Download Which is the odd one out and why?

What is mitochondria?
• Mitochondria are known as the powerhouse of the cell.
• The mitochondria is the part of the cell responsible for energy production.
• Mitochondria turn glucose and oxygen into energy – respiration.
• Mitochondria take in nutrients, breaks them down, and creates energy for
the cell.
• The process of creating cell energy is known as cellular respiration.
• Most of the chemical reactions involved in cellular respiration happen in
the mitochondria.
• A mitochondrion is shaped perfectly to maximise its efforts.
Mitochondria Structure
•
Mitochondria have two membranes. The outer
membrane covers the organelle and contains it.
The inner membrane folds over many times.
The folding increases the surface area inside
the organelle.
•
Many of the chemical reactions happen on the
inner membrane of the mitochondria.
•
The increased surface area allows the small
organelle to do as much work as possible.
•
Mitochondria numbers differ in cells as it
depends on the job of that cell, e.g. muscle cells
require a very large number of mitochondria
whereas nerve cells require less.
In order
of size...
What are the functions of DNA?
1. Make exact copies
of itself
2. Provide instructions
so that the cell can
make the right
proteins at the right
time
The Discovery of DNA
• In 1953 two
scientists called
Watson and Crick
worked out the
structure of DNA
• The structure is a
double helix – a bit
like a twisted ladder
DNA structure
• How many strands are there?
• 2 – DNA is double stranded (made of
phosphates and sugar (deoxyribose))
• How many bases (letters) are there?
What are they?
• 4 = T, A, C, G
• Which ones always pair up with
one another?
• T and A
Base
• G and C
pairing
• What are the shapes like for the bases
that pair up?
• They are complementary to one another
(like a jigsaw) – NOT THE SAME
SHAPE!! Hydrogen bonds hold them
together
The structure of DNA
• DNA is made up of
nucleotides.
• A nucleotide consists of:
1. A phosphate
2. A sugar
(deoxyribose)
3. A nitrogenous base
(1 of 4 - GTCA)
A always pairs with T
C always pairs with G
Proteins
• Proteins are made of amino acids
• DNA contains the instructions to make
amino acids
triplet
amino acid
• The amino acids join together to form a protein
• We need proteins to make and repair cells
• Proteins are made in the cytoplasm
DNA Replication
• The basis for biological
inheritance
• How living organisms copy
their DNA
• Growth and Repair
• Growth of new organisms
• Every cell needs a copy
– if new cells are made,
DNA needs to be copied
DNA replication
• Base pairing means that
it is possible to make
exact copies of DNA
strands
1. Weak bonds split. This
‘opens up’ the DNA to
form 2 strands
2. Immediately, new
strands start to form
from free bases in the
cell
3. The 2 new chains are
identical
The Role of the Ribosome in
Translation
The DNA controls the functions of the cell by coding for
proteins, for example DNA codes for the enzymes involved with
respiration. Without these enzymes respiration would not take
place.
Proteinsynthesis
Explain how proteins
are made in the cell
Animal Cell
1. What do genes code for?
2. Which of the following is
the odd one out and why?
Proteins
DNA
Proteins
• They are important in the cell for many things
including:
– Energy source
– Growth and repair (new/damaged tissues)
– Enzymes (for chemical reactions)
– Needed for cell membranes
– E.g.’s include:
• Haemoglobin – in the blood
• Collagen – most abundant protein (connective tissue)
How are they made?
Step 1: Inside the nucleus
The gene unzips, and mRNA
bases pair with DNA bases
•
•
•
This forms a matching
strand of mRNA
U matches up with A
instead of T
C and G match up like
normal
How are they made?
Step 2: Moving out the
nucleus into cytoplasm
The mRNA strand moves
out of the nucleus via
nuclear pores to one of the
many ribosomes in the
cytoplasm
The mRNA moves through
the cytoplasm towards a
ribosome
How are they made?
