Cell Biology Flashcards
Merocrine Gland
secretory vesicles released from golgi body to plasma membrane, exocytosis of individual vesciles to lumen or surface
Apocrine Gland
secretory vesicles released from golgi body, entire cell surface breaks off
Holocrine Gland
secretory vesicles released from golgi body, entire cell bursts open to release contents
Secondary Active Transport
moves a molecule against its concentration gradient by using the concentration gradient of another molecule -indirectly uses ATP
Symport
Type of Secondary active transport molecule moves in the same direction as its partner ion, “piggybacks” e.g. Na/K pump creates NA gradient in ECF, Na rushes back into cell with glucose via sodium glucose transporter
Antiport
- type of secondary active transport molecule moves in the opposite direction of its partner ion, “swap”, or exchange, countertransport
- Ex. Sodium/Calcium exchanger
Primary Active Transport
a carrier protein splits ATP directly in order to move a molecule against its concentration gradient i.e. Na/K pump NOKIA
Facilitated Diffusion
passive movement of molecules from a region of high concentration to a region of low concentration using a channel these channels allow large or polar molecules to cross
Second Messenger Example: Ca2+
- **First Messenger** Ligand binds to extracellular receptor
- Ligand receptor complex activates G-protein
- Activated G-protein reacts with GTP to activate Phospholipase C
- Phospholipase C converts DAG to IP3
- IP3 mobilizes Ca2+ from intracellular stores
- **Second Messenger** Ca2+ activates calmodulin
- Calmodulin modifies proteins within the cell
- Changes in cellular rxns and metabolic pathways occur
Rough Endoplasmic Reticulum
- contains ribosomes on its surface
- responsible for most of the cell’s protein synthesis, folding and sensing cellular stress
- it also synthesizes and stores proteins and glycoproteins
Smooth Endoplasmic Reticulum
no ribosomes or ribonucleic acis
- contains enzymes for the creation of steroid hormones and remove toxic substances from the cell
- synthesizes and stores lipids, fatty acids, carbohydrates
- drug detoxification
Cell Adhesion Molecules
Adhesion proteins on the surface of cells that hold cells together and binds cells to the extracellular matrix
3 types:
- desmosomes
- tight junctions
- gap junctions
Desmosomes
anchor two cells together with cell adhesion molecules
prevent the overstretching of tissue
Tight Junction
seal two cells together with small proteins
prevent leakage between cells
form tight barrier
Gap Junction
cytoplasm of cells is directly linked by a connecton protein
connecton protein essentially forms a tunnel between the two cells
allows for direct communication between cells
Proteasome
enzyme that breaks down proteins marked by ubiquitin
Peroxisome
catabolizes fats and organic compounds
neutralizes the toxic compounds generated in the process
produce antioxidants**
these are smaller than lysosomes
lysosome
membrane-bound organelle that carries over 40 digestive enzymes that are activated by Ca2+
also contains hydrolases which function best at an acidic pH
mitogen
induces or stimulates mitosis, cell growth, differentiation and survival
growth factors
stimualte increased cell mass and cell growth (via protein synthesis)
Cell Cycle Checkpoints
G1/S: prevents entry into S phase
G2/M: prevents entry into mitosis
Metaphase: prevents entry into anaphase
Mitosis Phase Order
Interphase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Prophase/Prometaphase
Chromosomes condense, nuclear envelope breaks down
centrosomes move toward opposite poles
mitotic spindle microtubules attach to kinetochores
Prometaphase
Metaphase
chromosomes are lined up in the middle
Anaphase
centromeres split in two
sister chromatids (now called chromosomes) are pulled toward opposite poles
Telophase
chromosomes arrive at opposite ends and begin to decondense
nuclear envelope envelopes each separate group of chromosomes
interphase
resting phase between successive mitotic divisions of a cell
also occurs between the first and second divison of meiosis
G1, S, G2 or G0
