LEARNING OBJECTIVES
- Read the Class Notes, using the Textbook
illustrations to help understand the concepts. Read the chapter using the
Class Notes as your guide. There are many questions included
to help tie the systems and concepts together into an integrated,
holistic understanding of anatomy and physiology.
- Take the
Ch.
3 self test in the online textbook.
DO NOT EMAIL THIS TEST TO YOUR INSTRUCTOR. It is a learning tool
only. These tests will also include
questions that are NOT covered in this course.
- Use any resources on the
Online Textbook,
to integrate your learning.
|
Class Notes
Chapter 3: Cells
Use the diagrams in the book to enhance comprehension
of these concepts.
Remember from chapter 1 – the cell is the basic unit of
all living things? Since the cell is the
building block of all living things – knowledge of the cells parts and
the function of each is essential to understanding how the larger
structure functions.
Let's expand Cell Theory (from Chapter 1)
|
A central
tenant of biology is:
Cell
Theory - has three parts
1. Each cell maintains its own homeostasis.
The cell has a cell
membrane which functions as a barrier
between the internal cellular environment and the
external, noncellular environment.
The cell, therefore, has the ability to control its INTERNAL
environment regardless of the conditions
outside the
cell membrane.
The cell maintains an internal environment that is
different from the environment outside the
cell
membrane - i.e. homeostasis.
The cell requires ENERGY to maintain this homeostasis.
Maintaining homeostasis is an ACTIVE
process - the
cell must do 'work' to maintain
homeostasis.
2. Each cell is produced by a previous cell.
A living cell can produce
another living cell.
Energy is required to organize the molecules into
organelles and then organize the organelles into
a
single unit with all the needed functions to
support 'life'.
NONliving things do NOT spontaneously begin to 'live'.
Nonliving things CANNOT produce a thing that is
alive.
3. The Cell is the basic structural unit of life.
All living things are made
up of cells.
Single celled bacteria are the smallest structures with
sufficient organization that the 5
characteristics of life
are present. This is due to the presence of
sufficient
organelles with the needed functions.
All large organisms are multicellular.
The structural unit of
NONliving things is the molecule.
The molecule is the highest level of organization for
nonliving things.
|
What is the basic structural and
functional unit of the human body?
How does 'Cell Theory' support the cell as the basic structural and
functional unit of the human body?
What does the phrase 'central
tenant' mean?
Why is 'cell theory' a 'central tenant' of biology?
Cell theory explains many of the
'characteristics of living things'.
'Cell Theory' explains the
concept of 'life' at a chemical, physical level.
Name the organic molecules that make up the cell
membrane and state their functions
The cell membrane (CM) function is to regulate what goes
into or out of the cell.
It is composed of Lipids, Proteins and Carbohydrates.
As a BARRIER, the cell membrane protects the cell and
acts as a filter to control entry into and exit from the cell.
List the organic molecules (review Chapter
2, Organic molecules)
What is a phospholipid?
(review Chapter 2, Organic molecules)
What are the two parts of the phospholipid?
What are the characteristics of it’s parts?
List the
six types of proteins found in the cell
membrane.
These are listed and described further down on this
webpage.
What are their functions?
Cholesterol is extremely important in the cell membrane
– it controls the ‘fluid-like’ nature of the CM. Too much cholesterol
and the membrane is too rigid – too little and the membrane is too
‘loose’.
Carbohydrate molecules are bound to CM molecules such as
phospholipids or anchor and identifier proteins. The carbohydrate functions as
a point of attachment for other molecules or for stabilizing the cell
membrane against other structures.
What is the function of the cell
membrane?
State the arrangement of the molecules in the cell
membrane
The cell membrane is also known as (aka):
archaic terms:
cytolemma
plasmalemma
plasma membrane
and terms still used today are:
semi permeable membrane
selectively permeable membrane
The Cell Membrane surrounds the cell and is a barrier between the
things ‘outside’ the cell and the contents of the cell. The
phospholipids are arranged in a phospholipid bilayer - two (2) layers of
phospholipids with the phosphate heads on the external and internal
surface and the lipid tails forming the inner layer of the CM.
See the diagrams in the book.
Because the phosphate heads are hydrophilic, polar
molecules, then water, enzymes, ions, etc stick to them.
