Anatomy Week 1 Flashcards
List the 3 main components of the cytoskeleton:
- Microfilaments
- Intermediate Filaments
- Microtubules
_______ extend through the cytoplasm are are associated with cell-cell junctions called ______ and cell-matrix junctions called ______.
- Intermediate filaments
- Desmosomes
- Hemi-desmosomes
Microfilaments are also called _____ and they form the core of ______. Also __________ is required for cell motility.
- Actin filaments
- Microvilli
- Actin Polymerization
Intermediate filaments are _______ structures that form _______ which come together to ultimately form ________.
- Non-polar
- Staggered Tetramers
- A rope-like structure
What are the two main functions of Intermediate filaments?
- Stabilize cell structure: Maintain organelle position, give mechanical strength
- Resist Shearing Forces: Extend across cytoplasm, form desmosomes and hemi-desmosomes
Differentiate between the 2 types of Actin:
- G-Actin: Free actin molecules in the cytoplasm.
2. F-Actin: Actin bound to ATP that is polymerized to form a filament.
Actin filaments are _______ structures, in which the _____ end is _______.
- Polar
- (+) ATP-bound
- Polymerizing (Fast-Growing)
List the 4 main functions of Actin Filaments:
- Anchorage (gap junctions)
- Structural core of microvilli/stereocillia
- Extension of Cell Processes
- Cell motility (via actin polymerization)
Define Microvilli:
Small, finger-like projections at the apical surface of some epithelial cells
What is the function of Microvilli/Stereocillia and where are Stereocillia found?
- To increase the surface area of the cell to allow for more absorption or other activity.
- Only in the inner ear and male reproductive tract
Stereocillia are essentially _______.
Very Long Microvilli
What is the Myosin family?
The only class of Actin Motor Proteins, of which there are many.
What is the function of Myosin 2?
It binds to Actin to cause a conformational change that leads to contraction in muscle
Describe the 3 types of Protrusions formed of various actin structuring:
- Filopodia: Finger-like projections.
- Lamellipodia: Ruffled, sheet-like protrusions found at the LEADING edge of motile cells.
- Pseudopodia: 3-D projections, found on macrophages and essential for phagocytosis.
Describe the 3 steps of cell movement:
- Protrusion: Actin polymerization at (+) end protrudes lamellipodia.
- Attachment: Focal adhesions anchor the actin cytoskeleton to the extracellular matrix via integrin proteins.
- Contraction: Bulk of the rear-end of the cell and cytoplasm is drawn forward.
What are the 3 domains of cellular life?
- Bacteria
- Archaea
- Eukaryota
What are the 3 main components of a Eukaryotic cell?
- Plasma Membrane
- Nucleus
- Cytoplasm
What are the two main components of the plasma membrane?
- Lipids
2. Proteins
What 3 types of lipids are in the plasma membrane?
- Phospholipids
- Cholesterol
- Glycolipids
Describe how lipids are “amphipathic”:
They two components:
- Hydrophobic NONPOLAR TAIL
- Hydrophilic POLAR HEAD
What are the 2 major classes of plasma membrane proteins?
- Integral Membrane Proteins: Embedded/Pass Through the lipid bilayer.
- Peripheral Membrane Proteins: Associate with Integral Membrane Proteins (NOT embedded though).
How are phospholipids arranged in the bilayer?
With polar heads facing out and non-polar tails towards the center of the bilayer.
How is Cholesterol arranged in the membrane and what function does it serve?
- Intercalated between phospholipids (also amphipathic)
2. Gives structural RIGIDITY to the membrane
How are glycolipids arranged in the membrane and what function do they serve?
- In the OUTER LEAFLET of the membrane
2. Important in cell recognition and distinguishing “self” from “non-self”
Describe how the bilayer is a “fluid mosaic model”:
Molecules are free to move within the bilayer to accomplish their roles
List the 6 categories of integral membrane proteins:
- Pumps/Carriers/Transporters
- Channels/Gap Junctions
- Receptors
- Linkers
- Enzymes
- Structural Proteins (cell-cell junctions)
List the 3 main properties of the plasma membrane:
- Fluidity
- Selective Permeability
- Transmembrane Proteins
Which substances is the plasma membrane more/less permeable to?
- Highly IMPERMEABLE: Ions, Polar/Charged Compounds
- Semi-Permeable: Small, polar, uncharged molecules and water
- Very Permeable: Hydrophobic, non-polar, uncharged compounds
List the 4 components of the nucleus:
- Nuclear Envelope
- Nuclear Lamina
- Nuclear Pores
- Nucleolus
What is the nuclear envelope?
The TWO-LAYERED nuclear membrane, in which the INNER nuclear membrane is in contact with the lamina and the OUTER membrane is facing the cytoplasm AND is continuous with the Rough ER.
Define Nuclear Lamina:
A thin, sheet-like structure beneath the inner nuclear membrane that is made up of lamin proteins (intermediate filaments).
What are the 2 functions of the Nuclear Lamina?
- Provide support for the envelope
2. Serve as a scaffold for the chromatin (DNA) within the nucleus
What must happen to the nuclear envelope/lamina during mitosis?
They must be disassembled and then reassembled after division of the cell.
What is a nuclear pore complex?
