Living and Growing

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Living and Growing
(OCR Gateway)
W Richards The Weald School
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B3a Molecules of Life
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A Typical Animal Cell
4)
Ribosomes protein synthesis happens here
Cytoplasm - this is where the reactions happen
and these are controlled by enzymes
1)
2)
Nucleus controls the cells activities
Mitochondria - energy is released here and
there are LOTS of these in the liver and muscles
5)
3)
Cell Membrane controls what comes in and out
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Genes, Chromosomes and DNA
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DNA
Some facts - Made up of paired bases - Contain
instructions on what a cell does, how the
organism should work etc - The instructions are
in the form of a code - The code is made up from
the four bases that hold the two strands
together - The bases represent the order in
which amino acids are assembled to make proteins
- The sequence of bases determines the order in
which a cell makes amino acids, which turn into
proteins - There are about 20 amino acids in
all, and different combinations produce different
proteins
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Making proteins
1) DNA unravels and a copy of one strand is
made
2) The strand copy is made to produce RNA
3) The copy (with its code) then moves towards
the ribosome
4) The ribosome decodes the code which tells
the ribosome how to make the protein
5) Amino acids are then joined together to form
a polypeptide (protein)
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DNA

• Task Find out how the structure of DNA was
  discovered, including
• An image of Crick and Watson with their original
  model
• A brief desciption of what Crick and Watson did
  to discover DNA
• How Franklin and Wilkins built on their work

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Watson and Crick
We discovered the structure of DNA in 1953. We
used data from other scientists (such as X-ray
data showing that there were two chains wound in
a helix) to come up with the double-helix
structure.
However, our discovery was not accepted by the
scientific community until other scientists
repeated and tested the work.
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B3b Proteins and Mutations
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Proteins
Proteins are basically long chains of amino acids
Every different protein has its own number and
sequence of amino acids which results in
differently shaped molecules with different
functions.
Some example proteins
Name of protein Function
Collagen Give structure
Insulin Hormones
Haemoglobin Carrier molecules
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Enzyme use in nature
Enzymes are proteins that speed up chemical uses.
Here are two important natural uses for them
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Introduction to Enzymes
Enzymes are biological catalysts. They help the
reactions that occur in our bodies by controlling
the rate of reaction.
An enzyme is basically a protein molecule made up
of long chains of amino acids. These molecules
are then folded to create a certain shape with
high specificity
The enzymes shape helps another molecule fit
into it
Substrate
This shape can be destroyed by high temperatures
or the wrong pH
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The Active Site
Enzyme
Substrate
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Enzymes
Enzymes work best in certain conditions
The Q10 value is a way of measuring the change
to the rate of reaction
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Mutations
Cells contain a nucleus and the nucleus contains
genes that carry instructions for what that cell
should do

• Some facts
• Some genes are switched off and dont do
  anything in that cell
• Genes basically tell the cell which proteins
  they should be producing
• Sometimes cells can mutate which may have a
  harmful effect on the cell and can be caused by
  natural or artificial means.

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Mutations
Mutations are changes in the base sequence of the
DNA molecule. They can be passed on to daughter
cells through cell division. They will result in
the wrong proteins being produced.
Mutations can be caused by - Ionising radiation
(UV, X-rays etc) - Radioactive substances -
Certain chemicals Effects - Mostly harmful -
Causes death or abnormality in reproductive
cells - Causes cancer in body cells - Some CAN
be neutral or even beneficial (e.g. the peppered
moth)
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B3c Respiration
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Respiration Introduction
I enjoy taking samples using quadrats. In order
to do this, I need energy. Where does this
energy come from?
Our energy comes from a process called
respiration, which basically involves turning
food and oxygen into energy and this reaction is
controlled by enzymes.
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(Aerobic) Respiration
Words breathing, energy, grow, respiration,
food, mitochondria
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The Effect of Exercise
Heart rate/min
Breathing rate/min
100
225
Rest
Exercise
Recovery
75
175
50
125
25
75
5 mins
10 mins
15 mins
20 mins
During exercise the following things happen
heart rate increases, breathing increases and
arteries supplying muscles dilate. These three
things all help muscles to get the oxygen and
glucose they need.
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Muscles and exercise
When we exercise our muscles are supplied with
more oxygen and glucose, increasing the rate of
respiration.
Respiration results in the production of ATP
which is used as an energy source in cells. This
process requires oxygen so the rate of
respiration can be measured by measuring the rate
of consumption of oxygen.
The rate of respiration is controlled by enzymes.
What are enzymes affected by?
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Anaerobic respiration
Unlike aerobic respiration, anaerobic respiration
is when energy is provided WITHOUT needing
_________
This happens when the body cant provide oxygen
quick enough for __________ respiration to take
place. Anaerobic respiration produces energy
much _______ than aerobic respiration but only
produces 1/20th as much. Lactic acid is also
produced, and this can build up in muscles
causing ______ and excess post-exercise oxygen
consumption (EPOC), which explains why
breathing and heart rates remain high after
exercise.
Words debt, oxygen, fatigue, aerobic, quicker
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B3d Cell Division
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Single celled or multi-celled?
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Cell Growth
There are three ways in which a cell might grow
1) Cell division
2) Cell expansion
3) Cell specialisation
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Mitosis
Mammal cells are diploid they have two copies
of each chromosome
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Making DNA copies
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Meiosis
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Mitosis vs. Meiosis

