Transcript THINK ABOUT IT - MacWilliams Biology

Cell Structure and
Function
Mrs. MacWilliams
Academic Biology
Levels of Organization
Atoms  molecules  macromolecules 
organelles  cells  tissues  organs 
organ systems  organism/species  populations 
community  ecosystem  biome  biosphere
I. DISCOVERY OF THE CELL
1665 (England) Robert Hooke- used
compound microscope to look at
cork  Looked like “cells”.
1673 (Holland) Anton van
Leeuwenhoek look at pond water
and samples from a human mouth 
discovered bacteria
A. Cell Theory
1. All living things are made up of cells.
2. Cells are the basic units of structure
and function in living things.
3. All cells are produced from existing cells.
B. Prokaryotes and Eukaryotes
1. Smallest cell  Mycoplasma bacteria are only 0.2
micrometers
2. Largest cell  Ostrich egg
3. All cells contain the molecule that carries biological
information—DNA.
4. All cells are surrounded by a thin, flexible barrier called a cell
membrane
5. Cells fall into two broad categories, depending on if
they contain a nucleus.
C. Form follows function
1. Examples:
a. Skin cells:
flat, tightly packed because they protect/cover
b. Nerve cells:
long & stringy because they transmit impulses
c. Red blood cells (RBCs):
small & doughnut shaped because they carry O2
D. Prokaryotes
1. cells that do not enclose DNA in a nucleus
2. Generally smaller and simpler than eukaryotic cells
3. Bacteria are prokaryotes
E. Eukaryotes are cells that DO enclose their DNA in a
nucleus!!!!
1. Generally larger and more complex than prokaryotic cells
2. Eukaryotic cells are highly specialized
3. Plants, animals, fungi, and organisms commonly called
“protists”
II. Cell Structure
A. Cell Organization
1. Cellular structures act as if they are specialized organs known
as organelles, literally “little organs.”
2. Cytoplasm - gel-like fluid surrounded by plasma membrane,
where organelles are found
3. Eukaryotic cells are much like a living version of a modern
factory with specialized machines and assembly lines = different
organelles
4. Cells, like factories, follow instructions and produce products
with the main product being PROTEINS!!!!
B. Nucleus- control center of the cell
1. Contains nearly all the cell’s DNA and the instructions for
making proteins
2. Surrounded by a nuclear envelope composed of two
membranes.
3. Nuclear envelope has thousands of pores, which allow material to
move into and out of the nucleus.
4. Chromosomes contain genetic information that is passed
from one generation of cells to the next.
5. Chromosomes are spread throughout the nucleus in the
form of chromatin—a complex of DNA bound to proteins.
6. Most nuclei also contain a
small, dense region known as
the nucleolus.
7. The nucleolus is where the
assembly of ribosomes begins.
Organelles That Store, Clean Up, and Support
A. Vacuoles
1. Large, saclike, membrane-enclosed structures that store
materials such as water, salts, proteins, and carbohydrates.
2. Plant cells single, large central vacuole filled with liquid
B. Vesicles
1. Smaller membrane-enclosed structures used to store and
move materials between cell organelles of eukaryotes
C. Lysosomes
Lysosome Animation
(lysis = to split soma=body)
1. Filled with enzymes that function as the cell’s “cleanup
crew”  breakdown of lipids, carbohydrates, and proteins into
small molecules that can be used by the rest of the cell.
2. Sometimes called “suicide sacks”  autolysis
D. Cytoskeleton
1. Give Eukaryotic cells support and internal
organization by a network of protein filaments
2. Microfilaments- threadlike structures that form
networks in cells and produce a tough, flexible
framework that also help cells move.
3. Microtubules- hollow structures made up of
proteins that play critical roles in maintaining cell
shape and are important in cell division
4. Centrioles- In animal cells, located near the
nucleus and help to organize cell division.
Organelles That Build Proteins
A. Ribosomes
1. Small particles of RNA and protein found throughout the cytoplasm
in all cells
2. Produce proteins by following coded instructions that come from
DNA
Ribosome = machine in a factory  proteins
DNA = boss giving orders to make proteins
B. Endoplasmic Reticulum
1. In eukaryotic cells  internal membrane system where lipids
are made for the cell membrane, along with proteins and other
materials that are exported from the cell.
