Transcript 1. Cell_structure_function Chapter 2

Cell Structure
& Function
Cell Theory
• All living things are made up of cells.
• Cells are the smallest working units of all
living things.
• All cells come from preexisting cells
through cell division.
• Cells are small so they can exchange
materials with their surroundings.
Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Two Types of Cells
•Prokaryotic
•Eukaryotic
Living cells classified into 2 different
types based on internal structure
• Prokaryotic cells – little defined internal
structure. Lack a clearly defined structure
to house their DNA. Organisms made up
of prokaryotic cells are called Prokaryotes
(all bacteria, all archaeans)
• Eukaryotic cells – more complex structure.
Contain many different kinds of
membrane-bound structures called
organelles suspended in cytosol.
Types of Cells
REVIEW
• What are the main differences between
Prokaryotic and Eukaryotic cells?
• List one key point from the cell theory
• What is the definition of a cell?
• Why does a small cell have more surface
area to volume?
Prokaryotic
• Do not have
structures
surrounded by
membranes
• Few internal
structures
• One-celled
organisms,
Bacteria
Prokaryotic Cells
• Prokaryotic cells include the bacteria and
archaea.
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Bacterial cells have these constant features:
Outer Boundary: Cell wall
Plasma membrane
Cytoplasm:
Ribosomes
Thylakoids (Cyanobacteria)
Many enzymes
Nucleoid:
Chromosome (DNA only)
Eukaryotic Cells
• Eukaryotic cells have a nucleus that
controls the workings of the cell.
• All cells are surrounded by a plasma
membrane made of phospholipids
and proteins.
Eukaryotic
• Contain organelles surrounded by membranes
• Most living organisms
Plant
Animal
• The plasma membrane regulates what
enters and exits the cell.
• Inside the plasma membrane, the nucleus
is surrounded by cytoplasm.
• Cytoplasm is a semi-fluid medium.
• Plant cells have a cell wall in addition to
the plasma membrane.
• Primary cell walls are made from cellulose. The secondary cell wall,
which forms inside the primary wall, is formed from lignin. Its
purpose is to give strength to the cell.
REVIEW
• List one main difference between plant
and animal cells
• Do plant and animal cells have
organelles?
• What is the function of organelles?
Animal cell anatomy
“Typical” Animal Cell
Plant cell anatomy
“Typical” Plant Cell
REVIEW
• What are the main similarities and
differences between plant and animal
cells?
Cell Parts
Organelles
• Animal and plant cells have organelles.
• Organelles compartmentalize functions
within the cell.
• The organelles of animal and plant cells
are similar to each other except that
centrioles are present only in animal cells,
and chloroplasts are present only in plant
cells.
Surrounding the Cell
Cell Membrane
• Outer membrane of cell
that controls movement
in and out of the cell
• Double layer
Cell Wall
• Most commonly found
in plant cells &
bacteria
• Supports & protects
cells
REVIEW
• Which structure surrounds a cell?
• Briefly outline the cell theory
Inside the Cell
Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA
Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus
Chromosomes
• In nucleus
• Made of DNA
• Contain instructions
for traits &
characteristics
Nucleolus
• Inside nucleus
• Contains RNA to build
proteins
Cytoplasm
• Gel-like mixture
• Surrounded by cell membrane
• Contains hereditary material
Endoplasmic Reticulum
• Moves materials around
in cell
• Smooth type: lacks
ribosomes
• Rough type (pictured):
ribosomes embedded in
surface
Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on rough
endoplasmic
reticulum & floating
throughout the cell
Mitochondria
• Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
Golgi Bodies
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
Cilia and flagella
• Cilia and flagella - 9 + 2 pattern of
microtubules
• Involved in movement (cell, eggs,
debris)
• Each cilium and flagellum has a basal
body at its base.
Structure of a flagellum or cilium
Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
Vacuoles
• Membrane-bound
sacs for storage,
digestion, and waste
removal
• Contains water
solution
• Help plants maintain
shape
Chloroplast
• Usually found in plant
cells
• Contains green
chlorophyll
• Where
photosynthesis takes
place
REVIEW
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List 5 structures within a cell
What do golgi do?
What does the mitochondria do?
What is the function of the cytoplasm?
What is the function of the nucleus?
What does the nuclear membrane allow to happen?
What is the function of the nucleolus?
What is the function of the lysosome?
What is the function of the endoplasmic reticulum?
Why don’t animal cells contain chloroplasts?