Question | Answer |
what are all organisms composed of? | cells |
what are all cells surrounded by and why? | a partially permeable membrane to control exchange between the cell and its environment |
what do animal and plant cells have in common? | cell surface membrane, cytoplasm containing mitochondria, ER, golgi apparatus, lysosomes and ribosomes, and a nucleus with a nucleolus and chromatin |
what types of cell have centrioles? | animal |
what do only plant cells have? | a rigid cell wall
chloroplasts
large vacuole |
why are some structures not visible with light microscopes? | the limit of resolution allowed by the use of light waves |
what can be viewed with an electron microscope? | dead material |
most biological material needs to be ...... to be seen clearly under a microscope | stained |
how do stains work? | the stains bind to specific chemicals or cell structures |
cells contain a network of fibres called ....... called the ........ | protein
cytoskeleton |
what does the cytoskeleton allow? | to keep the cells shape stable, and allow it to move through a liquid and ove organelles around inside the cell |
what does the production of protein involve? | an inter-relationship between the nucleus, rough er, vesicles and the golgi apparatus |
what is the difference between eukaryotic cells and prokaryotic cells? | prokaryotic cells are smaller, have free dna in the cytoplasm, no er, no nucleus, few organelles and smaller ribosomes |
what is resolution? | the ability to see two distinct points seperately |
what are most light microscopes capable of in magnification? | X1500 |
what is the resolution for a light microscope? | 200nm |
what is the resolution of a electron microscope? | 0.1nm |
what is the magnification of an electron microscope? | 100,000 with SEM
500,000 with TEM |
what type of microscope produces 3d images? | scanning electron microscope |
what is the structure of the nucleus? | large, darker patches of chromatin, surrounded by the nuclear envelope, and a large dense area called the nucleolus inside the nucleus |
what is the structure of the nuclear envelope? | two membranes with fluid inbetween and lots of pores |
what is the function of the nucleus? | houses all the cells genetic material. The chromatin consists of DNA and proteins. The nucleolus makes RNA and ribosomes which are passed into the cytoplasm |
what is the structure of endoplasmic reticulum? | a series of flattened membrane bound sacs called cristernae. rough er is studded with ribosomes |
what is the function of ER? | rough er transports proteins.
smooth er makes lipids |
what is the structure of the golgi apparatus? | a stack of membrane bound flattened sacs |
what is the function of the golgi apparatus? | recieves proteins from the er and modifies them, and then packs them into vesicles to be transported |
what is the structure of mitochondria? | spherical or sausage shaped, two membranes seperated by a fluid filled space. inner membrane is slightly folded to form critae. central part is called the matrix |
what is the function of mitochondria? | the site where ATP is produced |
what is the structure of chloroplasts? | only in plant cells
two membranes seperated by a fluid filled space. the inner membrane is continuous with a network of flattened sacs called thylakoids. |
what is the function of chloroplasts? | the site of photosynthesis. |
what is the structure of lysosomes? | spherical sacs surrounded by a single membrane |
what is the function of lysosomes? | contain powerful digestive enzymes which break down materials, eg the head of a sperm cell helps is penetrate the egg by breaking down the material surrounding the egg |
what is the structure of ribosomes? | tiny organelles. some in cytoplasm and some bound to ER |
what is the function of ribosomes? | the site of protein synthesis in the cell. act as an assembly line where mRNA from the nucleus is used to assemble proteins from amino acids |
what si the structure of centrioles? | small tubes of protein fibres |
what is the function of centrioles? | take part in cell division, they dorm fibres which move chromosomes during nuclear division |