Download Unit 1 Notes

Nat 5
Cell Biology
Pupil Notes
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Cell Bio
2013
1 (a) Cell structure / transport
Cell Structure
You have already learned about the basic structures
Remember?
that are found in plant & animal cells.
Complete the diagrams below.
Identify three structures that are common to both plant and animal cells:
_______________________________________________________
Identify three structures that are found only in plant cells.
______________________________________________________
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Cell Bio
2013
Cell structures and functions
Your teacher will introduce a few more structures found within a cell and
Cell organelle
Cell wall
Function
Mitochondria
Maintains cell shape / Fully permeable / Made of
cellulose
Site of aerobic respiration
Chloroplasts
Site of photosynthesis
Cell membrane
Controls entry and exit of material / Semi permeable
Vacuole
Contains cell sap
Cytoplasm
Site of chemical reactions
Nucleus
Controls cell activity
Ribosomes
Site of protein synthesis
Plasmids
Ring of DNA within a bacterial cell
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Cell Bio
2013
Structure of the Plasma Membrane
The plasma membrane is referred to as the FLUID MOSAIC MODEL
The reason for the name is that the phospholipids are constantly moving
(fluid) and has a scattered (mosaic) arrangement of proteins.
The proteins can function as:
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hormones,
antibodies,
enzymes
structural support
Cell Bio
2013
Fungi
The cells of fungi are similar to plant cells. They have a nucleus,
cytoplasm, ribosomes and mitochondria. They are however not green –
they don’t photosynthesise and so don’t contain chloroplasts. Fungi need
to feed on other organisms to obtain their energy source. Fungi are
involved in decomposition - recycling nutrients from dead organisms back
into the ecosystem. Humans have made great use of fungi, e.g. yeast are
single-celled fungi and are used to make wine, beer and bread.
Bacteria
Bacteria have a much simpler structure than either plant or animal
cells. They do not have an enclosed nucleus or mitochondria. The
bacterial cell contains a cell wall. ALL their chemical reactions, including
aerobic respiration occur in the cytoplasm. In the cytoplasm, bacteria also
have ribosomes, upon which bacterial proteins are made. The bacterial cell
also contains a cell wall.
Bacteria keep their genetic information in a structure called a nucleoid,
which is a large ring of DNA. In addition, they also have extra genetic
information in a small ring of DNA called a plasmid.
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Cell Bio
2013
Diffusion
Diffusion is the movement of molecules from a high concentration to a low
concentration until they are evenly spread.
Oxygen:
Will diffuse from the lungs into the blood and then into the cells
Carbon dioxide
Will diffuse from the cells into the blood and then into the lungs
Starch
Will not diffuse because it is too large
Water
Water does not diffuse. It moves by osmosis
Osmosis – A special kind of diffusion
Osmosis is the movement of water from a high concentration to a low
concentration through a selectively permeable membrane.
Some new words
• Hypertonic – LOW Water Conc
• Isotonic
– SAME Water Conc
• Hypotonic – HIGH Water Conc
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Cell Bio
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What happens to cells in different solutions?
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Cell Bio
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Explaining the changes in cell appearance
Plant cell placed in pure
Plant cell placed in
water
strong salt solution
The high water concentration
The high water concentration
is _________ the cell. Water
is _________ the cell. Water
will move _________ the cell
will move _________ the cell
from a _________ to a
from a _________ to a
_________ water
_________ water
concentation. The cell will
concentation. The cell will
become ____________
become ____________
Draw what the cell would look
Draw what the cell would look
like
like
Animal cell placed in
pure water
Animal cell placed in
strong salt solution
The high water concentration
is _________ the cell. Water
will move _________ the cell
from a _________ to a
_________ water
concentation. The cell will
_____________
The high water concentration
is _________ the cell. Water
will move _________ the cell
from a _________ to a
_________ water
concentation. The cell will
_____________
Draw what the cell would look
like
Draw what the cell would look
like
Doon Academy
Cell Bio
2013
Active transport
Active transport is when substances are absorbed against a concentration
gradient (like a ball being rolled up a hill). Like nitrates being taken in by
root hair cells
Active transport always requires energy.
