Transcript Cell Lecture I

Cell Unit Notes
Lecture I
Cell Biology Standards
in Lecture I
 1c
~ students know how prokaryotic cells,
eukaryotic cells, and viruses differ in
complexity and in general structure
 1e ~ students know the role of the
endoplasmic reticulum and the Golgi
apparatus in the secretion of proteins
 *1j ~ students know how eukaryotic cells are
given shape and internal organization by a
cytoskeleton, cell wall, or both
The Scientists involved in the
Cell Theory

In 1665 Robert Hooke
looked at a slice of cork
under a microscope
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The tiny chambers reminded
him of the “cells” in a
monastery so he called them
cells
In 1674 Anton von
Leeuwenhoek made better
lenses for the microscope
and was able to see cells in
greater detail
The Scientists involved in the
Cell Theory

In 1838 and 1839 Matthias
Schleiden and Theodore
Schwann observed that all
living things are made up of
cells
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Schleiden noted that all plants
are made up of cells
Schwann stated that all
animals are made up of cells
In 1855 Rudolf Virchow
states that all cells come
from pre-existing cells
The Cell Theory
 All
living things are composed of cells
 Cells
are the basic functional units of life
 New
cells are produced from existing cells
Prokaryotes vs. Eukaryotes

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Prokaryotes
smaller & simpler
Contain a cell
membrane &
cytoplasm
Sometimes a cell wall
Also have ribosomes
No nucleus
All bacteria are
prokaryotes
DNA is “free – floating”
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
Eukaryotes
Have a nucleus
containing DNA
 Most have specialized
structures called
organelles
 All plants, animals,
protists, and fungi are
eukaryotes
 Larger and more
complex
Prokaryote vs. Eukaryote
Cell membrane
Cytoplasm
Prokaryotic Cell
Cell membrane
Eukaryotic Cell
Cytoplasm
Nucleus
Organelles
Prokaryotes & Viruses
 Prokaryotes
are simple, living
organisms that can reproduce on
their own
 They have diverse ways of
obtaining nutrients:



Photosynthesis
Chemosynthesis
Heterotrophic consumers
Prokaryotes & Viruses
 Bacteria
(prokaryotes)
live in every habitat
possible and are the
most numerous of all
living things on our
planet
 All living things depend
upon bacteria –
including, especially,
humans!
3 Domains of Life on Earth
Prokaryotes & Viruses
represent the “ancient bacteria” and
they live in extreme environments such as
boiling water or extremely salty environments
 They are the oldest living organisms on this
planet. Evidence suggests that they were
present during the early stages of Earth over
3.9 billion years ago
 Archea
Prokaryotes & Viruses

Bacteria have cell
membranes and
most have a cell wall
 Their DNA is one
circular molecule
 They often have
many plasmids
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
Small circular rings of
DNA usually
containing one gene
Pili help bacteria
“stick” to things
Many bacteria have a
flagellum or many flagella
to help them move
Prokaryotes & Viruses
 Viruses
are extremely
small particles not
considered to be “alive”
 They act like parasites
because they can ONLY
reproduce in a host
 They consist of a protein
coat and contain either
DNA or RNA inside
Eukaryote Cell Structures
 Cell
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Wall
Found in many
organisms including
plants, algae, fungi,
and nearly all
prokaryotes
Not found in animal
cells
Cell Wall
The main function
of the cell wall is
to provide support
and protection for
the cell
Plant cell walls are
made of cellulose
The Nucleus
 The
nucleus is the “control center” of the cell
 The
nucleus controls most cell processes
and contains the hereditary information of
DNA
 Almost
all eukaryotic cells, including plant
and animal, contain a nucleus
The Nucleus
Nucleolus – small
dense region in
nucleus where
ribosomes are
produced
 Nuclear envelope –
double membrane
layer surrounding
the nucleus (aka.
Nuclear membrane)
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The Cytoskeleton

A network of protein
filaments that help the
cell maintain it’s
shape
 It is also involved in
many forms of
Microtubule
movement
Microfilament
The Cytoskeleton
 Made
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up of three types of structures:
Microtubules – hollow tubes of protein that help
maintain cell shape and serve as “tracks” for
organelles to travel on
Intermediate Filaments – smaller than
microtubules – gives a cell its strength
Microfilaments – long thin fibers that support cell
movement and support
Organelles in the Cytoplasm
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Ribosomes
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Organelle that
“assembles” proteins
A ribosome is made up
of 2 parts:
• a protein
• rRNA (ribosomal
RNA)
Ribosomes make
proteins from the “coded”
instructions of the DNA
inside the nucleus
Ribosomes
Endoplasmic Reticulum
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An internal membrane
where parts of the cell
membrane are made and
some proteins are
modified
Rough
endoplasmic reticulum
The Rough
Endoplasmic Reticulum
is where protein synthesis
occurs
 Ribosomes are on it’s
surface making it
appear “rough”
Endoplasmic Reticulum
 The
Smooth
Endoplasmic
Reticulum does
not have any
ribosomes on it’s
surface

It contains
enzymes that
make lipids (fats)
Smooth endoplasmic
reticulum
Golgi Apparatus
Golgi apparatus

After proteins are assembled and produced by the
Rough ER they move to the Golgi Complex where :
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Carbohydrates (sugars) and lipids (fats) are attached to the
protein
They are then sent to their final destination
Lysosomes
 Small
organelles that are
filled with digestive and
other enzymes
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They break down lipids
(fats), carbohydrates
(sugars), and proteins from
food particles so it can be
used by the rest of the cell
Lysosomes also break
down “old” organelles that
have outlived their function
Basically, they “take out the
trash”
Vacuoles

Serve as a storage for
water, salts, proteins,
and “carbs” (plant and
animal cells)
 In Plants :
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They usually have one
large vacuole filled
with water to support
structures like leaves
and flowers
Vacuole
Chloroplasts
 The
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
producer!
They use sunlight to
power a familiar
process called
Photosynthesis
The green pigment
(color) chlorophyll is
what gives leaves
their color and is
found inside
chloroplasts
Chloroplast
Mitochondria
 The
“powerhouse” of
the animal and plant
cell!
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Mitochondria use energy
from food to make highenergy compounds (ATP)
The cell uses these highenergy compounds for
growth, development, and
movement
In that way, the
mitochondria makes “fuel”
for the cell
Typical Plant Cell
Typical Animal Cell