- cell
- The basic unit of all living organisms; it is surrounded by a cell surface membrane and contains genetic material (DNA) and cytoplasm containing organelles.
Ch 01- organelle
- A functionally and structurally distinct part of a cell, e.g. a ribosome or mitochondrion.
Ch 01- nucleus
- A relatively large organelle found in eukaryotic cells, but absent from prokaryotic cells; the nucleus contains the cell’s DNA and therefore controls the activities of the cell; it is surrounded by two membranes which together form the nuclear envelope.
Ch 01- eukaryote
- An organism whose cells contain a nucleus and other membrane-bound organelles.
Ch 01- prokaryote
- An organism whose cells do not contain a nucleus or any other membrane-bound organelles.
Ch 01- cell surface membrane
- A very thin membrane (about 7 nm diameter) surrounding all cells; it is partially permeable and controls the exchange of materials between the cell and its environment.
Ch 01- chromatin
- The material of which chromosomes are made, consisting of DNA, proteins and small amounts of RNA; visible as patches or fibres within the nucleus when stained.
Ch 01- chromosome
- In the nucleus of the cells of eukaryotes, a structure made of tightly coiled chromatin (DNA, proteins and RNA) visible during cell division; the term ‘circular DNA’ is now also commonly used for the circular strand of DNA present in a prokaryotic cell.
Ch 01- nucleolus
- A small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA.
Ch 01- protoplasm
- All the living material inside a cell (cytoplasm plus nucleus).
Ch 01- cytoplasm
- The contents of a cell, excluding the nucleus.
Ch 01- mitochondrion
- The organelle in eukaryotes in which aerobic respiration takes place.
Ch 01- cell wall
- A wall surrounding prokaryote, plant and fungal cells; the wall contains a strengthening material which protects the cell from mechanical damage, supports it and prevents it from bursting by osmosis if the cell is surrounded by a solution with a higher water potential.
Ch 01- plasmodesma
- A pore-like structure found in plant cell walls; plasmodesmata of neighbouring plant cells line up to form tube-like pores through the cell walls, allowing the controlled passage of materials from one cell to the other; the pores contain ER and are lined with the cell surface membrane.
Ch 01- vacuole
- An organelle found in eukaryotic cells; a large, permanent central vacuole is a typical feature of plant cells, where it has a variety of functions, including storage of biochemicals such as salts, sugars and waste products; temporary vacuoles, such as phagocytic vacuoles (also known as phagocytic vesicles), may form in animal cells.
Ch 01- tonoplast
- The partially permeable membrane that surrounds plant vacuoles.
Ch 01- chloroplast
- An organelle, bounded by an envelope (i.e. two membranes), in which photosynthesis takes place in eukaryotes.
Ch 01- photosynthesis
- The production of organic substances from inorganic ones, using energy from light.
Ch 01- grana
- Stacks of membranes inside a chloroplast.
Ch 01- magnification
- The number of times larger an image of an object is than the real size of the object; magnification = image size ÷ actual (real) size of the object.
Ch 01- eyepiece graticule
- Small scale that is placed in a microscope eyepiece.
Ch 01- resolution
- The ability to distinguish between two objects very close together; the higher the resolution of an image, the greater the detail that can be seen.
Ch 01- stage micrometer
- Very small, accurately drawn scale of known dimensions, engraved on a microscope slide.
Ch 01- micrograph
- A picture taken with the aid of a microscope; a photomicrograph (or light micrograph) is taken using a light microscope; an electron micrograph is taken using an electron microscope.
Ch 01- nuclear envelope
- The two membranes, situated close together, that surround the nucleus; the envelope is perforated with nuclear pores.
Ch 01- nuclear pores
- Pores found in the nuclear envelope which control the exchange of materials, e.g. mRNA, between the nucleus and the cytoplasm.
Ch 01- endoplasmic reticulum (ER)
- A network of flattened sacs running through the cytoplasm of eukaryotic cells; molecules, particularly proteins, can be transported through the cell inside the sacs separate from the rest of the cytoplasm; ER is continuous with the outer membrane of the nuclear envelope.
Ch 01- ribosome
- A tiny organelle found in large numbers in all cells; prokaryotic ribosomes are about 20 nm in diameter while eukaryotic ribosomes are about 25 nm in diameter.
Ch 01- Golgi apparatus (Golgi body, Golgi complex)
- An organelle found in eukaryotic cells; the Golgi apparatus consists of a stack of flattened sacs, constantly forming at one end and breaking up into Golgi vesicles at the other end.
Ch 01- Golgi vesicles
- Carry their contents to other parts of the cell, often to the cell surface membrane for secretion; the Golgi apparatus chemically modifies the molecules it transports, e.g. sugars may be added to proteins to make glycoproteins.
Ch 01- lysosome
- A spherical organelle found in eukaryotic cells; it contains digestive (hydrolytic) enzymes and has a variety of destructive functions, such as removal of old cell organelles.
Ch 01- cristae
- Folds of the inner membrane of the mitochondrial envelope on which are found stalked particles of ATP synthase and electron transport chains associated with aerobic respiration.
Ch 01- ATP (adenosine triphosphate)
- The molecule that is the universal energy currency in all living cells; the purpose of respiration is to make ATP.
Ch 01- ADP (adenosine diphosphate)
- The molecule that is converted to ATP by addition of phosphate (a reaction known as phosphorylation) during cell respiration; the enzyme responsible is ATP synthase; the reaction requires energy.
Ch 01- microtubules
- Tiny tubes made of a protein called tubulin and found in most eukaryotic cells; microtubules have a large variety of functions, including cell support and determining cell shape; the ‘spindle’ on which chromatids and chromosomes separate during nuclear division is made of microtubules.
Ch 01- centriole
- One of two small, cylindrical structures, made from microtubules, found just outside the nucleus in animal cells, in a region known as the centrosome; they are also found at the bases of cilia and flagella.
Ch 01- centrosome
- The main microtubule organising centre (MTOC) in animal cells.
Ch 01- cilia
- Whip-like structures projecting from the surface of many animal cells and the cells of many unicellular organisms; they beat, causing locomotion or the movement of fluid across the cell surface.
Ch 01- flagella
- Whip-like structures projecting from the surface of some animal cells and the cells of many unicellular organisms; they beat, causing locomotion or the movement of fluid across the cell surface; they are identical in structure to cilia, but longer.
Ch 01- thylakoid
- A flattened, membrane-bound, fluid-filled sac which is the site of the light-dependent reactions of photosynthesis in a chloroplast.
Ch 01- bacteria
- A group of single-celled prokaryotic microorganisms; they have a number of characteristics, such as the ability to form spores, which distinguish them from the other group of prokaryotes known as Archaea.
Ch 01- peptidoglycan
- A polysaccharide combined with amino acids; it is also known as murein; it makes the bacterial cell wall more rigid.
Ch 01- plasmid
- A small circular piece of DNA in a bacterium (not its main chromosome); plasmids often contain genes that provide resistance to antibiotics.
Ch 01- virus
- A very small (20–300 nm) infectious particle which can replicate only inside living cells; it consists of a molecule of DNA or RNA (the genome) surrounded by a protein coat; an outer lipid envelope may also be present.
Ch 01- phospholipid
- A lipid to which phosphate is added; the molecule is made up of a glycerol molecule, two fatty acids and a phosphate group; a double layer (a bilayer) of phospholipids forms the basic structure of all cell membranes.
Ch 01
