Cells And Organelles Flashcards
What are organelles
Organelles are structurally distinct from each other and have specific functions
What is the nucleus surrounded by
A double membrane or an envelope
What is the largest organelle
The nucleus
What is the outer membrane in terms with the rough endoplasmic reticulum
The outer membrane is continuous with the rough endoplasmic reticulum
What are the pores in the nuclear envelope for
They let mRNA and ribosomes out and nutrients and hormones in
In the nucleus what are the chromosomes present as
They are in a loosely coiled state known as chromatin
What is chromatin
DNA coiled around proteins called histones
What is the nucleus’ purpose
It controls the activities of the cell
What is in the centre of the nucleus
The nucleolus
What is the nucleolus’ purpose
It makes rRNA (ribosomal RNA) and packages it with ribosomal protein to make ribosomes.
What are the two types of chromatin and how do they appear under an electron microscope
Heterochromatin is darker and is densely packed DNA
Euchromatin is lighter and is loosely packed DNA
What is the purpose of euchromatin
It acts as a template for mRNA synthesis
What is the Rough Endoplasmic reticulum made out of
Lots of membranous tubes are present in the cytoplasm. Many are studded with ribosomes giving it a rough appearance.
When the ribosomes make proteins what happens
It is transported within the ER’s flattened sac like sheets called cisternae.
What is the difference between the smooth and rough ER
The smooth ER lacks ribosomes
What is the purpose of the smooth ER
Makes lipids and steroids (cholesterol and sex hormones)
It contains enzymes that detoxify (remove toxic substances)
It is a storage site for calcium in skeletal muscle cells.
What is the Golgi apparatus made out of
A series of tightly packed flattened sacs or cisternae.
What does the Golgi apparatus do
it collects and processes protein and lipids
What happens at the maturing face of the Golgi apparatus
Vesicles bud off the maturing face and go to either the surface membrane (secretion) or form lysosomes
Do mitochondria have a double or single membrane
They have a double membrane or envelope
What happens to the inner membrane of the mitochondria
The inner membrane is highly folded to form crystae which project into the internal solution or matrix ( a jelly like substance similar to the cytoplasm.)
What do mitochondria do
They complete the later stages of aerobic respiration and synthesise most of the ATP for the cell.
What does the mitochondria have its own
It has its own DNA which is (mt)DNA so can produce their own enzymes and can reproduce themselves.