Because the lipid tails (the inner layer of the CM) are
hydrophobic, the polar molecules on the surface cannot easily pass
through the CM. The lipid tails form a BARRIER to the movement of polar
molecules. Nonpolar molecules can pass easily through the CM’s lipid
layer.
The Matrix (the most common component) of the CM is the
phospholipids.
What is a 'Matrix'?
The Matrix is the most common component of a system.
A grassland is called a
grassland because GRASS is the most common component - i.e. the
matrix of a grassland is 'grass'.
There are flowers, shrubs and even 'trees' in the grassland,
but the most common plant is a grass - therefore, it's a grassland.
What is a 'forest'?
Are there any 'grasses' in the forest?
What is the matrix of a 'forest'
What molecule is the 'matrix' of the Cell
Membrane?
What are the 'less common' molecules found in the matrix? |
Embedded within the phospholipid matrix are protein
molecules and cholesterol molecules.
The phospholipids move around each other in a ‘fluid’
like manner. The cholesterol in the membrane controls the movement
(fluidity) of the other molecules, i.e. the cholesterol controls how
easily the molecules within the cell membrane move around each other.
| Picture a
swimming pool full of water with ping-pong
balls floating side by side all over the surface of the water. Now,
picture ‘stirring’ the water surface and the way that the ping-pong
balls would move around on the surface without ‘mixing’ down into the
water. Now, put a few tennis balls into the surface of ping-pong balls
and stir it up. The tennis balls represent proteins ‘floating’ in the
CM. Now, put a few soccer balls floating on the surface. Add
some basket balls, and beach balls. |
Because the phospholipid molecules are somewhat ‘liquid’
and can move around one another, the protein molecules can also move
around in the layer of phospholipids, within the layer, or from one side
of the membrane to another.
List the names and terms by which
the cell membrane is also known.
The Fluid Mosaic Model of the Cell Membrane is the
name given to this arrangement of the molecules in the CM. It is a fluid
because the molecules can move around. It is a mosaic because of the
various types of proteins ‘floating’ in the CM.
Review Chapter 2.
Compare and contrast 'polar' and 'nonpolar' molecules.
What type of substance 'repels' water?
What types of molecules cannot
easily pass through the cell membrane?
What is the characteristic of these molecules that does not
'fit' the 'barrier'?
What is the characteristic of the barrier that allows the
barrier to 'repel' these polar molecules?
What types of molecules CAN easily pass through the cell membrane?
Why are they able to easily pass through the barrier?
Name the molecule that controls
the 'fluidity' of the phospholipid bilayer.
State the six
types of proteins in the cell membrane
There are 6 general classes of proteins found in the CM:
Anchors – anchor cells and cell structure to other
cells or cell parts. Provide internal
structure for the cell and move
things around inside the cell.
Identifiers – identify a cell as either a foreign
cell or a cell that is part of YOUR body.
Receptors – allow specific molecules or atoms to
bind to the cell and stimulate
chemical reactions.
Channels – allow specific molecules or atoms to
pass through the cell membrane.
Carriers – transport specific molecules or atoms
from one side of the cell membrane
to the other.
Enzymes – molecules that promote controlled
chemical reactions.
Remember - the CM is a barrier to polar ions and molecules
– it is IMPERMEABLE to POLAR molecules.
The Channels and Carriers transport specific polar ions and
molecules through the CM – they make the CM semi-permeable.
Semi-permeable means that some things can pass
through the CM. Polar molecules must
pass through a channel or be
'carried' by carriers.
Selectively permeable means that the membrane
controls what passes through it and is
a synonym for semi-permeable.
Channel and Carrier molecules are PROTEINS.
Therefore, they have a specific shape and
therefore, a specific function based
on that specific shape. (Review Chapter 2)
A Na-channel only permits Na to pass through.
A Ca-channel only permits Ca to pass through.
A K-channel only permits K to pass through.
A glucose carrier only carries
glucose.
What is the function of the
Channel and Carrier proteins?
NONpolar molecules diffuse easily through the nonpolar
phospholipids of the
CM.
|
Like dissolves like:
Polar solvents dissolve polar ions and molecules.
Water-soluble = polar ions are
soluble in a polar solvent
(water- the Universal solvent).
Hydrophilic - water loving;
water soluble
Water dissolves polar molecules
(Salt, sugar, proteins, etc)
Nonpolar solvents dissolve nonpolar atoms and molecules.
