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Chapter 3
CELL CTRUCTURE AND FUNCTION
Part 1: ORGANELLES, MEMBRANE, AND TRANSPORT,
Part 2: NUCLEUS/DNA/PROTEIN SYNTHESIS
Part 3: CELL CYCLE, CELL DIVISION
The study of cells- Cytology
Cyto- cell
logy- the study of
• Cells are very, very small…..so we can not see them. So we need to use a
microscope (instrument used to enlarge the image of something small)
• Light microscope: uses a series of glass lenses and a light source, low
magnification
• TEM microscope: uses electrons to shoot at the object, can see inside, very
high magnification
• SEM microscope: uses electrons to shoot at the object, very high
magnification, only see outside (3-D image)
Cell Theory (many scientists have added input to come up with
this theory that is true for any cell)
1)
2)
3)
4)
Cells are the building blocks of any living thing
Cells are the smallest functioning unit of life
Cells are produced through the division of other cells
Each cell maintains homeostasis individually and as a whole unit
Organelles
• Outside of Cell:
• Cell Membrane- protects and
covers cell from external
environment
• Flagella- tail like structure that
helps cell move (sperm)
• Cilia- tiny hairs that move
materials over cell surface
Nucleus- found in center of cell and used to
store DNA (info to make proteins)
• Nuclear Membrane/envelopeProtects and covers the nucleus
• Nucleoplasm- liquid inside the
nucleus
• Nucleolus- makes RNA for
building proteins
• Nuclear Pores- tiny holes in the
nucleus for the escape of RNA
Organelles involved in making Proteins (four amigos)
• Starting with the nucleus:
1) Rough Endoplasmic Reticulum (rough
ER)- has ribosomes attached to it,
storage and transport of proteins
2) Ribosome- where proteins are put
together (made), attached or free
3) Golgi Body- packages, process, and
ships of proteins to where they need
to go
4) Vesicle- form of transportation for
protein, breaks off of the Golgi
Other Organelles inside the cell
• Mitochondria- place for cellular
respiration, turning food and oxygen
into ATP (energy)
• Lysosomes- float around the cell and
kills bad stuff
• Smooth Endoplasmic Reticulum
(smooth ER)- makes and transports
lipids (fats)
• Centrioles- used for cell division,
shoots out spindle webs
• Cytoplasm- Liquid that fills the cell
made up of nutrients, ions, and waste
products
12)
11)
1)
2)
10)
3)
4)
9)
5)
6)
7)
8)
The Cell Membrane
• What does it do?
• Covers and protects the cell
• Controls what leaves and what
enters the cell (semi-permeable)
• Gives support
• Helps maintain homeostasis
• What is it made up of?
• Bi-lipid layer
• Hydrophilic heads
• 2 Hydrophobic tails
• Proteins (allow passage into/out of
cell)
• Channel proteins- have openings
thru middle
• Carrier proteins- catch, carry, release
• Carbohydrate chains (recognition)
Lipid Bilayer (cell membrane)
• 2 layers of phospholipids
arranged in a certain way to
produce a layer of fat around
each cell.
• This is good because…..FATS and
WATER DO NOT MIX!!!!!
• 1 Phospholipid is made up of a
HYDROPHILIC head and 2
HYDROPHOBIC tails
2 Types of Transport through the cell
Active Transport :
Passive Transport :
the movement of substances
across a membrane with the
use energy (ATP)
the movement of substances
across a membrane without
the use energy (ATP)
-
-
Will go from Low to High concentration
From where there is a little to a lot
“Up the Gradient”
Example: Sodium/potassium pump
Will go from High to a Low concentration
From where there is a lot to a little
“Down the Gradient”
Examples: Diffusion, Facilitated diffusion, Osmosis,
Ion Channels
Concentration amount of solute in the solvent
Gradient the difference from start to finish
BOTH WILL END AT EQUILIBRIUM
Diffusion
• Movement of particles throughout
a substance from an area of a lot to
an area of little…..does not need
membrane……can happen
anywhere.
