Cell diversity
Not all cells are alike. They vary in size, shape, and internal organization.
The body contains 10^3 or 10^4 cells, with 300 different types that can be classified into 4 groups.
Cell theory
All living things are composed of one or more cells
Cells are the basic units life.
Cells only come from the replication of other cells.
Cell size
Most cells are small
Some cells can be seen by naked eye. The ovum (human egg cell) is the largest body cell and can be seen without a microscope
Characteristics of cells
Need water Require energy-eat food Remove waste Grow, repair and reproduce Have a lifespan
Cell division - why perform?
Need to replace old cells
To grow
Reproduction (asexual and sexual)
DNA
Manual of life
Chromosome
Chapters in the manual of life-46 total for humans
Genes
Individual pages for a specific function
Cell Wall
- found just outside the cell membrane
- rigid, tough, porous structure made of cellulose
- provides support for cell and protection from physical
- only in plants
Cell Membrane
- flexible double-layered membrane that surrounds a cell
- supports the cell and allow some substances to enter while keeping others out (semi-permeable membrane)
- used for communication
cytoplasm
- suspends organelles inside a cell
- mostly water, also contains other substances that the cell stores until they are needed
- chemical reactions take place within, which can change from jelly-like to liquid, allowing organelles to be moved around
mitochondria
-supplies energy to cell through cellular respiration using glucose oxygen
nucleus
- controls all of the cells activities
- dense, spherical structure that contains DNA
vacuole
- single layer of membrane enclosing fluid in a sac
- storage tank for food, water, wastes or enzymes
centriole
-used with the spindle apparatus during mitosis
Stem cells
Cells that hAve not yet picked a specialization
When placed near a particular type of cells, stem cells will select the same role
