The Cell Flashcards
8 General Cellular Functions
- Covering
- Lining
- Storage
- Movement
- Connection
- Defense
- Communication
- Reproduction
3 Characteristics most cells have
- Plasma (cell) membrane
- Cytoplasm
- Nucleus
Plasma (Cell) Membrane
- function
- major constituents
- Phospholipid bilayer that is the extremely thin outer border on cell that selectively mediates what enters & leaves cell (gases, nutrients & wastes)
- Made of 2 components;
1. Lipids- Phospholipids (75%): hydrophilic polar head & hydrophobic nonpolar tail - constitutes majority of lipid in cell membrane
- Cholestrol (20%): strengthens & stabilises membrane against extreme temp.
- Glycolipids (5-10%): Have carbohydrate molecules attached & facing out - forms the glycocaylx (involved in cell - cell recognition.
- Proteins: Are complex molecules made of amino acid chains that give membrane functions
i) Integral: partially or fully embedded in membrane (e.g. channels)
ii) Peripheral: Proteins attached to surface - help w/ cell signalling
- Proteins: Are complex molecules made of amino acid chains that give membrane functions
- Both can serve as enzymes
Cytoplasm - 3 parts
*Includes all materials between plasma membrane & nucleus
3 parts;
-Cytosol; Viscous, syrup-like fluid containing many different dissolved substances (e.g. ions, nutrients, proteins, aa, carbs)
-Inclusions: Large storage aggregates of complex molecules found in cytosol (e.g. melanin - pigment, glycogen - long chains of sugars in liver & skeletal muscles)
-Organelles: Membrane bound or non-membrane bound structures that have unique functions and activities
Smooth Endoplasmic Reticulum (SER)
- General features of ER
- Function of SER
*network of intracellular membrane w/ enclosed spaces called cisternae.
-walls have smooth appearance -lack of ribosomes.
Functions;
-Synthesis, transport & storage of lipids (e.g. hormones & steroids)
-Metabolism of carbohydrates
-Detoxification of drugs, alcohol & poisons
Rough Endoplasmic Reticulum (RER)
-Function
-Rough wall appearance due to ribosomes (protein synthesizers)
-continuous w/ SER
Synthesise, transport or store proteins for;
-secretion by cell
-Incorporation into plasma membrane
-creation of lysosomes
Golgi Apparatus
- Function
- Terminology for 2 regions
-stacked cisternae - lateral edges bulge, pinch off & give rise to small transport & secretory vesicles
-receives proteins & lipids from RER for modification, sorting & packaging
Receiving region = cis-face
Shipping region = Trans-face
Lysosomes
- Function
- Autophagy & autolysis
- Are vesicles generated by Golgi Apparatus (or membrane sacs filled w/ digestive fluid)
- Contain enzymes that are used to digest & remove waste products/damaged organelles w/n cell (Autophagy)
- Lysosomes release their enzymes that digest cell when dying (Autolysis)
Peroxisomes
- Vesicles smaller than lysosomes.
- Are membrane enclosed sacs that usu. contain large amounts of specific enzyme to break down harmful substances
- Use O2 & enzymes to catalase (detoxify) harmful molecules taken into cell
- hydroxide to H2O
- Are able to break down fatty acids
Mitochondria
- shape
- where ATP produced
- Bean shaped organelles w/ double membrane (inner forms cristae; has internal fluid matrix)
- Produce ATP (high energy containing molecule) ON THE cristae
- Referred to as the “powerhouses of the cell”
Ribosomes
-Free & fixed ribosomes
- Made up of small & large subunit - are dense cytoplasmic granules
- Responsible for protein synthesis
- Free Ribosomes: float unattached w/in cytosol - synthesize proteins for use in cells
- Fixed Ribosomes: attached to outer surface of RER; synthesis proteins for secretion, incorporation into plasma membrane or lysosomes
Cytoskeleton
-3 parts
-Is an organised network of protein filaments or hollow tubules throughout cell
-Provides structural support; facilitates cytoplasmic straming, organelle & cellular motility, transport of materials & chromosomal movement & cell division.
3 Parts;
1. Microfilaments: Actin protein monomers formed into filaments (used to maintain cell shape, aid in muscle contract. & separate dividing cells)
2. Intermediate filaments: Various protein components - provides structural support, stabilises cell junctions
3. Microtubules: Hollow cylinders of tubulin proteins; able to lengthen & shorten - support cell, hold organelles in place, maintain cell shape & rigidity, direct organelle movement w/in cell as cilia & flagella; move chromosomes @ cell division
Centrosome & Centrioles
Centrosome: Amorphous regionattached to nucleus; contains a pair of centrioles at right angles to each other
Centriole: Nine sets of microtubule triplets
-involved in organising microtubules
-attach to chromosomes during cell division - causes chromosomal migration
Cilia & Flagella
- Projections on the cell containing cytoplasm & microtubules capable of movement
- Cilia: On cells that move objects across their surface (i.e. cells of respiratory tree & oviduct)
- Flagella: longer, usu. singular, to propel a cell (e.g. sperm)
Microvilli
- Extensions of cell NOT capable of motion (altho. look like cilia are in fact much smaller)
- Purpose is to increase SA to increase absorption of food (found on surface of cells of small intestine)
