year 12 biology

Biology

Study of life and living organisms.

Organisms

Are made up of chemical elements and their compounds.

Chemical Elements (List)

Carbon

Organic compounds (Characteristic 1)

Contain carbon.

Organic compounds (Characteristic 2)

Are complex.

Organic compounds (Characteristic 3)

Are produced / associated with living things.

Four major types of organic compounds

Carbohydrates, lipids, proteins and nucleic acids

Macromolecules

Very large organic molecules (macro – large).

Subunits/Monomers

Smaller molecules that make up macromolecules.

Macromolecules (Role 1)

Have vital roles within cells.

Macromolecules (Role 2)

Are used as energy reserves.

Important Macromolecules (Example)

Polysaccharides and lipids.

Carbohydrates (saccharides)

Molecules made of carbon

Monosaccharides and Disaccharides

Relatively small carbohydrate molecules.

Polysaccharides

Very large carbohydrate molecules.

Glucose (Primary Role)

Source of energy.

Starch and Glycogen (Primary Role)

Store of energy.

Cellulose (Primary Role)

Structural component.

Monosaccharides (Simple sugars)

Single sugar units.

Monosaccharides/Disaccharides (Properties)

Have a sweet taste and dissolve in water.

Disaccharides (Simple sugars)

Two monosaccharide units joined together.

Polysaccharides (Complex sugars)

Large molecules composed of 100s or 1000s of simple sugar units (monosaccharides) joined together.

Starch (Composition

Role

Glycogen (Composition

Role

Cellulose (Composition

Role

Chitin (Composition

Role

Starch (Formation)

Excess glucose molecules joined together during photosynthesis.

Starch (Storage Location)

Stored in chloroplasts and the cytoplasm of plants.

Starch (Solubility/Osmosis)

Not soluble in water

Starch (Breakdown)

Broken back down to glucose (hydrolysed) when needed.

Glycogen (Formation)

Excess glucose molecules joined together.

Glycogen (Storage Location)

Mainly in muscle and liver cells

Glycogen (Breakdown)

Converted back (hydrolysed) to glucose when needed.

Cellulose (Function)

Major component of plant cell walls

Cellulose (Physical properties)

Tough

Cellulose (Permeability)

Permeable to water.

Cellulose (Dietary role)

Forms roughage/fibre

Chitin (Specific Location 1)

Forms the exoskeleton structure of insects

Chitin (Specific Location 2)

Forms the cell wall in fungi.

Chitin (Support Role)

Acts as support.

Lipids (Role List)

Energy storage

Energy storage lipids (Triglycerides)

Organic molecules composed of fatty acid chains linked to a glycerol backbone.

Fat (Definition/Storage)

Solid at room temperature

Fat conversion

When food intake is reduced

Oils (Definition/Location)

Liquid at room temperature

Phospholipids (Composition)

Contain a phosphate group and 2 fatty acid chains attached to a glycerol backbone.

Phospholipids (Structural role)

Major component of cell membranes

Phospholipid arrangement in water

Phosphate groups towards water; fatty acid chains towards each other.

Steroids (Examples)

Many animal hormones such as oestrogen and testosterone.

Waxes (Role)

Protective layers in animals and plants.

Cholesterol (Role 1)

Component of animal cell membranes.

Cholesterol (Role 2)

Required for vitamin D synthesis.

Cell Theory (Point 1)

All organisms are made up of one or more cells.

Cell Theory (Point 2)

The cell is the simplest unit of life – the place where all chemical reactions occur.

Cell Theory (Point 3)

All cells are produced from pre-existing cells

Robert Hooke (1665)

Examined cork and used the term ‘cells’.

Antonie van Leeuwenhoek (1675)

Saw tiny animalcules (bacteria).

Mathias Schleiden (1837)

German Botanist who stated all plants are made of cells.

Theodor Schwann (1839)

German physiologist who stated animals were comprised of cells and that the cell is the basic structure of all organisms.

Rudolf Virchow (1855)

German doctor who stated every cell comes from pre-existing cells.

Light Microscopes

Pass a beam of light though a thin section and magnify up to 1500x.

Light Microscope Focusing

Light is focused through lenses

Electron microscopes

Pass a beam of electrons through a vacuum then a thin section

TEM

Transmission Electron Microscope

SEM

Scanning Electron Microscope

Micrometre (μm)

Unit used to measure cells; 1μm is 10−6m

Typical cell size range

10μm – 30μm.

Prokaryote size

1μm.

Eukaryote size

10μm – 100μm.

Nanometre (nm)

Unit used to measure structures within the cell; 1000nm=1μm.

Two basic types of cell organization

Prokaryote and Eukaryote.

Prokaryote example

Bacteria.

Eukaryote examples

Animals

Prokaryote nucleus structure

No separate nucleus.

Eukaryote nucleus structure

Membrane bound nucleus.

Prokaryotic cells (Characteristics)

Small

Prokaryotic DNA

Single

Prokaryotic organelles

No membrane bound organelles.

Prokaryotic ribosomes

Ribosomes found in the cytoplasm

Eukaryotic cells (Characteristics)

Are larger and more complex.

Eukaryotic DNA

Several linear chromosomes

Eukaryotic organelles

Have membrane-bound organelles.

Cell membrane (Composition)

Lipoprotein structure found in all living cells.

Cell membrane (Function)

Semi-permeable barrier that controls entry and exit of materials (nutrients and wastes).

Cell membrane structure (Layers)

Consists of two layers of phospholipid molecules (bi-layer) embedded with proteins.

Fluid Mosaic Model (Developers/Year)

Developed by Singer and Nicolson in 1972.

"Fluid" in Fluid Mosaic Model

The ability of proteins and lipids to move sideways within the structure.

"Mosaic" in Fluid Mosaic Model

The variety of protein molecules embedded/attached to the phospholipid bi-layer.

Proteins (Cell membrane role)

Determine the function of the cell membrane.

Phospholipid arrangement in bilayer

Hydrophobic tails point towards each other; hydrophilic heads are on the surface of the membrane.

Channel & carrier proteins

Span the membrane (pass all the way through) and allow substances to pass through.

Passive transport (Channel/Carrier)

Movement such as diffusion that requires no energy.

Active transport (Channel/Carrier)

Movement that requires energy.

Receptor type proteins (Function)

Involved in cellular communication and recognition of antigens and hormones.

Proteins on underside of membrane

Held in place by the cytoskeleton.

Cytoskeleton (Definition)

An internal framework of microtubules

Cytoskeleton attachment

Attached to the cell membrane.

Cytoskeleton Function 1

Gives cells shape and enables them to change shape.

Cytoskeleton Function 2

Anchors and moves organelles in and through cytoplasm.

Cytoskeleton Function 3

Involved in cell movement.