Cell Physiology Flashcards
principles of the cell theory
- the cell is the smallest structural and functional unit capable of carrying out the life process
- the functional activities of each cell depend on the specific structural properties of the cell
- cells are the living building blocks of all multicellular organisms
principles of the cell theory (cont)
- an organism’s structure and function ultimately depend on the collective structural characteristics and functional capabilities of its cells
- all new cells and new life arise only from preexisting cells
- because of continuity of life, the cells of all organisms are fundamentally similar in structure and function
cells three major parts
- plasma membrane
- nucleus
- cytoplasm
plasma membrane
- encloses the cell
- thin membranous structure
- keeps ICF within the cells and ECF outside the cells
nucleus
-houses the cells genetic material DNA and chromosomes
DNA (deoxyribonucleic acid)
- serves as a genetic blueprint during cell replication
- directing protein synthesis
cell composition
water ions: 70-85% of cell mass
proteins: 10-20%
lipids: 2-95%
carbohydrates: 1-6%
lipids
- barrier to water and water-soluble substances
- organized in a bilayer of phospholipid molecules
- keeps ECF and ICF separated
- hydrophobic tail- water fearing
- hydrophilic head- water loving
proteins
- provide specificity to a membrane
- has integral and peripheral types
integral proteins
- transmembrane
- proteins that go through the membrane
- channels, pores, carriers, enzymes
peripheral
- polar proteins that do not go all the way through the membrane
- enzymes, intracellular signal mediators (carry signal in, on the boundary)
- more commonly found on inner surface
carbohydrate
- located on the outer surface of cells
- protrude like tiny antennas
- glycolipids 10%
- glycoproteins, majority of integral proteins
- proteoglycans
- negative charge on chain repels other negative charges
- cell-cell attachments and interactions
- play a role in immune reactions
cholesterol
- varying amounts in membranes
- increases membrane flexibility and stability
- in between the phospholipid molecules
- prevent fatty acid chains from packing together and crystallizing
organelles
- highly organized structures that serve a specific function
- membranous (bound by a membrane that separates the organelles content from the cytosol) and nonmembranous
smooth ER
- serves primarily as a central packaging and discharge site for molecules to be transported
- abundant in cells specialized in lipid metabolism
- secretory product into transport vesicles that bud off and move to the Golgi complex
rough ER
- studded with ribosomes
- carry out protein synthesis and release new proteins into the ER lumen
ribosomes
- nonmembranous organelles
- carry out protein synthesis by translating mRNA into chain of amino acids in the ordered sequence from the original DNA code
Golgi complex
- membranous organelle
- modifies molecules delivered to it from the smooth ER into finished products
- sort, packages and directs molecules to appropriate destination
- in secretory cells, packages proteins for export by exocytosis
exocytosis
- finished products collects within the edges of the Golgi sacs
- pinched edge forms a membrane-enclosed vesicles containing the selected product
- the vesicle fuses with the plasma membrane and empties it contents
lysosomes
- vesicular organelle formed from budding Golgi
- contains hydrolytic enzymes (phosphatases, nucleases, proteases, lipid-degrading enzymes, lysozymes digest bacteria)
- fuses with pinocytotic or phagocytotic vesicles
pinocytotic
- “cell drinking”
- a droplet of ECF is taken up nonselectively
- forms endocytic vesicle (endosome)
phagocytosis
- “cell eating”
- large multimolecular particles are internalized
- certain types of white blood cells
- pseudopods (false feet) surround or engulf the particle and internalize it as a phagosome
- lysosome fuses (phagolysosome) and releases its hydrolytic enzymes
lysosomal storage diseases
- absence of one or more hydrolases
- not synthesized, inactive or not properly sorted and packaged
- lysosomal become engorged with undigested substrate
peroxisome
- similar physically to lysosomes
- self-replication and contain oxidases
- function: oxidize substances (alcohol) that may be otherwise poisonous
- use oxygen to strip hydrogen from certain organic molecules
- decompose hydrogen peroxide (H2O2)
endocytosis
- the internalization of extracellular material
- pinocytosis, receptor- mediated endocytosis and phagocytosis
receptor-mediated endocytosis
- highly selective process
- allows cell to import specific large molecules that it needs from the environment
- triggered by a specific target molecule to the surface of the membrane
- coated with clathrin
mitochondria
- they extract energy from the nutrients in food and transform it into a usable form for cell activities
- enclosed by two membranes