G1 = longest phase can last days to years
S, G2= prepare for mitosis and are committed to mitosis
OR you enter G0 which is a non-dividing phase
Meiosis
- cell division in reproductive cells
- invovles 2 complete rounds of nuclear and cell division
- begins with early reproductive stem cells
- formation of haploid gametes (single copy of each chromosome)
- Tetrad formation/chiasma: duplicated chromosomes touch and exchange genetic material
- Independent assortment: maternal and paternal homologues of chromosomes are randomly separated rather than being sorted
- **gametes are not identical–> allow for genetic variation due to recombination
Signals that regulate entry into the different phrases, daily progression, and allow time to repair are:
- cyclins and cyclin-dependent kinases as well as cyclin-dependent kinase inhibitors
- APC/C and SCF ubiquitin ligases
Epithelial Tissue
- Function:
- covering, lining, secreting
- protection, permeability, absorption, secretion, filtration, and sensation
- covering, lining, secreting
- no blood vessels (avascular)
- lots of sensory innervation
- LOTS of regeneration
Simple Squamous
- lines body cavities i.e. mesothelium
- lines major organs i.e. alveoli, heart, bowman’s capsule of the kidney
Stratified Squamous
mouth, rectum, vagina, skin, esophagus
Simple Cuboidal
glands, kidney tubules, covers the ovaries
stratified cuboidal
sweat glands
simple columnar
line digestive tract, uterine tubules, gall bladder
stratified columnar
large ducts of glands (i.e. salivary glands)
Pseudostratified columnar
upper respiratory tract, male urethra
transitional epithelium
bladder, lines the ureters, renal pelvis
4 Tissue Types
- Epithelial: covering, lining, secreting
- Connective: support, structure, energy storage, material transport
- Muscular: movement/contractions
- Nervous: electrical signals
stem cells
- are multipotent
- undergo cell divison with some asymmetric division
- then they migrate via chemotaxis and contact guidance
- then adhesion occurs:
- cells remain in place attached to each other and to the extracellular matrix
Passive Membrane Transport
- Simple Diffusion: small, non-polar molecules move from high concentration to low concentration
- osmosis: passive movement of water down its concentration gradient
- Facilitated Diffusion: large or polar molecules that cannot cross the phospholipid bilayer on their own move from areas of high concentration to low concentration using a channel
Tissue Type?
Fibrocartilage
Location: intervertebral discs, pubic symphysis
Tissue Type
Dense irregular
location: deep dermis, joint capsules
·Matrix: randomly arranged bundles of collagen fibers
Cells: fibroblasts
·Function: resists multidirectional stress
Tissue Type?
Dense Regular Connective Tissue
Location: ligaments and tendons
·Matrix: parallel bundles of collagen fibers·
Cells: fibroblasts
Tissue Type?
Hyaline Cartilage
Location: articulating surfaces and trachea, cartilage of the nose
Tissue Type?
Areolar Connective Tissue
type of loose connective tissue
location: surrounds blood and lymph vessels
Found “everywhere” – under epithelium, around organs and blood vessels
cells: fibroblasts, macrophages, mast cells, white blood cells
Matrix: fluid-gel containing all fiber types
Tissue Type
Reticular Connective Tissue
Type of Loose connective tissue
location: liver, spleen, lymph nodes, bone marrow
Function: form soft supportive skeleton for organs
Tissue Type?
Elastic Cartilage
Type of Supporting Connective Tissue
Location: exterior ear, epiglottis of larynx
Function: involved in detecting and producing sound
Cytokinesis Phases general
Anaphase and Telophase and after
Oncotic Pressure
the overall osmotic pressue due to plasma proteins
Osmolarity vs. Osmolality
- Osmolarity: (mOsm/L) solutes per volume
- Osmolality: (mOsm/kg) solutes per weight
- preferred for dense solutions like plasma
- Normal Values:
- intracellular: 280-294 mOsm/kg
- extracellular: 280-294 mOsm/kg
- Normal Values:
- preferred for dense solutions like plasma
Effective Osmolality
can the solute pass across the membrane and enter the cell, or will it stay in the blood?