The sodium/ potassium pump (which always requires active transport) is a
carrier protein which exchanges sodium and potassium across the
membrane to maintain nerve function.
Active transport is dependent upon several factors including;
 temperature
 availability of oxygen
 availability of respiratory substrate
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Cell Bio
2013
1 (b) Producing new cells/Genetic engineering
Cell division
 Cell division is a means of increasing the number of cell for
______________ organism.
 Single cell organisms use cell division as a menas of
reproducing _________.
 It is the _________ that controls cell division.
 Each of our cells (except our ______ cells) contains two
matching sets of chromomosomes. Each cell is therefore
said to be d___________.
 Human cells have 2 sets of _____ chromomosomes.
 Cell division ensures that each daughter cell has the
i______________ g______________ information to
that of the parent cell.
 The process of cell division is called _________
We use cell division for
1) Growth,
2) Repair,
3) Therapeutic uses
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Cell Bio
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Stages of Mitosis
There are two main stages in mitosis
1: The __________ divides
2: The cytoplasm divides
These two stages can be further broken down into
smaller steps, as shown below:
Stage 1
Stage 2
Stage 3.
The chromosomes
shorten and duplicate.
The chromosomes are
now visible
No chromosomes are
visible
The chromosomes line
up along the equator of
the cell.
The membrane around
the nucleus has
disappeared
Stage 5.
Stage 6.
The identical
chromatids arrive at
opposite poles
The cytoplasm is
now starting to divide
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Cell Bio
•The nuclear membrane
reappears.
•The cell now divides into
two identical daughter
cells.
2013
Growing Micro-organisms
Different types of micro-organisms require specific
conditions to grow. These conditions include appropriate
temperature and an appropriate food supply
Antibiotics can be used to treat bacterial infections
A range of antibiotics is required because:
1) Some people are allergic to certain antibiotics
2) Bacteria can become resistant to a particular antibiotic.
Watch this link from the Wellcome Trust to give you an insight
into the cell culturing process
http://www.wellcome.ac.uk/Education-resources/Teaching-andeducation/Big-Picture/All-issues/The-Cell/WTDV030777.htm
Doon Academy
Cell Bio
2013
Your turn - Streaking agar plates
Instructions
Disinfect your work
surface
Light bunsen burner
Open sample bottle
using your pinky and
heat the neck of the
bottle
Heat the inoculating
loop until it glows and
then allow to cool
Dip the loop into the
water
Gently streak the agar
plate in a zigzag fashion
Reason
To limits cross contamination.
Bacterial spores may be present on
surface
To destroy any bacteria present in the
air that may land on the agar plates
To destroy any bacteria present on the
bottle top and stops cross
contamination from your hands
To destroy any bacteria present on the
loop
To collect a water sample
To separate different bacterial colonies
Seal the petri dish using To avoid spread of germs
cellotape
Label your dish on the
To avoid confusion if the lids fall off.
bottom
Leave for 3-5 days
To allow bacterial growth to occur
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Cell Bio
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Genetic Engineering
Genetic engineering is the transfer of genetic material from one
organism to another.
Microorganisms, e.g bacteria and yeast are often reprogrammed
during genetic engineering to produce substances such as insulin
for the following reasons: 1) They multiply quickly 2)They are
inexpensive and 3) They are easier to reprogramme than other
organisms..
Stages of genetic engineering
1. An enzyme is used to cut the human gene out of the chromosome.
2. Plasmids are then removed from bacterial cells.
3. The plasmids are cut open with an enzyme.
4. A human gene is inserted into each plasmid.
5. Plasmids are inserted back into the bacteria.
6. Bacteria with the human gene are then multiplied.
7. Each bacterium will produce a tiny volume of insulin
8. By culturing the genetically engineered bacteria limitless supplies of
the useful product may be produced.
