Cell Structure and Function
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How thick is the Cell Surface Membrane?
7nm Thick
How many layers doe the cell surface membrane have?
3 layers
Purpose of cell surface membrane?
Partially permeable membrane controlling the exchange between the cell and its environment
what is the nucleus surrounded by?
2 membranes known as nuclear envelope
Features of Nuclear envelope
. tiny holes nuclear pores contains loosely coiled chromosomes : Chromatin Contains darker area : Nucleolus Pores allow mRNA and ribosomes to leave and nutrients and hormones to enter
Functions of Nucleus
Controls cell activities Chromosomes contain DNA Nucleolus manufactures ribosomes
what is ER?
Endoplasmic Reticulum: extensive system of membranes forming flattened sacks called cisternae
Appearance of RER?
has ribosomes
Appearance of SER?
no ribosomes
Function of RER?
transport proteins made by ribosomes- makes Golgi Apparatus
Function of SER?
make lipids and steroids
Features of Ribosomes?
Free in cytoplasm or on ER
Size of Ribosomes?
22nm
What are ribosomes made of?
RNA and protein
Function of Ribosomes?
site of protein synthesis
Appearance of Golgi Apparatus?
stack of flattened sacks : Cisternae
How is Golgi Apparatus formed?
from vesicles that bud off from RER, broken down at other end to form Golgi vesicles
Function of Golgi Apparatus?
molecules collected, processed and stored especially proteins. taken from RER put into vesicles transported around and out of the cell Used to make lysosomes
Appearance of Lysosomes
single membrane 0.1-0.5 micromertres
what do lysosomes contain?
Hydrolytic enzymes
Function of lysosomes?
Break down old organelles or cells e.g. white blood cells
How many membranes do mitochondria have?
2 called an envelope
why is the inner membrane of mitochondria folded?
To form projections called cristae
what’s the interior solution of the matrix called?
The Matrix