Cell structure advance.pptx

National 4/5 Biology Course Unit 1
National 4/5
Units:
• Complete Life on Earth – mid Sept
• Cell Biology – Sept - Dec
• Multicellular Animals – Jan - April

How is the course assessed?
• Course work:
– 3 end of unit tests (one for each unit) – can
have resits if necessary
– One Practical investigation
– One mini research project (100 words)
– One LARGE research project (Added Value)
(500-800 words)
– NATIONAL 5 – Final exam!

Work
Classwork to be done in jotter.
Remember it every day!
You will get set homework sometimes –
but expected to learn the work done
each day as you go along!!!

What is in Unit One?
• Cell Biology:
– Cell Structure
– Transport across membranes
– Producing new cells
– DNA and protein production
– Genetic engineering
– Proteins and enzymes
– Aerobic respiration
– Photosynthesis

Cell structure
LI: 1. Identify and name the structures
found in an animal cell.
2. State the function of the structures in
an animal cell.
3. Identify and name the structures
found in an plant cell.
an plant cell.

Cell Structure
Cells are the building blocks of all life.
Cells video

Cells
• What is cells ?
• How many type of cell do you know ?
• Why cells is important ?

Cells
• How to observe a cell ?
• Make a timeline of how the microscope
was developed.

Cell Structure
We will be looking at 4 different cell types:-
• Animal cells
• Plant cells
• Bacterial cells, and
• Fungal cells.
You have already looked at the basic structure of
animal and plant cells in S1- S3. We will be
looking at all of these cells in greater detail.

What can you remember from
last year?
Task One: Complete the revision
worksheet on cells.

Cell Structure
Task 2: Prepare slides for examination under a
light microscope.
Using the help sheets provided prepare one
type of slide – cheek cell, onion cell or Elodea
pondweed. After you have examined your own
slide share your slide with a group that has
prepared a different slide . You should look at
all 3 cell types.

Cheek Cells
These are cheek cells viewed at 100x magnification
using a light microscope.
http://www.stancoe.org/patterson/cms/staff/humancheekcellwebpage.htm

Onion Skin Cells
These are onion skin cells viewed at 40x
magnification using a light microscope.
http://www.baileybio.com/plogger/images/biology/lab_-_plant___animal_cells/onion_cells.jpg

Elodea Pondweed Cells
These are Elodea pondweed cells viewed at 100x
magnification using a light microscope
http://seys-science.wikispaces.com/elodea+g

Cell Structure
We will now look in more
detail at the structure of
animal and plant cells.
To see more detail or the
ultra structure of cells
we need to use and
electron microscope.
Image from Wikipedia commons http://en.wikipedia.org/wiki/File:Electron_Microscope.jpg

Cell Structure - Organelles
Organelle is the name given to the
structures found inside the cell e.g.
Nucleus, vacuole, chloroplasts etc.
You need to know about 2 more organelles.
Mitochondria and Ribosomes

Mitochondria
Mitochondria are the power houses of
cells. They convert energy into forms
that are usable by the cell. They are
found in the cytoplasm and are the sites
of cellular respiration which generates
fuel for the cell's activities.
Mitochondria are found in the
cytoplasm of the cell.

Electron microscope
image of a
mitochondrion
(credit: Tom Deerinck and Jeff Martell/MIT)
http://people.eku.edu/ritchisong/ritchiso/mitochondrion2.gif

Ribosomes
Ribosomes can be found
floating free in the
cytoplasm or attached to
another type of organelle
called Rough Endoplasmic
Reticulum or R.E.R. for
short. (you don’t have to
know about R.E.R!)

http://bioweb.uwlax.edu/genweb/molecular/theory/translation/ribosome.jpg
http://www.cbv.ns.ca/bec/science/cell/page11a.gif
Electron Microscope image of
ribosomes.
Ribosomes are
responsible for
protein synthesis,
i.e. this is where
amino acids are
assembled into
proteins.

Cell Structure – Organelles
Task 3 – Collect the diagram sheets of
the animal cell and the plant cell. Label
any structures you recognise.
You will need to include:- Cell membrane,
nucleus, cell wall, vacuole, chloroplast,
cytoplasm, ribosome and mitochondria.

Animal Cell Diagram
Nucleus
Mitochondrion
Ribosomes
Cell Membrane
Cytoplasm

Plant Cell Diagram
Vacuole
Chloroplast
Nucleus
Ribosomes Mitochondria
Cell
Wall
Cell Membrane
Cytoplasm

Cell Structure - Organelles
Task 4 – Collect and complete the
worksheet :–
Cell structures and functions.

Bacteria and fungi
LI: 1. Identify and name the structures
found in a bacterial cell.
a bacterial cell.
3. Identify and name the structures
found in a fungal cell.
a fungal cell.

