3.1.2 Anatomy Of A Generalized Cell Flashcards
3 Basic componentes of the cells
- Nucleus
- Plasma membrane
- Cytoplasm
The nucleus is the ________ _________ of the cell.
Control center
The main parts of the nucleus
Nuclear envelope
Nucleolus
Chromatin
What is the nuclear envelope?
Double membrane barrier around the nucleus
Function of the nuclear pores
Allow only selective substances to pass to the nucleus
What is the nucleoplasm?
Jellylike fluid present in the nucleus
Nucleolus
Site where ribosomes are assembled
Synthesis of ribosomes
Ribosomes are assembled in the nucleolus and then transported out to through the nuclear pores to the cytoplasm, where they serve as actual sites for protein synthesis.
Chromatin
When a cell is not dividing, its DNA is wound around histones to form a loose network of “beads on a string” called chromatin
Chromosome
When a cell is dividing, the chromatin threads coil and
condense to form dense, rodlike bodies called chromosomes.
What is the plasma membrane?
A barrier that contains the cell contents and separates them from the surrounding environment.
The structure of the plasma membrane contains:
Two phospholipid layers (Phospholipid bilayer)
Cholesterol
Floating proteins
What does the term “mosaic” refer to?
The scattering of the different proteins within the phospholipid bilayer
The phospholipids are arranged:
Tail to tail
Describe the properties of head and tail of the membrane in terms of polar and non polar
Head - hydrophilic (polar)
Tail - Hydrophobic (non polar)
True or False
The membrane is permeable to most of the water soluble molecules
False
The membrane is impermeable due to the hydrophobic layer
How can water enter the cell?
Through aquaporins
Con lipids enter the cells through the membrane without a channel?
Yes
The phospholipid membrane is lipid soluble
Membrane proteins
Transporters
Receptors
Enzymes
Anchor proteins
Function of the transporters
Carry a molecule from one side of the plasma membrane to another
Function of the receptors
Can bind to an extracellular molecule to activate an extracellular process
Function of the enzymes
Transform the molecules to another form
Function of the anchor proteins
Link the extracellular structure with the intracellular structures
What are glycoproteins
Branching sugar groups attached to most of the proteins in the extracellular space.
Function of the glycoproteins
1) Act as carriers in membrane transport
2) Provide receptor sites for hormones and other chemicals
3) They act as receptors that certain bacteria, viruses, or toxins can bind to
4) They act as enzymes in the membrane to transform a molecule into another form.
5) Facilitate cellular recognition (cell-cell interactions), which is important in development and immune
response.
What are the glycolipids
Phospholipids associated with sugar groups that are components of cell membranes.
Function of the glycolipids
Facilitate cellular recognition
Determination of blood groups
What do we mean by the term “glycocalyx”?
Because of the presence of glycolipids and glycoproteins in the plasma membrane, the cell surface is a fuzzy, sticky, sugar-rich area called the glycocalyx.
Function of the glycocalyx
•Protection: Cushions the plasma membrane and protects it from chemical injury
•Immunity to infection: Enables the immune system to recognize and selectively attack
foreign organisms.
•Defense against cancer: Changes in the glycocalyx of cancerous cells enable the immune
system to recognize and destroy them.
•Transplant compatibility: Forms the basis for compatibility of blood transfusion and organ
transplants.
•Cell adhesion: Glycoproteins in the glycocalyx act as an adhesive or cellular glue, which
bind cells together so that tissues do not fall apart
•Fertilization: Enables sperm to recognize and bind to eggs.
•Control the volume of red blood cells in the blood vessels
Footloose cells
Blood cells
Sperms
Three ways for bounding cells
Glycocalyx (glycoproteins act as an adhesive or cellular glue)
Wavy contours ( Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion)
Cell junctions
Types of cell junctions
Tight junctions
Desmosomes
Gap junctions
Tight junctions
Tight junctions are impermeable (not allowing fluid to pass through) junctions that encircle the cells and bind them together into leakproof sheets, adjacent plasma membranes fuse together tightly and prevent
substances from passing through the extracellular spaces between the cells