Biomedical Science - Cell Biology

Cell

basic living units, smallest subdivision able to carry out life processes, contains organelles, specialised from specific physiological roles

specialised cells

in embryonic development, cell differentiation from stem cells leads to different cells adapted to specific functions eg. RBC

organelles

carry out cell functions

cell/plasma membrane

separates inside/outside of cell

cytoskeleton

microtubules/filaments/centrosome for support/movement

cystoplasm

jelly like fluid containing organelles (not nucleus)

Nucleus

contains DNA arranged in chromosomes, contains nucleolus where ribosomes are synthesised for protein synthesis, membrane bound by nuclear envelope which has small pores

mitochondria/ion

they metabolise/break down glucose in the presence of O2 to produce ATP for energy: respiration Glucose + Oxygen -> CO2 + water + ATP, contain small amount of DNA

Rough Endoplasmic Reticulum

side of protein synthesis

Smooth ER

side of lipid synthesis

Golgi body

proteins are sorted and transported/processed and packaged to other parts of cell/exported to outside of cell

Lysosomes

break down old organelles

phospholipid bilayer

keeps molecules at opt conc inside and out, is made of bilayer of phospholipid molecules, lipids face inwards hydrophobic, phosphate faces outwards hydrophilic

cell membranes are permeable to

gases eg O2 or molecules made of lipid eg. hormones like oestrogen (cross rapidly), small molecules eg water/ethanol (cross slowly)

cell membranes are impermeable to

large molecules such as glucose and amino acids they need membrane proteins to help them pass in/out, & ions (charged molecules) eg calcium and potassium which are repelled by lipids, need membrane proteins to come in/out of cell

water diffuses directly across phospholipid bilayer of cell membranes by

osmosis

Isotonic

ion concentrations equal inside and outside the cell, no net movement

hypotonic

osmosis from high to low water conc, water moves into cell

hypertonic

water leaves the cell

active transport

requires energy to move material through cell membrane LOW to HIGH against conc grad

Ions

atom/molecule with +/- charge, come from substances in diet called electrolytes