Topic 3A.2 Eukaryotic Cells I

cytoplasm

a jelly-like liquid that makes up the bulk of the cell and contains organelles

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

protoplasm

the cytoplasm and nucleus combined

ultrastructure

the detailed organisation of the cell, only visible using the electron microscope

intracellular

inside the cell

chromatin

the granular combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing

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

mitochondria

rod-like structures with inner and outer membranes that are the site of aerobic respiration

cristae

the infoldings of the inner membrane of the mitochondria which provides a large surface area for the reactions of aerobic respiration

eubacteria

true bacteria (prokaryotic organisms)

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

a set of overlapping protein microtubules running the length of the cell, formed as the centrioles pull apart in mitosis and meiosis

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

70S ribosomes

the ribosomes found in the mitochondria and chloroplasts of eukaryotic cells and in prokaryotic cells

endosymbiotic theory

a theory that suggests mitochondria and chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts

lysosomes

organelles 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