Lipid-soluble (fat soluble) -
nonpolar molecules are soluble in a
nonpolar solvent (oils,
alcohol, gasoline, oil-based paint
thinners, etc.)
Hydrophobic - water
hating/fearing; Lipid soluble
Oil dissolves lipids (fat,
cholesterol, etc)
|
List the Polar organic molecules.
What is the polar solvent in the body?
List the polar solutes.
What are electrolytes?
List the NONpolar organic molecules.
Name some NONpolar solvents.
Describe the cytoplasm
The Cytoplasm is the intracellular liquid and all the
stuff dissolved or suspended in it.
The liquid is H2O.
There are many solutes, including nutrients (minerals, glucose, fat
droplets, etc), wastes (from cellular processes), bits and pieces of
proteins, etc in the cytoplasm - all these together with the liquid give
the cytoplasm a colloid texture.
What are the constituents of the cytoplasm?
What are the functions of each constituent?
What is the ‘liquid’ of the cytoplasm?
List the ions found in the cytoplasm.
Hint: see the periodic table of the elements.
List the macromolecules found in the cytoplasm.
Describe how the cell membrane regulates the composition
of the cytoplasm
What is the function of the cell membrane?
See the description above of the cell membrane.
What is the primary component of the CM?
How are these molecules ‘arranged’?
Name the two parts and the ‘water’ characteristic of
each part.
What does the lipid ‘tail’ layer do?
Remember the six proteins found in the CM?
List them.
How do polar molecules pass through the CM?
How do nonpolar molecules pass through the CM?
Explain isotonic, hypotonic, and hypertonic solutions
and their effects on the cell
A solution is a mixture of a solvent and solutes.
The solvent is the LIQUID part,
The solutes are
the particles dissolved in the liquid.
‘-tonic’ means ‘tension’ or in this case – concentration
of solutes, atoms, or molecules.
Iso – means ‘same’
Hyper – more than or excess.
Hypo – less than or lower.
Isotonic – same tension – in other words –when you are
talking about two solutions separated by a semipermeable membrane, the
solution has the same concentration of solutes on each side of the
membrane.
The intracellular solution (INSIDE the cell) is the
point of reference. If you put a cell into a hypotonic solution – the
intracellular fluid has a HIGHER concentration of solutes than the
extracellular solution. If you put a cell into a hypertonic solution –
the intracellular fluid has a LOWER concentration of solutes than the
extracellular fluid.
Hypertonic – the solute concentration OUTside the
membrane is greater than the solute concentration inside the membrane.
Hypotonic – the solute concentration INside the membrane
is greater than the solute concentration OUTside the membrane.
What is another name for the solution outside the CM?
extracellular
What is another name for the solution inside the CM?
Now – WHAT does this
mean to the cell?
When the solution outside the cell has a higher
concentration of solutes (i.e. lower concentration of water molecules)-
- a solute concentration gradient exists across
the CM - higher OUTSIDE and lower inside
therefore, the solute wants to diffuse into the
cell.
– AND
- a water concentration gradient exists across the CM - higher
INSIDE and lower outside
therefore, the water wants to osmose OUT of the
cell.
Solutes cannot easily pass through the CM – so what does
water do?
Remember: the cell membrane is a selectively permeable barrier to
solutes. The gated channels and active transport processes create
a solute concentration gradient across the cell membrane.
(i.e. between the extracellular vs.
intracellular fluids)
Water wants to OSMOSE out of the cell.
Why?
Because the concentration of
WATER molecules inside the cell is Higher than the concentration
of water
molecules OUTSIDE the cell.
Therefore, water passes through the tiny channels in the CM that are open
to water molecules.
What is the process called?
Osmosis.
Define: crenation and plasmolysis.
How are these terms related to solute concentration in
the intracellular and extracellular fluids?
What happens when you put a cell into a hypertonic solution.
Remember: the point of reference for the solution concentration is
INTRACELLULAR fluid.
What happens when you put a cell into a hypotonic solution?
Why is this an important concept?
What type of 'solution' do EMT/EMS's and Paramedics give to accident
victims who have lost blood volume?
What type of 'solution' do hospitals give to patients to increase their
blood volume?
ISOTONIC!
Why?
