Structure and
Function of The Cell
Reference:
Modern Biology
CHAPTER 4
BIG IDEA
There is a relationship between a
cell’s function and it’s size and
shape
Introduction to CELLS
Watch this video
Introduction to Cells…
Introduction to CELLS
Watch this video on
The Cell Theory Tonight !
DO NOW
Respond to the following in your
notebook:
Why do cells divide before they
get too big?
Introduction to CELLS
THE CELL
Cell - the smallest unit that can carry out all
the processes of life (take in nutrients, get
rid of waste, etc)
– Every living thing made of one or more cells.
• Unicellular-complete living thing made of only
one cell
– Example: paramecium
• Multicellular-living thing made of more than one
cell
– Example: humans
Introduction to CELLS
SOME SINGLE CELLS…
Introduction to CELLS
Just like one of those eggs, each
of you began as a single cell…
Discovery of the Cell
Robert Hooke-1665
• Observed thin slice of cork under
microscope
• Described it as a “great many little boxes”
• Called them “cells”
Anton van Leeuwenhoek-1675
First person to observe living cells
Cell Theory
1. All living things are made of
one or more cells.
2. Cells are basic units of
structure and function
3. Cells only come from other
cells.
DO NOW
Respond to the following in your
notebook:
Why do cells divide before they
get too big?
Cell Theory
Let’s watch a video on
why are cells small?
Cell Diversity
Not all cells are alike !
SIZE
Examples:
– Longest-giraffe nerve cell (2 meters)
– Smallest-bacteria (0.2 micrometers)
– Largest - egg cells
Cell Diversity
SIZE
• Cell size is limited by ratio of volume
to surface area.
The volume of a cube is obtained by multiplying the length by the width by the height, and the total
surface area by adding together the surface area of the six sides, (obtained by multiplying the length and
width of each side).
Volume:.........=...4 x 4 x 4..=... 64 cubic units. Surface Area....=...4 x 4 x 6....=....96 square units
Cell Diversity
Some differently sized cells …
Cell Diversity
SHAPE
– Cells have a shape (structure) to fit
their function
• Examples:
– Nerve cell-has extensions to allow it to
transmit and receive nerve impulses
– Skin cells-flat to cover body surface
– White blood cells-can change shape to
squeeze into spaces to isolate bacteria
that invade the body.
Cell Diversity
INTERNAL ORGANIZATION
Cells contain internal structures that
help it carry out all of its functions
– Organelles:
• Examples:
– Cell Membrane – surrounds the cell
– Nucleus – contains most of the cells genetic
material; directs most of the cells activities
Prokaryotes vs. Eukaryotes
VIDEO
2 Basic Types of Cells
PROKARYOTE
EUKARYOTE
No nucleus
Have nucleus
No membrane-bound
organelles
Have membrane-bound
organelles
Ex: Bacteria
Ex: cells of plants,
animals, fungi, algae.
Prokaryote vs. Eukaryote
Similarities:
 Both are surrounded by a:
◦ Cell Membrane-surrounds the cell and controls what
passes into and out of the cell
 Provides a selectively permeable barrier.
 Only allows selected molecules to pass through
 Both contain:
Cytoplasm-the area of the cell between the
membrane and the nucleus, where the organelles
are.
 Cytosol-gelatin-like fluid that surrounds organelles.
DNA
• Prokaryote-has DNA in a region of the cell
• Eukaryote-has DNA in the nucleus
Prokaryote vs. Eukaryote
Differences:
• Organelles: internal
structures that perform
specific functions in the
cell
– Prokaryote-DO NOT HAVE
membrane - bound organelles
– Eukaryote-HAVE membrane bound organelles
Summary:
Prokaryotic Cells
Eukaryotic Cells
Nucleus
NO
YES
DNA Location
Region of Cell
In Nucleus
Cell Membrane
Yes
Yes
Cytoplasm
Yes
Yes
Membrane-bound
Organelles
No
Yes
Check for Understanding
Make a Venn Diagram to show how
prokaryotic and eukaryotic cells are
different and what they have in common.
Just like your body is made up of many
organs that work together, the tiny cells in
your body are made up of smaller units that
work together.
These smaller units are called organelles.
