Transcript Prentice Hall Science Explorer Cells and Heredity

Holt
Cells, Heredity and
Classification
Chapter 1:
The Basic Units of Life
Section 1: Diversity of Cells
• Cell – the smallest unit that can
perform all the processes necessary
for life
- cells are covered by a
membrane and have DNA and
cytoplasm
Section 1: Diversity of Cells
• Cells - the basic units of structure
and function in living things.
Carry out all of organism’s
processes, such as:
obtaining oxygen, getting rid
of waste, obtaining food,
growing
Form the parts of
an organism
First Observations of Cells
• Microscope - an instrument that
makes small objects look larger.
• Made it possible to discover / learn
about cells
First Observations of Cells
Simple Microscope
• One lens
Compound Microscope
• More than one lens
Robert Hooke
• English scientist / inventor
• One of the first people to observe cells
• 1665 - used his microscope
to observe a piece of cork
• Called the empty spaces
cells - “little rooms”
• Thought animals weren’t made
of cells since their cells didn’t
have walls
Anton van Leeuwenhoek
• Dutch businessman
• 1673 built his own microscopes
• Observed fast-moving
one-celled organisms in pond
scum/water… called these
animalcules
• Also observed blood,
bacteria and yeast cells
Anton van Leeuwenhoek
• Leeuwenhoek is a long, unusual
word like animalcules
Development of
The Cell Theory
• Almost 200 years passed before
scientists concluded that cells are
present in all living things
• 1838 – Matthias Schleiden concludes
that all plants are made of cells
Development of
The Cell Theory
• 1839 – Theodor Schwann concluded that
all animal tissues were made up of cells
• Schwann wrote first 2 parts of Cell Theory
1) All organisms are made of one or more
cells
2) The cell is the basic unit of all living
things.
Development of
The Cell Theory
• 1858 – Rudolf Virchow, a doctor,
stated that all new cells could form
only from other cells that already
exist
• This then added the third part of the
Cell Theory
3) All cells come from existing cells
The Cell Theory
• The cell theory states that:
1) All organisms are made of one or
more cells
2) The Cell is the basic unit of all
living things.
3) All cells come from existing cells.
Cell Size
• Most cells are too small to be seen
without a microscope
• No one knew cells existed until they
could see them with a microscope
Skin cells
Cell Size
• As a cell’s volume increases, it’s
surface area grows too.
surface area
surface area-to-volume ratio = volume
Parts of a Cell
• Cell membrane = a protective
layer that covers the cell’s
surface and acts as a barrier
between inside of a cell and the
cell’s environment (outside)
Parts of a Cell
• Cell membrane - controls what
substances enter or leave the cell.
1 = cell wall
2 = cell
membrane
Parts of a Cell
• cell membrane - controls what
substances enter or leave the cell.
- all cells have them
- acts like a window screen
Parts of a Cell
• cytoplasm = fluid inside a cell
Parts of a Cell
• organelles - structures that perform specific
function within the cell.
organs
- structures that
carry out functions
in a body
organelles
- structures that
carry out functions
in a cell
Different types of cells
have different organelles
Parts of a Cell
• Nucleus – in a eukaryotic cell; a membrane
bound organelle that contains the cell’s
DNA and has a role in processes such as
growth, metabolism and reproduction
• the cell’s control center
• Acts as the brain of the
cell
Two Kinds of Cells
• prokaryote = an organism that
consists of a single cell that does
not have a nucleus
• Eubacteria and
Archaebacteria
Two Kinds of Cells
• eukaryote = an organism made
up of cells that have a nucleus
enclosed by a membrane
• animals, plants
and fungi
Section 2:
Eukaryotic Cells
Cell Wall
• cell wall - a rigid structure that
surrounds the cell membrane and
provides support to the cell
Onion cells
• Plants and algae
have cell walls made
of cellulose
• Fungi –yeast and
mushrooms
Eukaryotic Cells
• cell wall - a rigid layer of nonliving
material that surrounds the cells of
plants and some other organisms.