Bacterial Cells
“For the first half of geological time our
ancestors were bacteria. Most creatures still
are bacteria, and each one of our trillions of
cells is a colony of bacteria.”
Richard Dawkins

Bacteria
TThey are the oldest living
organisms on earth. They are
everywhere. We find them on and in
the human body, in the air we
breathe, on the surfaces we touch,
in the food we eat. Almost 99% of
these bacteria are helpful,
whereas the remaining are the
notorious ones. Some are essential
for proper growth of other living
beings. They are either free-living
or form a symbiotic relationship
with animals or plants.
http://en.wikipedia.org/wiki/File:Gram_Stain_Anthrax.jpg

Structure of Bacteria
Bacteria can occur in different shapes. However
their basic structure is the same.
Task: Collect the bacterial cell diagram handout
and the information sheet.
Use the information to complete the labels on
the diagram and to complete the table.

Capsule
Genetic
material
Cell Wall
Plasmid
Cell
Membrane
Cytoplasm

Structure Function and importance
Capsule
Cell Wall
Cell Membrane
Genetic Material
Plasmid
Cytoplasm
Provides additional protection from the
environment
It strengthens and supports the cell
Controls the movement of substances into and out of
the cell
Made of DNA and controls the activities of the cell
Circular genetic material. Can convey special
abilities, e.g. a resistance to certain antibiotics.
They can be manipulated by man to produce
bacterial cells that produce useful products e.g.
Insulin, hormones and enzymes.
Most chemical processes take place here
controlled by enzymes

Structure of a fungal cell
Task: Collect the diagram sheet and label
any of the structures and organelles you
recognise.

Structure of a fungal cell
Cell Wall
Cell Membrane Vacuole
Cytoplasm
Nucleus

All the cell parts are now familiar. You should be able to
compare all the cell types and identify which parts
are similar and which are not. While all the cell parts
have the same functions as before there is one
difference.
The fungal cell wall.
Just as the bacterial cell wall has a different chemical
structure from a plant cell wall, so does the fungal cell
wall.
The fungal cell wall is made from a chemical called
chitin.

It is important that you know
The cell walls in plant, bacterial and
fungal cells is structurally and
chemically different.

Measuring cell size
LI: 1. Be able to calculate the length and
breadth of cell seen through a
microscope.

Just how tiny are cells?
“How big?”
This link will show you how tiny cells are.
Cells can be seen more clearly using a
microscope.

Magnification
Total magnification is
worked out by
multiplying the
eyepiece lens
magnification by
the objective lens
magnification.
Eyepiece
Lens
Objective
Lens

Copy and complete this table
Eyepiece lens
magnification
Objective lens
magnification
Total
magnification
X 10 X 4
X 10
X 100

Working out the size of a cell
Field of view
Number of cells
Length
= of each cell
(mm)
e.g. 2 ÷ 5 = 0.4 mm
So each cell
measures 0.4 mm.
The field of view is the
area you can see down the
microscope.
Field of view = 2 mm

Field of view = 2 mm
Collect a version
of this diagram.
Your teacher will
tell you how
many cells to
draw in the
circle.
Calculate the
length of your
cell in
millimetres (mm).
Swap with other
and calculate the
length of their
cells.

2. Transport across cell
membranes

The cell membrane
LI: 1. Describe the composition of the cell
membrane
2. Describe how the structure of the
membrane relates to its permeability.
3. Define the term “passive transport”

• The cell membrane (or plasma
membrane) is made up of a bilayer of
lipids with protein scattered throughout
and is selectively permeable.
• Proteins can;
– be attached to the surface
– be embedded within the bilayer
– span the whole bilayer
– form channels in the lipid bilayer
The Cell Membrane

• Small molecules can pass through pores
in the membrane made by channel
forming proteins and enter or leave the
cell. This is why the plasma membrane is
selectively permeable.
• This transport of molecules is passive
and requires no energy as it is with the
concentration gradient.

Diffusion
LI: 1. Define the term “diffusion”
2. Explain how the process of diffusion
occurs across a selectively permeable
membrane.

• Diffusion is the name given to this
movement of the molecules of a
substance from a region of high
concentration of that substance to a
region of low concentration of that
substance until the concentration
becomes equal.
Diffusion

• Cut a 20cm piece of visking tubing and tie a knot
in one end.
• Soak the tubing in water and never let it dry out
during the experiment.
• Fill the visking tubing with 5-10cm3 starch and
glucose solution and seal with another knot.
• Place this in a boiling tube of water completely
submerged and leave until the next lesson.
Diffusion Activity

Take a small sample of the water from around
the test tube. Test for starch and sugar
Test
for
starch
1. Put sample on
tray
2. Add 4
drops of
IODINE
3. If starch is present it goes
from brown to black
Test for
sugar BOILING
WATER
1. Put sample in test tube – IN a
beaker of BOILING WATER
2. Add 4
drops of
BENEDICTS
SOLUTION
3. If sugar is present it goes from
blue to orange

• Perform Benedict’s test and starch test
on the water in the boiling tube from
Diffusion in a Model Cell experiment you
set up last lesson.
• Explain your results in terms of
diffusion. (LO1 assessment).
Activity

Importance of diffusion to
cells
In an animal cell, food (such as glucose),
oxygen and carbon dioxide will diffuse
like this:

Glucose
Oxygen
Carbon dioxide

Substances which diffuse in
or out of cells
Diffuse IN Diffuse OUT
Oxygen (raw material for
respiration)
Carbon dioxide (waste from
respiration)
Carbon dioxide (PLANTS
ONLY, raw material for
photosynthesis)
Oxygen (PLANTS ONLY,
made in photosynthesis)
Glucose (raw material for
respiration)
Urea (a cell waste product)
Amino acids (raw materials
to build the cell)

Osmosis
LI: 1. Define the term “osmosis”
2. Explain how the process of osmosis
occurs across cell membranes.
3. Describe the effects of osmosis on
animal and plant cells.