Step 3: In the cytoplasm
The ribosome attaches to one
end of the mRNA strand
•
•
•
•
As the ribosome moves along the
mRNA, the ribosome translates
(reads) the genetic code
Every 3 bases = 1 amino acid
As it moves along, it makes a lot
of amino acids (you will make 2)
joined together – a protein or
poly-peptide
When it is finished reading it
the protein is released into the
cytoplasm
• This process is called transcription. The original DNA strand
unzips and mRNA is created from the DNA bases
• REMEMBER G matches with C but in mRNA, A matches up
with U (uracil)
http://www.teachertub
e.com/video/proteinsynthesis-animation60707#
• This part of protein synthesis is called translation. The
mRNA is translated to make a chain of amino acids
(eventually a poly-peptide)
DNA double helix is
separated.
mRNA is made using DNA
strand. = Translation
The mRNA acts as a code
for tRNA. = Translation
Amino acid on
neighbouring tRNA join
together.
mRNA leaves nucleus and mRNA joins onto a
enters cytoplasm.
ribosome.
A chain of amino acids is
a poly-peptide.
The poly-peptide chain
folds to form a protein
which is used in the cell or
exported to the body.
Proteins and Amino Acids
• Proteins build up, maintain and replace the tissues in your body.
• Your muscles, organs and immune system are made up mostly of
protein.
• Your body uses the protein you eat to make lots of specialised
protein molecules that have specific jobs.
• Proteins are sometimes described as long necklaces with
differently shaped heads. Each bead is a small amino acid.
• Amino acids are the building blocks of proteins. They make
thousands of different proteins when they join together.
Proteins and Amino Acids
• In your body you have 22 amino acids. Your body
makes 13, the 9 other amino acids come from
proteins in food. It is essential for the body to eat
proteins.
• Protein is a major functional and structural
component of all our cells. They provide the body
with roughly 10-15% of all our dietary energy and is
needed for growth and repair.
Types of Proteins
• Contractile Proteins – are responsible for movement – cardiac
muscle.
• Hormonal Proteins – are messenger proteins which help to coordinate
certain bodily activities.
• Structural Proteins – are fibrous and stringy and provide support –
cardiac muscle.
• Transport Proteins – are carrier proteins which move muscles from
one place to another around the body, e.g. antibodies and
haemoglobin.
• Enzymes are proteins that speed up chemical reactions.
Structural Protein
• Collagen is a
protein found in the
walls of arteries. It
makes the walls
stronger.
• It is also found in
bones, tendons
and cartilage.
Protein Hormone
• Insulin is a hormone
used to control blood
glucose levels.
Insulin is made in
the pancreas.
• Hormones help
control many of your
body functions.
Haemoglobin
Haemoglobin is a carrier molecule. It is used
to carry oxygen around the body.
Enzymes
Enzymes are proteins which control many
activities in your body, like digestion.
Mutations
• Genes code for proteins. Sometimes a gene
code can change. This is called a mutation.
Mutations to genes can cause the shape of the
protein to change so it can no longer do its job
in the cell.
• Gene mutations can occur spontaneously or be
caused by:
- radiation
- chemicals (such as tar in cigarettes).
Multicellular and unicellular
• Amoeba is a unicellular organism. It has 1 cell
which makes up its entire body. It is microscopic
and reproduction is asexual – one cell divides into 2
• Organisms bigger than this have to be
multicellular. These can be very large (humans)
and have specialised cells which carryout certain
functions.
• Cell division in multicellular organisms is much more
complex
Multicellular cell division
• 100% chromosomes in all body cells
• 50% of chromosomes are found in sex cells
• In humans, 46 chromosomes are paired (23 pairs)
and each pair carries similar information
(homologous pair)
• Chromosomes in pairs – diploid cell (body cells)
• Singles chromosomes – haploid cell (sex cells)
What is mitosis?
Mitosis begins with a single cell.
How many chromosomes does
this cell contain?
original
cell
First the cell makes a copy
of each chromosome…
…then it divides.
cell
division
Each new cell has a full set
of chromosomes and is
identical to the original cell.