• Ex: a fart can diffuse through the
room, sugar can diffuse through my
coffee
• 3 things affect how fast diffusion
works: 1) temperature 2) size of
particle, small = fast big =slow
3) type of molecule
FACILITATED DIFFUSION needs helpers to
cross membrane
used for molecules that
can’t diffuse rapidly through
cell membrane….things
that are too large
Still will go from high to low
They will get the “help”
from carrier proteins
ex: glucose
ION CHANNELS
allow passage of important ions (examples: Na+, K+, Cl-, Ca2+);
ions anything that has a charge, +/Ions channels are very specific!!!! Only calcium will go through a
calcium channel protein……
OSMOSIS
• The movement of only WATER
through a membrane
• Still from high to low (a lot to a
little)
• Solution=Solute into solvent
• Concentration= amount of
solute/amount of solvent
TONICITY
• HYPERTONIC High solute, little water
• HYPOTONIC Low solute, a lot of water
SO WATER WILL ALWAYS TRAVEL FROM HYPOTONIC TO HYPERTONIC
• ISOTONIC transport will end here (equilibrium) both sides the same
concentration
CYTOLYSIS
cell swells so much that it bursts
CRENATE
Cell loses water that it shrivels
1) Which way will water move?
2) What is the tonicity of the environment?
3) What will happen to the cell?
10% NaCL
90% H2O
ENVIRONMENT
CELL
20% NaCL
80% H2O
1) Which way will water move?
2) What is the tonicity of the environment?
3) What will happen to the cell?
15% NaCL
85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
1) Which way will water move?
2) What is the tonicity of the environment?
3) What will happen to the cell?
3% NaCL
ENVIRONMENT
CELL
92% H2O
1) Which way will water move?
2) What is the tonicity of the environment?
3) What will happen to the cell?
94% H2O
ENVIRONMENT
CELL
13% NaCL
1) Which way will water move?
2) What is the tonicity of the environment?
3) What will happen to the cell?
15% NaCL
ENVIRONMENT
CELL
85% H2O
THINK…......don’t be scared….draw it out
1) Two solutions A and B, are separated by a membrane. Over a
period of time, the level on side A increases. Which solution, A or
B, initially had the higher concentration of solute?
2) Experimental evidence shows that the transport of a certain
molecule exhibits the following characteristics, 1) the molecule
moves down the gradient 2) at equal concentrations the movement
is the same and 3) cellular energy for transport did not use any
energy. Which type of transport is this?
PART 2 Nucleus, DNA, Protein synthesis
THE NUCLEUS:
- Largest structure in middle of cell
- Control center for cellular operations
- Stores the DNA (information) to make proteins
- Determines structure and function of cell
Most cells only contain 1 nucleus……however…
Muscles cells have many nuclei …..
And Red blood cells have none………..
DNA (deoxyribonucleic acid) the genetic
information to make proteins
• DNA is in the shape of a double helix…….it then coils up around
proteins to form chromatin……it continues to coil up into
chromosomes
• You have 23 pairs of chromosomes……23 came from mom and 23
came from dad
• A nucleotide is the monomer, Building block, of DNA….it is made up
of a sugar, phosphate, and nitrogen base (A, T, G, C)
• Many nucleotides together and correctly base paired on the opposite
side make the double helix
Genes
• A short segments of DNA that code for one protein.
