- Created by: puddlerevise
- Created on: 10-12-19 17:35
* As an Organisim develops, Cells differentiate to form different types of cells.
* As an animal cell differetiates to form a specailised cell it acquires different sub- cellular structures to enable it to carry out a function.
* Examples of specailised animal cells are nerve cells, muscle cells and sperm cells. * Animal cells may be specailsed to function within a tissue, an organ, organ systems or whole organisms.
* Animal cell feautures common to all cells - a nucleus, cytoplasam, cell membrane, mitochondria and ribosomes.
*Plant and agal cells contain all the structures seen in animal cells as well as a cellulouse wall.
*Many plant cells also contain chloroplasts and a permanent vacuole filled with sap.
* Eukaryotic cells all have a cell membrane, cytoplasam, and genetic material enclosed in a nucleus.
* Prokaryotic cells consist of cytoplasam and a cell membrane surrounded by a cell wall. the genetic material is not in a distinct nucleus. It forms a single DNA loop. Prokaryotes may contain one or more extra small rings of DNA called plasmids.
* Bacteria are all prokaryotes
* Plant cells may be specailised to carry out a particular function.
* Examples of specailsed plant cells are root hair cells, xylem cells, and pholem cells.
* Plant cells may be specialised to functionwithin tissues, organs, organ systems or whole organisims.
* Diffusion is the spreading out of particles of any substance, in a solution or gas, resulting in net movement from an area of lower concentration, down a concentration gradient.
* The rate of diffusion is affected by the difference in concentrations, the temprature, and the avalible sureface area.
* Dissolved substances such as glucose and urea gases such as oxygen and carbon dioxide move in and out of cells by diffusion.
* Osmosis is a special case of diffusion. it is the movement of water from a dilute to a more concentrated solute solution through a partially permable membrane that allows water to pass through.
* Differences in concentrations of solutions inside and outside a cell cause water to move into or out of the cell by osmosis.
* Animal cells can be damaged if the concentration outside the cell changes dramatically.
*Osmosis is important to maintain turgor in cells.
*There are a variety of investigations that can be used to show the affect of osmosis on plant tissue.
*Scientists have discovered ways of mesuring the turgour pressure inside cells by using very tiny probes.
* Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient.)
* Active transport uses engergy released from food in respiration to provide the energy required.
* Active transport allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentaration gradient.
* Active transport allows sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher.
* Single celled organisms have a relatively large surface area to volume ratio so all necassary exchanges with the enviroment take place over this surface.
* In multicellular organisims, many organisims are specialised with effective exchange surfaces.
* Exchange surfaces usally have a large surface area and thin walls, which give short diffusion distances. In animals,exchange surfaces will have an efficent blood supply or, for gaseous exchange, be ventitalted.