Bio Chapter 2- Cells Flashcards
Protoplasm
is the living substance of the cell and includes:
Cytoplasm and Karyoplasm
Karoyplasm
simply form the contents of the nucleus
Cytoplasm
Contents of the cell excluding the nucleus
Plasma membrane
Plasmalemma- separates the cytoplasm from its extracellular environment.
Allows cell to maintain homeostasis.
Selective barrier regulate materials into and out of the cell.
Lipid bilayer
Polar head (hydrophilic), attracted to H20. Non polar fatty acyl tail (hydrophobic), directed away from H20. Amphipathic
Fluid Mosaic Model
Lipids and many membrane proteins are in constant lateral motion.
Freeze fracture
Use to study the bilayer. Interior and exterior are not symmetrical.
Endocytosis
Uptake of a molecule and produce a new vesicle from the plasma membrane
Three types of endocytosis
Phagocytosis, Pinocytosis, and Cell mediated endocytosis. All require ATP
Phagocytosis
Cell eating. Engulfing microorganisms, cellular debris and old cells.
Pinocytosis
Cell drinking. Takes in droplets of extracellular fluid which contain solutes.
Cell mediated endocyotosis
Capture of macromolecules using receptor proteins in the cell membrane. Receptor proteins become associated intracellularly using Clathrin.
Exocytosis
Molecules are secreted by the fusion of vesicles with the plasma membrane. Release of contents goes to the ExCS without compromising cell membrane integrity. E.g. Beat cells of pancreas and Nt by synaptic cleft.
Glycocalyx
Carbohydrate chains covalently linked to the transmembrane proteins and/or phospholipids on the outer portion.
Many negatively charged sulfate and carboxyl groups. Involved with making up receptors that participate in functions cell recognition, hormone response, and adhesion.
Plasma membrane functions
1) Physical barrier: inside vs outside
2) Cell communication: receptors
3) Regulates ion and molecule flow
4) Protection and support: maintains cell integrity
Mitochondria
Aerobic respiration
The heart has the most mito, kidneys second.
Inner membrane is highly folded and is a closed space. Outer membrane allows passage.
Mitochondria inner membrane
ETC making 90% of the ATP.
Matrix of the mito is enclosed by the inner membrane.
Mitochondrial Matrix
Kreb Cycle (TCA cycle) and Fatty acid oxidative processes occur. Contains enzymes, ribosomes, and mDNA. Gel like and viscous.
mDNA
Double stranded but circular. Probable ancestral aerobic prokaryotic bacterium. Endosymbiotic Theory.
Mito are self replicating, avg life span of 10 days.
Lysosomes
Membrane bound organelle that contain hydrolytic enzymes used to digest macromolecules.
Neutrophils and macrophages are filled with lysosomes.
Do plants lack lysosomes?
No.
Lysosomes functions
Digest:
a) Microorganisms like fungi or bacteria
b) Cellular debris
c) Old organelles
Lysosome Enzymes
Proteases, nucleases, phosphatases, sulfatases
Inactive at pH 7.2
Phagosome
Formed by the fusion of the cell membrane around microorganism or senescent cell.
Tay Sachs disease
Lysosomal enzyme deficiency Lipids cannot be digested and cells become engorged and neuronal function suffers.
Golgi Apparatus (Complex)
Stacks of membranous sacs that involved the synthesis of carbohydrates and the mod of proteins. Post translational modification and packaging of proteins.
Golgi Apparatus Sections
Cis Golgi: molecules go in
Main Golgi: molecules get processed
Trans Golgi: molecules go outward
Trans Golgi sends to?
Inside the cell: released in vesicles towards lysosomes.
The plama membrane: repair, cell signaling, etc.
Outside the cell: release of hormones as an example.
How are lysosomes formed from the Golgi Complex?
Budding
Golgi complex makes?
Polysaccharides and most of the glycoaminoglycans of the ExCM.
The materials going to the Golgi comes from?
The Endoplasmic Reticulum.
Largest membranous system in the cell?
Endoplasmic Reticulum. It occurs about 50% of the total membrane volume.
The Smooth ER
Outer surface lacks ribosomes. Lipid biosynthesis.
Controls Ca++ release in skeletal muscle called sarcoplasmic reticulum.
Smooth ER functions
Synthesis of cholesterol, triglycerides and steroids. Liver contains high % of smooth ER, helps detoxifying drugs using cytochrome 450.
Rough Endoplasmic Reticulum
Continuous with the nuclear envelope.
Rough Endoplasmic Reticulum are abundant in
Pancreas and GI tract
RER functions
Works with ribosomes and continues protein assembly. Final mod and finishing.
Ribosomes
Protein factories. Made of rRNA and over 80 diff proteins. 2 main subunits.
Ribosomes can be found
a) Attached to RER
b) Attached to the Nuclear Envelope
c) Suspended in cytosol
Peroxisome (Microbody)
Spherical organelles, membrane bound and contain over 40 oxidative enzymes.
