Cells (II) Structures Flashcards
What are the 3 structures common in the animal and plant cell?
Nucleus, cell plasma membrane and the cytoplasm.
Describe the structure of the plasma membrane?
The plasma membrane is extremely thin (less than 10nm thick).
It consists of a lipid bilayer in which proteins are embedded.
At high magnification, the plasma membrane consist of 3 layers. 2 Dark lines being separated by a narrow gap.
Explain the function of the cytoplasm?
It is the site of the chemical reactions of life.
It is the medium for chemical reaction. It provides a platform upon which other organelles can operate within the cell. All of the functions for cell expansion, growth and replication are carried out in the cytoplasm of a cell.
Why does mature red blood cell not contain any nucleus?
The absence of a nucleus is an adaptation of the red blood cell for its role. It allows the red blood cell to contain more haemoglobin and, therefore, carry more oxygen molecules. It allows the cell to have its distinctive biconcave shape which aids diffusion.
In which cell, is the nucleus the largest organelle.
Th e Eukaryotic cell, typically 10-20 um in diameter.
Which 2 cells does not have nucleus.
Mature red blood cells in humans and the sieve tube elements of phloem of flowering plants.
They lose their nucleus as the mature.
Describe the structures of the nucleus.
1) Membrane is continuous with endoplasmic reticulum.
2) Nuclear envelop contains many pores, as tiny about 100nm. It makes up 1/3 of nuclear membrane’s surface area.
3) It contains chromosomes, nucleolus and nucleoplasm, chromatin and nuclear envelope.
What is the function of the pores in the nuclear envelop.
The pores speed the movement of molecules between nucleus and cytoplasm [RNA], between cytoplasm and Nucleus [ATP, Hormones]
What are chromosomes?
Chromosomes are thread-like structures made of DNA and protein, and are visible at the time the nucleus divides. At other times, the chromosomes appear as a diffuse network called “Chromatin”.
What are nucleolus?
Nucleolus are tiny, rounded, darkly-staining body. It is the site where ribosomes are synthesized.
Explain the function of the nucleus.
1) It controls and direct cell management, and its behavior when the cell divides.
2) It carries genes, which contains the cell’s hereditary information.
Describe the structure of the cytoplasm.
1) It contains larger suspended particles of pats and many structures called organelles.
2) It forms the larger part of the cell. It is made up of 90% water and contains dissolved proteins, sugars and enzymes.
Explain the function of the cytoplasm.
The cytoplasm is the site where numerous chemical reactions occur.
What is the difference between cytoplasm and cytosol.
The cytosol is the liquid portion inside the cell membrane, However, cytoplasm includes the cytosol and organelles, but not the nucleus.
Explain the meaning of division of labor?
Refers to the allocation of specific functions of the different parts of an organism among cells.
