Download Structure and Function of the Cell

Structure and
Function of the Cell
CH. 7 Section 1 & 2
Introduction
A. A cell is the smallest unit that can carry on the
processes of life.
B. A unicellular organism is a complete living
thing that is only one cell.
EX: paramecium, amoeba
C. A multicellular organism is a living thing that
consists of more than one cell.
EX: human, buttercup
Discovery of the Cell
 Development and refinement of
magnifying lenses and light
microscopes made the observation
and description of microscopic
organisms and living cells possible.
Discovery of the Cell
Began in the 1600's
A. Robert Hooke
1. Cut a thin slice of cork and
observed it with a microscope
2. Observed "little Boxes" that
reminded him of the small rooms
where monks lived, so he called
them cells. (He observed dead
cells)
Discovery of the Cell
B. Anton von Leeuwenhoek
1. The first person to observe
living cells.
2. He was a microscope maker
Discovery of the Cell
C. Led to the CELL THEORY
1. All living things are composed of
one or more cells.
2. Cells are organisms' basic units
of structure and function.
3. Cells come only from preexisting cells, by cell
reproduction.
Cell Diversity
Not all cells are alike, even within the same
organism
1. Size
 Range from 2 m (nerve cells of a giraffe's
leg) to 0.2 micrometers (some bacteria))
2. Shape
 Most are roughly cuboidal or spherical
 Some change shape (white blood cells)
3. Internal organization
 Some have membrane-bound organelles
and nuclei, some do not.
Prokaryotic and Eukaryotic Cells
A. Earth's 1st cells were prokaryotic
B. Prokaryotic cells exist in two major forms:
1. Eubacteria
2. Archaebacteria
C. Prokaryotes are the Earth's most abundant
inhabitants. They can survive in a wide range
of environments and obtain energy in a variety
of ways.
D. Eukaryotes arose from prokaryotes and
developed into lager more complex organism
from single-celled Protista to multi-cellular
fungi, plants and animals
Prokaryotic vs Eurkaryotic Cell
Differences between Eukaryotes
and Prokaryotes
Prokaryotes
Eukaryotes
0.1 micrometer (m)-10 m
10 m-100 m
genetic material NOT
surrounded by a nuclear
membrane (NO NUCLEUS)
genetic material surrounded
by a nuclear membrane
(HAVE A NUCLEUS)
NO membrane bound
organelles
HAVE membrane bound
organelles (mitochondria or
chloroplasts)
Parts of a Cell
A. The Cell membrane separates the cell from its
external environment.
1. made of lipids and proteins
2. lipids are waterproof
3. proteins allow food in and waste out
a. selectively permeable (semipermeable )only allows some molecules in and out of
the cell.
4. It flows- it is called the FLUID-MOSAIC
MODEL
Parts of a Cell
B. The Cytoplasm is a thick salty fluid that
protects the organelles.
1. It also flows: Cytoplasmic streaming
Parts of a Cell
C. There are 8 organelles ("little organs") present in
Eukaryotes.
Ribosomes
Endoplasmic Reticulum
Golgi apparatus
Mitochondria
Lysosomes
Nucleus
Plastids
Vacuoles
Parts of a Cell
D. Ribosomes: site of protein synthesis.
1. Most numerous organelle
2. Ribosomes floating freely make
proteins for the cell
3. Ribosomes attached to ER make
proteins for export to other cells.
Parts of a Cell
E. The Endoplasmic Reticulum (ER): a
system of folded sacs and tunnels
through which products made by the
cell are transported.
1. Rough ER is covered with ribosomes
2. Smooth ER has few or no ribosomes. It is
an intracellular highway.
Parts of a Cell
F. Golgi Apparatus: Cell products are
packaged for export
Parts of a Cell
G. Mitochondria: The powerhouse
1.
2.
3.
4.
5.
ATP is formed for later use.
Usually large
Identified by internal folds
Muscle cells have many Mitochondria
Mitochondria have their own DNA
a. They might have evolved from
Prokaryotes living Symbiotically in
Eukaryotes many millions of years ago.
Parts of a Cell
H. Lysosomes contain digestive enzymes.
a. In animal, fungus, and carnivorous
plant cells.
b. They digest food, bacteria, and old
cell parts
Parts of a Cell
I.
Microtubules and Microfilaments
a. support "skeleton" of the cells.
b. Special MT's called spindle fibers
move DNA during cell division
Parts of a Cell
J. Cilia and Flagella: locomotion
(movement) and feeding.
a. A paramecium has 17,000 cilia for
locomotion
b. A sperm's tail is the most familiar
flagellum
Parts of a Cell
K. The Nucleus: contains the genes (DNA)
of the cell. Site where RNA is made.
1. It is surrounded by a double membrane
(nuclear envelope) perforated with pores.
2. Contains Chromosomes, which are rod
shaped structures containing DNA and
protein.
3. The Nucleolus is also found in the nucleus.
It produces ribosomes. The nucleus
controls the cell's functioning.
Parts of a Cell
L. Vacuoles and Plastids: only in plants
1. Vacuoles: storage areas for enzymes and
waste products
2. A Vacuole can take up 90 % of the cell.
3. Plastids store food and pigment needed by
the plant.
4. Chloroplasts store chlorophyll (green)
(PHOTOSYNTHESIS)
5. Leucoplasts store starches, proteins,
and lipids.
6. Chromoplasts synthesize and store
pigments which function in trapping
sunlight
Parts of a Cell
M. Plant cells are also identified by their
cubic shape from the Cell Wall
1. Supports and protects cell.