Organelles
• Organelle-cell part that performs a
specific function for the cell
– Most are surrounded by a membrane
– Each helps to maintain life of the cell
– They are specialized
*Organelles are like the organs of your cells.
Organelles
CELL OR PLASMA MEMBRANE
The cell membrane is a thin, flexible covering
around the outside of each cell. The cell
membrane has several important jobs:
1. It holds the cell together
2. It protects the cell
3. It keeps harmful substances from
entering the cell
4. It membrane controls the movement of
needed materials, such as food, oxygen, and
water into the cell.
Organelles
CELL OR PLASMA MEMBRANE
• Mainly made of phospholipids and proteins.
• LIPID BILAYER –
– HYDROPHOBIC, non-polar “tails” of phospholipids
face in-ward
– HYODROPHYLLIC, polar head facing out-ward
Organelles
CELL OR PLASMA MEMBRANE
• Proteins attached to surface (inside or
outside) = peripheral proteins
• Proteins stuck into membrane = integral
proteins (can go partly or all the way
through).
• Cell membranes are selectively permeable they allow certain molecules to pass through,
but keep others out.
Organelles
CELL OR PLASMA MEMBRANE
OTHER MOLECULES:
• GLYCOPROTEINS with attached
carbohydrate tails to recognize
self.
• Contain the steroid cholesterol to
make membranes more flexible.
Organelles
CELL MEMBRANE MODEL
• Phospholipids and proteins move laterally, or
side to side for short distances.
• Proteins make a pattern on the surface known
as the fluid mosaic model.
cell
membrane
animation
Organelles
CYTOPLASM
• Cytoplasm is the “gel-like material” between
the nucleus and cell membrane.
– Contains various organelles of the cell.
• Cytosol- gelatin like aqueous fluid that
surrounds the organelles
Organelles
CYTOSKELETON
• Made of PROTEINS called microtubules
and microfilaments.
• FUNCTION: Help maintain cell size and
shape. Aid in movement of cellular
materials.
Organelles
CYTOSKELETON
• Made of PROTEINS called microtubules
and microfilaments.
• FUNCTION: Help maintain cell size and
shape. Aid in movement of cellular
materials.
Organelles
Nucleus and Nucleolus
NUCLEUS is:
• Surrounded by NUCLEAR MEMBRANE called
the NUCLEAR ENVELOPE.
• Serves as the COMMAND CENTER OF CELL.
• Nuclear pores allow molecules in and out.
• CONTAINS the CELL’S GENETIC MATERIAL
(DNA).
• Contains NUCLEOLUS (dark spot) which is
the site of RIBOSOME production.
Organelles
Nucleus and DNA
• DNA is scrunched up as chromosomes in
DIVIDING CELLS.
• DNA is spread out as chromatin in
NON-DIVIDING CELLS.
Organelles
LYSOSOME
• Sac containing digestive enzymes.
FUNCTION:
• Digests: food particles, disease-causing
bacteria and viruses, and worn out or broken
cell parts.
• Plays a role in apotosis “programmed cell
death”. Cell suicide for the good of the
organism.
Organelles
VACUOLE
• Storage space for: waste products, nutrients,
and water.
• Huge in plant cells, small in animal cells, NOT
in prokaryotic cells.
Organelles
CENTRIOLES
• Made of PROTEINS called microtubules.
• Only seen in eukaryotic cells during cell
division.
• FUNCTION: aid in movement of chromosomes
during cell division.
Organelles
CILIA & FLAGELLA
• Made of PROTEINS called microtubules
organized in a nine/two arrangement that help
with movement.
CILIA: short and hairlike
• FUNCTION: aid in movement and protection;
move fluid AROUND cells.
FLAGELLA: long and whiplike
• FUNCTION: aid in movement, protection, and
feeding; move cells through fluid
Flagella Video
• YouTube - Microscope view of sperm
Organelles
RIBOSOMES
• Can be free in the cytosol or bound to
the surface of Rough ER.
• MADE OF proteins and RNA
– FUNCTION: make protein for use in the
cell (free) or for export (bound).
Organelles
MITOCHONDRION (plural: MITOCHONDRIA)
•
•
•
•
•
•
•
Surround by double membrane.
Contains its own DNA.
Called the powerhouse of cell.
Burns sugar to release energy.
Stores energy released as ATP.