Gummi bears in water
1. Take a gummi bear (Haribo works
best) and measure its height and
width.
2. Place in a 50 ml beaker of water.
3. Leave for several days.
4. Carefully remove from the water, and
measure the height and width.
What has happened to the Gummi bear?
Why has this happened?

Osmosis: the diffusion of
water

• The diffusion of water through a
selectively-permeable membrane from
an area of high concentration of water
molecules to an area of low
concentration of water molecules is
called osmosis.
Osmosis

Effects of Osmosis on Plant Cells
Cells in a
dilute
solution
become
turgid
Cells in the
same
solution stay
the same.
Cells in
concentrated
solutions
become
flaccid.
Plasmolysed
cell – cytoplasm
is pulled away
from the cell
wall.

Turgid Cells
• Osmosis makes plant cells
swell. Water moves into
the plant cell vacuole and
pushes against the cell wall.
The cell wall stops the cell
from bursting. We say
that the plant is turgid.
This is useful as it gives
plant stems support.

Flaccid Cells
• If a plant lacks water, it
wilts and the cells become
flaccid as water has moved
out of the cell. If alot of
water leaves the cell, the
cytoplasm starts to peel
away from the cell wall.
We say the cell has
undergone plasmolysis.

Osmosis in Animal Cells

Active transport
LI:
1. Define the term “active transport”
2. Explain how active transport occurs
across cell membranes.

• Active transport is the movement of
molecules across a cell membrane from a
low to a high concentration i.e against a
concentration gradient.
• Active transport works in the opposite
direction to the passive transport of
diffusion and always requires energy.
• This energy is released during
respiration.
Active Transport

ENERGY

Producing new cells
LI:
1. Describe the stages of mitosis.
2. Describe the maintenance of the
diploid chromosome complement by
mitosis.
3. Explain why mitosis is used by cells.

Everyone in this room
started life as a single
cell, a fusion of a sperm
and egg cell.
What processes must
have happened to develop
you from that single cell?

How many new cells do you
think you will make in a day?
Cell Division throughout Life

330 000 000 in 20 minutes
so…
23,760,000,000 new cells every
day!

What do these pictures all have
in common?

They are all examples of Cell
Division in action for growth or
repair!

How do Cells Divide?
Mitosis – watch this clip on the process of
mitosis and answer the following questions:
1.How are new cells produced?
2.What are chromosomes? Where are they
found?
3.What kind of cells undergo mitosis?
4.What are the only kind of cells that do not
undergo mitosis?

Put the following stages of
mitosis in the correct order:
• New nuclear membranes form around the
chromosomes, followed by new cell membranes,
creating two new identical cells.
• Chromosomes replicate to form identical chromatids.
• Spindle fibres then pull the matching chromatids
apart, to opposite poles of the cell.
• The membrane around the nucleus breaks down, and
spindle fibres attach to the chromatids and line them
up in the centre of the cell - equator.

Why do chromosomes need to be
copied so carefully and put into each
new cell?
• Chromosomes carry GENES, which are
stretches of DNA.
• Each GENE codes for one protein e.g.
one gene codes for haemoglobin, the
substance in red blood cells that carries
oxygen. Other genes will code for other
molecules that make up the body.

Chromosome Complement
• The number of chromosomes that a
species of animal or plant possesses.
• Why so you think it is important that
each new cell has the same chromosome
complement as the parent cell?

• During growth and development of an
organism will be able to provide the
animal or plant with all the
characteristics of its species.
• Losing any chromosome would mean a
loss of genetic information – the
information that forms the code
allowing the cell to function correctly!

What goes wrong in Cancer?
1 1 1
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3 3
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Increased
cell
division =
more cells
Decreased
cell death
= more
cells
Loss of
contact
inhibition –
the cells no
longer stay
in one place
Ability to invade
surrounding tissues
Ability to move
- metastasis
Loss of DNA
Repair
Escape from immune
surveillance = cells not
destroyed

Cancer cells – Research Task
1. Find out the meaning of the following terms…
• Benign
• Malignant
• Metastasis
2. Research a type of cancer and find out the following:
• What part of the body does this cancer affect?
• What are the clinical symptoms?
• How common is this cancer (in the UK)?
• What is the treatment given for this cancer?
• What research is being done on this cancer?
• Is there a charity fundraising to help support people
affected by this type of cancer?

Cell culture
LI:
1. Describe how cells are produced using
cell-culture techniques.
2. Describe the aseptic techniques that
are used when culturing cells.

