Bridget Kelly

2

The Cell Theory

All organisms are composed of cells and the products of cells

All cells come from pre-existing cells

The cell is the smallest organisational unit of living things

Eukaryotic Cells Prokaryotic Cells

Organelle Functions

Organelle Description Function

Centrioles Pair of small cylindrical structures of microtubules.

Separation of chromosomes during cell division (animals and protists).

Chloroplast Green organelle made of many folded loops of thylakoid membrane.

Site of photosynthesis

Cytoplasm The contents of a cell other than the nucleus

Site of many chemical processes and reactions

Cytosol Fluid component of cytoplasm Location of organelles and site of anaerobic cellular respiration/glycolysis.

Cytoskeleton Network of microtubules and microfilaments

Provides support and framework for cells

Endoplasmic Reticulum

Network of intracellular membranes linked with plasma membrane and other membrane bound organelles

Rough – protein synthesis and processing, storage transport of materials

Smooth – processing, storage and transport of materials

Lysosomes Membrane bound vesicles Contain powerful enzymes that break down debris and foreign materials.

Mitochondria Composed of many folded layers of membrane

Site of aerobic respiration

Smaller and more primitive

Circular, free floating DNA

No Membrane bound organelles

Bacteria (Monera)

Larger and more complex

Linear, contained DNA

Membrane bound organelles

Animals, plants, protists, fungi

Bridget Kelly

3

Nucleus Large, surrounded by double layers of membrane containing pores to allow movement between nucleus an cytoplasm

Contains genetic material and controls cellular activities.

Plasma Membrane

Phospholipid ‘fluid mosaic’ bilayer with embedded cholesterol, protein and other molecules.

Controls movement of substances into and out of the cell and is responsible for recognition and chemical communication.

Plastid Group of organelles found only in plant cells Contain pigments or food

Ribosomes Tiny organelles located in the cytosol Site of protein synthesis

Tonoplast Vacuole membrane in plant cells Regulates movement of substances into and out of plant cells

Vacuole Membrane bound liquid filled sacs Provide physical support and may be involved in intracellular digestion and water balance

Vesicle Membrane bound organelles Transport within cells

The Cell Wall:

Non-living structure outside the plasma membrane

Plants = cellulose

Bacteria = Chitin

Plants vs Animal Cells:

The Plasma Membrane:

Cholesterol: A packing molecule that interacts with the phospholipids to regulate membrane consistency

Phospholipid Bilayer: Forms selectively permeable membrane that lets small molecules squeeze between and

lipid soluble molecules diffuse through hydrophobic tails.

Feature Animal Cell Plant Cell

Cell Wall Absent Present

Shape Irregular Rectangular (fixed)

Vacuole One or more (small) One (large)

Centrioles Present in all In lower forms

Chloroplasts Absent Present

Plastids Absent Present

Lysosomes Present Absent

Cilia Present Very rare