Definitions:Topic 3 Flashcards
What is a light microscope(optical microscope)?
A tool that uses a beam of light and optical lenses to magnify specimens up to 1500 times life size.
Define magnification.
A measure of how much bigger the image you see is than the real object.
What is an electron microscope?
A tool that uses a beam of electrons and magnetic lenses to magnify specimens up to 500 000 times life size
Define resolution(resolving power).
A measure of how close together two objects must be before they are seen as one.
What are artefacts?
Things observed in a scientific investigation that are not naturally present; they occur as a result of the preparation or investigation
What is a graticule?
A series of lines in the eyepiece of a microscope which help you measure specimens accurately.
What is a transmission electron micrograph(TEM)?
Micrographs produced by the electron microscope that give 2D images like those from a light microscope, but magnified up to 500 000 times.
What is a scanning electron micrograph(SEM)?
Micrographs produced by the electron microscope that have a lower magnification than TEMs, but produce a 3D image.
Define cytoplasm.
A jelly-like liquid that makes up the bulk of the cell and contains the organelles
Define the term ‘nucleus’.
An organelle containing the nucleic acids DNA (the genetic material) and RNA, as well as protein, surrounded by a double nuclear membrane with pores
Define protoplasm.
The cytoplasm and nucleus combined
Define the term ‘ultrastructure.’
The detailed organisation of the cell, only visible using the electron microscope
Define the term ‘intracellular’.
Inside the cell
Define the term ‘chromatin.’
The granular combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing
What is a nucleolus?
An extra-dense region of almost pure DNA and protein found in the nucleus; it is involved in the production of ribosomes and control of growth and division
Define the term ‘mitochondria’.
Rod-like structures with inner and outer membranes that are the site of aerobic respiration
Define the term ‘cristae’.
The infoldings of the inner membrane of the mitochondria which provide a large surface area for the reactions of aerobic
respiration
Define the term ‘eubacteria’.
True bacteria(prokaryotic organisms)
Define the term ‘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
What is a spindle?
A set of overlapping protein microtubules running the length of
the cell, formed as the centrioles pull apart in mitosis and meiosis
What are 80S ribosomes?
The main type of ribosome found in eukaryotic cells, consisting of ribosomal RNA and protein, made up of a 60S and 40S subunit; they are the site of protein synthesis
What are 70S ribosomes?
The ribosomes found in the mitochondria and chloroplasts of eukaryotic cells and in prokaryotic organisms
Define the embosymbiotic theory.
A theory that suggests mitochondria and
chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts
What are lysosomes?
Organelles full of digestive enzymes used to break down worn-out cells or organelles or digest food in simple organisms
Define apoptosis(programmed cell death).
The breakdown of worn-out, damaged or diseased cells by the lysosomes
What is the endoplasmic reticulum(ER)?
A 3D network of membrane-bound
cavities in the cytoplasm that links to the nuclear membrane and makes up a large part of the cellular transport system as well as playing an important role in the synthesis of many different chemical substances
What is the rough endoplasmic reticulum(RER)?
Endoplasmic reticulum that is covered in 80S ribosomes and which is involved in the production and transport of proteins
Define exocytosis.
The movement of large molecules out of cells by the fusing of a vesicle containing the molecules with the surface cell
membrane; the process requires ATP
What is the smooth endoplasmic reticulum(SER)?
A 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
What is the Golgi apparatus?
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