Cell culture
Growing cells in the laboratory is known as
cell culture.
To grow cells in the lab you need:
• A suitable growing medium
• Availability of oxygen
• A suitable temperature
• A suitable pH level

Cells can be grown in
nutrient broth in
fermenters or flasks.
Or the broth can be
mixed with agar to make
a solid agar plate.

To provide
ideal growing
conditions
cultures are
grown in
incubators.
These allow
temperature,
humidity, pH,
carbon dioxide
and oxygen
levels to be
controlled.

Aseptic techniques
In order to work with cell cultures you
have to use aseptic techniques in order
to prevent contamination.
Your teacher will then show you how to
streak out bacterial colonies using
aseptic techniques.

Read page 45 of the textbook. Using what
you learned streaking out the bacteria,
take a page in your jotter and create a
“Guide to being aseptic”.

DNA
LI:
1. Describe the structure of DNA.
2. State the names of the four bases
that make up the genetic code.

What is DNA?
Watch the following video that introduces DNA and its
importance.
DNA video

DNA, genes and chromosomes
Chromosomes
The cell’s nucleus contains chromosomes made from long
DNA molecules.
DNA
DNA molecules are large and complex. They carry the
genetic code that determines the characteristics of a
living thing.
Genes
Think back to the last section!

DNA, genes and
chromosomes
The diagram shows the relationship between the cell, its
nucleus and the chromosomes in the nucleus that are made
up of DNA, and genes.
DNA
Collect the handout sheet and stick it into your jotters.

From Genes to Proteins?
Watch the following video that gives a basic
definition of a gene and what genes do.
What exactly is a gene?

DNA Structure
DNA consists of two molecules that are
arranged into a ladder-like structure called a
Double Helix.
A molecule of DNA is made up of millions of tiny
subunits called Nucleotides.

Nucleotide Structure
Each nucleotide consists of:
Phosphate
Group
Deoxyribose
Sugar
Organic
Base
Copy this diagram into your jotters.

DNA Structure
The phosphate and
sugar form the
backbone of the
DNA molecule,
whereas the
bases form the
“rungs”. Collect
the handout and
stick it into your
jotters.

The Genetic Code
The genetic code determines the order in which
amino acids are joined together to produce a
specific protein.
The code itself is determined by the order of the
organic bases in the DNA molecule.
There are 4 different bases.
Guanine Cytosine Adenine and Thymine

Each base can only join with one other type of
base:-
Guanine always pairs with Cytosine
Adenine always pairs with Thymine
G-C
and
A-T
These are called complementary base
pairs.

Complementary Base Pairs

Build your own DNA
Molecule
Task 1: Collect the handout sheets
DNA origami instructions and template
Follow the instructions to complete your own
model DNA!

DNA and proteins
LI:
1. Explain the relationship between DNA
and proteins.
2. Explain the relationship between the
order of bases on DNA and the amino
acids in a protein.
3. Describe the role of mRNA in protein
production.
4. Name the basic units that proteins are
made from and where protein synthesis
takes place.

Protein Structure
Proteins are made up of amino acids.
The order of the amino acids determines
the proteins molecular structure, its shape
and its function.
The order of the amino acids is
determined by the order of the bases in
the DNA molecule – the genetic code.

So how does the genetic code get translated
into a protein?

Watch Again
Watch the ‘What is DNA?’ video again. This time try to
answer the following questions:- Video
• How is the genetic code from the DNA molecule
copied?
• What happens to the copy of the genetic code?
Where does it go?
• In which organelle is the copy of the genetic code
translated to form proteins?
• How are the proteins formed?

Translating the genetic
code
Task 1: Using the information in the video, the questions
and discussion with your teacher write a short paragraph to
describe how the genetic code from the DNA is translated
into a protein.
You could use a
diagram to help
illustrate you
description.

Translating the genetic code
The genetic code in the DNA is copied or
transcribed by another molecule called
Messenger RNA (mRNA).
The mRNA carries the code out of the nucleus to
the ribosomes in the cytoplasm.
The ribosomes then translate the code from the
mRNA into the specific protein using amino acids
found free in the cytoplasm.

mRNA
The DNA for the gene being turned into a
protein is copied into a mRNA molecule.
It is different from DNA, it is:
• Shorter
• Single stranded
• Have URACIL instead of THYMINE.

How does mRNA become a
protein
Every 3 letters in the mRNA tell the
ribosome which amino acid to add to the
protein.
A U G C G A U G G A C G mRNA
Alanine Serine Glycine Proline

Translating the genetic
code
Task 3: In groups produce an A4 poster to illustrate
protein synthesis.
Your poster should contain the following information:-
• DNA carries the genetic code for producing proteins
• mRNA copies the code
• mRNA carries the copy of the code to the ribosomes
• The ribosomes translate the copy of the code to
produce proteins

Genetic engineering
LI:
1. Describe how genetic information can
be transferred from one cell to
another.
2. Explain the process of genetic
engineering and the stages involved.

What is genetic
engineering?
What is it used for?

Watch the following clip on Genetic
Engineering and in pairs answer the
following questions:
1.What 3 things are produced by
genetically modifying microbes?
2.Name the first organisms to be
genetically modified and when this was
done.
3.What does insulin normally do? What
condition arises from not making insulin?