What would happen to a patient's body cells - and Red Blood
Cells, if the patient recieved 'pure water'?
Define each of these cellular transport mechanisms and
give an example of the role of each in the body: diffusion, osmosis,
facilitated diffusion, active transport, filtration, phagocytosis and
pinocytosis
Diffusion is the movement of solutes from an area of
high concentration to an area of low concentration (from a solution that is
highly concentrated with solute to an area where the solution has a
lower concentration of solute). Picture putting a sugar cube into a
glass of water – the sugar is all concentrated at first in the cube, the
cube starts to dissolve but remains concentrated on the bottom of the
glass. Without stirring, over time, the sugar will dissolve completely
into the water and the sugar molecules will be evenly distributed
throughout the water.
Diffusion follows a concentration gradient.
What is a gradient?
A gradient is a 'concentration that
changes over some distance'.
Picture a line that goes from
Black ------->------------>---------->-- ------ >--------->--------->------------>------->White
BBG BlkGr GGB Gray GGW GrWh WWG
100% black 50% B and 50% W 100%W
The concentration of black going to gray and
eventually to white is a ‘gradient’ - because the amount of black
gradually decreases over the distance from 100% black to 0% black.
On the ‘black’ end is 100% black; in the middle is 50%
B and 50% W; on the white end is 100% white.
We say that diffusion goes DOWN the concentration
gradient because it goes from HIGH concentration to LOW concentration
and is PASSIVE – i.e. it does not require energy and occurs in all
systems whether living or nonliving. It is a purely chemical/physical
process.
Osmosis is the diffusion of WATER through a
semi-permeable membrane. In the body, the CM is the semi-permeable
membrane.
Now - let's change the above illustration with Black and
White, so that:
Black = solutes ------------------------------- White =
water
The concentration gradient of solute is toward pure
water
i.e. High solute conc --------à
------à ----- low solute concentration.
While the concentration gradient of water is toward pure
solute.
i.e. low water conc ---ß
----------ß --------- high water
concentration
The main point here is that water flows toward a high
solute concentration!
Remember - water is the SOLVENT in the solution, while the DISSOLVED
SOLIDS are the solute.
Why is the solute gradient toward
pure water?
If it is PURE water, then, by definition, there are NO solutes - i.e. 0,
the lowest concentration of solute!
Why is the water gradient toward pure solute?
If it is PURE solute, then by definition, there are NO water molecules -
i.e. 0, the lowest concentration of water.
What makes it possible for the
solutes to diffuse?
Because they are dissolved in a liquid.
What is the name of the liquid?
Which two characteristics are
we discussing here?
Each solute diffuses according to ITs
concentration gradient. Na+ diffuses ONLY due to the concentration
of Na+. K+ diffuses ONLY due to K+. Ca++, only due to Ca++.
In other words:
The concentration of Ca++ does not affect the diffusion of
other ions - it only affects
the diffusion of Ca++.
The concentration of Na+ does not affect the diffusion of
other ions - ONLY Na+.
Living things concentrate solutes using energy... and water
PASSIVELY follows the solutes, because of the process of osmosis.
| A HIGHLY concentrated
solution, by definition, has LOTS of solute molecules, and
therefore FEW solvent (water) molecules.
Concentration - in
this concept - refers to the number of SOLUTE
molecules, not to the solvent.
You can discuss the specific solute concentration
(the number of
molecules of one type of
solute) - say... Na+, K+, Mg+, Cl-, (OH)-,
or sugar, etc.
You can discuss the TOTAL concentration of solutes -
adding up
all the molecules of all the
solutes in the solution.
The TOTAL concentration (of
solutes) in the solution drives Osmosis.
Osmosis is the diffusion of Water
- from an area with LOTS of
WATER molecules to an area with fewer water molecules
Water moves from a LOW
Concentrated solution (lots of water
molecules, FEW solutes) to a HIGH concentrated solution (few
water molecules, LOTS of solutes)
Osmosis REQUIRES a semi permeable
membrane - because the membrane allows the concentration of the
solution to be 'different' on one side versus the other side.
The Cell Membrane is the semi permeable
membrane -
it's function is to regulate what gets into or out of the
cell
The cell membrane permits the cell to maintain homeostasis of the
cell's internal environment. |
Osmosis is the FORCE that causes movement of water -
but...
