Transcript Cell Structure & Function

Cell Structure
& Function
Describe this picture. What is the
basic substance required to make
this structure.?
BRICKS ACT AS BUILDING
BLOCKS TO CREAT THE BRICK
BUILDING.
What are we made up of?
So what is the definition
of a cell??
 They
are building blocks of
all living things and they are
the basic unit of life !!!!!
What do you think the ‘building
block of a dog is ?
So what are the various
points you can think of
to describe a cell?
Cell Theory
 All
living things are made up of
cells.
 Cells are the smallest working
units of all living things.
 They are the structural and
functional unit of life. (why?)
 All cells come from preexisting
cells through cell division.
Refined Definition of Cell
A cell is the smallest structural and
functional unit of life.
Pay close attention to the
Video clip and write down
important points into your
Class work notebook.

http://www.youtube.com/watch?v=qEHQbjido
9I
UNICORN
UNICYCLE
Single celled Organisms / Uni Cellular organis
•A unicellular organism is any life form that
consists of just a single (uni=one) cell.
•Unicellular organisms replicate fast: colonies can
double their size in between 30 minutes and a few
hours.
•Some unicellular organisms have little tails they
use for locomotion (movement)
•Unicellular organisms vary in size, with the
smallest bacteria measuring only a third of a
micron (300 nanometers)
•To observe some of the
smallest unicellular organisms requires an
expensive electron microscope, why the very
largest can be seen with the naked eye.
PARAMECIUM
Hair like structures around the cell help it to move.
The groove in the middle help to draw food
inwards.They Feed mostly on bacteria.They are
found in freshwater environments.
Bacteria
Bacteria have a wide range of shapes –rods, spirals.They can be
found everywhere from hot springs, acidic environments to our
intestines.There are good and bad bacteria. They are used a
lot in the food industry to make cheese, wine curd etc.
Examples of Cells
Amoeba
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
tallest trees
adult human
chicken egg
frog embryo
most eukaryotic cells
mitochondrion
most bacteria
virus
proteins
diameter of DNA
double helix
atoms
“Typical” Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
“Typical” Plant Cell
http://waynesword.palomar.edu/images/plant3.gif
Cell Parts
Organelles
Surrounding the Cell
Cell Membrane
Outer membrane of cell
that controls movement in
and out of the cell
 Double layer

http://library.thinkquest.org/12413/structures.html
Cell Wall
Most commonly found
in plant cells & bacteria
 Supports & protects
cells
 Gives it shape and
rigidity.

http://library.thinkquest.org/12413/structures.html
Inside the Cell
Nucleus
Control center of the cell
 Directs cell activities
 Separated from cytoplasm
by nuclear membrane
 Contains genetic material
– DNA
 All the information
regarding the cell and its
activities are stored here.

Cytoplasm
Jelly-like substance
 Surrounded by cell membrane
 All cell organelles are embedded in this.
 It contains the chemicals which are
necessary to carry out all the reactions
that happen within a cell.

Mitochondria
Produces energy through
chemical reactions – breaking
down food.
 Controls level of water and
other materials in cell
 Recycles and decomposes
proteins, fats, and
carbohydrates

http://library.thinkquest.org/12413/structures.html
Vacuoles
Membrane-bound sacs
for storage, digestion,
and waste removal
 Contains water solution
 Help plants maintain
shape

http://library.thinkquest.org/12413/structures.html
Chloroplast
Usually found in plant
cells
 Contains green
chlorophyll
 Where photosynthesis
takes place

http://library.thinkquest.org/12413/structures.html
Plant & Animal Cells

Similarities
◦ Both contain similar organelles
◦ Both surrounded by cell membrane
Characteristics
Plant Cell
Cell Size
Large
Cell Shape
Vacuoles
Animal Cell
Smaller than plant
cells
Rectangular
Circular
A single centrally
If any, there are a
located vacuole. It
number of small
takes up almost 90% vacuoles spread
of the cell volume.
throughout the
The vacuole stores
cytoplasm that store
water and maintains water, ions and waste
turgidity of the cell.
materials.
Cell Wall
A rigid cell wall is
Cell wall is absent.
present around a
This allows animal
plant cell that helps it cells to adopt
maintain its shape.
different shapes.
Chloroplasts
Present. Chlorophyll is
the pigment that traps
sun's energy which is
Absent. As animals
utilized by plants to
lack this pigment,
make food through
they cannot make
the process of
their own food.
photosynthesis. This
pigment is present in
the chloroplasts.
Microscope Timeline

1665- Robert Hooke, an English scientist,
first glimpsed into the microscopic world
of
cells
by
examining
dead
cork cells under a primitive microscope
which he constructed. The thought
that cells might be the basis for life was
not to come for nearly two centuries.
1674- Antonie Philips van Leeuwenhoek
modified Robert hooks microscope and
discovered free cells in the form of
bacteria.
 The microscope consisted of bi-convex
lens capable of magnifications ranging
from 70x to over 250x, depending upon
the lens quality. A compound microscope
ranges from 10X to 100X.