GMO Defined…
• An organism that is generated through
genetic engineering is considered to be
a genetically modified organism (GMO).
• The first GMOs were bacteria in 1973;
GM mice were generated in 1974.
Insulin-producing bacteria were
commercialized in 1982 and genetically
modified food has been sold since 1994.

The process of Genetic
Engineering
• The control of all the normal activities of a
bacterium depends upon its single
chromosome and small rings of genes called
plasmids.
• In genetic engineering pieces of chromosome
from a different organism can be inserted
into a plasmid. This allows the bacteria to
make a new substance.

Task 1 – Use the cut out sheet
and put the stages of genetic
engineering in the correct
order.
Use the following diagram to
help you.

Uses of Genetic Engineering 1
Genetic engineering is used for the production
of substances which used to be both expensive
and difficult to produce. Examples include:
•insulin for the control of diabetes
•antibiotics such as penicillin
•various vaccines for the control of disease
•enzymes for laundry detergent

Uses of Genetic Engineering 2
Genetic engineering is a way of producing
organisms which have genotypes best suited for
a particular function. In the past man has used
selective breeding to achieve this. This was
done by choosing only his most suitable animals
and plants for breeding.

Genetic engineering has several advantages over
selective breeding. Some are:
• particular single characteristics can be
selected
• the selection may be quicker
• a desirable characteristic can be transferred
from one species to another

Genetic Engineering – now and
the future?
• It is not just bacteria that can be genetically
modified, plants and animals can be modified
too.
• It is therefore possible to genetically engineer
people!
• It holds the promise of curing genetic diseases
like cystic fibrosis, and increasing the immunity
of people to viruses.

• It is speculated that genetic engineering could
be used to change physical appearance,
metabolism, and even improve mental faculties
like memory and intelligence, although for now
these uses seem to be of lower priority to
researchers and are therefore limited to
science fiction.

Issues?
• There are dangers involved with genetic
engineering since it involves creating
completely new strains of bacteria.
There is a possibility of creating some
which are harmful to animal or plant
life.
• What is your opinion on GM Food (plant
and animal), GM organisms for research
and GM People?

Task 2 – Genetically Engineering
the Future
• Thinking about the possibilities and issues
surrounding genetic engineering, I want you to
imagine 50 years from now. Technology has
moved on and GMO is commonplace in
agriculture, medicine and all organisms.
• Write a letter to your present self,
describing this new world. Be honest in this
letter, what are the good and bad points
about GMO in the future?

Protein structure
LI:
1. Explain how the variety of protein
shapes and functions arises.
2. Describe some of the main functions
of proteins.

Protein structure
• Proteins are made up of sub-units called
amino acids.
• There are 21 amino acids.
• The order of amino acids in a protein is
dictated by the genetic code.
• Every protein has different amino acids
in different orders.

• The order of the amino acids affects
the shape of the protein.
• Proteins can be fibrous or globular:
• GLOBULAR – enzymes
• FIBROUS – keratin (hair)

Protein functions
Read pages 58 – 60.
Make a mind-map showing the 5 main
functions of proteins.

Enzymes
LI:
1. State what enzymes are and where they
can be found.
2. Describe the main function of an
enzyme.
3. Define the terms “active site” and
“substrate”.
4. Explain the relationship between the
active site of an enzyme and its
substrate.

Catalysts
A catalyst speeds up a chemical reaction,
but is unchanged in the process and can
be used over and over again.
In living things, catalysts are known as
enzymes.

If cells did not have enzymes in their
cytoplasm, then the chemical reactions
which happen in our cells would happen
so slowly that life would be impossible!

An example of an enzyme:
CATALASE
Hydrogen peroxide (H2O2) is a liquid
similar to water (H2O), but with one
extra oxygen.
Over a long period of time hydrogen
peroxide naturally breaks down into
water and oxygen.

The word equation for this reaction is:
Hydrogen peroxide water + oxygen
This process can be sped up using an
enzyme.

Into each test tube – measure out 5 ml of
Hydrogen peroxide AND 5 drops of
detergent.
CAUTION!!
Hydrogen
peroxide is a
dangerous
chemical.
Safety goggles
must be worn!!
1. Add nothing 2. Potato 3. Carrot 4. Liver
Leave for 10 minutes. Measure the
height of the foam bubbles.

Test tube contents Height of foam (mm)
Nothing – “CONTROL”
Potato
Carrot
Liver

Conclusion
Only the plant and animal tissues speed up
the breakdown of hydrogen peroxide.
This is because the cells contain catalase.
Catalase is an enzyme found in living
cells.

Catalase
Hydrogen peroxide water + oxygen
The tissue which contained the most
catalase was ______________.

Breakdown and Synthesis
Catalase is an enzyme involved in chemical
breakdown.
“Breakdown” means chopping up larger
molecules into smaller molecules.

Other enzymes do the opposite – the
build large molecules from smaller
molecules. This is called synthesis.

An example of a synthesis
enzyme: Phosphorylase
Glucose-1-phosphate is a chemical made
by plants during photosynthesis. It is
stored in plant cells be converting it
into a large molecule called starch.

