Cell Structure
L2 Biology
Chapter 7
What is a cell?
• Smallest unit of life that can carry out
all the functions of a living thing.
• Various sizes and shapes
• Organism- living thing
– Unicellular
– multicellular
Microscope Development
• 1500’s – first microscope developed
• 1665 – Robert Hooke named cell
• 1674 – Anton van Leeuwenhoek -
looked at cells in pond water and blood
Cell Theory Developed
• 1838 – Schleiden – all
plants are made of cells
• 1839 – Schwann – all
animals are made of cells
• 1855 – Virchow – all cells come from
pre-existing cells
Modern Cell Theory
• Cells are the basic units of all life.
• All organisms are made of one or more
cells
• All cells come from pre-existing cells
Microscopes
• Hand lens
• Compound light microscope
Electron Microscope
• Uses electrons for energy source
• Specimen must be killed
• Transmission electron microscope –
take pictures of slices of specimen
• Scanning electron microscope – take
pictures of surface of specimen
TEM Examples
SEM Example
Cells from Labs:
BASIC CELL STRUCTURES
• Cell Membrane – double lipid bilayer with
proteins embedded within it and through it
Cytoskeleton
• Cell support
• Anchors
organelles
• Transports
materials
• Helps cell
move
Nucleus
• Control center of cell
• Contains genetic material
– Chromosomes
• Humans have 46 in each cell
• Made of DNA
- control heredity
- control protein synthesis
• Surrounded by double membrane –
nuclear envelope – contains pores
Nucleolus
• Within nucleus
• May be more than one
• Makes ribosomes
• Rich in RNA
Types of Cells
• Prokaryotic • Eukaryotic
– Simple cell – Complex cell
– No membrane-bound – Membrane-bound
organelles organelles
– Chromosome not – Chromosomes
contained in nucleus contained in nucleus
– Small cells – Larger cells
– Ex - bacteria – Ex – all other
organisms
Cellular Organelles
Ribosomes
• Sites where proteins are produced.
• Some are free.
• Some are attached
to endoplasmic
reticulum.
• Smallest
organelles
Endoplasmic Reticulum
• Transport passages throughout
cytoplasm
• Rough ER – have ribosomes attached
– Transport proteins
– Helps make membranes
• Smooth ER – no ribosomes attached
– Makes lipids
– Detoxifies wastes
Golgi Apparatus
• Packages cell secretions
• Makes lysosomes
– Contain digestive enzymes
for breaking down food in
food vacuoles
– Contains digestive
enzymes for breaking
down un-needed
structures – ex – sperm
tail after fertilization.
Mitochondrion
• Site of cellular respiration – food is
broken down to release energy.
Structures used for Movement
• Cilia • Flagella
Eukaryotic Cells include Plant and
Animal Cells
ANIMAL CELL STRUTURE
Plant cells have some parts that
animal cells don’t
• Cell Wall
• Central Vacuole
• Plastids
– Chloroplasts
– Leukoplasts
– chromoplasts
What animal cells have that plant
cells don’t
• Centrioles – function during cell division
• Lysosomes – contain digestive enzymes
Now you are ready to have a test on
parts of a cell and what they do:
Cell Part Appear- Function In Animal In Plant
ance cell cell
Cell
membrane
Cytoplasm
In addition, you should be able to name some
differences between prokaryotic and eukaryotic
cells
Make a chart like this:
Feature Prokaryotic Eukaryotic
THE END