- A polar molecule, which has no overall charge.
- When 2 water molecules contact, opposites attract, forming a Hydrogen bond.
- The sticking together of water molecules is called Cohesion.
- High surface tension.
- Water is a solvent.
- Water has a specific heat, a large anount of water is needed to heat water.
- High latent heat.
- Maxium density is 4 degrees.
- Ice is less dence than water.
- The higher WP implies a greater tendency of water to leave a system. Water will diffuse from a region of less negative (higher) WP to one of more negative (lower) WP.
- Contain carbon, hydrogen, oxygen.
- Two main functions,
- Act as a source of energy for plants + animals.
- To play a structural role in plant cell walls, eg Cellulose.
- Relitivly small molecules, (CH20), building blocks for bigger ones.
- When n= 3 Triose- metabolism.
- When n= 5 Pentose- Nucleic acid.
- When n=6 Hexose- eg glucose, main source of energy.
- Two Monosaccharides linked together.
- Formed by a Glycosidic bond, this eliminates water, this is called a Condensation reaction.
Monosaccharides Disaccaharides Found
- Glucose+Glucose= Maltose: Malt sugar
- Glucose+Fructose= Sucrose: Cane sugar
- Glucose+Galactose= Latose: Milk sugard
- Large complex molecules. Many monosaccharides together.
- 2 types: Starch (plants) and Glycogen ( animals)
- Controles the cells activity and retains chromosomes.
- Bound by a double membrane, the nuclear memebrane (Nuclear envelope) has pores in it to allow transport or mRNA and nucleotides.
- Contains coils of chromatin. The nucleolous makes RNA needed for Ribosomes.
- Double membrane,
- Aerobic respiration occurs here.
- Production of ATP.
- Rough ER and Smooth ER.
- Rough ER has Ribosomes on the out side of it. Transports protiens made by the ribosomes, found in large cells.
- Smooth ER has membranes with less ribosomes. Concerned with the nucleolous.
- 1 large + 1 small sub unit. Made in the nucleolous, from ribosomal RNA and protein. Improtant in protein synthisis.
- Similar to the ER but more compact. Formed by rought ER.
- It is like a packaging center, as it packages and then sends of proteins.
- Small vacuoles are formed when portions of the golgi body are pinched off.
- Contains digestive enzymes.
- Destroy worn out cells.
- Found in animal cells.
- Located outside the nucleous.
The following things are all found in plants.
- Found in photosynthesising tissue.
- They have a double membrane.
- Used to make energy from light energy.
- A large fluid- filled membrane sac, with a single membrane (The tonoplast)
- Contains cell sap.
- Used as structural support for the cell.
Cellulose cell wall
- Cell wall consits of cellulose microfibrils.
- Main functions:
- Provide strenghts+ support
- Permit the movement of water from the cell to cell.
Prokaryote & Eukaryote cells
· No membrane bound organelles.
· Found in plants, animals, fungi and protocists.
· DNA lies free in the cytoplasm.
· Membrane bound organelles.
· No nuclear membrane in ER.
· DNA located in chrosomes.
· Ribosome’s are smaller.
· Distinct membrane bound nucleus.
· Cell wall containing marein.
· Ribosome’s are larger.
Cell wall in plants made of cellulose
Mitosis and Meiosis.
- Mitosis produces two daughter cells geneticaly identical to the parent cell.
- Interphase- Longest part, produces organelles. DNA is doubled during this period.
- Chromosomes condense, to long thin threads.
- The centrioles devide, and move to opposite ends of the cell.
- Protein microtubules form from each centriole and a spindle develops from pole to pole.
- Nuclear membrane distegates and nucleolus disappears.
- Pairs of chromatids can be clearly seen.
- Metaphase-Chromosomes arange themselves at the center of the spindle.
- Anaphase- Rapid stage.
- Centromere splits and spindle fibers contract and pull chromatids to the poles.
- Telophase- The final stage.
- Chromsomes at the poles, they then uncoil and lengthen,
- spindle brakes down,
- centrioles replicate, Nucleoli appears.
- A new cell wall is laid down.
- Two devisons resulting in 4 daughter cells. The number of chromosomes are halved.
- Homologous chromosomes pair up.
- Daughter cells are genetically different.
Meiosis and variation
- Sources of variation are essential.
- Three different ways to create variation.
- Each of the chromosomes carry different genetic material.
- Pairs of homologous chromosomes arrange themselves randomly on the spindle during metaphase.
- Crossing over during chiasmata formation during prophase.+