Combined science: Biology-Section 1

Cells can either be eukaryotic or prokaryotic.

Eukaryotic: complex cells

Prokaryotic: Single cell organism

An animal cell contains:

• Nucleus: Contains genetic materials
• Cell Membrane: Holds the cell together+controls what goes in and out
• Cytoplasm: Where chemical reactions happen
• Ribosome: Where proteins are made
• Mitochondria: Where areobic respiration happens

Plant cell contains the same things as animal cells but also contains:

• Cell wall: Made of cellulose+supports and strenthens the cell
• Chloroplast: Contains green substance(chlorophyll)+where photosynthesis occurs
• Vacuole: Contains cell sap

Differentiation: Process by which a cell changes to become specialised for its job.

Most differentiation happens when an organism develops. Cells that differentiate in mature animals are usually for repairing and replacing cells.

Examples of specialised cells:

• Sperm cell: Specialised for reproduction + Tail and streamlined head to help it swim + lots of mitrochondia for energy.
• Nerve cell: Specialised for rapid signaling + Long cells to cover mor distance and have branched connections.
• Muscle cells: Specialised for contractions + Long cells for space + lots of mitrochondria for energy.
• Root hair cells: Specialised for absorbing water and minerals + Large surface area to absorb water and minerals from the soil.
• Xylem and Phloem cells: Specialised for transporting substances.
• Xylem: Hollow so stuff can flow through them.
• Phloem: Have a few subcellular structures so stuff can flow through them.

Microscopes lets us see things we cannot see with a naked eye.

There are two types of microscopes:

• Light microscopes: Uses light and lenses to magnify and form an image.
• Electron microscope: Uses electrons to magnify and form an image.

Formula for magnification: Magnification= Image size/Real size

Osmosis is like diffusion but with water particles instead.

However it contains a semi-permeable membrane.

Osmosis: The movement of water molecules across a semi-permeable from a region at higher water concentration to a region of low water concentration.

Semi-permeable membrane: A membrane with small holes in which only small molecules can pass through them but not large molecules.

Osmosis can happen both ways.

Diffusion happens both in both solutions and gases.

Diffusion: The spreading out of particles from an area of higher concentration to an area of lower concentration.

The bigger the concentration gradient, the faster the diffusion rate.

Concentration gradient: The difference in concentration.

Diffusion rate: How quick diffusion happens.

Enzymes are biological catalysts which are produced by living things. Enzymes reduce the need for high tempreture and we only have enzymes to speed up useful chemical reactions.

Catalysts: A substance which increases the speed of reaction, without being changed or used up in the reaction.

Enzymes have an active site with a unique shape that fit onto a substance. Enzymes usually only catalste one specific reaction: The lock and key.

Both tempreture and pH affects enzymes. All enzymes have an optimum tempreture and optimum pH.

Optimum tempreture: The tempreture where the enzymes work best at.

Optimum pH: The pH where the enzymes work best at.

What happens if the tempreture or the pH is too high or too low?

If the tempreture or pH is too high or too low then the enzymes get denatured.

Digestive enzymes break down large molecules into smaller, soluble molecules, so they can be absorbed into the bloodstream.

Carbohydrates convert carbohydrates into simple sugars.

Amylase is a carbohydrate but what does it break down?

Starch---amylase/enzyme---Maltose.

Where is amylase found?

• Salivary gland
• Pancreas
• Small intestines

What does protease convert protein into?

Proteins---protease/enzymes---Amino acids

Where is protease found?

• Stomach (Pepsin)
• Pancreas
• Small intestines

What does lipases convert lipids into?

Lipid---lipase/enzymes---Glycerol + Fatty acids

Where is lipase found?

• Pancreas
• Small intestines

Bile is produced in the liver.

Where is bile stored?

Bile is stored in the gall bladder before it is released into the small intestines.

The pH of the hydrochloric acid is too acidic for the enzymes to work in. The bile neutralises the acid and makes it more alkaline and the enzymes can work better. 

What else does the bile do?

Bile also emulsifies fatso they can have a big surface area which makes digestion faster.