Biology ( Cells 1 )

Characteristics of Life, Cells, and Cell Theory

First characteristic of life

Made of one or more cell

Second characteristic of life

Displays organization

Third characteristic of life

Growth ( addition of mass ) and development ( natural changes / new abilities gained during life )

Fourth characteristic of life

Reproduces

Fifth characteristic of life

Responds to stimuli ( anything part of the environment and causes a reaction )

Sixth characteristic of life

Requires energy

Photosynthesis, chemosynthesis, consumption, etc.

Seventh characteristic of life

Maintains homeostasis ( Regulation of an organism’s internal condition to live )

Eighth characteristic of life

Adapts ( inherited characteristics caused by changes in the surrounding ) and evolves

Unicellular

Composed of one cell ( uni = one )

Bacteria

Smallest life form

Archaea

Similar to bacteria but closer to eukaryotes / different in structure / functionality

Protists

More complex then the other unicellular beings but still small

Multicellular

Multiple cells working in a system

Cell Theory

Proposed by Matthias Schleiden, Theodore Schwann, and Rudolf Virchow in 1839

First cell theory

All living organisms are composed by one or more cells

Second cell theory

Cells are the smallest entity that retains the properties of life

Third cell theory

Cells come from pre-existing cells

Prokaryotes cells

All unicellular

Eukaryotic cells

More complex than prokaryotes

Can either be uni or multicellular

Cell wall

Rigid structure keeping the shape of the cell

Cytoplasm

Where chemical reactions essential for life occur

Includes the cytosol

Cytosol

Jelly like fluid filled with minerals, ions, and nutrients

Ribosomes

Build proteins for amino acids

Prokaryotic DNA

A single circular chromosome in a nucleoid region ( where the cell's primary genetic material is located )

Chloroplasts

Found only in eukaryotic / plant cells

Organelle for photosynthesis

Eukaryotic cell wall

Rigid structure keeping the shape of the cell

Less rigid than prokaryotic cell walls

Organelles

Sub cellular structures performing specialized tasks

Mostly membrane bound as it separates the organelles from the rest of the cell improving efficiency by increasing chemical reactions

Cells

The smallest unit of life with many tiny parts carrying out specialized functions

Contains all characteristics of life / maintaining life

Phospholipid Bi-layer

Hydrophobic

Hating / averting water ( oil, etc. )

Hydrophilic

Loving / inclined to water

Power of cell membranes

Repair itself when punctured, change shape, and grow / shrink as needed

Plasma membranes

A viscous ( thick and highly resistant to flowing easily ) fluid, high temp increases it’s fluidity / permeability while low temp decreases it

Permeability

Membrane’s ability to allow liquids / gases / magnetic fields to pass through

Cholesterol in the bi-layer

Helps control fluidity of the plasma membrane ( reduces fluidity at high temp, lowers temp for the membrane to solidify )

Fluid mosaic model

Membrane as a dynamic sea of lipids with proteins for various functions

Types of proteins

Receptor proteins ( hormone detection ), Recognition ( ID tags ), Adhesion ( cell interaction ), and transport ( ions, glucose )