus and attaches to a ribosome, serving as a protein production template.
- Amino acids are attached to tRNA, which enters the ribosome, which is then bound to mRNA
- The ribosome moves along the mRNA, “reading” its sequence and producing a chain of amino acids.
Ribosomes
- make proteins from amino acids via Translation (protein synthesis)
- Possesses two subunits
- Smaller subunit binds to the mRNA.
- Larger subunit binds to tRNA and amino acids.
Free Ribosomes
- can move about anywhere in the cytosol
- excluded from the cell nucleus and other organelles.
- Proteins that are formed from ___ are released into the cytosol and are used within the cell.
Transfer RNA (tRNA)
serves as the physical link between the mRNA and the amino acid sequence of proteins. It does this by carrying an amino acid to the protein synthesizing machinery of a cell called the ribosome.
Cytosol
- the aqueous component of the cytoplasm of a cell, within which various organelles and particles are suspended.
- all the metabolic reactions occur here.
- the fluid contained in the cell cytoplasm
Membrane-bound ribosomes
- Ribosomes that synthesize proteins needed in some organelles or for exocytosis (i.e. transmitters)
- Bound into the rough endoplasmic reticulum.
- The newly produced polypeptide chains are inserted directly into the ER by the ribosome and are then transported to their destinations through the secretory pathway.
The endoplasmic reticulum (ER)
- Network of tubules, vesicles, and cisternae throughout cells
- Consists of
- Rough ER
- Smooth ER
rough endoplasmic reticulum (RER)
- synthesizes proteins.
- Is studded with ribosomes.
- Works with the Golgi complex to target new proteins to their destination
smooth endoplasmic reticulum (SER)
- synthesizes lipids and steroids, metabolizes carbohydrates and steroids.
- In spines, it regulates calcium levels and the attachment of receptors onto the membrane.
The Golgi apparatus
- Factory in which proteins received from the ER are further processed and sorted for transport to their final destinations, e.g. the cell membrane or secretion.
- Has a cis face and a trans face
- Molecules discharged in secretory vesicles
Proteasome
large multienzyme organelles that degrade ubiquitinated proteins (via proteolysis)
Proteolysis
mechanism by which cells regulate the concentration of proteins (e.g. endocytosis of vesicles and receptors) and degrade misfolded (unneeded) proteins.
Endocytosis
the taking in of matter by a living cell by invagination of its membrane to form a vacuole.
Invagination
The action or process of being turned inside out or folded back on itself to form a cavity or pouch.
Proteases
enzymes that break peptide bonds.
Ubiquintin
- A small protein that tags proteins for degradation
- Tagging a protein with this results in a poly__ chain that is bound by the proteasome
Mitochondria (Primary Function)
Generate energy in the form of Adenosine Triphosphate (ATP)
Mitochondria (Additional Functions)
- Building, breakdown, and recycling of proteins
- Regulation of Ca2+ -storage and release →
- affects membrane potential and signal transduction
- Apoptosis or programmed cell death
- (essential for differentiation during development and infections)
- Formation of parts of blood and hormones, such as estrogen and testosterone
- Synthesis of steroids
Cristae
- numerous layers of folded, inner membrane
- One of two membranes that bind the mitochondria
Matrix (mitochondria)
A compartment lying inside the inner membrane
outer compartment (mitochondria)
lying between the two mitochondrial membranes
The inner membrane…
…contains proteins that carry out oxidative metabolism
Oxidative metabolism
oxidative phosphorylation of ADP to ATP via the electron transport chain
Redox
a type of chemical reaction in which the oxidation states of substrate change.
oxidation
the loss of electrons or an increase in the oxidation state of a chemical or atoms within it.
Reduction (Redox)
the gain of electrons or a decrease in the oxidation state of a chemical or atoms within it.
Mitochondria have…
…their own DNA (mtDNA).
- containing genes that produce proteins essential to oxidative metabolism.
Mitochondria can protect neurons by…
supplying ATP and adsorbing excessive Ca++
Mitochondria can kill neurons by…
releasing pro-apoptotic factors
Mitochondrial function is tightly linked to…
their morphology
Healthy mitochondria are…
thin and long
dysfunctional mitochondria are
thick (swollen) and short (fragmented)
Cytoskeleton
- provides a structural framework for the cell
- serving as a scaffold that determines
- cell shape
- the position of organelles, and
- the general organization of the cytoplasm
- responsible for cell movements.
- This includes
- the movements of entire cells, but also the transport of organelles, mitotic chromosomes, and vesicles.
- This includes
- serving as a scaffold that determines
Three types of cytoskeletal fibers
- Actin filaments (microfilament)
- Intermediate filaments (“neurofilaments” in neurons)
- Microtubules
Actin filaments (microfilament)
- Smallest (~5 nanometers diameter).
- Two protein chains twined together like strands of pearls. Each “pearl” is an actin protein.
- Responsible for cellular movements such as contraction, “pinching” during division, and cellular extensions
Neurofilaments
- Intermediate in size (8-10 nm diameter). Intermediate filaments are very stable.
- (Example: Keratin in epithelial cells and structures such as hair and fingernails)
Microtubules
Hollow tubes (~20 nanometers in diameter).
They are very unstable (halflife of ~10 min. in a nondividing cell, to as short as 20 sec. in a dividing cell), unless stabilized by guanosine triphosphate (GTP),
They are responsible for moving materials within the cell, and they enable cellular movement,.
guanosine triphosphate (GTP)
inhibits depolymerization.
“+” refers to the end of the microtubule that is
away from the nucleus
“-” refers to the end of the microtubule that is
toward the nucleus
Motor proteins
move organelles around the cell on microtubular tracks.
- Two types
- Kinesin
- Dyneins
Kinesin
Motor proteins move organelles toward the “+” end (toward periphery)
Dyneins
motor protein that move organelles toward the “−” end (toward nucleus).