2 new cells
What is mitosis?
Each new cell can keep on
dividing by mitosis.
Mitosis makes new cells for
growth and repair in all living
things. That’s how you get
from one cell to 50 billion!
Mitosis is also called
copying division.
What does this mean?
Mitosis activity
Mitosis animation
Key Words
•
Active Site – the part of the molecule where the reaction occurs – used
particularly with reference to enzymes.
•
Denature – active site of the enzyme changes size, it can no longer act on the
body.
•
Enzyme – special proteins found in living organisms that speed up the rate of a
chemical reaction.
•
Lock-and-Key Mechanism – where the substrate fits into an active site.
•
pH – level of how acidic or alkaline a substance is.
•
Specific – relating to a particular type of species.
•
Temperature – how hot or cold something is.
Enzymes
• Enzymes are catalysts. They speed up chemical reactions that
occur in cells.
• Enzymes are made from proteins. Each enzyme is specific to the
substance (substrate) it acts on.
• Examples of chemical processes where enzymes are important
include:
- Photosynthesis
- Respiration
- Protein Synthesis
- Cheese Making
- Detergents (breaks down stains).
Amino Acids
• Enzymes are made from amino acids, and they are proteins.
• When an enzyme is formed, it is made by stringing together
between 100 and 1000 amino acids in a very specific and
unique order. The chain of amino acids then folds into a
unique shape.
• That shape allows the enzyme to carry out specific chemical
reactions – an enzyme acts as a very efficient catalyst for a
specific chemical reaction.
• The enzyme speeds that reaction up tremendously.
What do enzymes do?
• Enzymes can put
atoms and molecules
together and break
molecules apart.
• There is a specific
enzyme for each
chemical reaction
needed to make the
cell work properly.
Why do living things respire?
• Plants and animals need
energy to carry out processes
such as:
- Movement (by contracting
muscles)
- Maintain body temperatures
- Make proteins for growth and
repair.
Aerobic Respiration
• Aerobic respiration uses oxygen to release energy
that is trapped in glucose. Aerobic respiration releases
lots of energy.
Word Equation
glucose + oxygen  carbon dioxide + water (+ energy)
Symbol Equation
C6H12O6 + 6 CO2  6 H2O (+ energy)
Burning Sugar
• If you burn sugar it releases a lot of energy. Your body
can release energy in sugar, however it does it in a
very controlled way.
• To release energy the cells need glucose and oxygen.
Respiration is the releasing of energy in cells.
• Respiration is controlled by enzymes. Changes to the
pH and temperature can affect enzymes. This is why
respiration is dependent on pH and temperature.
Respiratory Quotient
• Once the volumes of carbon dioxide and oxygen
have been found, the respiratory quotient (RQ)
can be calculated using the following formula:
Carbon dioxide produced
Oxygen used
• For aerobic respiration that uses glucose the RQ
is always 1.
Where does respiration occur?
Respiration occurs in
the mitochondria.
Respiration releases
energy which is stored
in ATP (adenosine
triphosphate)
molecules. The ATP
molecule is used as an
energy source for many
processes inside the
cell.
Mitochondrion
The Circulatory System
• The circulatory system consists of the
heart, arteries, veins capillaries and
blood.
• Arteries transport blood away from the
heart.
• Veins transport blood towards the
heart.
• Capillaries join arteries to veins,
materials such as oxygen are
exchanges between capillaries and
body tissue.
Red Blood Cells
• These cells transport oxygen around
the body. They contain haemoglobin
which oxygen joins to become
oxyhaemoglobin.
• Red blood cells have no nucleus, this
means they can carry more oxygen.
• They are disc shaped, this means
there is more surface area for oxygen
to move in and out. They are small so
they can get to all parts of the body.
White Blood Cells
These cells destroy microbes. They wrap
around microbes and engulf them. They are
small cells so that they can squeeze through
capillary walls to reach microbes.