Catalase breaks down H202 which is harmful to cells.
Peroxisome functions
Lipid metabolism. Beta oxidation of long chained fatty acids 18C >. Separate from mitochondrial enzymes. Chains are made shorter than shuttle to the matrix of the mitochondria.
Peroxisomes make H2O2
H202 detoxified substances such as ethanol and even kills microorganisms. Xs H202 is broken down by catalase.
Nucleolus
Ribosome production factory. Non membranous organelle. One or Two may be found within the nucleus. rRNA synthesis and assembley of large and small ribosomal subunits.
Nucleolus #2
Small amounts of DNA are present but doesn’t stain with Feulgen stain. In cancer cells nucleolus is often hypertrophic. Can either be sign of actively synthesizing proteins or cancer.
Nucleus
Largest organelle. Enclosed by double membrane nuclear envelope.
Nucleus three major components
a) Nucleolus: rRNA synthesis
b) Chromatin: genetic material
c) content of the nucleus, excluding nucleolus
Chromatin
Can be either heterochromatin or euchromatin
Heterochromatin vs Euchromatin
Heterochromatin is dark staining and found near the nuclear envelope. It’s condensed and not actively transcribed. Eurchromatin is the light area, less compact and has genes that are actively transcribing.
Which cells are examples of multinucleated cells?
Osteoclasts, Cancerous cells, skeletal muscle, and liver cells.
Which cells are examples of cells without a nucleus?
Red blood cells and platelets(thrombocytes).
Proteasomes
Protein complexes found in the cytoplasm.They degrade denatured or unneeded proteins. Quality control department. Lysosomes do the bulk of the job but these organelles assist with primarily individual proteins. Four stacked ring structure.
Inclusion
Nonliving components of the cell.
a) Pigments- melanin
b) Lipid drops
c) Glycogen granules in liver and skeletal muscle cells
d) Vacuoles: membrane bound vesicle
e) Crystals: remnants of certain proteins
Cyanobacteria
Gives us O2. Only form of oxygenic photosynthetic bacteria known to date. They contain chlorophyll. Mainly found in water but can be on coral, rocks, and land. Blue green algae. Kingdom Monera and represent prokaryotes.
Prokaryotes
Unicellular and lack membrane bound nucleus, mitochondria, and other membrane bound organelles.
Microtubules
Cytoskeleton. Are involved with molecular motors. Attaching to organelles and vesicles as well as chromosomes to help pull them apart.
Colchicine
Disrupts microtubules and used to treat gout. Microtubule disruption block WBC migration which is responsible for inflammation.
Mitotic Poison and stopper.
Cilia and flagella
are composed of microtubulues and motor proteins and are used for movement.
Microtubules
Strongest cytoskeletal polymers. Holds their shape. A mature neuron uses microtubules for strength while a young neuron uses it for help with movement.
Dyneins and Kinesins
Molecular motors enzymes that walk along microtubulues.
Dynein walking is responsible for the bending movements of the cilia and flagella.
Microfilaments
Made from actin (globular protein). Myosin is a motor protein built from microfilaments.
Muscle contraction and microfilaments
Actin and myosin filaments slide past one another. Amoebas move by pseudopodia and this movement also involves actin and myosin.
Actin plays a critical role in
Cytokinesis and phagocytosis
Axoneme
9+2 arrangement of flagella and cilia.
Actin
Most abundant protein and participates in more protein protein interactions than any other protein.
Intermediate Fibers
More permanents than microtubules or microfilaments. These fibers anchor the nucleus in place and provide structural support for the cell. They make up the nuclear envelope framework.
Keratins
Predominant type of intermediate fiber. Diverse family of 20 proteins that provide protection against abrasion and prevent water loss in epidermal cells.
Centrioles
Found in animals, not plants. 9 sets of microtubules triplets arranged in a cylinder. 9 + 0 pattern.
Centrosome
Most common microtubule organizing center. A pair of centrioles and associated proteins comprise the centrosome. Centrioles replicate before cell division.
Centrioles role in cell division
Centrioles move to opposite ends of the cell. Microtubules extend from the centrioles to form the spindle. Kinetochores on each chromosome are attached by microtubules. Kinetochores control the metaphase/anaphase transition.
Intercellular Junctions
Gap Junctions, Plasmodesmata, Tight Junctions, Desmosomes
Gap Junctions
Rapid exchange occurs between these junctions. Connexins are proteins gap junctions. Cyclic AMP is involved with cell signal transduction. Popular in the heart and muscle.
Plasmodesmata
Intercellular channels that connect plant cell walls.
Tight Junctions “Zona Occludens”
Tight seals around cells to prevent leaking. E.g. skin cells and intestinal barrier.
Celiac diease or inflammatory bowel disease involves leaky intestinal barrier.
Desmosomes
Intermediate filaments which are very strong, they are common in epipthelia that need to withstand abrasion such as skin.
