Cell organelles and their functions

key definititions + labelled diagrams

cell

the basic unit of a living organism composed of organelles suspended in a cytoplasm with a cell membrane surrounding it

structure of a eukaryotic animal cell (labelled diagram)

structure of a eukaryotic plant cell (labelled diagram)

structure of a prokaryotic cell (labelled diagram)

function of the nucleus

contains chromosomes and nucleolus. chromosomes are made up of DNA, which contains genes and controls the synthesis of proteins

function of the nucleolus

dense body within the nucleolus where ribosomes are synthesised

function of the nuclear envelope

made of two membranes perforated by pores that allow mRNA to pass through

function of mitochondria

two membranes, the inner one is folded to form the cristae- site of the later stages of aerobic respiration

function of ribosomes

the site of protein synthesis

function of the rough endoplastic reticulum

system of interconnected membrane-bound sacs with attatched ribosomes. polypeptide chains formed on these ribosomes pass through the rough ER and assume secondary or tertiary structure

function of the golgi apparatus

flat membrane-bound sacs involved in modifying proteins and packaging them into vesicles for transport

function of a lysosome

sacs containing digestive enzyme that carry out the breakdown of unwanted substances in the cell

function of the centrioles

hollow cylinders made of protein microtubules, involved in formation of the spindle during nuclear division

function of the cell surface membrane

phospholipid bilayer containing proteins, is responsible for entry and exit of substances in and out of a cell and is the site of cell communication via receptors

function of a chloroplast

site of photosynthesis

function of an amyloplast

stores starch

function of a tonoplast

membrane surrounding the vacuole that seperates its contents from that of the cytoplasm

function of a plasmodesmata

channels between plant cells that allow the transfer of substances between adjacent cells

function of the cell wall (plant)

provides support and mechanical strength- made of cellulose

function of a vacuole

maintains cell structure and acts as a temporary energy store

function of a mesosome

infolding of cell surface membrane- suspected site of respiration

function of a plasmid

small circle of DNA

function of a capsule

slimy layer on surface for protections and to prevent dehydration

function of the pili

thin protein tubes that allow the bacteria to adhere to surfaces

function of the cell wall (bacterial)

made of peptidoglycan- can be gram positive (no outer membrane nor periplasmic space and suseptable to peniciillin) or gram negative (thinner peptidoglycan wall, contains outer membrane, periplasmic space, murein proteins and exotoxins that block antibiotics)

function of a flagellum

hollow cylindrical thread-like structure that rotates to move the cell

function of circular DNA

contains genes that control cell activity