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Cell Bio
2013
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Cell Bio
2013
1 (c) DNA and Proteins
DNA STRUCTURE
1. DNA is made up of nucleotides.
2. Each nucleotide is made up of a phosphate, a deoxyribose sugar and
an organic base.
phosphate
organic base
deoxyribose sugar
3. There are 4 types of organic base – adenine, thymine, cytosine and
guanine.
4.
adenine
thymine
guanine
ytosine
5. Nucleotides are joined to form long strands – a covalent bond forms
between the deoxyribose sugar of one nucleotide and the phosphate
of the next nucleotide.
strong
covalent
bond
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Cell Bio
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6. DNA is made of 2 strands of nucleotides joined together by the
organic bases.
7. Adenine pairs with thymine and cytosine pairs with guanine.
8. The base pairs are held together by weak hydrogen bonds.
A
G
T
C
Adenine always pairs with Thymine
Hydrogen bond Cytosine always pairs with Guanine
They are “Complementary Base Pairs”
9. The two strands are coiled round to form a double helix.
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Cell Bio
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Sequence of DNA Bases
 The chemical components of DNA are the same in all species.
 However, the DNA of one species differs from another species in
_____________ and in the _____________ in which the bases (A,
T, G and C) occur.
 It is this __________________ of bases along the DNA strand
which is unique to the organism.
 The base sequence contains the GENETIC instructions which control
the organism’s ____________ characteristics.
The Genetic Code and Protein Synthesis
 The genetic code is the information present in a molecule of DNA.
It is like a molecular code language.
 The sequence of bases along a DNA strand represents a sequence of
‘codewords’.
 A molecule called Messenger RNA carries a copy of this code from
the _________________ to the ________________ where
protein is synthesised.
 Proteins are made up of one or more Polypeptide chains, and the
building blocks for this chain are _________ ___________.
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Cell Bio
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 Each amino acid is coded for by THREE bases (a “triplet”) called a
CODON
 The instructions for protein synthesis are coded by the triplet code
(_____________) of DNA bases.
 This is because each codon corresponds to a specific _________
_____
e.g. DNA codon AAT codes for the amino acid Leucine.
So Codons are the basic units of the genetic code because each strand of
DNA has codons arranged in a particular order.
In other words, the order of amino acids is determined by the base
sequence on the DNA.
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Cell Bio
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Variety of Proteins
Proteins consist of long chains of AMINO ACIDS.
There are ______ different amino acids.
As the 26 letters of the alphabet permit the construction of an infinite
number of words, so the 20 different amino acids allow for an infinite
variety of proteins.
The amino acids form long chains which can fold in various ways. These
chains are called ______________. A particular protein might consist of
two or more polypeptides.
All amino acids (and hence proteins) contain carbon, hydrogen, oxygen, and
______________
Some amino acids also have sulphur.
A protein might have hundreds or even thousands of amino acids.
VARIETY OF PROTEINS.
There are many functions which are undertaken by a variety of proteins
Complete the following table
Name
Collagen
Keratin
Enzymes
Antibodies
Haemoglobin
Actin and Myosin
Insulin
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Function
Cell Bio
2013
1 (d) Enzymes
How do enzymes work?
Every reaction requires a certain level of energy to allow it to happen.
This energy is called the ACTIVATION ENERGY.
An enzyme LOWERS the activation energy required, hence allowing the
reaction to take place.
Enzyme Equations
Substrate
Enzyme
Products
Catalase
Hydrogen Peroxide
Amylase
Starch
Protein
Pepsin
Phosphorylase
Glucose 1 Phosphate
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Lipase
Cell Bio
O2 and H20
Maltose
Amino Acids
Starch
2013
Biological Catalysts
Are in all living
cells
Fits with substrate
like a Lock & Key
OPTIMUM
means best
Have active sites
Speed up chemical
reactions
DENATURED
means destroyed
ENZYMES
Made of protein
Specific
Unchanged by
reaction.