Nuclear pores are made up of several proteins (nucleoporins) that form a ring and basket structure that spans BOTH layers of the envelope to allow passage of certain substances in/out of the nucleus.
Differentiate between the 2 types of chromatin:
Heterochromatin: More tightly packed chromatin that is LESS transcriptionally active.
Euchromatin: Less condensed, MORE transcriptionally active
What is the nucleolus?
The site within the nucleus where ribosomes are produced, involving Ribosomal RNA transcription and subsequent assembly of Ribosomal subunits.
What is the fundamental, structural unit of chromatin?
The Nucleosome: An octamer of Histones with DNA wrapped twice around it.
How do the assembled ribosomes reach the Rough ER?
They are exported from the nucleus through nuclear pore complexes
Differentiate between the 2 types of ribosomes:
Free Ribosomes: Translate mRNA with no ER signal sequence, will remain in the cytoplasm
Membrane-Bound Ribosomes: Translate mRNA with an ER signal sequence, proteins will be moved into the ER lumen.
Define Endoplasmic Reticulum: (What does each component do?)
A network of flattened sacs and tubules that is distributed throughout the cytoplasm.
Smooth ER: Lipid Synthesis
Rough ER: Protein Synthesis
Which cells would have a more developed Rough ER versus a more developed Smooth ER and vice versa?
Steroid hormone secretory cells would have a developed Smooth ER since they need to make a lot of lipids (cholesterol). Protein secretory cells would have a more developed Rough ER for the same reason.
Define Golgi Apparatus: (What function does it serve?)
A stack of flattened, membrane-enclosed CISTERNAE.. It mainly functions in POST-TRANSLATIONAL modification.
What are the 2 faces of the Golgi Apparatus?
The Cis- Face: “Entry”
The Trans- Face: “Exit”
How do proteins reach the Golgi? What are the 3 most common things that they undergo in the Golgi?
- After being translated into the ER lumen, they are transported in secretory vesicles to the Cis-Face of the Golgi for modification.
- Phosphorylation, Glycosylation, Sulfation.
What happens when proteins reach the Trans- face of the golgi? What are the only 3 possible destinations for these proteins?
- They are sorted and packaged for distribution
- They go to:
- Lysosomal Vesicles: Proteins are sent to the lysosome
- Secretory Vesicles: Proteins undergo exocytosis
- Membrane Vesicles: Proteins remain at membrane
Mitochondria possess both a _______ and a ________ membrane. They are also divided into 2 compartments: The ____ and the ____.
- Internal Membrane
- External Membrane
- Inter-membrane space
- Matrix
What exists within the mitochondrial matrix and what function does it serve?
Enzymes/Proteins exist in the mitochondrial matrix between CRISTAE (folds) and they function to conduct the Citric Acid Cycle, Oxidative Phosphorylation, and B-oxidation of fatty acids to produce ATP.
Define Lysosome:
A membrane-bound, DIGESTIVE organelle that possesses hydrolytic enzymes to degrade molecules and recycle materials.
Define Peroxisome:
Organelles that contain Peroxidase and Catalase that function to compartmentalize and DEGRADE toxic, reactive oxygen species. (Converts substances like Hydrogen peroxide into O2 and Water).
Which of the 3 components of the cytoskeleton is the largest?
Microtubules
Define Microtubule:
Rigid, hollow, tubular structures that are anchored to the centrosomes and polymerize toward the cell periphery.
What are microtubules composed of?
Two proteins called Alpha and Beta Tubulin that form a dimer which binds to GTP in order to polymerize.
Microtubules are ______ structures, having a _______ end anchored at the centrosome, and a _____ end that is polymerizing toward the periphery.
- Polar
- Minus (-)
- Plus (+)
Describe the 5 functions of microtubules:
- Intracellular Transport: Provide TRACKS for movement of vesicles and organelles.
- Cell Motility: Structural core of CILIA and FLAGELLA.
- Mitotic Spindle Formation: Attachment/Movement of chromosomes during cell division.
- Rigid Intracellular Skeleton: Maintenance of cell shape and polarity.
- Assembly/Disassembly accordingly with changing cell needs at any given time.
What is the Centrosome? What is it made up of?
- The MTOC: Microtubule Organizing Center.
- Made up of two parts:
- The Centriole
- Protein Matrix
What are Centrioles?
Structures formed from 9 TRIPLETS of microtubules arranged around a central axis.
What are the 3 functions of centrioles?
- Organize the centrosome
- Form the basal body of cilia and flagella
- Mitotic Spindle: They are duplicated and migrate to cell poles
What is the Kinesin Family? What do they do?
One of two families of MICROTUBULE motors. They walk along microtubules TOWARD the (+) polymerizing end.
What is the Dynein Family?
One of two families of MICROTUBULE motors. They walk along microtubules TOWARD the (-) centrosome-bound end.
Differentiate between the two subclasses of Dynein Motor Proteins:
- Axonemal Dyneins: WITHIN the cilia, responsible for binding of adjacent microtubules and causing MOVEMENT of those cilia.
- Cytoplasmic Dyneins: Movement of different cargo throughout the cytoplasm.
Define Cilia:
A structure made up of a core of microtubules which are attached to DYNEIN ARMS, which are motor proteins that bind adjacent microtubules and walk in the minus direction to cause movement via bending the cilia in what’s called the “Power Stroke”.
