Download 1 SNC2P Introduction to Biology 2011

L1 -Introduction to Biology,
Cell Theory
Grade 10 Science
Nicole Klement
What is Biology
 Bio : Life
 Ology: Study of Life
 In Grade 9 Science you studied Ecosystems &
Human activity in your biology unit (the Large
picture)
 This year (Grade 10) year we will study cells,
tissues & organs (the middle picture)
 If you take Grade 11 Biology you will focus on
microbiology (the small picture)
What is Life?
How can you tell something is living…..
Talk to the members at your lab bench and
brainstorm a list of characteristics that
belong to ALL living things.
Characteristics of Living Things
All living things have common characteristics:
 Require food for energy
 Respire break down food for energy
 Limited lifespan
 Respond to the environment
 Grow
 Reproduce
 Produce waste
 Are made of CELL(S)
Did you know?
That viruses do not actually meet the
definition of life as described in the cell
theory?
They are made up of DNA (or RNA),
encased in a protein shell.
You are living. Where did you come from?
Since you fulfill all the criteria for a living
organism you are alive.
If you are alive you are made of cells.
Where did these cells come from?
Cell Theory
Original Cell Theory
The original Cell Theory, developed mainly
in the 1800s, claimed that:
1. All living things are composed of one or
more cells.
2. Cells come from pre-existing cells.
3. Cells are the smallest unit of life.
Modern Cell Theory
The Modern Cell Theory has added several refinements
because of technological advances that have given
scientists a better idea of what actually happens at the
cellular level.
 Cells contain DNA (deoxyribonucleic acid) which
contains their genetic information and it is passed on
each time a cell divides.
 All cells are similar with regards to chemical
composition and metabolic functions.
 All basic chemical and physiological functions are
carried out inside the cell, such as digestion and
locomotion.
 Cell activities are dependent upon sub-structures
known as organelles.
History of cell study
 Robert Hooke (1665) coined the word “cell”
when studying cork cells
 Antonie Van Leewenhoek ( ) created the first
basic microscope allowing him to be the first to
visualize single cells
 Robert Brown (1831) discovered the nucleus
 Theodore Schwann (1838) viewed animal cells
in cartilage and stated “cells may be the basic
unit of plants and animals”
 Virchow (1858) “all cells come from cells”
Did you know?
 That very little progress was made for about 150
years after Hooke and Leuwenhoek, mainly due to a
belief in something called Spontaneous
Generation? This theory claimed that life could be
generated spontaneously and did not have to come
from pre-existing organisms.
 For example, people believed that maggots came
from dead meat, and frogs came from mud. This
was because people didn't know about things they
couldn't see, like fly eggs laid on meat and frog
eggs buried in mud.
Cells
Cell Size
Cells are small (1-100µm)
Cell Surface Area
Cells are small for good
reason (transport):
a)
b)
Surface-to-volume
ratio
Distance from surface
to centre
Cell types
Until high school you learn about TWO cell
types.
a) Animal
b) Plant
These are important to distinguish.
Cell Sub-types
Animal cells are not just of one type (as
you have learned to date).
There are variations.
Different types of Animal cells
But there is more too categorizing cells
There are varieties among animal cells:
a)
Prokaryotic
Ex: Bacteria cell; no nucleus (or other
membrane bound organelles), circular DNA,
ribosomes
b) Eukaryotic
Ex: YOU are made of Eukaryotic cells;
larger, nucleus, linear chromosomes and
membrane bound organelles
Cell Structure
To review cell structure we visited: the
virtual image gallery “cells alive”
Be sure you are comfortable with the
following terms and functions….
Part of a cell - Organelles
Cells are made up of smaller parts called
organelles.
These organelles perform the functions
that the cell needs in order to live, much
like your organs do for you.
Similarities among cells
All cells you’ve study have the same components:
 Plasma membrane (phospholipid bilayer)
 DNA (deoxyribonucleic acid; the Genetic material in
nucleus)
 Cytoplasm (water, salts and organelles)
 Endoplasmic reticulum (synthesis & packaging, rough;
proteins, smooth; lipids)
 Golgi Apparatus (packaging and transport)
 Lysosomes (digest or destroy)
 Mitrochondria (provides energy)
 Cytoskeleton (network of fibres to which organelles
attach)
Differences among Plant & Animal Cells
Plant cells
 Have cell walls
 Have vacuoles
 Have chloroplasts
Animal Cells
 No cell walls
 No vacuoles
 No chloroplasts
(in charge of photosynthesis)
(or photosynthesis)
Organelles specific to Animal vs Plant
cells
 The Animal Cell: In addition to the organelles
listed on the previous page, animal cells contain
centrioles. They play a role in the reproduction
of the cell.
 The Plant Cell: In addition to the organelles
listed on the previous page, plant cells contain
chloroplasts and have a cell wall. Chloroplasts
contain chlorophyll, the chemical that enables
plants to convert sunlight into a useable type of
energy in the form of sugar. Without chlorophyll,
life could not exist. Plant cells also contain
plastids, which store chemicals and pigments.
Why do plants wilt?
Plants have
vacuoles that
maintain
turgor
pressure.
That’s why
water is so
important for
plants!
Did you know?
Did you know that crickets can regenerate
their legs?
Humans have a limited ability to
regenerate lost organs. However, up to
75% of the liver may be lost and have
regeneration.
Children up to the age of 12 may
regenerate severed fingertips.
Tomorrow
Tomorrow’s lecture will cover “cell
reproduction” and will explain how humans
are able to grow and regenerate
Links
Inside a cell
http://learn.genetics.utah.edu/content/begi
n/cells/insideacell/
Cell mitosis
http://www.cellsalive.com/cells/cell_model.
htm
History of cell
http://library.thinkquest.org/12413/theory.ht
ml
For review if needed….
Parts of a Cell

1.
2.
3.
4.
5.
6.
7.
8.
9.
All cells, whether animal or plant, contain the following parts:
Cell membrane - This is a semi-permeable (it allows some things to pass through it and stops
others) membrane that surrounds a cell and allows it to keep its integrity. Think of it like your
skin.
DNA - This is the genetic code that dictates what the cell will be like and what function it will
have. For example, people have 46 chromosomes (bundles of DNA) in their cells. Dogs have
78 chromosomes.
Cytoplasm - This is a gel-like material that fills the spaces inside a cell. It contains water and
nutrients for the cell.
Endoplasmic Reticulum - This is the circulatory system for the cell and it moves materials
around in the cell. It is like your blood vessels. It can be smooth or rough. If it is rough, then it
has ribosomes stuck to it.
Ribosomes - They make protein for the cell and they can be free-floating or attached to the
endoplasmic reticulum.
Golgi Bodies - They store energy for the cell in the form of ATP (adenosine triphosphate).
Mitochondria - They act like your stomach in that they digest food, releasing energy for the
cell. They are known as the powerhouses of the cell.
Lysosomes - They contain chemicals that break down dead organelles and other types of cell
waste.
Vacuoles - They are storage areas where the cell can place chemicals and other substances,
like food, that it will need later. Think of them like your fat cells. Animal cells have many small
vacuoles, while plant cells have a few large ones.