Antonie Philips van Leeuwenhoek
with the microscope he invented.
1674






1831 – Robert Brown discovered and named the
nucleus in the plant cell.
During the next 170 years, other scientists used
microscopes to further advance their knowledge
of cells.
1838, German botanist named Matthias Schleiden
suggested that all plant tissues are made of cells.
1839, zoologist Theodore Schwann made a similar
proposal for animals.
1858, Rudolf Virchow suggested that
all cells come from preexisting cells.
The ideas of these three scientists led to the
creation of what is now called the cell theory.
1831
1838
1839

Theodore Schwann
Matthias Schleiden
Rudolf Virchow 1858
MICROSCOPE

Electron Microscope
Compound Microscope
How to use a microscope

View the video below to get an idea of
how exactly to use a compound
microscope

http://www.youtube.com/watch?v=bGBgA
BLEV4g&feature=related
Why are these shoes all different?
SPECIALISED CELLS
Some plant and animal cells are specialised
to carry about special functions. So as to
enable them to do these functions they are
structurally modified that means their
structure and function is much different
from a normal plant /animal cell.
 Specialised cells in plant: root hair cell,
palisade cell
 Specialised cells in Animals: Red blood cells,
nerve cell/neuron.

Describe the cell's shape and how
it helps it do it job.
Describe the cell's shape and how
it helps it do it job.
Red Blood Cell-disc
shaped to carry
oxygen around the
body
Red blood cells transport oxygen
cell surface membrane
cytoplasm contains no
nucleus
allows more room for
haemoglobin
cytoplasm contains
haemoglobin
haemoglobin is a protein
which carries the oxygen
molecules
bi-concave disc shape
increases surface area over
which absorption of oxygen
can occur
Red Blood Cell
•Designed to carry oxygen
•Found in blood.
•Large surface area, for oxygen to pass through.
•Contains haemoglobin, which joins with oxygen.
•Has no nucleus
Describe the cell's shape and how
it helps it do it job.
Describe the cell's shape and how
it helps it do it job.
Nerve Cell- long,
thin and 'wire-like'
to send messages
around the body
Nerve Cell (neurone)
Nucleus
•They are long
•They have connections at each end
•Can carry electrical signals
•Their job is to carry nerve impulses to different parts
of the body.
Image 3 - Nerve Cells
Example
of cell
Specific
function
Specialised features suited to the
function
1.
Nerve
cell
Dendrites to make connections with other
neurones.
Pass sensory
impulses
2. Long axon or nerve fibre to carry the
impulse to the target organ.
3.passes messages from 1 neuron to another.
Describe the cell's shape and how
it helps it do it job.
Describe the cell's shape and how
it helps it do it job.
Palisade Leaf CellFilled with green
chloroplasts to get
energy from
sunlight.
Palisade Cell

Designed for Photosynthesis
Nucleus

Found in the top of a leaf

Tall and has a large surface
area to absorb water and
minerals.

Packed with chloroplasts to
help make plant food.
Chloroplasts
Image 4- Leaf Cells
Example of
cell
Leaf palisade
cell
Specific function
Carries out
photosynthesis
Specialised features suited to the
function
1. Packed with chloroplasts containing
the light absorbing pigment
chlorophyll.
2. Regular shaped, closely packed
cells forming a continuous layer for
efficient absorption of sunlight.
VIDEO
Describe the cell's shape and how
it helps it do it job.
Describe the cell's shape and how
it helps it do it job.
Root Hair Cell- Hairlike projection to
absorb water
Root Hair Cell

Designed for
absorbing.
Vacuole
•Thin cell wall
makes it easy for
minerals to pass
through.
thin cell wall
•Has a large
surface which
helps it to
absorb water
and minerals.
Cell membrane
•Found in a plant root.
Root hair cells absorb minerals and water
from the soil
Cross-section of a root hair cell
cell membrane
cytoplasm
contains no chloroplasts
as no photosynthesis is
needed
semi-permeable, so will
allow water and mineral
ions into the cell
root hair cell
increases surface area for absorption of
water and mineral ions
Pollen Cell
Example of cell
Specific function
Specialised features suited to the function
1. Tiny grain with half the genetic information ,
2. Have a hard protective outer coat to survive
bad conditions.
Pollen cell
Helps in plant reproduction
3. Shape and surface of outer coat is adapted to
method of dispersal - eg smooth and sticky for
insect dispersal, larger surface area for wind
dispersal.
4. Germinate on reaching the stigma of another
flower of the same species.
Copy and fill in the gaps:
Some cells have special jobs to do. They often have special
shapes to help them do their job. We say that these cells
are _________________ to do their jobs.
A group of the same type of cells, all working together, is
called a _________________ .
A group of muscle cells all grouped together is called
_________________ . Muscle cells help us to
_________________ .
adapted
move
muscle
tissue
Questions
1.
2.
3.
4.
5.
Why are nerve cells so long?
What is palisade cell specialised to do?
Why does a root hair cell have a thin wall?
How are red blood cells different from other
cells?
Why do the pollen cells have a ‘spiky’
exterior?