Transcript Cells - TeacherWeb

Cells
All living things are made
up of cells. They are the
basic units of structure and
function in all living things.
Introduction to Cells
Living things can be Unicellular:
-An organism made of only one cell
-examples: amoeba, paramecium, bacteria
Paramecium
Bacteria
Amoebas
Single-Celled
Organisms
Or multicellular…
-An organism made up of more than one
cell, having various functions
-example: animals, plants, fungus
Many-celled organisms
Animal vs. Plant Cells
The 2 main types of cells are:
1. Animals Cells
AND
2. Plant Cells
Cell Structure
Most cells have three basic structures in
common:
1. Cell membrane
2. Cytoplasm
3. Nucleus (Chromosomes/DNA)
Cell Membrane & Cell Wall
Cell Membrane
Function:
1. To hold the cell together
2. Controls what goes in & out of the cell
3. Keeps cell’s contents separate from
external environment
Cell Membrane
Composition:
Lipid Bilayer- Made of phospholipids
Hydrophilic: “Water loving”
Hydrophobic: “Water hating”
Cell Wall
1. Pectin Layer: Outer
2. Primary Cell Wall: Middle
3. Secondary Cell Wall: Inner
Nucleus
Instructions for cell function command
center...
Prokaryotes: No nucleus (bacteria)
Eukaryotes: Have a nucleus (all other cells)
1. Nuclear envelope: Pourous membrane
that surrounds the nucleus
2. DNA: Deoxyribonucleic Acid-instructions
for
cell activity
(located in the
Nucleolus)
Cytoplasm
A mix of protein, water & other particles ->
organelles suspended in it
Function: Where cell’s activity takes place.
Organelles within the Cytoplasm:
1. Energy Factories
A. Mitochondria: Power-house of cell
Function: Inner & Outer membrane
breaks down food molecules so that cell can
get energy (in the form of Glucose)
Mitochondria
B. Chloroplasts: Only found in plant cells
Function: Stores chlorophyll used for
photosynthesis
Chloroplasts
2. Ribosomes: Tiny structures floating in
cytoplasm or attached to Rough ER
Function: the place where protein is
synthesized (made) with the help of
mRNA (messenger RNA is formed in the
nucleus)
Ribosomes
3. Endoplasmic Reticulum (ER): Network
of membranes attached to nucleus.
Function:
A. Smooth ER: Creates steroids, collects and
stores ions to keep correct levels of nutrients in
the cell.
B. Rough ER: Collects proteins, creates a
bubble around them (vesicle), sends them to
golgi apparatus or through cell membrane.
4. Golgi Apparatus: Made up of a stack of
flattened out sacs (like pancakes)
Function:
-Collects vesicles from Rough ER… Takes the
simple molecules and combines them together
to make larger molecules, then packages them
into packs called Golgi vesicles for exportation
and lysosomes.
5. Lysosomes: Vesicles that Hold
enzymes to break down food & old
organelles.
6. Vacuoles: Bubbles that hold waste &
food (larger in plant cells because it helps
support cell wall).
Function: to store and transport waste &
food within the cell.
7. Cytoskeleton: Made up of proteins, can
change their shape to move cell.
A. Microtubules: help maintain shape, thicker
than microfilaments & more abundant
B. Microfilaments: helps maintain shape also,
found in muscle cells… pulls & releases for
relax and contracting of muscle.
Movement of materials
through the Cell Membrane
Passive Transport
1. Diffusion: Molecules move from area of
higher concentration to area of lower
concentration while trying to reach
equilibrium.
2. Osmosis: Movement of WATER through
membrane to obtain equilibrium.
Facilitated Diffusion: Large molecules move
through large proteins located in the
membrane.
Active Transport
Endocytosis1. Phagocytosis: taking in “food” molecules
from the external environment by pinching off
cell membrane to create a vacuole.
2. Pinocytosis: taking in liquids by the same
method as above.
pinocytosis
Phagocytosis
* White blood cells use endocytosis to
engulf harmful bacteria in our blood
stream...
Exocytosis:
4. Exocytosis: Opposite of phago &
pinocytosis- process of expelling waste
molecules.
Levels of Organization
Types of cells:
1. Muscle Cells-smooth cells, found in
cardiac muscles, digestive, urinary,
reproductive, and skeletal muscles as well
as veins and arteries.
2. Nerve Cells:
Axon, dendrite, body
3. Blood Cells: Red & White
4. Sex Cells: Sperm & Ovum
5. Epithelial: lining of organs, body
cavities & skin
B. Tissues
Similar kinds of cells that work together to
perform the same function.
Types of Tissue:
1. Epithelial
2. Nervous
3. Muscle
4. Skeletal
C. Organs
A structure in the body made up of
several types of tissues that work together
to perform a particular task.
Example: heart, skin, intestines, kidney,
brain, etc.
D. Organ Systems
Groups of organs working together to
perform a specific task.
Example: circulatory, nervous,
reproductive, lymphatic, etc.
The highest level of organization is an
ORGANISM: several organ systems
working together to achieve homeostasis
(balance).