• Remember a protein is a chain of linked amino acids…..can be 100s of
amino acids long…….DNA has the code to assemble the chain in the
correct order for that 1 protein
• Genes have: “start here” signals…….”end here” signals… “read these”
signals…….and “do not read” signals
PROTEIN SYNTHESIS: the making of a protein
through transcription and translation
TRANSCRIPTION
What: converting DNA into mRNA
Where: nucleus
Base pair rules:
DNA  RNA
A
U
T
A
G
C
C
G
How: An enzyme breaks open DNA
reads the code and puts together a
complementary mRNA strand that
leaves the nucleus and brings to a
ribosome
TRANSLATION
What: taking the mRNA and putting
together the amino acids in the
correct order to make the
protein
Where: ribosome
Base pair rules:
mRNA  tRNA
A
U
U
A
G
C
C
G
How: Ribosome reads the mRNA in groups of 3
letters, A tRNA that has the complement to it brings
the amino acid needed, then the ribosome keeps
reading and attaching the amino acids until it reads
“stop”. Then the protein is complete.
Answer these:
1)
2)
3)
4)
Why is it said that the nucleus is the Control center?
What process would be affected by the lack of ribosomes in a cell?
What are chromosomes made up of? (2 things)
What is one of the nucleotide base pairs made a mistake, ( a
mutation), what affect would it have on the end product?
Part 3: Cell cycle and Cell Divisions
• Cycle starts when a new cell forms
• Has 3 stages of CELL CYCLE
• Interphase G1, S (replication of DNA…making a copy for new cell), G2
• Mitosis phase  (dividing of nucleus) thru p,m,a,t
• Cytokinesis division of everything else from cell
start
Division of
everything
else,
cytoplasm
P, M, A, T
Division of nucleus
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Mitosis
• The division of the nucleus of a body/somatic cell…..that
is all cells in your body except for your sex cells
(sperm/egg)
• Mitosis happens for growth and repair
• Occurs in 4 stages:
– Prophase
– Metaphase
– Anaphase
– Telophase
P
M
A
T
Prophase
 Nuclear membrane goes
away….makes it easier to
divide
 chromatin coils into
chromosomes
 Kinetochores
form….handlebars on the side
of the chromosome
 Spindle fibers form from
centrioles
 Centrioles start moving to
opposite sides of the nucleus
Metaphase
Spindle fibers attach to the kinetochores
and move the Chromosomes to the
MIDDLE…equator
Equator of Cell
Pole of
the Cell
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Anaphase (break apart)
• Chromosome breaks in half
into Chromatids ….they are
pulled apart
• Centrioles bring the half
back to its side
• Cell elongates
Telophase
• Chromatids uncoil to chromatin
• Spindle fibers go away
• Nuclear membranes start to form
• Cell continues to get bigger
Starts to look like Two cells
(Opposite of Prophase)
Cytokinesis
Division of the rest of the cell
into 2…..cytoplasm, organelles,
nutrients
In animal cells, cleavage furrow
forms to split cell
Results of Mitosis
• 2 cells with identical
DNA
• Cell CYCLE
STARTS OVER
AGAIN for each of
them…G1
1)
2)
3)
4)
5)
6)
What are the 3 phases of the cell cycle?
What can interphase be broken down into?
What major event takes plac during the S phase?
What does mitosis mean? What cells do this process?
What does cytokinesis mean?
How many cells will there be by the end of the cell cycle if
we started with 1 cell?
7) What if the cell didn’t form spindle fibers?
Division gone wild
If more cells are being made then are dying…..a build up
will occur in the tissue.
This results in a tumor abnormal cell growth and division
Benign tumors: confined to a single capsule, not harmful
or
Malignant tumors: not confined and can spread, these lead to cancer
Cancer
An illness resulting from the effects of a malignant tumors.
A disruption to the mechanism that controls the cell cycle
How:
- They lose their resemblance to normal cells
- Their presence stimulates the growth of blood vessels into the
area
- Increase blood flow leads to increase of nutrients to the bad tumor
cells….killing the good cells (the ones we need)
- Increase of nutrients means that they can rapidly multiply even
more
Differentiation
-When cells become different from each other, they have a
special job to perform so need to look and act different.
How: The Nucleus with the genetic code
- some genes for proteins are turned “on” and some
are turned “off”….this results in some proteins to be made
and others not to…..leading to different looks and functions