Download Inside and Out!—A Look From Within

The Cell
Packet #11
Thursday, August 3,
2017
1
Cytology

The study of cells.
 There are two basic types
– Prokaryotic cells
– Eukaryotic cells
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The Discovery

Cells discovered by Robert Hooke in 1665
– However the subcellular structures could not be
seen--the organelles

It wasn’t until the 1950’s, with the
invention of the electron microscope that
cell biology really took off
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Organelles Isolation

Can be isolated by a process called cell
fractionation
– Taking cells apart and separating the major organelles
so that their individual function can be isolated
– Centrifuge


Is the instrument that is used to fractionize cells
Spins fast as much as 80,000 revolutions per minute and apply
forces on particles up to 500,000 times the force of gravity
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Organelle Isolation II

Micromanipulation
– Another technique for the removal of parts of the cell
– Can also insert material into a living cell
– Done while looking through a microscope
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In-Vitro Fertilization
In-Vivo Fertilization
Cell Cultures**
– Isolate one type of cell and you grow it in large
numbers--bacteria for example
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Cell Theory

Observations and conclusions from various
scientists
– All living things are composed of cells
– Cells are the basic units of structure and
function in living things
– All cells come from preexisting cells
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Prokaryotic versus Eukaryotic

Prokaryotic
– No nuclear membrane


No nucleus
Lack membrane bound organelles
– No chromosomes--circular strands of DNA
– May contain chlorophyll but not chloroplasts
– Small Ribosomes
– Cell wall is present**
– No mitosis or meiosis occurs
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2017
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Prokaryotic versus Eukaryotic
II

Eukaryotic Cells
– Nuclear membrane is present
 Nucleus is present
 Membrane bound organelles
– Chlorophyll when present, contained in
chloroplasts
– Ribosomes are larger
– Cell wall is present in some
– Mitosis and meiosis occurs
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Eukaryotic Cells

Most organisms are composed of eukaryotic
cells.
 There are two basic types
– Plant cells
– Animal cells
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Plant Cells





Cell wall that contains cellulose
Large vacuole filled with cell sap
Larger than animal cells
Shape**
Cilia and flagella absent in higher plants
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2017
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Animal Cells





No cellulose cell wall-only membrane
Some vacuoles but usually small and numerous
Cytoplasm throughout the cell
Nucleus anywhere in cytoplasm by often central
Cilia common in higher animals
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2017
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Cell Specialization
{Animal Cell}

Cells are often uniquely suited to perform a
particular function within the organism
– Nerve Cells
– Muscle Cells
– Rods and Cones in the eye
– Sex cells
– Determined by complex processes of turning on
and off genes.
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Plant Cell vs. Animal Cell

Similarities
– Both Eukaryotic Cells
– Have membrane bound organelles

Differences
– Plant cells are “generally” larger than animal cells
– Plant cells have a cell wall of cellulose

Adds stability and protection to the plant cell
– Plant cells have vacuoles


That are used as space fillers
Fulfils digestive functions in plants--similar to lysosomes that
are also found in plant cells.
– Animal cells have centrioles
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2017
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Cell Structure and Function I

Chromatin
– The complex of DNA and histome proteins
which make up chromosomes in eukaryotic
cells

Chromosomes
– Long threadlike association of genes composed
of chromatin and found inside the nucleus of
the cell

Nucleolus
– The region of the eukaryotic nucleus that
engaged in ribosome synthesis
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2017
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Cell Structure and Function II

Nucleus Structure
– Contains a eukaryotic cell’s genetic library

Nucleus Function
– In eukaryotic cells, this is a membrane bound organelle that
contains the cell’s genetic material
– Acts as the control center for the cell
– Produce ribosomes and RNA*
– Play an essential role in cell division

Nuclear Envelope
– Surrounds the nucleus
– Contains nuclear pores
 Allow things in and out of the nucleus
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Cell Structure and Function II
Rough or Smooth?

Rough Endoplasmic Reticulum
– Functions in the synthesis and transport of proteins
– This is where we find ribosomes

Smooth Endoplasmic Reticulum
– Functions in the synthesis and transport of lipids
– There are no bound organelles—that is why they look
so smooth

Ribosomes
– Cytoplasmic organelle that is the site for protein
synthesis
– Small complex particles consisting of proteins and
RNA
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Cell Structure and Function III

Golgi Apparatus
– Stack of membranous sacs
– Packages and distributes lipids and proteins that form in
the ER
– If we have time we will have a closer look at this
process
– Something inportant—know the ends and structure

Cis—entry; Trans—exit—People always forget this
– Vesicles enter and leave here

Lysosome
– Contains digestive enzymes that degrades the cell and
other malfunctioning organelles
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Cell Structure and Function IV

Peroxisome
– Contains enzymes that carry out redox reactions
and is key in detoxification of drunks

Mitochondria
– This is where we produce our energy—AKA
ATP
– We’ll get all up in the Kreb’s cycle soon 
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2017
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For Biology 1 Honors Only

Cells are composed of filaments
– Microtubules
– Microfilaments
– Intermediate filaments
 Details to come in AP Biology
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2017
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Other Important Features in
the Cell

Chloroplasts
– In plants—used in photosynthesis
– We’ll get to know this process later as well
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2017
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Cell to Cell Connections

Tight Junctions
 Gap Junctions
 Desomeres
– Details to come in AP Biology
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2017
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Components of the Cell Membrane

Microfilaments, Microtubules and Intermediate
filaments—we have already touched—but what
else is there?
 Glycoproteins
 Carbohydrates
 Cholesterol
– Used in rigidity and fluidity of the membrane

Peripheral Protein (small) and Integral (big)
proteins—useful in hormonal signals—later
 IT IS IMPORTANT TO KNOW WHAT
EVERYTIHNG LOOKS LIKE AND WHERE
THEY ARE IN THE CELL MEMBRANE
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2017
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Diffusion

Ok, now that we know some of the ways proteins
enter organelles (from earlier), let’s have a closer
look at some mechanisms in which how molecules
and proteins are transported across the membranes
of these organelles.
 Firstly let’s define the word Diffusion
– The three types of diffusion



Regular Diffusion—we travel down the concentration
gradient—no energy is required
Facilitated Diffusion—we travel down the concentration
gradient using a protein molecule--no energy is required
Active Transport—flow of molecules against the concentration
gradient with the use of a protein molecule--ATP (energy) is
required.
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2017
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2017
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Diffusion II

Which of the two previous are considered
passive transport and why?
– Regular and facilitated—reason is because
there is no use of energy

Examples
– Active transport—transport of proteins
through nuclear pores
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2017
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Diffusion III

Migration of substances from regions or
high concentration to regions of low
concentration.
– Occurs in our lungs--CO2 out O2 in
 Regular Diffusion
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2017
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Diffusion IV

Special Diffusion
 Osmosis
– Notes from Previous Lecture

Solution
– Solvent--Major
– Solute--minor
– Transfer of a liquid solvent through a semi permeable
membrane that does not allow dissolved solids (solutes)
to pass.
– Osmosis refers only to the transfer of the solvent.
– High Concentration to an area of low concentration.
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2017
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