3.1 Cell Theory KEY CONCEPT Cells are the Basic unit of life.

3.1 Cell Theory The cell theory grew out of the work of many scientists and improvements in the microscope.

3.1 Cell Theory

The Cell theory has three principles. 1. All organisms are made of cells.

3.1 Cell Theory The Cell theory has three principles. 1. All organisms are made of cells. 2. All existing cells are produced by other living cells.

3.1 Cell Theory The Cell theory has three principles. 1. All organisms are made of cells. 2. All existing cells are produced by other living cells. 3. The cell is the most basic unit of life.

3.1 Cell Theory All cells share certain characteristics.

3.1 Cell Theory All cells share certain characteristics. 1. Cells tend to be microscopic. Bacterium (colored SEM; magnification 8800x)

3.1 Cell Theory All cells share certain characteristics. 1. Cells tend to be microscopic. 2. All cells are enclosed by a membrane. Bacterium (colored SEM; magnification 8800x) cell membrane

3.1 Cell Theory All cells share certain characteristics. 1. Cells tend to be microscopic. 2. All cells are enclosed by a membrane. 3. All cells are filled with cytoplasm. Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells.

3.1 Cell Theory

There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus. nucleus cell membrane

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus. Eu = true Karyote = nucleus Eukaryotic cells have membrane-bound organelles. Ex: All animals & plants Some single celled organisms nucleus cell membrane organelles

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Prokaryotic cells do not have a nucleus. nucleus cell membrane organelles

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Prokaryotic cells do not have a nucleus. Prokaryotic cells do not have membrane-bound organelles. Ex: bacteria nucleus cell membrane organelles cytoplasm

3.1 Cell Theory Differences between cells Size – limited by ratio between their outer surface area & their volume Shape – diversity of form reflects a diversity of function Internal Organization – organelles – perform specific functions for the cell

3.1 Cell Theory 3.3 KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment. 3.3

3.1 Cell Theory The cell membrane has two major functions. – –forms a boundary between inside and outside of the cell – –controls passage of materials cell membrane 3.3

3.1 Cell Theory Homeostasis Cell membrane maintains a stable internal environment inside the cell by allowing some molecules to pass through and not others Selectively Permeable 3.3

3.1 Cell Theory The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot. 3.3

3.1 Cell Theory The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot. 3.3

3.1 Cell Theory Cell membranes are composed of two phospholipid layers. polar head (hydrophilic – likes water) 2 nonpolar tails (hydrophobic – repelled by water) 3.3

3.1 Cell Theory Cell Membrane –Fluid Mosaic Model – constant motion the phospholipids move within the membrane Proteins in the membrane also move like boats Peripheral proteins – found on the inside & outside of the cell Integral proteins – extend through membrane 3.3

3.1 Cell Theory Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. 3.3

3.1 Cell Theory Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor 3.3

3.1 Cell Theory Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor – –membrane receptor 3.3

3.1 Cell Theory 3.3

3.1 Cell Theory 3.2 KEY CONCEPT Eukaryotic cells share many similarities. 3.2

3.1 Cell Theory Cells have an internal structure. 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell – –helps position and transport organelles 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell – –helps position and transport organelles – –provides strength 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell – –helps position and transport organelles – –provides strength – –assists in cell division 3.2

3.1 Cell Theory Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell – –helps position and transport organelles – –provides strength 3.2

3.1 Cell Theory Centrioles are tubes found in the centrosomes (cytoskeleton) 3.2

3.1 Cell Theory Centrioles are tubes found in the centrosomes. – –Centrioles help divide DNA. 3.2

3.1 Cell Theory Centrioles are tubes found in the centrosomes. – –Centrioles help divide DNA. – –Centrioles form cilia and flagella. Cilia & flagella assist in movement and feeding – –Cilia – short, numerous hair-like extensions – –Flagella – longer, move with a whip-like motion – cell usually only has 1 or 2 3.2

3.1 Cell Theory The nucleus stores genetic information. 3.2

3.1 Cell Theory Nucleus Nuclear matrix – nucleus skeleton Nuclear envelope – double membrane Chromatin – strands of DNA Chromosomes – formed from chromatin during cell division Nuclear pores – small holes in the nuclear envelope Nucleolus – site where ribosomes are formed 3.2

3.1 Cell Theory 3.2

3.1 Cell Theory Endoplasmic reticulum. –Series of highly folded membranes 3.2

3.1 Cell Theory There are two types of endoplasmic reticulum. 3.2

3.1 Cell Theory There are two types of endoplasmic reticulum. 1. rough endoplasmic reticulum covered in ribosomes makes proteins for use outside of the cell 3.2

3.1 Cell Theory There are two types of endoplasmic reticulum. 1. rough endoplasmic reticulum 2. smooth endoplasmic reticulum makes and stores steroids (lipids) 3.2

3.1 Cell Theory Ribosomes link amino acids to form proteins. Free floating ribosomes make proteins for use inside of the cell 3.2

3.1 Cell Theory Vesicles are membrane-bound sacs that hold materials. Found in animal cells 3.2

3.1 Cell Theory Vacuoles are fluid-filled sacs that hold materials. Found in plant cells 3.2

3.1 Cell Theory Mitochondria supply energy to the cell. 3.2

3.1 Cell Theory Mitochondria – sites of chemical reactions transfer Energy (E) from organic compounds (food) into ATP (cellular E) Cell respiration -Cristae – folded inner membrane -Increases the surface area -Increases E production 3.2

3.1 Cell Theory 3.2

3.1 Cell Theory Golgi Apparatus – processes, packages, & secretes substances 3.2

3.1 Cell Theory Lysosomes contain enzymes to digest unwanted or broken material. 3.2

3.1 Cell Theory Plant cells have cell walls and chloroplasts. 3.2

3.1 Cell Theory Plant cells have cell walls and chloroplasts. A cell wall provides rigid support. 3.2

3.1 Cell Theory 3.2

3.1 Cell Theory Plant cells have cell walls and chloroplasts. A cell wall provides rigid support. Chloroplasts convert solar energy to chemical energy (photosynthesis) Thylakoids – stacks of sacs filled with chlorophyll Increase surface area - increase photosynthesis 3.2

3.1 Cell Theory 3.2