Cell Biology &

Cell Organelles

Get Hooke-d on Cells!Scientist Discovery

Robert Hook (1665)

Described the empty spaces between cork as “cells”Actually viewed the cell walls of dead cells

Anton von Leeuwenhoek (1674)

First observed a living cell (identified bacteria)

John Dalton (1808)Atomic TheoryAll matter is made of atoms

Louis Pasteur (1864)

Living organisms can only arise from other living organisms

Cell Theory

• Cells are the basic unit of life

• All organisms are made of one or more cells

• All cells must come from pre-existing cells

• The activity of an entire organism depends on the total activity of its independent cells

Prokaryote Cells• Pro: before; karyote: nucleus• First cells to evolve• Do not contain a membrane-

bound nucleus• Do not contain organelles smaller

than a ribosome• Bacteria

– DNA is single, circular strand– Cell wall used as a target for

antibiotics

Pseudomonas Bacteria

Eukaryote Cells• Eu: good/true; karyote: nucleus• More complex internal structure

and includes a nucleus• Include membrane-bound

organelles• Early prokaryotes were engulfed

by other prokaryotes and remained within– This formed a symbiotic relationship– Created a eukaryotic cell

• Plant, animal, fungi, protists

Nucleus• Structure

– Large oval structure in the centre of the cell

– Bound by the nuclear membrane

– Contains the chromosomes and the nucleolus

• Function– Control centre of the

cell– Regulates all

activities of the cell

Nucleolus

• Structure– Small, dark area

within the nucleus

• Function– Where ribosomes

are made

Nuclear Membrane

• Structure– Encloses the nucleus of the eukaryotic cell

• Function– Prevents the contents of the nucleus from

being spread in the cytoplasm

Nuclear Pores

• Structure– Openings in the nuclear

membrane

• Function– Allows contact between the

nucleus and cytoplasm– Allows ribosomes produced by

nucleus (nucleolus) to move into the cytoplasm

Chromosomes• Structure

– Threadlike structures found in the nucleus

• Function– Made of DNA which carries

genetic information– DNA coils and become visible

during cell division– Directs cell activities – Hereditary material– Chromosome = DNA + protein

Cell Membrane

• Structure– Bilayer of phospholipids

with proteins embedded within it

– Fluid and flexible– Phospholipid

• Hydrophilic head • Hydrophobic tail

• Function– Regulates the passage of

materials in and out of the cell

Cytoplasm

• Structure– Everything between the cell and nuclear

membrane– Consists of cytosol (mostly water) and

organelles

• Function– Organelles carry out functions within the cell

Cytoskeleton• Structure

– Microtubules & Microfilaments

• Tiny, tube-like fibres found in cytoplasm, cilia, flagella

• Function– Maintains the shape of

the cell– Microtubules

• Transport materials throughout cytoplasm

– Microfilaments• Help provide shape and

movement for cells

Organelles - Mitochondria• Structure

– Rod-shaped– Smooth outer membrane with

a greatly folded inner membrane (cristae) which increases the surface area

• Function– Powerhouse of the cell– Where food molecules are

broken down and their energy used to make special energy-rich molecules

Organelles - Ribosome

• Structure– Small, grain-like body made primarily of RNA– Lack a membrane– May be attached to endoplasmic reticulum or

floating freely in cytoplasm– Made in the nucleolus

• Function– Site of protein synthesis

Organelles – Endoplasmic Reticulum

• Structure– System of clear, tubular passageways which spreads

through cytoplasm– Smooth: No ribosomes attached– Rough: Ribosomes attached

• Function– Smooth: Transports proteins produced by ribosomes

throughout the cell– Rough: Transports fats and proteins (synthesized on

SER) throughout the cell

Organelles – Endoplasmic Reticulum

Smooth Rough

Organelles – Golgi Apparatus

• Structure– Membranous sacs piled on top of each other

• Function– Modifies, collects, packages, and distributes

proteins made in one location and used in another

– Proteins released by exocytosis

Organelles – Lysosome

• Structure– Small, round sac in cytoplasm– Contains digestive enzymes – Formed by the golgi apparatus

• Function– Suicide sacs– Breaks down food, old cell

parts, and dead or injured cells

Organelles – Vacuoles

• Structure– Sac-like structures– Larger in plants than animals

• Function– Store water, salts, proteins, and

carbohydrates.– Allow plants to support leaves and flowers

Organelles – Plastids

• Structure– Found only in plants– Similar structure to the vacuole

• Function– Chloroplast: use sunlight for energy– Leukoplast: store starch granules– Chromoplast: Store pigment molecules

(orange, yellow)

Organelles – Chloroplast• Structure

– Large, green structure in the cytoplasm

– Contains chlorophyll – Thylakoid: outer

membrane– Stroma: inner membrane– Grana: stacks of

chlorophyll

• Function– Captures energy in

sunlight and uses it to produce food

Organelles – Centrioles• Structure

– Two bundles of fibres at right angles

– Found in animal cells only– Present during mitosis (cell

division)

• Function– Migrate to poles during

mitosis– Microtubules form between

centrioles to pull chromosomes apart

Plant vs. Animal Cells

• Plant cells– Cell wall made of cellulose for support– Chloroplasts which convert energy through

photosynthesis– Large vacuoles– No lysosomes

• Animal Cells– Centrioles aid in cell division– Small vacuoles

Animal Cells

Plant Cell