Science - Grade 10 Biology - 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
Eukaryotic 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

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