Plasma membrane structural arrangement
double layer arrangement of phospholipids - phospholipid bilayer
proteins that deeply penetrate the bilayer- integral
proteins that loosely attach to surface of plasma membrane- peripheral
hydrophobic region - tail (nonpolar)
hydrophilic region - head (polar)
passive transport - simple diffusion
- passes directly through plasma membrane
- unassisted passage of very small molecules (O2, CO2) or lipid soluble particles
- does not use ATP
- driven by concentration gradient
passive trasnport - facilitated diffusion
- Channel mediated
> allows passage of ions (Na+, K+, Ca2+)
> does not use ATP
> driven by concentration gradient
- carrier mediated > sugars, amino acids > shape change to transport through membrane > does not use ATP > driven by concentration gradient
passive transport - osmosis
- movement of solvent (water)
- does not use ATP
- driven by concentration gradient
- greater conc of water > less conc of water
the concentration of a solution can change the sahpe of a cell by altering its internal water volume.
isotonic
hypertonic
hypotonic
- same solute concentration as inside the cell
- greater solute concentration than inside cell > less water (solvent)
- lower solute concentration than inside cell > more water (solvent)
Active transport
- uses ATP to drive movement of solutes across plasma membrane
- against concentration gradient
- primary active transport
- vesicular transport
active transport - primary active transport
- ATP used
- eg. Na+/K+ pump
active transport - vesicular transport
- molecules/ particles are transported across the plasma membrane in vesicles
- uses ATP
- transport substances out of the cell
- vesicle fuses with plasma membrane and releases contents
active transport - vesicular transport ENDOCYTOSIS
- transport of substances into cell
- infolding of the plasma membrane fuses to create a vesicle
- phagocytosis - solids
- pinocytosis - liquids
active transport - vesicular transport EXOCYTOSIS
- transport substances out of the cell
- vesicle fuses with plasma membrane and releases contents
nucleus
nuclear envelope
nucleolus
- control centre of cell, houses DNA
- membrane that surrounds the contents of the nucleus
- site of ribosome production
ribosomes ( free and membrane bound)
- site for production of proteins
Free ribosomes
- floating in cytoplasm.
- proteins destined to stay inside cell and used by cell
membrane bound ribosomes
- attach to surface of endoplasmic reticulum
- proteins destined for packaging and used in plasma membrane or released from cell
Endoplasmic reticulum (smooth and rough)
- network of connected sacs or tubules that are connected to the nuclear envelope
smooth ER
- no ribosomes attached
- synthesis of lipids and cholesterols
rough ER
- covered with ribosomes
- proteins produced by ribosomes are packaged into vesicles for shipping to golgi
mitochondria
golgi apparatus
- site for ATP production and used by cell as energy source
- stack of flattened membranes
- modify and package proteins sent from the rough ER destined for secretion out of the cell
lysosomes
perioxomes
- small vesicles containing digestive enzymes that break down worn out organelles and unwanted substances
- small vesicles containing enzymes that neutralise toxins and free radicals
enzymes
- inc speed of reactions in the body
- w/o enzymes reactions would take too long
- do not force reactions between substances that would not ordinarily react together
- sensitive to temperature and pH
chromosomes
DNA
gene
- located in nucleus and carry genetic info in DNA
- cells genetic info and inheritable features of individual
- segment of DNA that represents a specific protein or feature of the person, inherited from parents
cell division and specialisation
- begin as single cell
- cells divide by mitosis to produce identical cells
- cells begin to specialise and differentiate
- generic cells change into specific cells
- embryo cells specialise for normal development
- adult body - stem cells specialise to replace cells (blood or skin cells)
mitosis
- cell division in general body cells
- growth and cell replacement
- eg. cells in the skin reproduce themselves continually to replace those lost on surface
- identical cells
meiosis
- cell division in ovaries and testes
- production of sex cells
- introduces genetic variety in the cells
- half number of chromosomes
cell cycle
interphase
- non dividing phase
- cell growth and normal activities
- period from cell formation to cell division
mitotic phase
- division of cell to produce two identical daughter cells
