B1 - Cells Flashcards
What is the equation for MAGNIFICATION?
Magnification = image size / object (size) image
What are LIGHT MICROSCOPES?
Light microscopes are cheap to make - allow you to see the outlines of cells.
What are ELECTRON MICROSCOPES?
Electron microscopes allow you to visualise finer details including organelles due to their greater resolving power and higher resolution.
What do EUKARYOTIC CELLS have?
Nucleus
Mitochondria
Ribosomes
Cell wall
Cell membrane
Chloroplasts
Cytoplasm
PLANT CELLS contain a Permanent Vacuole.
What are examples of EUKARYOTIC CELLS?
Animal/plant cells.
What does a PROKARYOTIC CELL contain?
Contains a plasmid (loop of DNA)
Example of a PROKARYOTIC CELL
Bacterial cells
Process of MITOSIS
- Nucleus dissolves, genetic material is duplicated - 2 sets of chromosomes move to each side of the cell.
- Mitochondria, ribosomes and other organelles are duplicated.
- The cell divides, producing 2 genetically identical diploid cells (daughter cells) - new nuclei are formed.
Where are STEM CELLS found and why do they SPECIALISE?
Found in animal embryos and plant meristems.
Some stem cells are made in the bone marrow but these can only specialise into blood cells.
Stem cells specialise to perform specific functions.
What are EMBRYO CLONES used for?
Embryo clones can be made of a person to harvest the stem cells which can be used to treat medical conditions as they won’t reject in the patient’s body.
CLONING can also be utilised to preserve species or to obtain plants with desired traits.
What is DIFFUSION?
DIFFUSION is the movement of particles from a high concentration to a low concentration.
This is passive - no energy is required.
What is OSMOSIS?
OSMOSIS is the diffusion of water across a semi-permeable membrane to balance the concentrations of a solution, inside and outside of the cell.
Water must be moved as larger molecules cannot fit through the holes - if concentration is higher outside, water moves in.
How can the RATE of OSMOSIS and DIFFUSION be INCREASED?
Can be increased by increasing the: difference in concentrations, surface area and temperature.
Describe the OSMOSIS practical
- Weigh and place identical cylinders of same vegetable into a test tube with different concentrations of a sugar solution.
- After set time, remove excess water and weigh again. Calculate percentage change in mass by,
final mass - initial mass / initial mass x 100 - Plot percentage change in mass against conc. , conc. at 0% change in mass is the same as inside of the vegetable.
What is ACTIVE TRANSPORT?
ACTIVE TRANSPORT is the movement of particles through a membrane via carrier proteins. This requires energy, and so can move against the conc. gradient.