ATP (adenosine triphosphate)
- energy source for cellular work
- the terminal phosphate bond of ATP is split
- yielding ADP, inorganic phosphate (Pi) and energy
glycolysis
- in cytosol
- chemical process that break down glucose into two pyruvate molecules
- produce 2 ATP and 2 NADH
citric acid cycle
- pyruvate is transferred into the mitochondrial matrix
- pyruvate is turned into acetate (makes two NADH) then two acetyl-CoA which enters the citric acid cycle
- two turns make 2 ATP, 6 NADH and 2 FADH2
oxidative phosphorylation
- process by which ATP is synthesized using energy released by electrons as they are transferred to O2
- inner mitochondrial membrane
- proteins: electron transport system and ATP synthase
electron transport system
- consists of electron carriers found in 4 large stationary protein complexes
- extract hydrogens held in FADH2 and NADH from the glycolysis and citric acid cycle
- energy released in used to create a H+ gradient
- transfers electrons to successively lower energy levels
- H+ flow down the gradient and activate ATP synthase and synthesize ATP in a process called chemiosmosis
- aerobic
- 28 ATP
hydrogen carriers
- nicotinamide adenine dinucleotide (NAD+), vitamin B niacin
- flavine adenine dinucleotide (FAD), vitamin B riboflavin
anaerobic condition
- glycolysis makes 2 ATP
- no O2 available
- makes lactate
vaults
- hollow, nonmembranous, octagonal structures
- believed to pick up particles for transport from nucleus to cytoplasm
- may transport mRNA from nucleus to the cytoplasm for protein synthesis
- play a role in drug resistance
centrioles
form and organize microtubules during assembly of the mitotic spindle during cell division and form cilia and flagella
cytosol
- 55% of cell volume
- semiliquid portion of the cytoplasm that surrounds the organelles
- contains vesicles and enzymes involved in intermediary metabolism and ribosomes protein synthesis
- storage of unused nutrients in the form of glycogen granules or fat droplets (inclusions)
intermediary metabolism
the collectively large set of chemical reactions inside the cell that involve the degradation, synthesis and transformation of small organic molecules
cytoskeleton
- contain microtubules, microfilaments and intermediate filaments
- dispersed throughout the cytosol that supports and organizes the cell components and controlling their movements
microtubles
- made of tublin
- largest, slender, long, hollow, unbranched tubes
- maintain asymmetric cell shapes
- highway for intracellular transport by molecular motors
- main component of cilia and flagella
- make up mitotic spindle, moves chromosome (prophase, metaphase, and anaphase)
cilia
short, tine hair like protrusions usually found in large number of surfaces
goblet cells
secrete mucus
microfilaments
- made up of actin
- important in various cellular contractile systems
- amoeboid movement and muscle contraction
- mechanical stiffeners for microvilli
intermediate filaments
- made up of different proteins in different cell types
- irregular threadlike proteins that help cells resist mechanical stress
- abundant in skin cells where they are composed of keratin
lysosomal storage disease: hurler’s syndrome
- iduronidase def
- cornea clouding, mental retardation
- mucopolysaccharides build up
lysosomal storage disease: Hunter’s syndrome
- iduronate sulfatase def
- milder form of hurler’s
- no corneal clouding
- mild mental retardation
- heparin sulfate and dermatan sulfate build up
Golgi I cell disease
- impaired post-translation modification
- unable to add mannose which serve as marker for them to be normally a target to lysosomes and secreted out of the cell
mitochondrial dysfunction
- maternal inheritance
- Laber’s hereditary optic neuropathy (LHON)
- loss of vision in the center of visual fiels
- less mitochondrial function
- less energy in optic nerve and retina
microfilaments- G (globular) actin
-listeria spreads cell to cell by inducing actin polymerization
epidermolysis bullosa
- intermediate filaments
- blister formation due to mechinal stress
microtubules - tubulin
immotile cilia syndrome and male infertility
-antimitotic drugs: colchicine inhibit microtubule function
hereditary spherocytosis
- mutated spectrin gene
- spectrin protein in RBC membrane
- spherical, unstable, inflexible, rupture within blood vessels
- lodged in spleen
- less RBC
kartagener’s syndrome
- structures that make up the cilia
- inner and or outer dynein arms
- central apparatus, radial spokes, ect are missing or dysfunctional and thus the axoneme structure lacks the ability to move
- axonemes: elongated structures that make up cilia and flagella
- PCD: primary ciliary dyskinesis
- cilia dysmotility- triad of bronchiestasis, chronic sinusitis and situs inversus
membranous organelles
- ER
- Golgi complex
- lysosomes
- peroxisomes
- mitochondria
nonmembraneous organelles
- ribosomes
- vaults
- centrosomes with centrioles
