Cells

The Cell

• The basic unit of life

• Self-replicating

• Bound by a membrane

• May contain organelles with specific structures and functions

• Contains biological molecules like DNA, proteins and sugars

Cell Theory

• All living things are made up of one or more cells and the products of those cells

• Cells are the functional units of life

• All cells come from pre-existing ones

Types of Cells

Prokaryotic Cells

• Simple Cells

• No nucleus

• No organelles

• e.g. bacteria

Eukaryotic Cells

• More complex cells

• Nucleus

• Membrane-bound organelles

• e.g. plant cells, animal cells, protists and fungi

Specialized Animal Cells

• Red blood cells

• Cheek cells

• Sperm and egg cells

• Brain cells

Organelles

• Little “organs” of cells

• Membrane-bound

• Allow for cellular functions like:

  • DNA replication

  • cell division

  • excretion of wastes

Cell Wall

• Protects the cell

• Gives shape

• Made of cellulose

• Found in plants, algae, fungi, & most bacteria

Cell Membrane

• Outer covering, protective layer around ALL cells

• For cells with cell walls, the cell membrane is inside the cell wall

• “selectively permeable”

  • Allows food, oxygen, and water into the cell and waste products out of the cell

    • Diffusion and Osmosis

Cytoplasm

• Gelatin-like inside cell membrane

• Constantly flows

• Holds organelles in place

Cytoskeleton

• Scaffolding-like structure in cytoplasm

• Helps the cell maintain or change its shape

• Made of protein

Nucleus

• Directs all cell activities

• Contains DNA – hereditary instructions for everything the cell does

• Usually the largest organelle

Nucleolus

• Aka “little nucleus”

• Found in the nucleus

• Makes components of ribosomes

Endoplasmic Reticulum

• Network of tubes or membranes

• Carries materials through cell

• Can be

  • Smooth (no ribosomes on the surface)

  • Rough (ribosomes on the surface)

Ribosome

• Small bodies free or attached to the endoplasmic reticulum

• Their function is to produce proteins

Mitochondrion

• Bean-shaped with inner membranes

• Place where sugar molecules are broken down into ENERGY - called “cellular respiration“

Golgi Bodies

• Stack of membrane-bound vesicles

• Packages, modifies and sorts substances to be transported around the cell

Vacuoles

• Fluid-filled sacs found in both plants and animals

• Storage site for food, water, waste

Lysosomes

• Small, round structures with a membrane

• Digestion -breaks down larger food molecules into smaller molecules

• Protection

  • Attack “foreigners”

Chloroplasts

• Green, oval structures found in plant cells ONLY

  • Contain the green pigment chlorophyll

• Place where energy from sun is utilized to make food for the plant

  • called “photosynthesis”

Centrioles

• Cylindrical structures found only in animal cells

• Produce spindle fibres

  • Important for moving chromosomes during cell division

Flagellum

• Found in animal cells

• A projection of the cell that helps with locomotion

Comparison of Plant and Animal Cells

Animal Cell

• Only a cell membrane

• No chloroplasts

• Centrioles

• Lysosomes present

• Irregular shape

• Many tiny vacuoles

Plant Cell

• Cell wall and cell membrane

• Chloroplasts

• No centrioles

• Lysosomes uncommon

• Regular shape

• Usually only one large vacuole