Topic 1

chemical/molecular level cellular level tissue level organ level organ system level the organism level

contains atoms (smallest unit of matter), molecules such as ions, proteins, carbs, lipids and nucleic acids. function - structure/function, storage, messengers, control

a group of atoms, molecules and organelles working together, forms the basic unit of life.

a group of similar cells working together 4 main types of tissue - epithelial, connective, muscle and neural.

made up of different tissues (organ is a group of tissues) organ functions are supplied by the tissues, there are multitasking tissues and specialist organs.

an organ system is a group of organs working together. humans have 11 organs with various functions

all the organ systems working together to form a functional organism.

the basic unit of life, structural and functional unit of the body. they can undertake metabolic reactions, maintain homeostasis, reproduce themselves and communicate

• plasma membrane • cytosol • nucleus

lipid bilayer • phospholipids 70% • cholesterol 20% • glycolipids 5% two phospholipids layers with fatty acid tails in the center (hydrophobic tails) and hydrophilic heads. it is flexible/fluid - the fluid mosaic membrane is a constantly moving sea of lipids with a mosaic of proteins - lipids and many proteins can rotate and move sideways in their half so it is not rigid.

depends on two things: • number of double bonds in fatty acid tails and cholesterol. more double bonds = more flexible more cholesterol at body temp = less flexible more cholesterol at low temp = increases fluidity.

a flexible membrane allows self-sealing if it penetrated, allows movement during cell division and secretion of substances (helps to import and export substances if needed).

• acts as a barrier separating inside and outside. • controls the flow of substances into and out of the cell. • helps identify the cell to other cells such as immune cells. • participates in intercellular signaling.

nucleus ribosomes endoplastic reticulum - rough and smooth golgi apparatus mitochondria chloroplast vacuole centriole centromere cytoskeleton lysosome flagellum cilia, microvilli and flagella peroxisomes proteasomes

contains the cytosol and other organelles where most cellular activities occur such as metabolic pathways including glycolysis and processes such as cell division.

small individual structures within the cytoplasm that have various functions

organelles without membranes have more functioning with structural support or moving substances within cells but membrane bound organelles allow specialised functions to be performed within them,

is a network of three filaments types (proteins) in cytosol. it helps maintain cell and organelle shape and structure, generate movement. functions as a scaffold that helps determine a cells shape and organise the cellular contents and aids movements of organelles within the cell, of chromosomes during cell division and of whole cell such as phagocytes.

microfilaments - thinnest, actin, myosin, help generate movements. e.g. white blood cells moving into tissue. intermediate filaments - intermediate size, made of several proteins, very strong, stabilise organelle position, found where cell subjected to stress. microtubules - largest (tubulin) grow from centrioles, move organelles and secretory vesicles and chromosomes.

located near the nucleus, it consists of a pair of centrioles and pericentriolar material. function - the pericentriolar material of centrosome contains tubulins that build microtubules in nondividing cells. that pericentriolar material of the centrosome forms the mitotic spindle during cell division. peri = around

are extensions of the cell membrane that are supported by the cytoplasm cilia - short hair like projections, extend from cells surface: beat in a coordinated manner in order to sweep away substances. appear in clusters. flagella - long projections that propel an entire cell; only in sperm microvilli - finger like projections from the cell membrane, greatly increase surface area of a cell.

composed of rRNA and proteins in large and small subunits, made in nucleus; join together in cytosol. site of proteins production ribosomes on rough endoplasmic reticulum (RER) make proteins for the cell membrane or secretion out of the cell.

flat, folded, membranous sacs attached to nuclear membrane. two types: • rough • smooth

continuous with nuclear membrane, has ribosomes attached, synthesizes membrane protein, secretory proteins and organelle proteins that are transferred into organelles, inserted into the plasma membrane or secreted during exocytosis.