2. Rough ER- involved in the synthesis of proteins It is given this
name because of the ribosomes found on its surface.
3. Smooth ER- ribosomes are NOT found on its surface
(therefore does not make proteins- MAKE LIPIDS!)
C. Golgi Apparatus
1. Rough ER makes proteins  are bundled into tiny vesicles that bud
from the ER  move into Golgi apparatus
2. Golgi apparatus modifies, sorts, and packages proteins and other
materials from the ER for storage in the cell or release outside the cell
3. From the Golgi apparatus, proteins are “shipped” to their final
destination inside or outside the cell.
KNOW: The Life of a Protein Molecule
The NUCLEUS holds the instructions (DNA) to
make proteins  translated instructions and sent
out nuclear pores to cytoplasm  ROUGH ER where
RIBOSOMES make PROTEIN protein “buds” off
into a transport VESICLE goes through cytoplasm
to GOLGI APPARATUS  Golgi modifies and
packages protein  protein buds off into a transport
VESICLE goes to PLASMA MEMBRANE and
fuses  protein leaves the cell (exocytosis)
THIS IS AN ESSAY ON THE EXAM. MEMORIZE AND BE ABLE TO EXPLAIN
EACH STEP!
http://wps.pearsoncustom.com/wps/media/objects/3014/3087289/Web_Tutorials/0
4_A02.swf
Organelles That Capture and Release Energy
A. Chloroplasts
1. Plants and some other
organisms contain
chloroplasts.
2. Biological equivalents of
solar power plants. They
capture the energy from
sunlight and convert it into
food that contains chemical
energy in a process called
photosynthesis.
3. Two membranes surround chloroplasts.
4. Inside the organelle are large stacks of other membranes, which
contain the green pigment chlorophyll.
B. Mitochondria
1. All eukaryotic cells, including plants, contain mitochondria.
2. Two membranes enclose mitochondria.
3. Mitochondria are the power plants of the cell.
4. Convert the chemical energy stored in food into usable
compounds.
ENDOSYMBIOTIC THEORY!
 Endosymbiotic theory proposes that MITOCHONDRIA
AND CHLOROPLASTS were once prokaryotic cells.
They were ingulfed by larger eukaryotic cells and
began living inside the host cells. The prokaryotes
may initially have been parasites or even an intended
meal for the larger cell, somehow escaping digestion.
 Endosymbiosis
Key evidence for endosymbiotic theory
 Mitochondria and chloroplasts divide by binary fission, just as bacteria
do, and not by mitosis as eukaryotes do.
 Mitochondria and chloroplasts have their own single, circular DNA and
their own ribosomes
 Mitochondria and chloroplasts are similar in size and shape to bacterial
prokaryotic cells.
 Mitochondria and chloroplasts have similarities in membrane structure
and function to prokaryotic cells.
 Mitochondria and chloroplasts have similar enzymes to prokaryotic cells.
CELLULAR BOUNDARIES
1. Cell Wall - maintains shape of cell (only very specific
things go in and out of the cell wall)2. Cell/Plasma membrane - phospholipid bilayer, regulates
what goes in and out of a cell. (more goes in and out of cell
membrane)
Plant vs. Animal Cells
DIFFERENCES
1.
2.
3.
4.
5.
6.
Plant
Cuboidal
LARGE vacuoles
Chloroplasts
Cell wall
NO Centrioles
NO lysosomes
1.
2.
3.
4.
5.
6.
Animal
Spherical
Few (if any) vacuoles
NO Chloroplasts
NO cell wall
Centrioles
lysosomes
Plant vs. Animal Cells
SIMILARITIES
BOTH
1. Eukaryotic- has membrane bound nucleus
and organelles (all organisms except
bacteria are eukaryotic)
*Bacteria are PROKARYOTIC
2. Nucleus
3. Cell (plasma) membrane
4. Golgi Body/Apparatus
5. Mitochondria
6. ER
7. ribosomes
Plant Cell Anatomy
Animal Cell Anatomy