HOW do water molecules enter the cell (pass
through the cell membrane)?
CHANNEL proteins in the CM allow the
passage of water molecules.
HOW do polar molecules pass through the
cell membrane?
Channel proteins (either gated or
non-gated) allow polar molecules to pass through the
cell membrane, down the concentration
gradient of each respective solute.
Osmosis is DIFFUSION of WATER...
What is the
force that causes polar solutes to move through the channel proteins?
DIFFUSION!
| Diffusion (and Osmosis) are
PASSIVE processes - they do NOT require energy, and take place any
time there is even the slightest concentration gradient - until
the system reaches equilibrium.
Equilibrium - there are NO differences in concentration- i.e. NO
concentration gradients
Since no energy is required - these
processes can occur in NONliving systems as well as in living
systems.
Indeed, 'life' can use the function
of diffusion withOUT expending energy. |
Active Transport – the transport of solutes from LOW
solute concentration to HIGH solute concentration – AGAINST the
concentration gradient.
This process REQUIRES Energy.
Living things concentrate solutes AGAINST the
concentration gradient –
HOW?
By using energy.
What is the
form of energy used for metabolic processes?
What is metabolism?
The sodium/potassium pump, Na/K pump, is the
Active Transport process that we will talk about most in this course.
The Na/K pump pumps 3 Na out of the cell, and 2 K into the cell.
What is its function?
Is it active or
passive?
What does 'pump'
mean?
Is this an active or passive process?
|
Active Transport uses ENERGY to concentrate solutes on one side of a membrane -
and WATER osmoses until the fluids on either side of the membrane
are Isotonic, or in other words - in equilibrium.
Active transport ONLY occurs in living systems -
because only LIVING systems control and regulate the flow of energy
through their systems.
'Life' must SPEND resources to make active
transport take place.
'Life' must replace the resources that it
'spends'. |
Facilitated Diffusion and Carrier Mediated Diffusion
are the movement of solutes and suspended particles along the concentration gradient AIDED by
special transport mechanisms.
NOTE - these are both DIFFUSION processes - i.e. passive,
and down a concentration gradient.
Remember - 'Passive' means that the process
does NOT need energy; and takes
place in both NONliving and living systems.
Glucose (sugar - THE major source of STORED energy) is
moved into the cell by carrier mediated diffusion. Glucose
molecules are too large for normal diffusion to be effective.
INSULIN increases the number of carrier proteins that can 'carry'
glucose across the cell membrane into the cell.
The more carriers you have, the faster things can enter the cell. |
List the PASSIVE transport
processes.
List the active transport processes.
Exocytosis – Secretion or excretion; the mass movement of the stuff inside a
vesicle in the cell out of the cell. The vesicle with contents moves to
the CM, the vesicle fuses to the CM, opens a hole and dumps the contents
into the extracellular fluid (outside the cell).
Endocytosis – the movement of large structures, esp
bacteria and cell parts, into the cell. The CM gradually forms a fold
around the structure and eventually completely surrounds the structure.
The CM fuses and the structure is now in a large vesicle inside the
cell. The cell attaches lysosomes to the vesicle, dumps lysozymes into
it and digests the contents of the vesicle.
Macrophage - A cell that ingests extracellular
substances.
'-phage' - to eat
Phagocytosis - cell 'eating' - moving solid particles into
the cell -and subsequent digestion (eating)
of those solids.
Phagocyte - a cell that 'eats'.
AKA - macrophage, microphage, and other specialized names.
Pinocytosis - cell 'drinking' - moving a 'liquid' into the
cell, in a vesicle and subsequent use of that
liquid.
What is Phagocytosis?
Pinocytosis?
What is a macrophage?
In phagocytosis, the cell must physically,
intentionally, surround something outside the cell, and move it into the
cell.
Is this 'active' or 'passive'?
In exocytosis (excretion and secretion), the cell must intentionally
move something to the cell membrane, open a 'hole' and dump the
substance out of the cell.
Is this 'active' or 'passive'?
Compare and contrast excretion vs. secretion.
Describe the 'cellular transport'
processes.
|
These cellular transport mechanisms are the FORCES that move small
(molecule and atom size) particles within the body.
