Levels of Organization OrganismOrganOrgan System Tissues CellsOrganelles

Cells  A cell is the smallest unit that is capable of performing all 8 life functions.  MRS C GREN

Cells  The size & shape of a cell relates to its function.  Two main types of cells: 1. Prokaryotic 2. Eukaryotic

Prokaryotic Cells  Cells that lack a cell nucleus, or any other membrane-bound organelles.  Chromosome is a simple DNA chain with the ends joined to form a circle.

Prokaryotic Cells  Most are unicellular, but some prokaryotes are multicellular. E.g. bacteria, blue-green algae

Eukaryotic Cells  Higher organisms whose cells are arranged into complex structures enclosed within membranes.  The chromosome is a length of DNA folded. It is wound around proteins.  E.g. Animals, plants, fungi and protists.

Organelles  No plant or animal cells are alike but they do share some common organelles.

In your Notes.... OrganelleLocationFeaturesFunction Plant Animal Uni

Cell Membrane  All cells are separated from their environment by a cell membrane.  For cells with cell walls, the membrane is inside the cell wall.

Cell Membrane  Consists of two layers of lipids (lipid bilayer).  One lipid includes a hydrophilic (water- loving) head and hydrophobic (water- hating) tails.

Lipid Lipid Bi-layer Cell Membrane

Semi-Permeable Membrane  Proteins in the membrane allow nutrients, oxygen, and water into the cell and waste products out of the cell.  These proteins also limit other molecules from entering or leaving the cell.

Protein Gate Lipid

Cytoplasm  Cytoplasm is the semi-fluid solution found inside the cells.  It contains dissolved substances, enzymes and all other cell organelles.

Cytoskeleton  Scaffolding-like structure made of protein found in cytoplasm.  Helps the cell maintain or change its shape.

Nucleus  Usually the largest organelle the nucleus contains genetic material that directs all cell activities.  Separated from the rest of the cell by a nuclear membrane. Nucleus Nucleolus Pores Nuclear Membrane

Nucleus  Made up of three parts: 1. Nuclear envelope – a double membrane covering that controls the entry and exit of the large molecules and particles that need to go in and out.

Nucleus 2. Genetic Material – In a resting cell the DNA is unravelled (chromatin) and too small to be seen. When a cell is about to divide the DNA coils, thickens and can be seen (chromosomes).

Nucleus 3. Nucleolus – The main function of the nucleolus is the production and assembly of ribosome components (RNA, proteins).

Endoplasmic Reticulum (ER)  Continuous with the cell membrane and the nuclear envelope.  The ER is a series of membranes and connecting tubes that provide a work surface for chemical reactions as well as a passageway for moving materials around the cell.

Endoplasmic Reticulum (ER)  There are two types or ER: 1. Smooth ER 2. Rough ER (ribosomes attached)

Ribosomes  Found either bound to the ER or free floating within the cytoplasm.  Site where proteins are made (protein synthesis).

Ribosomes  Free ribosomes make proteins to be used in the cell.  The ribosomes bound to the ER make proteins to be secreted by the cell.

Golgi Bodies/Apparatus  A series of flattened sacs found in the cytoplasm.  The primary function is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell.

Lysosomes  Tough, membranous bags containing digestive enzymes.  They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.

Vacuoles  Vacuoles are membrane-bound compartments that can serve a variety of storage functions.  They often contain water, food or wastes.

Vacuoles  In animal cells food vacuoles engulf food where it is digested by the lysosome's enzymes.  In plants it acts as a storage, a fluid skeleton and it also hold colour and poisons.  In unicellular organisms contractile vacuoles pump water out of the cells. Video

Contractile Vacuoles  These specialized vacuoles pump excess water out of a cell and is found prominently in freshwater protists.

Mitochondria  Converts energy from food into a form that a cell can use, called ATP.  It is the site of aerobic respiration. A cell with a large energy requirement will have lots of mitochondria.

Mitochondria  It has its own circular DNA, ribosomes and transfer RNA and protein making machinery.  In the matrix the krebs cycle takes place.  The electron transport chain takes place in the cristae.

Cell Wall  Found in plant cells, algae and most bacteria.  Made of cellulose to provide strength and shape.

Chloroplasts  Found in the cytoplasm of plants.  Function is to manufacture glucose through photosynthesis.  Contains the green pigment chlorophyll.

Chloroplasts  Made of thylakoid discs arranged in stacks called grana.

Centrioles  Found in all animal cells and most unicellular organisms.  During cell division, the centriole pair extends to form spindles to move chromosomes apart.

Cilia and Flagella  Found in some animal cells and unicellular organisms.  Both are cellular projections and are almost identical in structure, although cilia are shorter and often more numerous.  Many cells that line surfaces within our bodies are ciliated.

Cilia and Flagella  Both are often associated with movement.

Eyes Spots  Photoreceptive organelle found in green algae and other unicellular photosynthetic organisms.  It allows the cells to sense light direction and intensity and respond to it by swimming either towards or away from the light.

Eye Spots  This helps the cells in finding an environment with optimal light conditions for photosynthesis.  Eyespots are the simplest and most common "eyes" found in nature.

Cilia and Flagella