Prokaryotes (Bacteria) do not have mitochondria and a true nucleus
A bacterial cell contains:
Cell wall made of peptidoglycan, not cellulose
Cell membrane
Cytoplasm
Ribosomes
Circular DNA
Plasmids
Levels of Organisation:
Cells: Building Blocks of Life
Tissue: Groups of cells with similar structures working together to perform a shared function
Organ: Group of tissues working together to perform a specific function
Organ system: Group of organs with related functions working together to perform body functions
Specialised Cells:
Ciliated cells: Movement of mucus in the trachea and bronchi
Root Hair cells: Absorption
Palisade Mesophyll cell: Undergo photosynthesis
Neurones: Conduction of electrical impulses
Red Blood cells: Transport of oxygen
Sperm and Egg cells (gametes): For reproduction
Size of Specimens:
Magnification = size of drawing / size of specimen
Actual size = image size / magnification
Image size = magnification x actual size
Unit Conversions (um - micrometre):
1cm = 10mm
1mm = 1000um
Magnification does not have any units ('x 50' or 'x 5000')
Movement In and Out of Cells:
Diffusion: Net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient
Energy for diffusion comes from the kinetic energy of random movement of molecules and ions
Some substances move into and out of cells by diffusion through the cell membrane
Factors that Influence diffusion:
Concentration gradient
Temperature
Surface area
Distance
Osmosis
Osmosis is the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
Water moves into and out of cells by osmosis through the cell membrane
In animals, increasing solute concentration inside a cell can cause it to burst (lysis) because it has too much water and no cell wall
In plants, increasing solute concentration inside the cell causes the cell to become turgid, and the vacuole fills up
Decreasing solute concentration inside the cell causes the cell to become flaccid, losing water, and the vacuole gets smaller. The cell body shrinks, pulling away from the cell wall
Plants are supported by the water pressure inside the cells pressing outwards on the cell wall
Active Transport is the movement of particles through a cell membrane from a lower concentration region to a higher concentration region (against a concentration gradient), using energy from respiration
Carrier proteins are used during active transport
Active transport is needed when an organism wants to optimize the nutrients it can take up - ion uptake by root hair cells
Biological Molecules:
Carbohydrates: made from Carbon, Hydrogen, and Oxygen (CHO)
Fats and oils: made from Carbon, Hydrogen, and Oxygen (CHO)
Proteins: made from Carbon, Hydrogen, Oxygen, Nitrogen, and sometimes Sulfur (CHON(S))
Dialysis Tubing Experiment:
Dialysis tubing (or Viking tubing) is a non-living, partially permeable membrane made from cellulose
Pores are small enough to prevent the passage of large molecules (such as sucrose) but allow smaller molecules (simple sugars and water) to pass through by diffusion and osmosis
Smaller molecules that can pass through: simple sugars, fatty acids and glycerol, amino acids