Basic
Physics and Chemistry
Diffusion
Facilitated
diffusion
Carrier
mediated diffusion
Osmosis - requires a semipermeable membrane
Living cells -
Using energy
Active Transport
Exocytosis
Endocytosis
Phagocytosis
Pinocytosis
No energy required (diffusion) -
BUT requires special transport
mechanisms. Especially useful in the
digestive system.
Facilitated diffusion
Carrier mediated
diffusion
These forces operate at the atomic and molecular scale - the
particles must be small enough that these forces can efficiently
move them. |
How is glucose moved INTO the cell - i.e. across the
cell membrane?
State the function of the nucleus and chromosomes
The nucleus is the MEMBRANOUS organelle that
houses the chromosomes inside the cell. Each gene is transcribed
and then that 'copy' passes out of the nucleus and is used in the
cytoplasm.
What is a chromosome?
The chromosome is a molecule made up of 2 strands of DNA,
wound around each other in a 'double' helix.
What is the main component of a chromosome?
Each DNA molecule is made up of GENEs.
Each gene contains the information
that makes each individual unique - the genetic code.
Describe the nuclear membrane.
What is a nucleopore?
Nucleopores are 'holes' in the
nuclear membrane through which liquid and other molecules and substances
pass between the liquid inside the nucleus and the cytoplasm.
Describe the function of the cell organelles
There are two main types of cell organelles:
Nonmembranous do NOT have a membrane shape. They include
structures made of proteins
Cytoskeletion - support organelles inside the
cell. Helps keep all the other organelles in their
proper place relative to
each other.
Centrioles - cell reproduction
Ribosomes - site of protein synthesis.
The
workbench where new proteins are synthesized.
Membranous organelles are based on a membrane that
is very similar to the phospholipid bilayer
of the CM.
Nucleus - contains Chromosomes - DNA - genes -
genetic information
produces mRNA
-the recipe/instructions for making a protein
Nucleolus- a dense area within the nucleus
- production of ribosomes.
Endoplasmic reticulum (ER)
RER - rough ER, Has
Ribosomes attached - looks 'rough' under microscope
- produces proteins from mRNA
SER - smooth ER -
no ribosomes attached - looks 'smooth' under microcope
- produces lipids and new membranes using info from the RER.
- the workbench where new membranes (lipids) are produced.
Golgi body - modifies and packages the proteins
produced by the RER.
Vesicles - the actual PACKAGE of substance
produced by the Golgi body.
Lysosome - a package of lysozymes (digestive enzymes)
Lysosomes are also called the 'digestive system of the cell'
because lysozymes are digestive enzymes.
Peroxisome - a package of enzymes (peroxidase) that detoxify
Oxygen atoms.
What is the function of the nucleopores?
Why is Rough ER called ‘rough’?
Why is Smooth ER called ‘smooth’?
L ist the different types of vesicles and the function of
each.
What is a lysosome?
What is lysozyme?
What is a peroxisome?
What is a peroxidase?
What is the 'digestive system' of the cell?
What is the name of the digestive enzymes?
What is the workbench where proteins are produced?
What is the workbench where new membranes and lipids are produced?
What is a ribosome?
What is the SER?
The suffix ‘-some’ – means ‘body’ – therefore a lysosome
is a ‘body’ that contains what substance?
What does ‘lyse’ mean?
What does ‘peroxi’ mean?
Hint: what is hydrogen
peroxide?
MAKE a TABLE to compare and
contrast the Organelles and the specific, unique function of each.
List each organelle (grouped as nonmembranous or membranous) and
the function and location.
Villi - fingerlike structures on the surface of cells
that increase the surface area of the cell.
Microvilli - smaller fingerlike structures that increase cell surface
area.
The more surface area available, the more secretion,
excretion, and absorption possible.
Villi and microvilli increase the surface area and
therefore increase the efficiency of absorption and secretion of that
cell.
Microvilli are especially found on the surface of cells that are
actively engaged in absorption -
such as the lining of the digestive system.
What is the function of villi and microvilli?
Where are villi and microvilli most likely to be found?
Why is it advantageous to have microvilli on the
surface of the cells lining the digestive tract?
Describe what happens in mitosis and meiosis and
describe the importance of each
Make a TABLE to compare mitosis
and meiosis
Mitosis and Meiosis are two different types of cell
reproduction
Mitosis – produces normal body cells that are
Diploid. Function of mitosis is growth, maintenance and
repair of normal body cells/tissues.
