Cell Organelles Flashcards
(22 cards)
What are microvilli?
Finger like extensions of the cell surface membrane.
What is the function of microvilli?
To increase surface area of the membrane for faster absorption.
What is the function of the nucleus?
It contains DNA which controls cell activity.
Name four constituents of the nucleus:
1) nuclear envelope (double membrane)
2) nuclear pores
3) chromatin
4) nucleoli
What is the nuclear envelope and its function?
It is situated in the nucleus and it separates DNA from the rest of the cell. It consists of a doubt membrane, the outer membrane leads to the Endoplasmic Reticulum.
What are nuclear pores?
Situated in the nucleus, they allow chemicals to move in and out of the nucleus.
What is chromatin?
Situated in the nucleus, it consists of DNA and proteins. DNA in euchromatin is in an uncoiled, working form.
If a cell undergoes cell division, both euchromatin and heterochromatin will coil up to form chromosomes.
What is nucleoli and its function?
Nucleoli is mostly DNA. One or more nucleoli are present in the nucleus. They manufacture RNA needed for ribosomes and enzymes needed for manipulation of DNA.
What are ribosomes and their function?
Ribosomes consist of two subunits, both made up of protein and ribosomal RNA (made in the nucleoli).
Function= Site of protein synthesis. (RNA from nucleus binds to ribosomes and controls the assembly of protein molecules.
Lots of ribosomes in a cell, some free in cytosol, others fixed to the ER.
Describe the structure of RER:
Rough endoplasmic reticulum. A 3 dimensional network of cisternae running through the cytosol. A unit membrane separates the network of spaces from the cytosol. Ribosomes are fixed to the membranes outer surface.
What gives the RER its rough appearance?
The ribosomes are fixed to the membranes outer surface.
What is the function of the RER?
To transport proteins across the cell.
Describe how the RER carries out its job?
Proteins are synthesised on the ribosomes on the outer membrane of the RER. The proteins pass through the membrane into the cisternae and move across the cell towards the golgi apparatus.
Describe how proteins might be chemically changed as they pass through the RER?
As the proteins move through the RER they may become chemically changed, e.g. enzymes may add carbohydrate to proteins to form glycoproteins.
The SER is similar to the RER except that… Give two points:
1) It is more tubular.
2) It doesn’t have ribosomes.
What is the function of the SER?
Synthesis of lipids.
What is the function of the Golgi apparatus?
It is a processing system for chemicals. e.g.. proteins, glycoproteins and lipids. Releases vesicles to various destinations.
Describe the structure of the Golgi apparatus:
It is a stack of flattened cisternae (spaces), each surrounded by a unit membrane. It has vesicles which move across the cytosol.
What is the function of Mitochondria?
They are the site of respiration reactions, they supply the cell with energy in the form of ATP.
Name a type of cell which is likely to have lots of Mitochondria:
Muscle Cells and cells which require energy for active transport.
Describe the structure of mitochondria:
It is surrounded by an envelope (consists of a double membrane). The inner membrane is folded to form cristae to increase the surface area. The matrix is in the middle and contains enzymes, some ribosomes and a DNA molecule.
What are lysosomes?
Lysosomes are organelles containing digestive enzymes. They digest unwanted material in the cell and they are separated from the rest of the cell.
