Structure and Functions Cells Structure and Functions

Flash Cards Cell theory Prokaryotic Cells Eukaryotic Cells Organelles Homeostasis Metabolism Mitosis Meiosis

Table 1: Organization of Living Organisms Cells – the building blocks of all living things that carry out the processes necessary for life (ex. nerve cells) Tissues – a group of similar cells that perform a specific function (ex. nerve tissue) Organs – a group of tissues that work together to carry out a specific function (ex. brain, spinal cord) Organ systems – a group of organs that work together to perform a bodily function (ex. nervous system) Organism - all the organ systems working together to form an individual life form (ex. you) Species - a group of organisms that can reproduce to form viable offspring (ex. Homo sapiens)

1. Cell Theory 1. All living things are made of up cells (single-celled or multicellular). 2. The cell is the basic unit of structure and function (basic unit of life). 3. All cells come from pre-existing cells (i.e. new cells form when parent cells divide).

1. Cell Theory Exceptions: Viruses are not living cells. Mitochondria and chloroplasts have their own DNA and can reproduce themselves. The very first living cells on Earth could not have formed from pre-existing cells.

2 types of cells: Bacteria 2. Prokaryotic Cells 3. Eukaryotic Cells Bacteria Contain: cell membrane, cell wall, cytoplasm, ribosomes, but not membrane bound organelles present On circular DNA, no nucleus present Plants, animals, protists and fungi Contain: cell membrane, cytoplasm, ribosomes, and membrane bound organelles DNA found within the nucleus of the cell

4. Organelles Small structures inside the cell that perform specific life functions for the cell Organelles are specialized to maintain homeostasis within the body Plant cells DO NOT have lysosomes or small vacuoles Animal cells DO NOT have a central vacuole, cell wall or chloroplast

5. Homeostasis Maintaining a stable environment in spite of internal or external changes “homeo” = same + “stasis” = staying Organisms become sick or die when they fail to maintain homeostasis Ex. maintaining a safe body temperature

6. Metabolism All the chemical activities an organism must carry on in order to remain alive To be considered living, all organisms must perform the following life functions: respiration, growth, synthesis, regulation, nutrition, transport, excretion and reproduction

Table 2: Life Functions of Organelles Respiration – making energy for the cell Growth – increasing in cell size or cell number Synthesis – combining small molecules to make larger ones (ex. photosynthesis) Regulation – maintaining a stable internal environment Nutrition – obtaining and processing nutrients Transport – circulation of materials throughout the organism Excretion – removing metabolic wastes, ex. carbon dioxide, ammonia Reproduction – producing new individuals

7. Mitosis Cell division: body cells grow and divide to make more cells Passes on DNA to new cell Daughter cell is genetically identical (clones) to parent cell Allows organisms to reproduce, grow and repair damaged tissues Form of asexual reproduction Most of the cells in your body divide by mitosis

8. Meiosis Occurs in multi-cellular reproduction and is a form of sexual reproduction Forms gametes (sex cells) that are NOT genetically identical to parent cells (creates variations) Offspring receive half their genes from each parent in sexual reproduction