B1 Cell Biology Flashcards
What are the differences between light and electron microscopes?
Light - cheap to make, outlines of cells can be seen.
electron - see finer details including organelles. Higher resolution, resolving power.
Equation of Magnification
Magnification = image size / real cell size
how to convert from micrometres to millimetres
divide by 1000
Eukaryotic cells (characteristics)
nucleus which stores genetic material, cell membrane (semi-permeable), cell wall, cytoplasm, mitochondria, ribosomes, chloroplasts, permanent vacuole.
Prokaryotic cells (characteristics)
Plasmid (loop of DNA) stores genetic material, flagella, ribosomes, cell membrane.
how do bacteria reproduce?
Binary fission - divide every 10 mins.
how many chromosomes do humans have?
23 pairs (46). Chromosomes are DIPLOID.
How many chromosomes have gametes got?
23 chromosomes. These are HAPLOID.
What is mitosis?
Mitosis occurs for growth and repair of cells
How does mitosis occur?
- Nucleus dissolves, and genetic material is duplicated.
- The two sets of chromosomes move to different sides.
- Mitochondria, ribosomes and other organelles are duplicated.
- The cell divides, producing two genetically identical diploid cells (daughter cells)
What are examples of specialised cells?
muscle cells, nerve cells, root hair cells, xylem and Phloem, sperm cells.
What are stem cells?
stem cells are cells which have not yet specialised for a specific function. They are found in animal embryos and plant meristems.
where are stem cells made in humans?
bone marrow but these can only specialise into blood cells.
What are embryo clones?
can be made of a person to harvest stem cells from. These can be used to treat conditions without them being rejected by the patient.
What is diffusion?
The movement of particles from an area of high concentration to low concentration down the conc gradient. This is passive.