2.1. Eukaryotic cells - Key words Flashcards
Light microscope
Tool that uses a beam of light and optical lenses to magnify specimens up to 1500 times life size
Electron microscope
Tool that uses a beam of e- & magnetic lenses to magnify specimens up to 500k times life size
Magnification
Measure of how much bigger the image you see is than the real object
Resolution
Measure of how close together two objects can be before they’re seen as one
Transmission electron micrographs (TEMs)
Micrographs produced by the e- microscope that give 2D images like those from a light microscope, but magnified up to 500k times
Scanning e- micrographs (SEMs)
Micrographs produced by the e- microscope that have a lower magnification than TEMs, but produce a 3D image
Organelles
Sub-cellular bodies found in the cytoplasm of cells
Eukaryotes
Group of organisms with cells that have the genetic material contained in a membrane-bound nucleus and also contain a number of membrane-bound organelles such as mitochondria and chloroplasts
Prokaryotes
Group of organisms including bacteria and blue-green algae that have a few organelles and do not have the genetic material contained in a membrane-bound nucleus
Cell surface membrane
Membrane that forms the outer boundary of the cytoplasm of a cell and controls the movement of substances into and out of the cell
Vesicles
Membrane “bags” that hold secretions made in cells
Polar lipids
Lipids with one end attached to a polar group
Gated channels
Protein channels through the lipid bilayer of a membrane that are opened or closed, depending on conditions in the cell
Fluid mosaic model
Current model of the structure of the cell membrane including floating proteins forming pores, channels and carrier systems in a lipid bilayer
Cytoplasm
Jelly-life liquid that makes up the bulk of the cell and contains the organelles
Nucleus
Organelle containing the nucleic acids DNA and RNA, as well as protein, surrounded by a nuclear envelope with pores
Protoplasm
Cytoplasm and nucleus combined
Ultrastructure
Detailed organisation of the cell, only visible using the e- microscope.
Intracellular
Inside a cell
Chromatin
Granular combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing
Nucleolus
Extra dense area of almost pure DNA and protein found in the nucleus involved in the production of ribosomes and control of growth and cell division
Mitochondria
Rod-like structures with inner and outer membranes that are the site of aerobic respiration
Cristae
Infoldings of the inner membrane of the mitochondria which provide a large surface area for the reactions of aerobic respiration
Eubacteria
True bacteria (prokaryotic organisms)
Endosymbiotic theory
Theory that suggests that mitochondria and chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts
Centrioles
Bundles of tubules found near the nucleus and involved in cell division by the production of a spindle of microtubules that move the chromosomes to the ends of the cell
Spindle
Set of overlapping protein microtubules running the length of the cell, formed as the centrioles pull apart in mitosis and meiosis
Cytoskeleton
Dynamic, 3D web-like structure made up of microfilaments and microtubules that fills the cytoplasm and gives it structure, keeping the organelles in place and enabling cell movements and transport within the cell
Microfilaments
Protein fibres that make up part of the structure of the cytoskeleton
Microtubules
Tiny protein tubes about 20 nm in diameter that make up part of the structure of the cytoskeleton
Vacuole
Fluid-filled cavity within the cytoplasm of a cell surrounded by a membrane
Contractile vacuoles
Vacuoles that can fill and empty to hep control the concentration of the cytoplasm of simple freshwater animals
Endoplasmic reticulum
3D network of membrane-bound cavities in the cytoplasm that links to the nuclear membrane and makes up large part of the cellular transport system as well as playing an important role in the synthesis of many different chemicals
80S ribosomes
Main type of ribosome found in eukaryotic cells, consisting of rRNA and protein, made up of a 60S and 40S subunit. They are the site of protein synthesis
70S ribosomes
Found in the mitochondria and chloroplasts of eukaryotic cells and in prokaryotic organisms
Rough endoplasmic reticulum (RER)
Endoplasmic reticulum that is covered in 80S ribosomes and which is involved in the production and transport of proteins
Exocytosis
Energy-requiring process by which a vesicle fuses with the cell surface membrane so the contents are released to the outside of the cell
Smooth endoplasmic reticulum (SER)
Smooth tubular structure similar to RER, but without the ribosomes, which is involved in the synthesis and transport of steroids and lipids in the cell
Golgi apparatus
Consists of stacks of membranes that modify proteins made elsewhere in the cell and package them into vesicles for transport, and also produce materials for plant cell walls and insect cuticles
Lysosome
Organelle full of digestive enzymes used to break down worn out cells or organelles, or digest food in simple organisms
Apoptosis
Programmed cell death - the breakdown of worn out, damaged or diseased cells by the lysosomes
Cell wall
Freely permeable wall around plan cells, made mainly of cellulose
Suberin
Chemical that impregnates cellulose cell walls in cork tissues and makes them impermeable
Lignin
Chemical that impregnates cellulose walls in wood and makes it impermeable
Middle lamella
First layer of the plant cell walls to formed when a plant cell divides, made mainly of calcium pectate that binds the layers of cellulose together
Pectin
Polysaccharide that holds cell walls of neighbouring plant cells together and is part of the structure of the primary cell wall
Primary cell wall
First very flexible plant cell wall to form, with all the cellulose microfibrils orientated in a similar direction
Secondary cell wall
Older plant cell in which the cellulose microfibrils have built up at different angles to each other making the cell wall more rigid
Plant fibres
Long cells with cellulose cell walls that have been heavily lignified so they are rigid and very strong
Plasmodesmata
Cytoplasmic bridges between plant cells that allow communication between the cells
Symplast
Interconnected cytoplasm of plant cells, connected by plasmodesmata
Tonoplast
Specialised membrane that surrounds the permanent vacuole in plant cells and controls movements of substances into and out of the cell sap
Cell sap
Aq solution that fills the permanent vacuole
Osmosis
Specialised form of diffusion that involves the movement of solvent molecules down a concentration gradient through a partially permeable membrane
Chloroplast
Organelle adapted to carry out photosynthesis, containing the green pigment chlorophyll
Chlorophyll
Green pigment that is largely responsible for trapping the energy from light, making it available for the plant to use in photosynthesis
Amyloplasts
Plant organelles that store starch
Tissue
Group of specialised cells carrying out a particular function in the body
Organ
Structure made up of several different types of tissues grouped together to carry out a particular function in the body
Epithelial tissue
Tissues that form the lining of surfaces inside and outside the body
Organ system
A group of organs working together to carry out particular functions in the body