Specificity of Enzymes
During an enzyme controlled reaction the substances involved – the
substrates – become joined to the surface of the enzyme molecule. The
chemical reaction then takes place very rapidly.
The spot on the enzyme molecule where the catalytic activity takes place
is called the ___________ SITE. Enzyme molecules, that fit the active
sites exactly, react on the surface of the enzyme.
Substrate molecules fit into these active sites rather like a key fitting
into a lock. The enzyme is said to be “SPECIFIC” to the __________.
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Cell Bio
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Synthesis Reactions
Active sites
Enzyme
Molecule
Stage 1
Substrate Molecules
Substrate and
enzyme join
together
Stage 2
Unchanged enzyme
molecule now free to
react with more
substrate
Stage 3
Product Molecule
Colour in using the following key
Enzyme Molecule
Substrate Molecules
Product Molecules
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Cell Bio
Blue
Red and Yellow
Orange
2013
Using class room resources, find definitions of the
following
a) Specific
b) Enzyme
c) End Product
d) Substrate
e) Synthesis
f) Active Site
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Cell Bio
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Optimum Enzyme Activity and working ranges
Enzymes work best at certain temperatures and pH’s. The
condition in which the enzyme works best is known as the
‘Optimum’ condition.
Enzyme activity
Enzymes can however work at other temps and PH’s other than
the optimum one, however not as efficiently. The range of
conditions in which an enzyme can work is known as the working
range.
At high temperatures the shape of the enzymes active site is
permanently altered, and is Denatured.
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Cell Bio
2013
1 (e) Respiration
Energy from food
Method
1) Set up the experiment as shown below.
Thermometer
Boiling tube
Clamp Stand
Burning spoon
Burning food
2. Measure 20cm3 of water into a boiling tube.
3. Record the starting temp of the water in the boiling tube. Leave the
thermometer in the boiling tube.
4. Measure out 1g of each food using the balance. You should have a
carbohydrate, a protein and a fat food to test.
5. Using the deflagrating spoon as shown by your teacher, heat the
first piece of food until it catches fire.
6. Hold the burning food underneath the boiling tube of water until it
stops burning.
7. Record in your jotter the final temperature of the water.
8. Repeat the above for the 2nd and 3rd piece of food
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Cell Bio
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Results
Food
Starting
Final temp
Change in
sample
temp (oC)
(oC)
temp (oC)
Pasta
20
49
Cereal
24
12
Rice
26
15
Conclusion
The food that contains the most energy is
_________________________
Evaluation
The above experiment may indicate less energy than is actually present in
the food because
______________________________________________________________
_______________________________________________________________
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Cell Bio
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Respiration
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Cell Bio
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Respiration
All organisms require energy.
Respiration is the release of ____________ (in the form of ATP) from
___________ in a series of ________________ controlled reactions.
ATP
• ATP is an immediate source of energy for your cells particularly your
muscles that need it when they are contracting.
ATP is required by our cells as an energy source for:
• Muscle contraction
• Cell division
Synthesis of ATP
• Building up (synthesis) of proteins
• Transmission of nerve impulses
Adenosine diphosphsate
phosphate
Adenosine tri-phosphate
Energy in
adenosine
P
P
P
adenosine
P
P
Energy out
Types of respiration
There are two kinds of respiration:
1.
Aerobic respiration
2 . Anaerobic respiration
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P
1. Aerobic respiration
Aerobic respiration is broken down into 2 stages:
1 . In the cytoplasm, glucose is partially broken down into a
molecule called pyruvic acid. Only a little energy is
released to form 2 molecules of ATP.
GLUCOSE
2ADP + 2Pi
2ATP
2 x PYRUVIC ACID
3C
2 . Pyruvic acid enters the mitochondria where it is
completely broken down to form carbon dioxide and
water and enough energy is released to form 36
molecules of ATP.
