Levels of Organization

Organism OrganOrgan System

TissuesCellsOrganelles

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. Prokaryotic2. 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....Organelle Location Features Function

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 proteinsalso limit other molecules from entering or leaving the cell.

Protein Gate

Lipid

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.

Nucleus2. Genetic Material – In a resting

cell the DNA is unravelled (chromatin) and too small to be seen.

When a cell is aboutto divide the DNA coils, thickens and can be seen (chromosomes).

Nucleus3. 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