Exercise 1 Flashcards
What are the three statements involved in cell theory.
Cell theory states:
- all living things are made of cells.
- The cell is the basic unit of life.
- New cells arise only from old cells.
Where is the plasma membrane found?
Surrounds and protects the cell. It is responsible for what enters and exits the cell.
Where is the nucleus found and what is its function?
The nucleus is located centrally within the cell. It contains DNA in the form of chromatin or chromosomes. It is responsible controls how the cell looks and functions.
What makes up the cytoplasm of the cell?
The cytoplasm is semi fluid that contains water and various types of molecules and organelles.
What are organelles and where are they found?
Organelles are small structures usually formed from membranes. Each organelle has a specific function. Organelles are found within cytoplasm and usually can only be seen by an electron microscope.
Briefly describe the cytoskeleton of the cell and state its purpose.
A network of interconnected filaments and microtubules in the cytoplasm. It maintains the cells shape and allows the cell and contents to be moved. Comparable to the skeleton in animals.
What substances form the plasma membrane?
Plasma membrane is made up of a phospholipid bilayer with protein molecules found throughout it. Cholesterol (lipid), is also found in the membrane giving it support.
The plasma membrane is said to be selectively permeable. What does this mean? List some of the substances which flow in and out of the cell.
It only allows certain molecules to enter or exit the cells cytoplasm. Substances that commonly enter and exit are; oxygen, carbon dioxide and water.
List the different ways substances enter and exit the cell.
Two main forms of transportation.
1. Passive transportation does not require energy to move substances and includes diffusion and osmosis. Facilitated transport is another passive transportation but it requires a protein molecule to cross the membrane.
- Active transportation involves energy and a carrier to move substances across the membrane because they are moving from an area from low concentration to high concentration.
What are the two types of structures which make up the cytoskeleton? What are the functions of the cytoskeleton?
The 2 structures that make up the cytoskeleton are microtubules and actin filaments. The cytoskeleton helps maintain the cells shape and will anchor the organelles or help them move about the cell.
Why are cells so small?
The surface to volume ratio accounts for the small size. Cells are more efficient at a small size. As a cell gets larger in volume, the surface area available to take in nutrients gets proportionally smaller.