A single cell replicates all its organelles, especially
the chromosomes, and then divides, producing two cells that are
genetically and functionally identical to each other and to the original
cell. These cells increase the size of the organ, or replace old,
nonfunctional, or dead cells.
Meiosis – produces the SEX cells that
are Haploid. Function of meiosis is to ‘shuffle the genes’ and
produce GAMETES that can fuse to a gamete from another individual to
produce a new diploid organism with a unique genetic makeup.
A single cell replicates all its organelles, especially
the chromosomes, and then Divides, separating the homologous chromatids
into two separate cells, and then Divides again, this time separating
sister chromatids putting one set into two cells. – This replication and
then division and division starts with 1 (one) diploid cell and produces
4 (four) Haploid cells. (It copies itself and then divides 2 (two) times
- producing cells with 1/2 the normal number of chromosomes)
Diploid means the cell has a full set of
chromosomes. Normal body cells in humans have 46 total
chromosomes - or i.e. 23 pair of chromosomes.
Each pair is made up of a chromosome from the mother and one
from the father. Each individual
has 2 (two) chromosomes in the first pair,
2 in the second, and so on...
Each chromosome of a pair contains the genes that control the
same trait. I.e. if in a pair of
chromosomes, the chromosome from the mother
contains the gene for eye color, then the other
chromosome (from the father) will
also contain the gene for eye color.
How many total chromosomes does a human
body cell have?
How many pairs of chromosomes does a normal human cell
have?
Haploid means the cell has ½ of a full set.
Haploid cells in humans are the SEX cells and are called Gametes. When two gametes
(haploid cells) fuse following sexual intercourse they form a new
DIPLOID cell – the zygote.
How many chromosomes is ‘1/2 of a full set’ of
chromosomes in humans?
The zygote undergoes mitosis and becomes the embryo
which, through more mitosis, becomes the fetus. Notice that
mitosis is the process by which the zygote grows and matures into the
subsequent stages.
How many chromosomes are in a diploid cell?
How many chromosomes are in a haploid cell?
What is a chromosome?
How many pairs of chromosomes do humans have?
How many TOTAL chromosomes do humans have?
Where do we get our chromosomes?
How many chromosomes does each parent give us?
Name the process that produces normal body cells for
growth and development; and tissue repair.
Name the process that produces cells used for reproduction of the
species.
Describe Protein Synthesis
DNA molecules are made up units called genes.
Genes are made up of a specific sequence of nucleotides
(see chapter 2). This specific sequence codes for a specific sequence of
amino acids for a protein.
Remember, the repeating units
for DNA molecules are the nucleotides.
Amino Acids (AA) are the building block of proteins.
The specific sequence of AAs give the protein a unique,
specific shape.
The specific shape of the protein gives that protein a
specific function.
The specific sequence of AAs that make up a protein, is
determined by the specific sequence of nucleotides on the DNA.
What happens when you change the shape of the protein?
What are some conditions that can change the shape of
the protein?
Temperature, pH, pressure
What is a mutation?
A mutation is a change in the sequence of nucleotides
that make up a gene.
How would this affect the sequence of nucleotides and in
turn the sequence of AAs?
Changing the sequence
of nucleotides, can change the sequence of amino acids - which
can produce a
protein with a new shape and therefore a different function.
What happens when you change the shape of a protein?
What does
'denature' mean?
Chromosomes are found in the nucleus of the cell and are made up of DNA.
A gene is a segment of DNA that codes for a
specific protein. Each gene codes for only one (1) protein. A
protein is a chain of amino acids - the chain of amino acids are arranged
in a specific order.
A central tenant of
biology is:
ONE gene produces ONE protein. |
DNA makes up chromosomes in the Nucleus. The DNA molecule
is two strings of nucleotides wound around each other in a 'double helix'
shape. Picture a corded telephone cord - the helical cord that
allows the phone to 'stretch' away from the phone base. The
nucleotides that make up a strand are covalently bonded to each other.
The two strands of nucleotides are held together by H-bonds between
adjacent nucleotides (one on each strand). This means that it is
difficult to break a strand, but easy to pull the two strands apart.
Each strand is a sequence of nucleotides.
There are four (4) nucleotides that make up DNA.