Phosphorylase
Phosphorylase
Glucose-1-phosphate Starch

Substrates and products
The substrate is the substance the
enzyme works on.
The product is the substance the enzyme
makes.
Enzyme
Substrate Product

Enzyme Substrate Product
Catalase
Phosphorylase
Amylase
Pepsin
Lipase

How enzymes work
Enzymes are made of protein. This
protein has a special shape which is
unique to each enzyme.
Enzyme Active site

Enzyme
The active site is the correct shape to fit the
substrate.
Substrate
Enzyme
Substrate
Turned into
the products

Enzyme
Substrate
Other substrates are the wrong shape to fit in
the active site of the enzyme.
Therefore the enzyme will only work with one
substrate. This is described as being SPECIFIC.

“Specific”
When talking about enzymes, SPECIFIC
means that the ENZYME WILL ONLY
WORK WITH ONE SUBSTRATE.

One enzyme = one substrate
5 ml Starch 5 ml Starch 5 ml Starch 5 ml Starch
3 ml Water 3 ml Amylase 3 ml Pepsin 3 ml Lipase
Put in waterbath for 10 minutes. Test all 4 test-tubes with
Benedict’s Solution

Results
Sugar present?
Starch + water
Starch + amylase
Starch + Pepsin
Starch + Lipase

Conclusion
The test-tube containing Starch and
Amylase had the most sugar.
This shows that only Amylase can convert
starch to sugar.
Amylase is said to be SPECIFIC to starch.

Factors affecting enzyme
activity
LI:
1. Explain the meaning of the term
“optimum” as applied to enzymes.
2. Give factors that affect enzymes and
their proteins, and describe their
effect.
3. Explain the meaning of the term
“denatured” and why it happens to
enzymes.

Effect of temperature on
enzymes

5 ml Starch 5 ml Starch 5 ml Starch
3 ml Cold Amylase 3 ml Amylase 3 ml 80oC Amylase
Iced water 37oC 80oC
Put in waterbath for 10 minutes. Test all 3 test-tubes with
Benedict’s Solution

Temperature Was sugar present?
0 oC
37 oC
80 oC

All enzymes have a temperature at which
the work fastest.
This is called the optimum temperature.
In humans the optimum temperature for
all enzymes is 37oC.

Enzymes work slowly at cold
temperatures.

At very high temperatures enzymes
become changed and do not work.
This is called being denatured.
Once an enzyme is denatured it will never
work again.

The effect of pH on enzymes
Into all 5 test tubes put 5ml Hydrogen Peroxide and 5
drops of soap
3ml pH1 buffer 3ml pH4 buffer 3ml pH7 buffer 3ml pH9 buffer 3ml pH 14 buffer
LAST: Add 1 cm cylinder of potato to each
test tube. Measure height of foam after 10
minutes.

Results
pH Height of foam (mm)
1
4
7
9
14

Conclusion
The optimum pH for the catalase enzyme
is pH _______.
All enzymes have a different optimum pH
depending on where they are found in
the body.

Uses of enzymes
Yoghurt and cheese making
Biological detergents

Yoghurt and cheese
Yoghurt and cheese making depend on the
activities of enzymes in bacteria.
Bacteria used lactose sugar in milk as a
source of energy.

They make the waste product called lactic
acid which makes the milk increasingly
acidic and sour tasting.
Lactose energy + lactic acid

• This is another example of
fermentation.

1. Yoghurt making
• Milk is heated to kill microbes
• Special yoghurt bacteria are added
• The lactose in the milk is fermented
by the bacteria.
• The milk becomes acidic and so it:
– Thickens
– Tastes sour

2. Cheese making
The process is similar to yoghurt making,
but after the fermentation, rennet is
added which curdles the milk.
The solid curds are separated from the
liquid whey.
The curds are then pressed into hard
cheese.

Task 3 – Note Taking
• The following slides will tell you about biological
detergents; how they are made, why they are
useful and their environmental impact.
• Your task is to take notes from the slides – this
could be mind mapping key words and concepts
under the headings above or a table of
information or bullet point. Decide quickly which
method you find most useful when revising and
try it this way.

How Biological Detergents are
produced:
• Biological detergents contain enzymes such as protease,
amylase and lipase to digest proteins, starch and fats
respectively.
• Enzymes can be produced using bacteria that have been
genetically engineered to make these enzymes. They
are grown in industrial fermenters in vast quantities.
This equipment ensures that the bacteria receive food
and oxygen so that they grow well. The bacteria will
produce the enzymes and pass them out into the culture
liquid. The bacteria and the filtered off and the
enzymes extracted from the liquid. The enzymes are
purified and added to washing powder.

Value and Use of Product:
• Advantages of using biological detergents
include reducing fuel costs as clothes can be
washed at lower temperatures reducing the
electricity consumption; Less damage to
delicate fabrics such as acrylic and wool
whilst still cleaning effectively and the ability
to remove difficult stains such as grass and
blood. These will be completely removed by
biological washing powder but not by non-
biological even at high temperatures.