Plasma
Liquid in the blood to transport dissolved
substances such as, water, hormones,
antibodies and waste around the body.
Blood Vessels
There are three types of blood vessels:
• Arteries go away from the heart.
• Veins go towards the heart.
• Capillaries join the arteries to the veins.
• Substances (oxygen and glucose) are exchanged between
capillaries and the body tissue. These are very small blood
vessels. The beating of the heart squeezes the blood
through blood vessels called arteries.
Adaptations of Blood Vessels
Arteries
• They have a thick muscular and
elastic wall to help it withstand high
blood pressure as blood leaves the
heart.
Veins
• They have a large lumen to help
blood flow at low pressure. Valves
stop blood flowing the wrong way.
Capillaries
• They have thin, permeable walls to
allow exchange of material with body
tissue.
The Structure of the Heart
• The heart pumps blood around the body. It has two sides:
• Right side – pumps blood to the lungs.
• Left side – pumps blood to the rest of
the body.
• There are four parts of the heart called
chambers.
• Two atria – receive blood from veins.
• Two ventricles – pumps blood into arteries.
• Valves prevent the blood flowing backwards when the heart relaxes
and so keeps the blood under pressure.
Double Circulatory System
• Humans have a double circulatory system.
• One circuit links to the heart to the lungs.
• One circuit links to the heart and the body.
• The heart is made up of two pumps. This is an
advantage because blood going to the body can
be at a much higher pressure than blood going
to the lungs.
Growth
• When plants and animals grow, cells need to
divide and change into specialised cells. For
example, nerve cells and bone cells.
• The specialised cells can carry out different
jobs.
• When a cell changes to become specialised
the process is called cell differentiation.
Growth in Animals
• Only grow in the early stages
of their lives.
• The whole animal grows.
• Tend to grow a certain size
then stop.
• Growth is by cell division only.
• Cells lose the ability to
differentiate.
Growth in Plants
• Keep on growing all their life.
• Only specialised parts of the plant
continue to grow.
• Cell division takes place in special areas
called meristems. Meristems are found
at the tips of the roots and shoots.
• Plants increase in height because their
cells get larger rather than just cell
division.
• Cells retain their ability to
differentiate.
Genetic Engineering
• Genetic engineering is also
called genetic modification or
GM. It is not the same as
closing. Although cloning
techniques are used in genetic
engineering, the two things
should not be confused.
• Humans, plants, animals and
food can be genetically
modified.
How Genetic Engineering Works
Modifying DNA by genetic engineering follows these basic steps:
•
•
•
•
Select the characteristic
Identify and isolate the gene
Insert the gene into the chromosome of a different organism
Replicate (copy) the gene in the organism and produce the protein.
Examples of Genetic Engineering
Insulin
• A bacterium called E-coli has been
genetically engineered to make human
insulin.
• This is needed to control blood sugar.
• Diabetics cannot produce enough
insulin and rely on daily injections of
insulin.
Rice containing Vitamin A
• Rice is the main diet for people living
in Asian countries.
• Scientists have taken the gene to
make beta-cartone from carrots and
put it into rice plants.
Advantages and Disadvantages
Advantages
• Allows organisms with new
features to be produced rapidly.
• Saves peoples lives.
Disadvantages
• The inserted genes may have
unexpected harmful effects.
• Not natural.
Ethical Considerations
Benefits
• Producing diseaseresistant crops and higher
yields which could feed
more of the world’s
population.
• Creating crops that will
grow in poor or dry soil to
feed people in poor areas.
• Potentially replacing faulty
genes to reduce certain
diseases.
Concerns
•
GM plants may cross-breed with wild plants
and release their new genes into the
environment.
•
GM foods may not be safe to eat in the long
term.
•
It could lead to the genetic make-up of
children being modified or engineered
(‘designer babies’).
•
Unborn babies with genetic faults could be
aborted.
•
Insurance companies could genetically
screen applicants and refuse to insure
people who have an increased risk of illness.