– Helps to protect and support the cell
– Made mostly of cellulose (a strong
material)
– Allows some materials (such as water
and oxygen) to pass through
Cell Membrane
• All cells have a cell membrane
• Protective barrier that encloses a
cell
• Separates contents
from environment
• a gel-like fluid
• Contains proteins,
lipids, and
phospholipids
• Lipids – include fats and cholesterol,
are a group of compounds that do
not dissolve in water
• Phospholipids – a lipid that contains
phosphorous
Cytoskeleton
• a web of proteins in the cytoplasm
• acts as both a muscle and a
skeleton
• keeps the cell’s
membranes from
collapsing
• helps some cells move
• made of 3 types of
proteins
Nucleus
• all eukaryotic cells have a nucleus
• a large organelle
• contains the
cell’s DNA =
genetic material
Nucleus
• Nucleus has a
dark area of
many cells called
the nucleolus
which is where a
cell begins to
make its
ribosomes
Ribosomes
• ribosomes – cell
organelle
composed of
RNA and protein;
the site of protein
synthesis (small,
grainlike bodies
that produce
proteins)
Ribosomes
• ribosomes - small,
grainlike bodies
that produce
proteins.
important
chemicals
needed to carry
out bodily
functions.
Protein Jobs
Endoplasmic Reticulum
• endoplasmic
reticulum – a
system of folded
membranes that
in which proteins,
lipids and other
materials are
made
Endoplasmic Reticulum
• The internal delivery
system of the cell
• Its folded
membranes contain
many tubes and
passageways
• Substances move
through the ER to
different places in
the cell
Rough ER
• Covered in
ribosomes
• Usually found near
nucleus
• Ribosomes on rough
ER make many of
cell’s proteins
• ER delivers these
throughout the cell
Smooth ER
• Not covered in
ribosomes
• Functions include
making lipids and
breaking down
toxic materials
that could
damage cell
Mitochondria
• mitochondria –
main source of
power in a cell
- where sugar is
broken down to
produce energy
Mitochondria
• energy released
by mitochondria
is stored in a
substance
called ATP
which a cell
used to do work
Chloroplasts
• chloroplasts –
where
photosynthesis
takes place
sunlight + CO2 + H2O
=(makes) sugar + O2
Chloroplasts
• only found in
plant and algae
• contain
chlorophyll =
makes plants
green
Golgi Complex
• Golgi complex -
receives proteins
and other newly
formed materials
from the
endoplasmic
reticulum, packages
them, and
distributes them to
other parts of the
cell, or outside the
cell.
Golgi Complex
• Lipids and proteins from ER may be
modified to do different jobs
• Final products are enclosed in a piece of
golgi complex’s membrane that is
pinched off – forms a bubble and is
transported to other parts of cell or out of
cell
Vesicle
• The bubble that
forms from the
golgi complex’s
membrane is a
vesicle
• A small sac that
surrounds material
to be moved in or
out of cell
Lysosomes
• lysosomes – vesicles responsible for digestion
inside a cell
• contain digestive enzymes
• destroy worn out or damaged organelles, get rid
of waste materials and protect cell from foreign
invaders
• mainly in animal cells
Organelles in the Cytoplasm
• vacuoles – large vesicle
• In plants & fungi may
act like lysosomes
• Store digestive enzymes
and aid in digestion
within cell
• Other vacuoles in plant
cell store water and
other liquids to help
support cell (or will wilt)
Section 3
The Organization
of Living Things
Benefits of Being
Multicellular
Larger size: even if small still larger than
single celled organisms
Longer life: life span not limited to that of a
single cell
Specialization: each type of cell has a
particular job making the organism more
efficient
Cells Working Together
• A tissue is a
group of cells
that work
together to
perform a
specific job.
Tissues
• Animals have 4
basic types of
tissues:
• Nerve tissue
• Muscle tissue
• Connective tissue
• Protective tissue
TIssues
• Plants have
three types of
tissues:
• Transport tissues
• Protective
tissues
• Ground tissues –
where photosynthesis
takes place
Tissues Working Together
• A structure that is
made up of two or
more tissues
working together
to perform a
specific function is
called an organ
Plants also have organs – example a leaf is a plant organ
Organs working together
• A group of
organs working
together to
perform a
particular
function is
called an organ
system.
Organisms
• Anything that
perform life
processes by
itself is an
organism.
• An organism
can be single
celled or
multicellular.
Organization of Cells
cell
tissue
organ
organ system
Structure and Function
• In organisms, structure
and function are
related.
• Structure is the
arrangement of parts
in an organism.
• Function is the job the
part does.