Environmental Impact 1:
• Reduced Fuel Consumption - using
Biological Detergents has a positive
impact on our environment as it reduces
CO2 and SO2 production from burning
fossil fuels in Power Stations to
generate electricity.

Environmental Impact 2:
• Detergents are rich in chemicals called phosphates.
This chemical passes from waste water from people’s
homes to sewage works. Unfortunately it is hard to
remove during processing and can end up in local
rivers where they cause algal bloom. This single celled
plant can overwhelm the balance of the ecosystem
and when it dies can cause bacterial numbers to
increase. The bacteria use up oxygen in the water
which leads to the death of other organisms.

Task 3 – Note Taking
• Your task was to take notes from the
slides – it would be useful to check your
notes with a peer. Have you covered
similar key areas?
• If you are not sure, the check with your
teacher!

Cellular respiration
LI:
1. Explain what is meant by the term
“respiration”.
2. Describe the build up and break down
of ATP in cells.
3. Name the cellular uses of ATP.
4. Give the summary word equation for
aerobic respiration.

Why do cells need energy?

Respiration
Why do cells need energy?
Living cells need energy to carry out a variety of
cell functions.
energy in
living cells
cell
growth
muscular
contraction
cell
division
nerve
impulses building
up large
molecules
chemical
reactions

energy from food

• The three main food groups are _____,
____________, and __________.
• _____ contains the most energy.

Aerobic Respiration
glucose +oxygen +
water
carbon
dioxide
energy released
Energy in a cell is produced by a chemical
reaction called aerobic respiration.

ATP
The energy produced during aerobic
respiration is stored in a molecule called
ATP (Adenosine triphosphate).
Every molecule of glucose that is “burned”
in the cell produces 38 ATP molecules.

ATP structure
ATP is made up of one Adenosine and
three phosphates
3 PHOSPHATE
GROUPS
ADENOSINE
High Energy
Bond
P P P

ATP is made by joining ADP (Adenosine
diphosphate) and phosphate.
ADP  Pi ATP

• As a molecule to transfer energy in cells
Glucose
+
Oxygen
Carbon
Dioxide
+
Water
Energy
Energy
ATP
ADP
+
Pi
e.g.
Amino
Acids
Protein
molecule
Energy
Energy
RESPIRATION ENERGY
TRANSFER
WORK

Aerobic respiration
LI:
1. Describe the stages of aerobic
respiration with reference to the
number of ATP molecules produced.
2. State the location of aerobic
respiration in cells.

Respiration should be seen as a series of
enzyme controlled reactions in which
• 6-carbon glucose is oxidised (broken
down) to form carbon dioxide
• this is accompanied by the synthesis of
ATP from adenosine diphosphate (ADP) and
inorganic phosphate (Pi).
Glycolysis

2ADP + 2Pi
Pyruvic Acid
Glucose
2ATP
(6C)
(2x3C)

The first stage of respiration is called Glycolysis.
• This process takes place within the cytoplasm.
• does not require oxygen
• involves the step by step breakdown of a 6-
carbon sugar such as glucose to form two 3-
carbon pyruvic acid units
Glycolysis results in a production of 2ATP.

What happens next?
If there is oxygen available ( the normal
situation), then the pyruvic acid produced
by glycolysis diffuses into an organelle
called mitochondrion for further
breakdown if oxygen becomes available.

Structure of a
Mitochondrion Outer Membrane
Cristae
Matrix Fluid
Inner Membrane

• Pyruvic acid from glycolysis diffuses
into central matrix fluid
• Pyruvic acid is broken down further in
the presence of oxygen by a cycle of
reactions called the Kreb’s cycle
releasing most of the 38 ATP produced
during respiration

Anaerobic respiration
LI:
1. State when anaerobic respiration
occurs.
2. Describe what happens in anaerobic
respiration in animal cell.
3. Describe what happens in anaerobic
respiration (fermentation) in
yeast/plant cells.

• If there is no Oxygen- Anaerobic
Respiration occurs.
• Anaerobic respiration occurs in human
after heavy exercise.

Pyruvic acid is converted to either
(i) Lactic Acid (in animal and bacterial cells)
(ii) Ethanol and carbon dioxide (in plant and
fungal cells)
• No further ATP is made – so only the net 2
ATPs are produced.
• In animal cells the Lactic Acid is converted
back to Pyruvic Acid when oxygen becomes
available.

Complete this summary table
Aerobic
respiration
Humans Yeast/Plant
Site in the
cell
Number of
ATP
Final
products

Complete this summary table
Aerobic
respiration
Humans Yeast/Plant
Site in the
cell
Cytoplasm &
Mitochondria
Cytoplasm Cytoplasm
Number of
ATP
38 2 2
Final
products
Carbon
dioxide &
water
Lactic acid Ethanol &
Carbon
dioxide

The importance of plants
LI:
1. Explain why plants are important.
2. Give examples of plants that are
useful to man, and explain what they
are used for.

Photosynthesis
 Why are plants important?
 What is photosynthesis?
 What do plants need for
photosynthesis?

