Chapter 3 - Cells Flashcards
What is the cell theory?
All living organisms are made up cells and materials produced by cells. Cells are the basic structural and functional units of plants organisms- the building blocks and make up all living organisms.
- all cells are very small - so microscope is needed to see most. They vary in size and shape. Despite these variations all human cells have a similar basic structure
What is a cell membrane
Cell membrane surrounds the cell and forms the outer boundary of the cell
- separates it from neighbouring cells and from external environment
- made up of double layer of lipid molecules and associated proteins
- determines what substances go in and out
What is the cytoplasm
The cytoplasm is a thick jelly like fluid that fills the inside of the cell and the suspended structures it contains
Fills between the nucleus and cell membrane
What is cytosol?
Cytosol is the liquid part of the cytoplasm
75-90% water
Salts and carbs are dissolved
Protein and fats are suspended in the watery fluid
What are organelles?
Organelles are specialised structures suspended in the cytoplasm that carry out particular functions.
What is a cytoskeleton
A cytoskeleton is the internal framework of protein fibres with the cytoplasm.
Consists of
- microfilaments assists the movement of materials, organelles or whole cell
- microtubules which are hollow rods that gives organelles it shape or that give the cell its shape
What are inclusions?
They are chemical substances occurring as granules or liquid droplets (not part of cell structure) but are in the cytoplasm.
- Eg haemoglobin in RBCs, pigments in cells of skin, shoe and eyes
What is the nucleus?
The nucleus is an ovoid or spherical shaped organelle which contains genetic material.
- mostly DNA, separated from cytoplasm by nuclear membrane
- the membrane is doubled and has gaps called buckled pores through which large molecules can pass
- an area in the nucleolus is composed of mainly RNA
- the DNA and nucleolus are suspended in jelly like nucleoplasm
What are centrioles?
Centrioles are a pair of cylindrical structures usually located near the nucleus
Are involved in the reproduction of the cell
What are ribosomes?
Ribosomes are small and spherical packages of amino acids are joined together at the ribosomes to make proteins
What are lysosomes
Lysosomes are small spherical structures which contain enzymes that are able to breakdown proteins, lipids, nuclei acids and some carbohydrates.
Lysosomes break down materials that are taken into the cell or break down worn-out organelles
What is the Golgi body?
The Golgi body are flattened membranous bags stacked on top of each other.
They modify proteins and packages them in vesicles for secretion from the cell
vesicles are produced and pinched off from the edges of the membranes
What is the endoplasmic reticulum
The ER are pairs of parallel membranes extending through the cytoplasm and connecting the cell membrane with the nuclear membrane.
It provides a surface area for chemical reactions to occur
The channels of between the paired membranes are used for storage or transport of materials.
Most are rough or granular - they have ribosomes attached
Some have no ribosomes - smooth or agranular
What does the mitochondria do
Spherical or elongated structures spread throughout the cytoplasm
Have a double membrane - outer is smooth and the inner is folded in growths the centre of the mitochondrion
Mitochondria releases energy for cell through the process of respiration
Difference between Cilia and Flagella
Cilia and flagella are fine projections found on some cells. These are used to beat back and forth to move substances over the surface of the cell or move the cell entirely
Cilia are short and numerous resembling tiny hairs Eg. Lining of windpipe, moved trapped mucus away
Flagella are long and one come by themselves or in pairs Eg sperm cell
Why are cells so small?
All cells are tiny - to function effectively all cells are to be microscopic
All requirements of a cell and all the products of a cell, must pass across the membrane thar surrounds the cell
Thus the relationship between the surface area of the cell and the volume is all important.
As cells increases in size it’s ability to exchange enough materials to support its increasing volume is diminished because the volume increases at a greater rate than the surface area.
A large cell could not support itself because it would not have enough surface to absorb the nutrients required and remove the wastes produced, by its large volume.
1x1 = 1 (A) 1x1x1 = 1 (V)
2x2 = 4 (A) 2x2x2 = 8 (V)
How to work out total magnification?
Total magnification = Ocular Lens X Objective Lens
How to work out the size of a cell?
Size of Cell = FOV / Number of cells to fit across the FOV
What is the FOV?
The circle of light you see when you look through the microscope is the field of view.
Look at the microscope diagram
Study it