• Mitosis
• Used for growth and repair of cells
• Used in asexual reproduction
• Cells with identical number of chromosomes and
  genetic information are produced

• Meiosis
• Used to produce gametes for sexual reproduction
• Each daughter cell has half the number of
  chromosomes of the parent

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Sexual Reproduction
The human egg and sperm cell ( HAPLOID GAMETES)
contain 23 chromosomes each and are created by
meiosis.
When fertilisation happens the gametes fuse
together to make a single cell called a DIPLOID
ZYGOTE. The zygote has 46 chromosomes (23 pairs)
and continues to grow through mitosis.
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Eggs and sperm
The female egg cell and the male sperm cell are
examples of ____________ cells
The ______ cell is specialised in two ways
The egg cell is basically an enlarged cell with
massive _____ reserves
Words food, swimming, sperm, specialised, digest
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B3e The Circulatory System
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The Circulatory system
The circulatory system is responsible for pumping
______ around the body. We need blood to be
taken around the body because blood contains
________ and _______. These are needed so that
all the ____ in our bodies can produce _____
through _________. The main organs in the
circulatory system are the _____, the lungs and
the kidneys.
Words energy, heart, blood, glucose,
respiration, oxygen, cells
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The four parts of blood
1. RED BLOOD CELLS contain haemoglobin and
carry ______ around the body. They have no
_______ and a large surface area.
2. PLATELETS small bits of cells that lie
around waiting for a cut to happen so that they
can ____ (for a scab).
3. WHITE BLOOD CELLS kill invading _______ by
producing _________ or engulfing (eating) the
microbe.
These three are all carried around by the PLASMA
(a straw-coloured liquid). Plasma transports CO2
and ______ as well as taking away waste products
to the ______.
Words antibodies, clot, kidneys, oxygen,
nucleus, glucose, microbes.
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The role of haemoglobin
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The Double Circulatory System
Having a double circulatory system enables
mammals to pump blood at higher pressure and with
a greater flow rate.
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Arteries, veins and capillaries
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The Heart
1. Deoxygenated blood (i.e. blood without oxygen)
enters through the vena cava into the right atrium
4. Oxygenated blood from the lungs enters through
the pulmonary vein into the left atrium
2. Its then pumped through the tricuspid valve
into the right ventricle
5. Its then pumped through the bicuspid valve
into the left ventricle
3. Its then pumped through the semi-lunar valve
up to the lungs through the pulmonary artery
6. Its then pumped out of the aorta to the rest
of the body
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B3f Growth and Development
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Revision of a Typical Animal Cell
4)
Ribosomes protein synthesis happens here
Cytoplasm - this is where the reactions happen
and these are controlled by enzymes
1)
2)
Nucleus controls the cells activities
Mitochondria - energy is released here
5)
3)
Cell Membrane controls what comes in and out
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A typical plant cell
Cell wall made of cellulose which strengthens
the cell
Cell membrane controls what comes in and out
Chloroplasts (containing chlorophyll) this is
needed for photosynthesis
Nucleus controls what the cell does and stores
information
Large vacuole contains sap and helps support
the cell
Cytoplasm Chemical reactions happen here
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Plant cells vs. Animal cells
Only plant cells have these
Both types of cell have these
Cell wall
Cytoplasm
Nucleus
Chloroplasts
Cell Membrane
Large Vacuole
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Bacteria
Consider a bacteria cell in more detail
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Measuring Plant Growth
Im bored of using quadrats now. I think Ill
measure the growth of this plant instead. How
can I do it?