1. Adenosine (A) and 2. Thymine (T)
3. Guanine (G) and 4. Cytosine (C)
There are 4 nucleotides that make up an RNA molecule:
1. Adenosine (A) and 2. Uracil (U)
3. Guanine (G) and 4. Cytosine (C)
See the diagrams of a DNA
molecule in your textbook.
Notice that there are two strands of DNA, wound
around in HELIX.
Further, each strand is a chain of nucleotides, AND
the each nucleotide of each strand shares a Hydrogen Bond with a
nucleotide
on the opposite strand.
The Rule of Complementary Base Pairing states that:
on a DNA molecule, Adenosine on one DNA strand always pairs (H-bonds) with Thymine
on the opposite strand of DNA;
while Cytosine on one strand always pairs with Guanine on the other
strand. I.e. when A occurs on
one strand of DNA, it will be H-bonded to T on the other strand.on an RNA molecule, the Thymine nucleotide is replaced by the
nucleotide Uracil. Therefore an A on DNA produces a U on an mRNA
molecule.
The DNA molecule strands - split- i.e. the H-bonds break
-and one strand is transcribed (copied) to form a mRNA molecule.
The mRNA molecule is translated into a protein.
Remember that the repeating unit for
DNA and RNA are the nucleotides and the repeating unit
for proteins is the
AAs?
In translation, the nucleotide sequence produces a sequence of AAs.
Transcription
-the process of producing an RNA molecule (from a DNA template).
Translation -the
process of producing a protein from an RNA recipe.
How does a DNA molecules contain information?
The specific sequence of nucleotides on a DNA
strand is the 'recipe' for a specific protein. Remember from above - 1
gene codes for 1 protein? The sequence of nucleotides that make up
a gene is the 'recipe' for a specific sequence of amino acids in a
chain.
Remember from chapter 3
that a protein has a specific function that depends on the specific
sequence of AAs?
How is that specific sequence of AAs created?
The specific sequence of nucleotides that make up a gene!
Consider the English alphabet - picture a sequence of
letters of the alphabet:
ttttthheeebbiiggcaaar - this sequence has no meaing –
NOW, rearrange the letters to: thebigcatatethebigrat (put
some spaces in between the 'words' and- the big cat ate the big rat).
The SEQUENCE of letters is a 'word' that has a specific meaning and
a
string of 'words' creates a sentence with a specific meaning.
Nucleotides are the 'letters' of DNA. There are
only 4 'letters' in the DNA alphabet - A, T, C, and G. These letters
(nucleotides) are arranged in a specific sequence, in groups of 3
nucleotides called 'triplets'.
Triplets are the 'words'.
Each triplet codes (means) for a specific AA in the chain of AAs that make
up a protein.
DNA is transcribed
(copied)
to mRNA which is
translated (used as a recipe for)
into a protein.
DNA cannot leave the nucleus, therefore, the nucleotide sequence of DNA is copied to mRNA,
which travels out of the nucleus and binds to a ribosome. There, the
mRNA copy directs the synthesis of a specific sequence of AAs - i.e. a
specific protein with a specific shape.
How does DNA contain information?
The information is contained in the SPECIFIC SEQUENCE of the nucleotides
that make up a gene.
The specific sequence of nucleotides produces a protein
with a specific sequence of amino acids.
That specific sequence of amino acids
produces a protein with a specific shape -which gives
the protein a specific
(unique!) function.
If the nucleotides get out of sequence, then the gene 'loses meaning' -
and produces a different sequence of AAs - and therefore a protein that is
nonfunctional.
Remember the 6 types of proteins?
List them and the functions of each type.
What is an enzyme?
What is the function of an
enzyme?
What happens if the
'shape' of the enzyme changes?
How
would this 'stop' metabolism?
LAB
Cellular Anatomy
- Cell Membrane
- Cytoplasm
- Cytosol - the solution - fluid
- solvent - made up of H2O
- solutes - nutrients, wastes, molecules, etc. dissolved in the
solvent
- Organelles - molecules 'suspended' in the solution
- Non-membranous Organelles
- Microvilli
- cytoskeleton
- Cilia
- Centrioles
- Ribosomes
- Membranous Organelles
- Endoplasmic Reticulum (ER)
- Golgi Apparatus
- Lysosomes
- Mitochondria
- Nucleus
- Nucleolus
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