Wk 1: cells & membranes Flashcards
Atoms
smallest chemical units of matter
Molecule
a group of atoms working together
Macromolecules
- Proteins
- Carbohydrates
- Lipids/fats
- Nucleic acids: building blocks of DNA
Functions of macromolecules
- Structure/form work
- Storage
- Messengers
- Control
Tissue
a group of similar cells working together
Primary tissue
- Epithelial tissue 2
- Connective tissue
- Muscle tissue
- Neural tissue
Organ
group of different tissues working together
- Organ functions are supplied by tissues
- Multi-tasking (skeletal muscle)
- Specialists (heart)
Organ system
a group of organs working together
Organ system functions
- Control/direct
- Cool and warm
- Digest
- Move
- Protect
Body cavities
spaces that enclose internal organs
Organs located in cavities
Functions: protect (fluid), separate and support internal organs
Major cavities
separated by diaphragm
- Thoracic cavity
- Abdomino pelvic cavity
Cells
the basic structural and functional units of the body
Classes of cells
- Germ cells: either spermatozoa (sperm) of males or oocytes (eggs) of females
- Somatic cells: all body cells except germ cells.
Nucleus
Stores the hereditary material (DNA)
controls and coordinates cell functions
Cytoplasm
Cytosol plus organelles expect the nucleus
Vesicle
membrane enclosed sac used to take in, transport and secrete substances in & out of cell
Ribosome
Protein synthesis
Rough endoplasmic reticulum
a major site of protein synthesis because of the presence of attached ribosomes
also modifies and packages newly synthesised proteins
Smooth endoplasmic reticulum
Functions in several metabolic processes, including synthesis of lipids and steroids and the metabolism of carbohydrates
Golgi Apparatus
storage, alteration and packing of secretory products and lysosomal enzymes (SAP)
Mitochondria
Produce 95% of the ATP required by the cell – energy powerhouse
Lysosome
Specialised vesicle formed from the Golgi responsible for intracellular breakdown (lysis) and removal of damaged organelles or pathogens by enzymes
Cytoskeleton
Network of protein filaments that provide support for cell contents, strength and structure to cell and facilitate movement.
Centrioles
Roll in cell division by supporting chromosomes as they separate and migrate
Protein filament structure located close to the nucleus
Microvilli
Has small folds to provide cell with increased surface area for exchange with the extracellular environment
Cillia
Projections of the cell membrane (longer than microvilli) that are internally supported and strengthened by protein filaments which move in a coordinated process to move fluid and other substances along the external cell surface
Cell membrane functions
- Maintains composition of inter and extra cellular fluid
- Determines what substances move in and out of cell
- Communicates with other cells and organs
Phospholipid (cell membrane)
- Hydrophilic phosphate heads (water loving)
- Hydrophobic lipid tails (water hating)
Proteins: peripheral or integral (cell membrane
determines what functions the membrane and perform
- Channels, gates, pumps
- Carrier proteins
- Anchoring proteins
- Receptors
Selective permeability
phospholipid lipid bilayer lets some substances in and out of the cell but stops others
Based on: size, charge and solubility
Passage across membrane (passive)
No energy expenditure
Substances can move with a concentration or electrical gradient
Passage across membrane (active)
Requires energy expenditure
Substances can move against a concentration or electrical gradient.
Simple diffusion
the movement of a molecule directly through the phospholipid bilayer from high to low concentration
Substances that can utilise simple diffusion
small
uncharged
lipid-soluble
Factors affecting rate of simple diffusion
concentration gradient
substance solubility/size/charge
temperature
Substances that can utilise facilitated diffusion
hydrophilic
charged
larger materials
Facilitated diffusion
the movement of a molecule from high to low concentration via a channel or carrier protein
Factors affecting rate of facilitated diffusion
concentration gradient
availability of carrier proteins
Osmosis
movement of water
Water is water soluble: use a channel (aquaporin) to cross membrane
Move from high to low water concentration
Water from area of low to high solute
Factors affecting rate of osmosis
Hydrostatic presssure
Osmotic pressure
Active transport
the movement of a molecule from an area of low to high concentration, via a channel or carrier protein
Primary and secondary active transport
Primary: uses energy
Secondary: uses energy stored in ionic concentration gradient
Vesicle transport
moves substances in membrane-bound compartments to and from the cell membrane
type of active transport
Factors affecting rate of vesicle transport
Availability of ATP
Carrier protein
Substrate
Exocytosis
the release of fluids and/or solids from the cell via intracellular vesicles
Energy required
Substances of exocytosis
fluid and cellular wastes
secretory products from some cells
Endocytosis
packaging of extracellular materials into a vesicle for transport into the cell
Energy required
Receptor-mediated transport
target molecules bind to receptor proteins on the membrane surface triggering vesicle formation
Factors affecting rate of receptor mediated transport
the number of receptors on the plasma membrane
concentration of target molecules
Pinocytosis
vesicles form at the membrane and bring fluids and small molecules into the cell
Phagocytosis
vesicles form at the membrane to bring solid particles into the cell
Diffusion rates are influenced by
Distance
Surface area
Molecular size
Temperature
Concentration
Electrical force
Tonicity
the capability of a solution to modify the volume of cells by altering their water content
Isotonic solution
same solute water concentration as inside the cell
equal inside and outside cell
Hypotonic
outside the cell high in water and low in solute
Hypertonic
outside the cell low in water and high in solute