• There are a number of ways to measure plant
  growth, including measuring
• Length/height
• Wet mass
• Dry mass

What are the advantages and disadvantages of each?
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Measuring Human Growth
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Adult Stem Cells
It is also possible to have adult stem cells
these are unspecialised cells that can become
specialised later (but they cant form ALL types
of cell)
Adult stem cells can be found in places like bone
marrow.
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Stem cell research
Stem cells are cells that have not yet
specialised
These stem cells have the potential to develop
into any kind of cell. The rest of the embryo is
destroyed. Most of these embryos come from
unused IVF treatments unless the stem cells are
taken from bone marrow in adults.
Embryo
Egg and sperm
Cloned embryos
The ethical issue Should these embryos be
treated as humans?
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Human Growth vs Plant Growth
There are many differences between the way humans
grow and the way plants grow

1. Plants grow continually and wont stop until they
   die
2. Plant cells retain their ability to differentiate
   whereas animal cells lose it at an early stage
3. Plant cell division is restricted to areas called
   meristems

1. Humans have two main stages of growth straight
   after birth and during adolescence
2. Human growth occurs throughout the human

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Plant Growth Introduction
Plants grow due to their cells dividing through
mitosis. The cells then specialise into root
hair cells, palisade cells etc. Unlike animals,
plants continue to grow for the rest of their
lives.
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Plant Growth - Meristems
Plant growth occurs in areas called meristems.
These meristems are mitotically active
Cells from the meristem behave like stem cells
they can develop into any kind of cell. Cloned
plants can be produced from these cells.
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B3g New Genes for Old
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Selective breeding
I raise cows. Each type of cow is good at a
certain job. The Friesian cow produces large
quantities of milk, the Jersey cow produces very
nice milk and the Hereford cow produces lot of
beef.
If, for example, I want lots of milk I would only
breed Friesian cows with each other this is
SELECTIVE BREEDING. The only trouble is that Im
reducing the gene pool by doing this.
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Examples of Selective Breeding
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Uses of Genetic Engineering
Genetic engineering is the idea of transferring
a gene from one organism into another in order to
give it extra features, such as

• With genetic engineering I can produce milk that
  contains
• Extra protein
• Lower levels of cholesterol
• Human antibodies

Other current examples of genetic engineering
include transferring genes from carrots that are
involved in humans producing vitamin A and
putting them into rice instead and engineering
crops that are resistant to herbicides.
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An example - Insulin
Step 1 Using RESTRICTION ENZYMES cut out the
part of the human chromosome that is responsible
for producing insulin.
Step 2 Using another restriction enzyme cut open
a ring of bacterial DNA (a plasmid). Other
enzymes are then used to insert the piece of
human DNA into the plasmid.
Step 3 Place the plasmid into a bacterium which
will start to divide rapidly. As it divides it
will replicate the plasmid and make millions of
them, each with the instruction to produce
insulin. Commercial quantities of insulin can
then be produced.
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Genetic Engineering
Should genetic engineering be allowed?
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Gene Therapy
Gene therapy is when diseases are treated by
modifying a persons genome. For example, take
cystic fibrosis
1) Take a disease-causing virus
2) Remove the genetic material that causes
excessive mucus to be produced
3) Insert the genetic material that stops cells
producing excess mucus
4) The virus then works on the cells in the lung
Gene therapy often involves gametes why is this
controversial?
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B3h Cloning
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Dolly the sheep
My name is Dolly and I was born in 1997. I made
history as I was the first mammal clone. In
other words, I was a genetically-identical copy
of my parent.
Of course, clones have been around for many years
as identical twins are basically clones
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Cloning Animals
Heres how Dolly the sheep was cloned
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Applications of Cloning

1. Animal organ donors animal organs could be
   potentially cloned and modified so that they can
   be used in humans.
2. Human cloning cloning can be used to provide
   stem cells but these could be used to clone a
   human.
3. Animals with desirable characteristics could be
   cloned.

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Cloning
Should cloning be allowed?
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Cloning Plants
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Cloning Plants by tissue culture
1) Scrape of a few cells from the desired plant
2) Place the scrapings in hormones and nutrients
3) 2 weeks later you should have lots of
genetically identical plants