• Therefore a total of ______molecules of ______are made when 1
molecule of _________ is broken down in the presence of
__________ .
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Cell Bio
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Simple respirometer - Measuring the oxygen uptake
 The sodium hydroxide absorbs ___________
______________
produced by the snail during respiration. This means that carbon
dioxide does not interfere with the movement of the coloured liquid.
 The coloured liquid moved upwards to replace the space the
___________ molecules once took up.
 There is a ____________in pressure ____________ the apparatus
since oxygen is being used up.
 There is a ___________ pressure ___________ container pushing
on liquid resulting in it moving upwards towards the snail.
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2) Anaerobic respiration
• Anaerobic respiration is known as _________________.
• It is the incomplete breakdown of glucose in the absence of
____________ and occurs only in the cytoplasm of the cells.
a) In animals
Glucose is broken down into pyruvic acid which is then converted into
_______________. Only ___ ATP are made.
A build up of lactic acid can cause muscle ___________________.
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Cell Bio
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b) In plants and yeast
Glucose is broken down into ______________ __________ which is
then converted into ____________ _____________ and
_____________. This occurs in the absence of ____________.
Yeast is used in baking and brewing.
The __________ _____________ causes the dough to rise in bread.
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Cell Bio
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1 (f) Photosynthesis
Conditions required for photosynthesis
1. Is light needed?
Experiment
Result
Conclusion
2. Is carbon dioxide needed?
Experiment
Result
Conclusion
3. Is chlorophyll needed?
Experiment
Result
Conclusion
Part with chlorophyll
Part without chlorophyll
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Cell Bio
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Raw Materials
 Green plants use simple chemicals – _____________ & __________
from the environment as raw materials to make food.
 Water is absorbed by the plant from the soil and it travels
through the plant to the leaves where photosynthesis takes
place.
 Carbon dioxide enters the plant through small pores in the leaf
called ____________.
 Sunlight provides the energy to drive this process.
 The light energy is absorbed by ___________________, the green
pigment found in chloroplasts in the leaf.
Photosynthesis Equation
+
water
chlorophyll
Word bank Sugar
carbon dioxide
xygen
raw materials
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Products
Cell Bio
+
light energy
essential requirements
2013
Photosynthesis
Carbon dioxide + water
Light energy
Glucose
+
Oxygen
Chlorophyll
Starch
(storage)
Cellulose
(structural)
Photosynthesis is a series of ______________ controlled reactions.
There are two stages : 1) Photolysis
2) Carbon Fixation
Both stages occur within the _______________ of a plant cell.
1) Photolysis
Light
Trapped by ____________
Splits water
_________ (by-product)
ADP + Pi
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________
Photophosphorylation
Cell Bio
2013
2) Carbon Fixation
Carbon
dioxide
Glucose (6C)
Starch
(storage)
Cellulose
(structural)
Starch
Starch molecules are long chains of glucose molecules.
Starch is a plant’s store of food and can be converted back to glucose sugar for
energy when needed. Starch is therefore called a ____________ carbohydrate.
Cellulose
Cellulose molecules are also long chains of glucose molecules, but they are arranged
differently to Starch – every other glucose is “upside down”
Cellulose is therefore called a _____________ carbohydrate.
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Limiting factors
A limiting factor is any factor that is restricting the rate of
photosynthesis.
The rate of photosynthesis is usually measured by the number of
_________ bubbles produced or the _______ of food produced.
 The limiting factor at A is: ______________________
 The limiting factor at B is: ______________________
 The limiting factor at C is: ______________________
At point D the rate if photosynthesis may have levelled out for 2 reasons:
1)
2)
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Measuring the rate of photosynthesis in Elodea
What must be done to the Elodea sample before carrying out the
experiment?
_______________________________________________
The rate of photosynthesis is measured by the
____________________________________
The sheet of glass is placed between the light and elodea to ensure
________________________________________
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Cell Bio
2013