Gene Therapy
• Changing a person’s genes in an attempt to
cure genetic disorders is called gene therapy.
• Gene therapy can involve body cells or gametes.
• Gene therapy involving gametes (sex cells –
sperm and egg) is very controversial. This is
because the genetic changes that are made
don’t just affect the individual being treated
but affect all future generations as those are
the genes passed on to the offspring.
• The future generations don’t have a say in the
treatment and it may affect them especially if
it leads to problems.
Making Copies
• The process of cloning is used to make
copies of animals and plants. The copies
are called clones.
• Clones are genetically identical. They all
have the same DNA as the original animal
or plant.
• Cloning involves only one parent. This is
called asexual reproduction.
Natural Clones
• Clones are genetically
identical organisms.
• Sometimes clones
are produced
naturally.
• Human twins can be
genetically identical.
They are called
natural clones.
Cloning Animals
• Animals can be cloned
artificially. The most famous
example is Dolly the sheep, who
was the first mammal to be
successfully cloned from an
adult body cell.
• A cloning technique called
embryo transplantation is now
commonly used in cattle
breeding.
Nuclear Transfer
• Dolly was produced by the process
of nuclear transfer.
• This involved scientists placing the
nucleus of a body cell (an udder
cell) from the sheep the wanted to
clone into an empty egg cell, which
had its nucleus removed.
• A short sharp electric current
helped the cell start dividing. It was
then implanted into another sheep
to grow.
Uses of Cloning
• It’s possible to clone human embryos in the
same way that animals are cloned. This
technique could be used to provide stem cells
for medical purposes.
• The mass production of animals with desirable
characteristics.
• Producing animals that have been genetically
engineered to provide human products.
Ethical Issues
• The cloning process is very unreliable – the majority of cloned
embryos don’t survive.
• Cloned animals seem to have a limited life span and die early.
• The effect of cloning on a human’s mental and emotional
development isn’t known.
• Religious views say that cloning humans is wrong.
• Using human embryos and tampering with them is
controversial.
Cloning in Plants
• Many plants can reproduce
asexually.
• Asexual reproduction
produces identical copies.
Plants can reproduce
asexually, i.e. in the absence
of sex cells and fertilisation.
• Spider plants, strawberry
plants and potato plants all
reproduce in this way.
Strawberries
• Strawberries grow
stems called
runners.
• The runners spread
over the ground and
have buds that grow
into tiny strawberry
plants called
plantlets.
Potatoes
• If potatoes are left
long enough they
begin to sprout.
• It will begin to grow
shoots and roots and
eventually another
potato plant will
grow.
Spider Plants
• Spider plants grow new
plants on their stems.
• The new plants are
called plantlets.
• If the plantlets are cut
off the parent plant and
are planted in the soil.
They grow into adults.
Commercial Cloning of Plants
ADVANTAGES
• All the plants are genetically
identical.
• Plants can take a long time to
grow from seeds. Cloning is a lot
quicker.
• Cloning enables growers to
produce plants that are difficult to
grow from seeds, such as
bananas.
• Can be used to keep good
characteristics in a plant.
DISADVANTAGES
• If an environment changes or a
new disease breaks out, all the
plants will die out.
• Cloning plants over many years
can result in little genetic
variation because genes do not
mix.
Tissue Culture
• Small sections of plant tissue can be
cloned using tissue culture.
• Plants with the desired
characteristics are chosen.
• Tissue samples are taken
from the plant.
• They are put in sterile test tubes and
grown in sustainable conditions.
Grafting
• Grafting is where you
cut part of a tree off
(i.e. a branch) and you
fix it onto another tree.
• On an apple tree,
which has been
grafted, it will have
different apples from
different trees when
they fruit.
Differentiation
• Cloned plant cells can differentiate into
many different cells. Root cells used in
tissue culture have been found to change
cell type required for a plant to grow.
• Most animal cells have lost the ability to
differentiate.