The importance of plants

Raw materials

Food

Medicines

Photosynthesis
Importance of plants
FOOD RAW MATERIALS MEDICINES
Wheat – for bread Wood – for building Poppy – pain killers
Grapes – for wine Cotton – for clothes Foxglove – heart
medicine
Sugar cane – for
sugar
Flowers – for
perfumes
Mint – menthol for
cough sweets

Photosynthesis
LI:
1. Give the summary word equation for
photosynthesis.
2. Describe what happens during the
light reaction.
3. Describe what happens during carbon
fixation.
4. State the possible uses of the sugar
made in photosynthesis.

Green plants make their own food using
light energy
Green plants convert
light energy to
chemical energy (food)
using a green pigment
in the leaves called
chlorophyll.
Photosynthesis

Carbon Dioxide
taken up from air
Water - from soil
Light energy
- from sun
Oxygen given
off as waste
Glucose
used for energy
or stored as
starch

This can be summarised by the following
equation
Carbon
dioxide
Water Light energy
Chlorophyll
Glucose Oxygen
Raw Materials
Energy
source
and pigment
which
traps it
Products
Glucose is used for
energy, stored as
starch or built up into
cellulose
Oxygen is waste gas

Chloroplast structure

Stages of Photosynthesis
biochemistry
• There are two stages of photosynthesis. The
equation you have just learned is actually
more complex and occurs at two separate
stages.

Stage 1
• The first stage is called PHOTOLYSIS.
• This stage involves using energy from the
sunlight to split water molecules into
hydrogen and oxygen.

WATER
ATP
ENERGY
Oxygen Hydrogen
Passed on to
second stage
Passed on to
second stage
Released to the
air as oxygen gas

Light energy
Chlorophyll
Chemical
energy
ADP + Pi
ATP
Water
Hydrogen + Oxygen
Passed on to
second stage
Passed on to
second stage
Released to the
air as oxygen gas

Stage 2
• The second stage is known as the
Carbon Fixation stage
• Here the energy and hydrogen from
stage one are used along with the
carbon dioxide.
• It is at this stage where glucose
molecules are produced.

Hydrogen
Carbon
dioxide
ATP ADP + Pi
Glucose
From the first
stage
From the first
stage
From the air
Enzyme
controlled
reactions

• This stage is energy consuming so that
is where the ATP comes in.
• This stage is also controlled by
enzymes.
• Carbon dioxide and hydrogen join to give
us glucose

• Glucose which are used for energy
(respiration)
• Storage carbohydrates such as starch -
these can be broken
down to simple sugars if needed
• Structural carbohydrates such as
cellulose - these are used to build
the cell wall
What happens to the glucose?

Limiting factors
LI:
1. Describe the limiting factors of
photosynthesis.
2. Explain the impact of limiting factors
on photosynthesis and growth.

Three possible factors can limit the rate of
photosynthesis in a plant when they are in
short supply :-
• Light intensity – this limits the energy
available.
• Carbon dioxide concentration – this is an
essential raw material
• Temperature – this limits the rate at which the
enzymes controlling photosynthesis work.
Limiting factors

Effect of light on the rate of photosynthesis
We can use the rate of production of oxygen
bubbles by pond weed to measure the rate of
photosynthesis
Diagram “bubbler”

• A large water trough or sheet of glass
stops the heat from the lamp from
affecting the experiment.
• Lamp moved away -> less oxygen bubbles
produced
• The amount of light therefore limits the
rate of photosynthesis. It is called a
limiting factor.

Increasing
rate
of
photosynthesis
Increasing light intensity
Part A
As light intensity
increases the rate of
photosynthesis
increases.
Part B
Further increases in light causes
no further increase in the rate of
photosynthesis since the rate is
limited by a shortage of some other
factor e.g. carbon dioxide or
temperature
Point X Optimum

Increasing
rate
of
photosynthesis
Carbon Dioxide Concentration
Part A
As CO2 conc.
increases the rate of
photosynthesis
increases.
Part B
Further increases in CO2 conc.
causes no further increase in the
rate of photosynthesis since the
rate is limited by a shortage of
some other factor e.g. light or
temperature
Point X Optimum

Increasing
rate
of
photosynthesis
Increasing light intensity
0.2% CO2
0.3% CO2
0.4% CO2
light intensity is
limiting factor
CO2 is limiting factor

Increasing
rate
of
photosynthesis
Increasing temperature
Part A
As temperature
increases the rate
of photosynthesis
increases.
Part B
Further increases in
temperature results in a drop in
the rate due to the denaturing
of the enzymes that carry out
photosynthesis
Point X Optimum

Photosynthesis and horticulture

Photosynthesis and horticulture
Horticulture is the cultivation of plants in
gardens and greenhouses.
The use of a greenhouse helps remove
limiting factors:

(a) Lighting and heat
By increasing the light, the rate of
photosynthesis increases and leads to
an increase in the growth rate of the
crop:
• crop is ready to be picked earlier.
• increased crop yield.

(b) Carbon dioxide enrichment
Increased carbon dioxide in the atmosphere
increases the yield (size) of crops. This
happens because the rate of photosynthesis
is increased.

Cell structure advance.pptx

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