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
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 – 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