- permeable: enters and reaches an equilibrium
- non-permable: stays and effectively contributes to osmotic pressure
Tonicity
the effect of a solution (plasma/ECF) on a cell (ICF)
- isotonic: no effect
- hypotonic solution: cell gains water and swells
- hypertonic solution: cell loses water and shrinks
Types of Endocytosis (4)
- pinocytosis: uptake of fluid, ECF
- phagocytosis: large particles, debris, or pathogens are engulfed
- receptor mediated endocytosis: specific uptake of target molecules with the assistance of surface protein receptors (clathrins)
- Caveolae-mediated endocytosis: microdomains of membrane compartmentalize (membrane envaginations called caveolae) certain molecules ( driven by cavins, a type of peripheral membrane proteins )
Filtration
movement of water and solutes due to high pressure
3 Catabolic Phases of Metabolism
- (Phase 1) food breakdown:
- breadown of macromolecules in food via digestion
- (Phase 2): glycolysis:
- simple sugars broken down into pyruvate
- does NOT require oxygen, but limited to 2 ATP
- occurs in the cytosol
- Without oxygen or mitochondira pyruvate will be reduced to lactic acid
- with oxygen pyruvate will get oxidized and become acetyl-CoA
- simple sugars broken down into pyruvate
- (Phase 3): Citric Acid (Kreb’s) Cycle and Oxidative Phosphorylation
- requires oxygen
- produces waste: CO2, H2O, NH3, and urea
- ATP = 18-34+
- Acetyl-CoA enters the citric acid cucle within mitochondria
- yields NADH
- NADH then completes final step in the electron transport chain located in the mitochondiral membrane
Second Messenger Example: cAMP
- **First messenger** Ligand binds to extracellular receptor located in the cell membrane
- ligand receptor complex activates the G-protein
- G-protein reacts with GTP to activate adenylyl cyclase
- Adenylyl cyclase converts ATP to cAMP
- **Second Messenger** cAMP activates protein kinases
- protein kinases phosphorylate proteins within the cell
- Change in cellular reactions and metabolic pathways
Direct Gene Activation Example: Steroid Hormones
- Hormone detaches from carrier protein
- Hormone enters cell (small, nonpolar can cross phospholipid bilayer)
- Hormone binds to intracellular receptor, forming hormone-receptor complex
- Hormone-receptor complex binds to DNA
- DNA transcription of mRNA is affected
- mRNA is translated to proteins
- Changes in cellular reactions and metabolic pathway
Endocrine Gland
Secrete INTO tissue layers, then diffuses into blood stream
ductless, secrete hormons
e.g. thryoid, pituitary, adrenal
Exocrine Glands
Secrete OUT of tissue layers onto body surface or lumen
duct present, secrete mucus, oil, other body fluids
e.g. sweat and oil glands, goblet cells
ependymal cells
(Central Nervous System)
line cavities of brain and psinal cord
produce small amounts of CSF
beat CSF around with villi
microglia
(Central Nervous System)
type of protective macrophase
small
only immune cell allowed within the CNS
Satellite Cells
(Peripheral Nervous System)
help control immediate environment and neuronal cells
cover ganglia cell bodies
Astrocytes
(Central Nervous System)
form the blood brain barrier
cling to neurons and capillaries in order to hold them close to the nutrient supply
act as support/scaffolding
bind everything together
oligodendrocytes
(Central Nervous System)
create myelin sheaths for nerves within the CNS
can myelinate multiple points on one axon or on multiple axons
Schwann Cells
(Peripheral Nervous System)
form myelin sheaths for one segment of one axon
phagocytes
important role in nerve repair
Neuroglia
cells that surround and support neurons
Skeletal Muscle
- found attached to bones of the skeleton
•voluntary, striated, multinucleate, long cylindrical cells
Cardiac Muscle
- found in the heart
- involuntary, striated, cylindrical and branching cells, single nucleus
- intercalated discs
Smooth Muscle
- found in digestive tract, uterus, urinary bladder, blood vessels
- involuntary, non-striated, single central nucleus, spindle shaped cells
