Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Animal Cell Plant Cell Bacterial Cell

Cell Structure and Function Cells are a collection of living matter enclosed by a barrier that separates the cell from its surroundings

Every Cell Contains: Membrane – thin layer of material that serves as a covering or lining Structure containing the cells genetic material

Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize

Cells May be Prokaryotic or Eukaryotic Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles Eukaryotes include most other cells & have a nucleus and membrane-bound organelles

Prokaryotes Genetic material is not contained in the nucleus Less complicated than eukaryotic cells Bacteria are examples of prokaryotes

Eukaryotic Cell Larger and more complex than prokaryotes Plants, Animals, Fungi are eukaryotes Contain 3 basic cell structures: Nucleus – contain genetic info Cell Membrane Cytoplasm with organelles

Nucleus Nucleus – a large membrane-enclosed structure that contains the cell’s genetic material in the form of DNA Controls many of the cells activities

Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells.

Basic Structure of a Eukaryotic Cell

Two Main Types of Eukaryotic Cells Animal Cell Plant Cell

Plant Cell Plant Cell Smooth endoplasmic Vacuole reticulum (free) Nuclear envelope Ribosome (attached) (free) Smooth endoplasmic reticulum Nucleus Rough endoplasmic reticulum Nucleolus Golgi apparatus Mitochondrion Cell wall Cell Membrane Chloroplast Vacuole Plant Cell

Animal Cell Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

Organelles – “little organs” Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm

Nucleus “The Control Center” Contains nearly all the cell’s DNA with the codes for the cells proteins and other molecules Surrounded by the nuclear envelope Full of nuclear pores Chromatin – DNA and proteins spread throughout the nucleus

Nucleus Chromosomes – condensed form of chromatin Passes on from one generation to the next Nucleolus – place where ribosomes are assembled

Ribosomes “Protein Factories” Small particles of RNA and protein Located in the cytoplasm Organelle where proteins are assembled Ribosomes get codes for proteins from nucleus

Endoplasmic Reticulum “Highway System of the cell” Internal membrane system Transports- Proteins Other macromolecules Two types: Smooth Rough

Smooth & Rough Endoplasmic Reticulum Smooth ER lacks ribosomes & makes proteins USED In the cell Rough ER has ribosomes on its surface & makes proteins to EXPORT

Golgi Apparatus “The Shippers of the cell” Closely stacked membranes, resembles stacks of pancakes Modifies, sorts, and packages proteins from the ER for storage or secretion Sends proteins to their final destination

Lysosomes “Clean-up Crews” Small organelles filled with enzymes Breaks down lipids, carbohydrates, and proteins into smaller molecules that can be reused by the cell Also breaks down old organelles

Mitochondria Nickname: “The Powerhouse” Function: Energy formation Breaks down food to make ATP ATP: is the major fuel for all cell activities that require energy Two membranes – outer and inner Inherit mitochondria from mother Contains its own DNA

Vacuole Saclike structure Stores materials Water, salts, proteins, carbohydrates Plants have a large central vacuole Single-celled organisms use a contractile vacuole to maintain homeostasis

Cell or Plasma Membrane Cell membrane Living layer Controls the movement of materials into and out of the cell Selectively permeable

Cytoplasm of a Cell Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place

Cytoskeleton Supporting framework of the cell Cytoskeleton = cell skeleton Many components Microtubules / microfilaments made of proteins. Move organelles w/in the cell.

Cytoskeleton Continued Microtubules / Microfilaments make up Cilia Flagella Used in cellular locomotion

Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

Now let’s talk about structures only found in PLANT Cells!!

Figure 7-5 Plant and Animal Cells Plant Cell Figure 7-5 Plant and Animal Cells Section 7-2 Vacuole Cell Membrane Go to Section:

Chloroplast Organelles that capture energy from sunlight and convert it into chemical energy Photosynthesis Two membranes Contains pigment chlorophyll

Eukaryotic Cell Organelles and Function Cell Wall Function: provides support and protection to the cell membrane Found outside the cell membrane in plant cells

Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells

Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria

Differences between plant cells and animal cells Animal cells Plant cells Relatively smaller in size Relatively larger in size Irregular shape Regular shape No cell wall Cell wall present

Differences between Plant Cells and Animal Cells Animal cells Plant cells Vacuole small or absent Large central vacuole Glycogen as food storage starch as food storage Nucleus at the center Nucleus near cell wall

Endosymbiont Hypothesis Lynn Margulis U-Mass. Found that mitochondria / chloroplasts did not fit the roles of organelles. They had unusual properties.

3 properties of Mito / Cplasts Contain own DNA Both surrounded by 2 membranes Most organelles only surrounded by one membrane. Both reproduce separately from the rest of the cell

Margulis’s Model Both Mitochondria / Chloroplasts had ancestors that were free-living organisms. These formed endosymbiotic relationships with other cells. Over time offsprings of these organisms lost their independence becoming organelles of larger cells.

Further Evidence Studies of DNA in chloroplasts show that they are much like the DNA prokaryotic cells. Mitochondria / chloroplasts contain their own ribosomes and make many of their own proteins. These ribosomes are smaller / chemically different from those in eukaryotic cells. More closely resemble ribosomes in prokaryotic cells.

Levels of organization Cells are grouped together and work as a whole to perform special functions Known as “Cell Specialization”

Tissue A group of similar cells to perform a particular function Animals : epithelial tissue, muscular tissue Plants : vascular tissue, mesophyll

Organ Different tissues group together to carry out specialized functions Heart : consists of muscles, nervous tissue and blood vessels Leaf : consists of epidermis, mesophyll and vascular tissue

The Structures of a Leaf (Plant Organ) Chloroplast Palisade Mesophyll Cell Spongy Mesophyll Cell Air Space Stoma

The Structures of a Heart (Animal Organ)

Organ System Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way Human : digestive, respiratory, excretory, circulatory and reproductive systems Plant : root and shoot systems

Human Body Systems Examples of systems : Digestive System Respiratory System Circulatory System Nervous System Reproductive System

Examples of a Human Body System

Examples of a Human Body System

Levels of Organization CELLS (muscle cells,nerve cells) TISSUES (muscle, epithelium) ORGANS (heart, lungs, stomach) SYSTEMS (circulatory system) ORGANISM (human)

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