CELLULAR LEVEL OF ORGANIZATION Flashcards
Cell Structure
— Plasma membrane
— Cytoplasm: cytosol + organelles
— Nucleus
cytosol + organelles
Cytoplasm
— Phospholipid bilayer
— Cholesterol
— Proteins (integral and peripheral)
— Attached carbohydrates (glycolipids and glycoproteins)
Cell Membrane
integral and peripheral
Proteins
glycolipids and glycoproteins
Attached carbohydrates
Membrane Function
- Ion Channel (integral)
- Receptor (Integral)
- Carrier (Integral)
- Enzyme (Integral and Peripheral)
- Linker (Integral and Peripheral)
- Cell Identity Marker (Glycoprotein)
Allows specific ion to move through water-filled pore. Most plasma membranes include specific channels for several common ions
Ion Channel (integral)
Transports specific substances across membrane by changing shape. For example, amino acids, needed to synthesize new proteins, enter body cells via carriers. Carrier proteins are also known as transporters.
Carrier (Integral)
Carrier proteins are also known as _________
Transporters
Recognizes specific ligand and alters cells function in some way. For example, antidiuretic hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.
Receptor (Integral)
Catalyzes reaction inside or outside cell (depending on which direction the active site faces). For example, lactase protruding from epithelial cells lining your small intestine splits the disaccharide lactose in the milk you drink.
Enzyme (integral and peripheral)
Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell. May also participate in movement of the cell or link two cells together.
Linker (Integral and Peripheral)
Distinguishes your cells from anyone else’s (unless you are an identical twin). An important class of such markers are the major histocompatability (MHC) proteins.
Cell Identity Markers (glycoprotein)
• Barrier between inside and outside of cell
• Controls entry of materials: transport
• Receives chemical and mechanical signals
• Transmits signals between intra- and extra- cellular spaces.
Membrane Function
Cell Organelles;
• Cytoskeleton
• Flagella, cilia & centrioles
• Endoplasmic reticulum
• Golgi apparatus
• Mitochondrion
• Nucleus, nucleolus, nuclear envelope
• Vesicles, e.g. lysosome
• Cell contents
• Includes organelles and cytosol
• Excludes nucleus
Cytoplasm
a network of protein filaments
Cytoskeleton
• a network of protein filaments
• Includes: microfilaments, intermediate filaments, microtubules
• help generate movement, provide mechanical support
• stabilize position of organelles
• Help determine cell shape
Cytoskeleton
moves chromosomes to ends of
cell during cell division
Centrosome
Structure of Centrosome:
• Two centrioles arranged perpendicular to each other
— Composed of microtubules: 9 clusters of 3 (triplets)
• Pericentriolar material
— Composed of tubulin that grows the mitotic spindle
Composed of microtubules: 9 clusters of 3 (triplets)
Two centrioles arranged perpendicular to each other
Composed of tubulin that grows the mitotic spindle
Pericentriolar material
- The prricentriolar material of the centrosome contains tubulins that build microtubules in nondividing cells
- The pericentriolar material of the centrosome formation the mitotic spindle during cell division
Functions of Centrosome
Specialized for motion
Cilia and Flagella
— in groups
• Found in respiratory system: move mucus
Cilia
— single tail like structure on sperm
• Propels sperm forward in reproductive tract
Flagellum
• Made within the nucleus (in nucleolus)
• Sites of protein synthesis (on E.R. or freely
within cytoplasm)
• Consist of ribosomal RNA (rRNA) + proteins
• Contain large and small subunits
• Can be attached to endoplasmic reticulum or free in cytosol
Ribosomes
Sites of protein synthesis (on E.R. or freely
within cytoplasm)
Ribosomes
Made within the nucleus (in nucleolus)
Ribosomes
Consist of ribosomal RNA (rRNA) + proteins
Ribosomes
Structure: network of folded membranes
Endoplasmic Reticulum (E.R.)
synthesis of glycoproteins & phosholipids,
intracellular transport
Endoplasmic Reticulum (E.R.)
Types of E.R.
- RoughE.R.
- Smooth E.R.
— studded with ribosomes (sites of protein synthesis)
RoughE.R.
lacks ribosomes
Smooth E.R.
lipid synthesis (FA & steroids)
Smooth E.R.
storage and release of Ca2+ in muscle cells (where smooth E.R. is known as ____________)
sarcoplasmic reticulum or SR
Flattened membranes (cisterns) with bulging
edges (like stacks of pita bread)
Structure of Golgi Complex
Modify proteins -> glycoproteins and lipoproteins that:
• Become parts of plasma membranes
• Are stored in lysosomes, or
• Are exported by exocytosis
Functions of Golgi Complex
Small Bodies
- Lysosomes
- Tay-Sachs Disease:
- Peroxisomes
- Proteasomes
— contain digestive enzymes
• Help in final processes of digestion within cells
• Carry out autophagy (destruction of worn out parts of cell) and death of old cells (autolysis)
Lysosomes
destruction of worn out parts of cell
autophagy
death of old cells
autolysis
— hereditary disorder most often affects children of Ashkenazi (eastern European Jewish) descent; one missing lysosomal enzyme (Hex A) leads to nerve destruction.
Tay-Sachs Disease
excess ganglioside GM2 in the nerve cells.
Tay-Sachs Disease
detoxify; abundant in liver
Peroxisomes
contain the enzyme catalase, which decomposes H2O2.
Peroxisomes
digest unneeded or faulty proteins
Proteasomes
Faulty proteins accumulate in brain cells in persons with Parkinson or Alzheimer disease
Proteasomes