Permeable outer membrane.
Folded inner membrane = cristae (increases
surface area for more chemical reactions).
Organelles
ENDOPLASMIC RETICULUM (ER)
• Internal network of membranes.
– Rough ER: ribosomes attached
– Smooth ER: no ribosomes attached.
Organelles
ENDOPLASMIC RETICULUM (ER)
ROUGH ER vs. SMOOTH ER
– FUNCTION: ROUGH ER: makes proteins to be exported
outside the cell.
– FUNCTION: SMOOTH ER: move molecules around
the cell, store proteins to be exported.
Organelles
GOLGI APPARATUS (BODY)
• Looks like a stack of flattened sacs.
– FUNCITON: Modify, sort, and package
substances from ER for transport out of
cell
Organelles – Eukaryotic Animal Cell
Golgi Body
2
1
Ribosomes
Vacuole
Cytoplasm
3
4
Endoplasmic
Reticulum
Mitochondria
5
6 Nucleus
Cell Membrane
7
8 Lysosomes
Organelles in Eukaryotic Plant Cell
CHLOROPLASTS (plastids)
•
•
•
•
Surrounded by double membrane.
Has its own DNA
Outer membrane is permeable.
Flattened membrane sacs called thylakoids
contain CHLOROPHYLL where photosynthesis
happens. Stacks of thylakoids called grana. Gel
like material around thylakoids called stroma.
• FOUND ONLY IN PLANT CELLS.
Organelles
CELL WALL
• Found OUTSIDE the cell membrane.
• Provides structure and support.
• Cellulose in the cell wall makes plant cells
sturdy.
• Bacteria have cell walls made of sugar and
proteins instead of cellulose.
• FOUND ONLY IN PLANT CELLS & BACTERIA
Plant Cells (another eukaryote!)
Animal cells and plant cells have
some similar cell parts.
Plant Cells
Endoplasmic
Reticulum
Golgi Body
Vacuole
Cell Wall
2
1
4
3
6
5
7
Nucleus
8
Cytoplasm
9
Cell Membrane
Ribosomes
Mitochondria
10Chloroplasts
Prokaryotes
Bacteria are the most common prokaryotic
cell.
• They do not contain membrane-bound
organelles
• They do not have a nucleus, but do contain a
single loop of DNA.
• Like all cells, bacteria are surrounded by a
cell membrane which contains the gel- like
cytoplasm of the cell.
• They also have a cell wall.
Eukaryotes vs. Prokaryotes
MULTICELLULAR ORGANIZATION
In multicellular organisms, groups
of cells organize or work together
to do a certain job.
MULTICELLULAR ORGANIZATION
Multicellular Organisms
-Contain many cells
-Each cell has specific job (its
structure fits its function or job)
MULTICELLULAR ORGANIZATION
4 Levels of Organization
1. Cell
-performs functions that work with other
cells to keep organism alive
-many different types of cells
2. Tissue
-group of similar cells that carry out a common
function
Ex: epithelial tissue made of sheets of
closely packed cells that form surface
coverings.
MULTICELLULAR ORGANIZATION
3. Organ
-group of several types of tissues that
interact to perform a function
Example: Your heart is made up of muscle
tissue, nerve tissue, and connective
tissue. Muscle tissue makes
your heart pump, nerve tissue
tells it when to pump and
connective tissue holds the parts together.
MULTICELLULAR ORGANIZATION
4. Organ System
-group of several organs working together
to perform a series of related tasks
Example: mouth, esophagus,
stomach, intestines work
together to digest food.
*All organ systems work together
to carry out all the functions
of life for the body.
MULTICELLULAR ORGANIZATION
Plants also have cells, tissues, and organs.
Plant cells form different kinds of tissues. For
example, one tissue type covers the outside of a
leaf. Another tissue transports water and
nutrients.
Special kinds of tissue
form plant organs.
Flowers, leaves, stems,
and roots are all plant
organs.
MULTICELLULAR ORGANIZATION
COLONIAL ORGANISMS
Group of genetically identical cells
that live in a closely connected
group.
Example: Volvox
– Contains 500-6000 cells.
– Cells maintain individual existence.
» Some are specialized to carry out a
specific task.
Volvox Video
Volvox Dances - Bing Videos