Bio- Cells Flashcards
What is protoplasm?
It is made up of cell membrane, nucleus, cytoplasm
What is the function of the cell surface membrane?
It controls substances entering and leaving the cell
What is the function of the cytoplasm?
It is where most cell activities occur and it contains specialised structures called organelles
What is the function of the nucleus?
It controls cell activities such as cell growth and the repair of worn out parts. It is essential for cell division. It contains genetic information
What is the function of the cellulose cell wall?
It protects the cell from injury and gives the plant cell a fixed shape.
What does the nucleus contain?
The nuclear envelope, nucleoplasm(has chromatin) , nucleolus
What is chromatin?
It is a mass of long thread-like structures found within the nucleus. Each chromatin thread is made up of proteins and a compound called DNA. DNA stores hereditary information and also carries instructions that a cell needs for carrying out its activities.
What happens to the chromatin when cell division occurs?
The chromatin threads condense and become highly coiled (thick rod shaped) structures called chromosomes.
Why are the rough endoplasmic reticulum near nucleus?
Nucleus contains genes, which determine inherited features, and these inherited features need proteins. Proteins are produced in the ribosomes found on the surface of the rough endoplasmic reticulum. So it is logical to have nucleus near the rough endoplasmic reticulum(ribosomes).
What is the rough endoplasmic reticulum?
It is a network of flattened spaces lined with a membrane, ribosomes are attached to its outer surface. The outer surface of the rough endoplasmic reticulum is continuous with the nuclear envelope.
What are ribosomes?
They are small round structures. Proteins are synthesised here in the cell. ribosomes attached to the endoplasmic reticulum usually synthesise proteins that are usually transported out of the cell. Ribosomes lying within the cytoplasm make proteins that are used within the the cell.
What does the smooth endoplasmic reticulum do?
It is connected to the rough endoplasmic reticulum. It synthesises substances such as fats and steroids.It also converts harmful substances into harmless substances (carries out detoxification).
What is the golgi apparatus/body?
It is shaped like a disc that consists of a stack of flattened spaces surrounded by membranes(looks like wifi). It chemically modifies substances made by the ribosomes on the rough endoplasmic reticulum, and it stores and packages these substances in secretory vesicles for secretion out of the cell.
What are vesicles?
They transport substances within the cell. vesicles are tiny spherical spaces enclosed by a membrane. They contain proteins synthesised by the ribosomes on the rough endoplasmic reticulum and are pinched off from it. Then they fuse with the golgi body/apparatus and release their contents into it. Substances made by the endoplasmic reticulum are chemically modified inside the golgi body. Then the secretory vesicles containing these chemically modified substances are pinched off from the golgi body, and are transported to the cell surface membrane for the contents to be secreted out of the cell.
What is the mitochondria?
They are small oval shaped organelles. They carry out cellular respiration to release energy.
