Cell Biology - P1T1

Active transport

The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration.

Adult stem cell

A type of stem cell that can form many types of cells.

Agar jelly

A substance placed in petri dishes which is used to culture microorganisms on.

Cell differentiation

The process where a cell becomes specialised to its function.

Cell membrane

A partially permeable barrier that surrounds the cell.

Cell wall

An outer layer made of cellulose that strengthens plant cells.

Chloroplast

An organelle which is the site of photosynthesis.

Chromosomes

DNA structures that are found in the nucleus which are made up of genes.

Concentration gradient

The difference in concentration between two areas.

Diffusion

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Embryonic stem cell

A type of stem cell that can differentiate into most types of human cells.

Eukaryotic cell

A type of cell found in plants and animals that contains a nucleus.

Magnification

How much bigger an image appears compared to the original object.

Meristematic cells

A type of stem cell that can differentiate into any type of plant cell.

Mitochondria

An organelle which is the site of respiration.

Mitosis

A type of cell division which produces two genetically identical daughter cells from one parent cell.

Nucleus

An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell.

Organelle

A specialised structure found inside a cell.

Osmosis

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Plasmid

Loops of DNA found in the cytoplasm of prokaryotic cells.

Prokaryotic cell

A type of cell found in bacteria that does not contain a nucleus.

Resolution

The ability to distinguish two different points in a specimen.

Specialised cells

Cells that are adapted to perform a specific function.

Stem cell

An undifferentiated cell that can divide to produce many specialised cells of the same type.

Surface area

The amount of contact an object has with its environment.

Surface area to volume ratio (SA:V)

The size of the object compared with the amount of area where it contacts its environment.

The cell cycle

A series of stages preparing the cell for division.

Therapeutic cloning

Producing an embryo that has the same genes as a patient.

Vacuole

An organelle that stores cell sap.

Light Microscope

Uses light and lenses to form an image; used to see cells and large organelles.

Electron Microscope

Uses electrons for higher resolution and magnification; used to see ultrastructure like ribosomes and mitochondria.

Transmission Electron Microscope (TEM)

Gives 2D images; very high resolution.

Scanning Electron Microscope (SEM)

Gives 3D images; lower resolution than TEM.

Magnification

How much larger the image is than the actual object.

Resolution

The ability to distinguish between two points; higher resolution shows more detail.

Magnification Formula

Magnification = Image Size ÷ Real Size

Millimetre (mm)

1 mm = 1000 micrometres (µm).

Micrometre (µm)

1 µm = 1000 nanometres (nm).

Nanometre (nm)

Used to measure extremely small structures like molecules.

Preparing Slides

Place specimen on slide, add stain, cover with coverslip.

Staining

Makes cell parts more visible under microscope (e.g. methylene blue, iodine).

Focusing Microscope

Start with low-power lens, focus, then switch to higher magnification.

Advantages of Light Microscope

Can view living cells; cheaper and easier to use.

Advantages of Electron Microscope

Much higher magnification and resolution; can see internal structures.

Limitations of Light Microscope

Lower resolution and magnification than electron microscopes.

Limitations of Electron Microscope

Very expensive; specimen must be dead; requires training to use.