Transcript Life is Cellular Cell Structures & Functions

Life is Cellular
Cell Structures & Functions
Biology I
Introduction to Cells
• Before the 17th century, no one
knew cells existed
• Most cells are too small to be seen
with the unaided eye
• In the early 17th century
microscopes were invented & cells
were seen for the 1st time
• Anton Von Leeuwenhoek, a
Dutchman, made the 1st hand-held
microscope & viewed microscopic
organisms in water & bacteria from
his teeth
• In 1665, an English scientist named
Robert Hooke made an improved
microscope and viewed thin slices
of cork viewing plant cell walls
• Hooke named what he saw "cells“
•
The Cell Theory
The combined work of scientists Schleiden, Schwann, &
Virchow is known as the Cell Theory :
• Principles of the Cell Theory
• All living things are made of one or more cells
• Cells are the basic unit of structure & function in
organisms
• Cells come only from the reproduction of existing cells
Cell Diversity
• Not all cells are alike
• Cells differ in size, shape, and function
• The female egg cell is the largest cell in the body & can be
seen without a microscope
• Bacterial cells are some of the smallest cells & are only
visible with a microscope
Cells come in a variety of
shapes, & the shape helps
determine the function of the
cell
(e.g. Nerve cells are long to
transmit messages in the
body, while red blood cells
are disk shaped to move
through blood vessels)
Basic Structure of a Cell
Introduction to Cells
Cells are the basic units of organisms
Cells can only be observed under
microscope
Basic types of cells:
Animal Cell
Plant Cell
Bacterial Cell
Number of Cells
Organisms may be:
• Unicellular –
composed of one cell
• Multicellularcomposed of many
cells
Cells May be Prokaryotic or
Eukaryotic
Prokaryotes include bacteria &
lack a nucleus or membrane-bound
structures called organelles
 Eukaryotes include most other
cells, have a nucleus and
membrane-bound organelles
Prokaryotes
•Nucleoid region
contains the DNA
•Cell membrane &
cell wall
•Contain ribosomes
to make proteins in
their cytoplasm
Prokaryotic Cell - Bacteria
Eukaryotic Cell
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles
Eukaryotic Animal Cell
Eukaryotic Plant Cell
Two Main Types of Eukaryotic
Cells
Plant Cell
Animal Cell
Cytoplasm
• Entire region between the nuclear membrane and
the cell (plasma) membrane.
• This includes all organelles!
• Jelly-like substance enclosed by cell membrane
Cytoplasm
cytoplasm
Nucleus
• Membrane-bound cellular
organelle in eukaryotes.
• Contains the genes
(DNA)
• Brain of the cell (controls
all activities)
nucleus
Vacuoles
Vacuole
•Large membraneclosed sac
for cellular storage.
• Contains sugars,
proteins, minerals,
wastes, & pigments
Organelles Found in Cells
 Nucleolus – makes ribosomes
 Golgi Bodies– wrap & export
proteins (Modifies, stores and
routes products from the ER to the
plasma membrane)
 Lysosomes – digests & gets
rid of wastes
 Ribosomes- site of
protein synthesis
1
2
3
4
5
6 7 mRNA
incoming
polypeptide
small subunit
Smooth & Rough Endoplasmic
Reticulum
•Smooth ER lacks
ribosomes &
makes proteins
used in the cell
•Rough ER has
ribosomes on its
surface & makes
proteins to export
Mitochondria
• Found in both plants and animal cells.
• It is the site of cellular respiration, a process
that uses energy extracted from organic
macromolecules (like glucose) to produce ATP.
• Also known as the “powerhouse”
Outer
membrane
Inner
membrane
Chloroplast
• Found in photosynthetic plants cells.
• The site of photosynthesis, a process that uses light energy
(sun) and water to produce organic macromolecules (glucose).
Stroma
Outer Membrane
Inner Membrane
Thylakoid
Granum
Plasma (Cell) Membrane
•
•
•
•
The boundary of every cell
Separates the living cell from its nonliving surroundings.
Acts as a selective barrier
Made of protein and phospholipids
Hydrophobic region
Hydrophilic
region
• Network of fibers through out the cytoplasm.
• Aids in cellular support and movement.
• Composed of three components:
1.
Microfilaments - support and cellular contraction
2.
Intermediate filaments - support
3.
Microtubles - support and cell motility
Cilia and Flagella
• Extensions of the plasma membrane.
• Aids in movement….
Cell Wall
Cell wall
• Strong cellulose fibers
surrounding plant cells and some
bacteria only!
• Composed of polysaccharides and
proteins.
• Freely permeable
• Protect and support the
enclosed substances
• Resist entry of excess
water into the cell
• Give shape to the cell
Different kinds of animal cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
Differences between plant
cells and animal cells
Animal cells
Plant cells
Relatively
smaller in size
Relatively
larger in size
Irregular shape
Regular shape
No cell wall
Cell wall present
Differences between Plant
Cells and Animal Cells
Animal cells
Plant cells
Vacuole small or
absent
Large central
vacuole
Glycogen as food
storage
Starch as food
storage
Nucleus at the
center
Nucleus near cell
wall
Levels of organization
• Cells are
grouped
together
and work as
a whole to
perform
special
functions
Levels of Organization
 CELLS
(muscle cells,nerve cells)
 TISSUES (muscle, epithelium)
 ORGANS (heart, lungs, stomach)
 SYSTEMS (circulatory system)
 ORGANISM (human)
It’s You!