09/06/2015 Living and Growing W Richards The Weald School (OCR Gateway)

18/04/23

Living and GrowingLiving and Growing

W Richards

The Weald School

(OCR Gateway)

18/04/23

B3a Molecules of LifeB3a Molecules of Life

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4)1)

5)

3)

A Typical Animal CellA Typical Animal Cell

Ribosomes – protein synthesis happens here

Mitochondria - energy is released here and there are LOTS of these in the liver and muscles

Cell Membrane – controls what comes in and out

Cytoplasm - this is where the reactions happen and these are controlled by enzymes

2) Nucleus – controls the cell’s activities

18/04/23Genes, Chromosomes and Genes, Chromosomes and DNADNA

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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

DNADNA

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Making proteinsMaking proteins1) 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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Task: Find out how the structure of DNA was discovered, including:

1) An image of Crick and Watson with their original model

2) A brief desciption of what Crick and Watson did to discover DNA

3) How Franklin and Wilkins built on their work

DNADNA

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Watson and CrickWatson 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 MutationsB3b Proteins and Mutations

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ProteinsProteinsProteins 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 natureEnzyme use in nature

Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes.

Photosynthesis is catalysed by enzymes in the cells.

Enzymes are proteins that speed up chemical uses. Here are two important natural uses for them:

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Introduction to EnzymesIntroduction to EnzymesEnzymes 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 enzyme’s shape helps another molecule “fit” into it:

This shape can be destroyed by high temperatures or the wrong pH:

Enzyme Substrate

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The “Active Site”The “Active Site”

Enzyme Substrate

Active site

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Enzymes are denatured

beyond 40OC

EnzymesEnzymesEnzymes work best in certain conditions:

Enzyme activity

Temp pH pH400C

Could be protease (found in the stomach)

Could be amylase (found in the intestine)

The “Q10” value is a way of measuring the change to the rate of reaction:

Q10 = Rate at higher temperature

Rate at lower temperature

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MutationsMutationsCells contain a nucleus and the nucleus contains genes that carry instructions for what that cell should do:

Genes

Some facts:

• Some genes are “switched off” and don’t 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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MutationsMutationsMutations 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 RespirationB3c Respiration

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Respiration IntroductionRespiration IntroductionI 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(Aerobic) Respiration

Words – breathing, energy, grow, respiration, food, mitochondria

All living organisms have to move, _____, reproduce etc. Each of these life processes needs ENERGY. ___________ is the process our bodies use to produce this energy:

The glucose we need comes from ______ and the oxygen from _________. Water and carbon dioxide are breathed out. The MAIN product of this equation is _________. Respiration happens in _________ in cells.

Glucose + oxygen water + carbon dioxide + ENERGYC6H12O6 + 6O2 6H2O + 6CO2 + ENERGY

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The Effect of Exercise The Effect of Exercise Heart rate/min

Breathing

rate/min100

75

50

25

225

175

125

75

5 mins 10 mins 15 mins 20 mins

Rest Exercise Recovery

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 exerciseMuscles and exerciseWhen 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.

RQ = Carbon dioxide produced

Oxygen used

The rate of respiration is controlled by enzymes. What are enzymes affected by?

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Anaerobic respirationAnaerobic respirationUnlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________:

This happens when the body can’t 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

Glucose lactic acid + a bit of energy

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B3d Cell DivisionB3d Cell Division

18/04/23Single celled or multi-Single celled or multi-celled?celled?

Advantages of being single-celled: Advantages of being multi-celled:

Disadvantages of being single-celled: Disadvantages of being multi-celled:

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Cell GrowthCell GrowthThere are three ways in which a cell might “grow”:

1) Cell division:

2) Cell expansion:

3) Cell specialisation:

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MitosisMitosis

Each daughter cell has the same number of chromosomes and

genetic information as the parent.

Mammal cells are “diploid” – they have two copies of each chromosome

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Making DNA copiesMaking DNA copies

1) The double helix unzips

2) New bases pair up with the exposed bases

3) An enzyme bonds these bases together

4) Two identical pieces of DNA are formed

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MeiosisMeiosis

Each daughter cell has half the number of

chromosomes of the parent.

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Mitosis vs. MeiosisMitosis vs. MeiosisMitosis:

1. Used for growth and repair of cells

2. Used in asexual reproduction

3. Cells with identical number of chromosomes and genetic information are produced

Meiosis:

1. Used to produce gametes for sexual reproduction

2. Each daughter cell has half the number of chromosomes of the parent

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Sexual ReproductionSexual 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 spermEggs and spermThe female egg cell and the male sperm cell are examples of ____________ cells:

The egg cell is basically an enlarged cell with massive _____ reserves

The ______ cell is specialised in two ways:

Words – food, swimming, sperm, specialised, digest

An acrosome that releases enzymes to ______ its way through the egg

Strong tail for ________

Nucleus

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B3e The Circulatory SystemB3e The Circulatory System

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The Circulatory systemThe Circulatory systemThe 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 bloodThe four parts of blood1. 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 haemoglobinThe role of haemoglobin1) Red blood cells are packed with haemoglobin. When they are pumped to the heart the haemoglobin picks up oxygen (“oxyhaemoglobin”)

2) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and then to the lungs to start again

18/04/23The Double Circulatory The Double Circulatory SystemSystem

1) Blood gets pumped from the heart to the lungs and picks up oxygen

2) The blood is then taken back to the heart…

3) The heart pumps the blood to the intestine (where oxygen and glucose are removed)…

4) … and to the rest of the body (where oxygen is removed)

5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again

Having a double circulatory system enables mammals to pump blood at higher pressure and with a greater flow rate.

18/04/23Arteries, veins and Arteries, veins and capillariescapillaries

Arteries carry high pressure blood away from the heart.

They have smaller lumen and no valves.

Veins carry low pressure blood back to the heart. They have thinner, less elastic walls

and have valves to prevent backflow of blood.

Capillaries have thin walls (one cell thick) to

allow glucose and oxygen to pass through.

Also used to connect arteries to veins.

“Lumen”

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The HeartThe Heart1. Deoxygenated blood (i.e. blood without oxygen) enters through the vena cava into the right atrium

2. It’s then pumped through the tricuspid valve into the right ventricle

3. It’s then pumped through the semi-lunar valve up to the lungs through the pulmonary artery

4. Oxygenated blood from the lungs enters through the pulmonary vein into the left atrium

5. It’s then pumped through the bicuspid valve into the left ventricle

6. It’s then pumped out of the aorta to the rest of the body

18/04/23B3f Growth and B3f Growth and DevelopmentDevelopment

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4)1)

5)

3)

Revision of a Typical Animal Revision of a Typical Animal CellCell

Ribosomes – protein synthesis happens here

Mitochondria - energy is released here

Cell Membrane – controls what comes in and out

Cytoplasm - this is where the reactions happen and these are controlled by enzymes

2) Nucleus – controls the cell’s activities

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A typical plant cell:A typical plant cell:Cell wall – made of cellulose which strengthens the cell

Cell membrane – controls what comes in and out

Nucleus – controls what the cell does and stores information

Large vacuole – contains sap and helps support the cell Cytoplasm –

Chemical reactions happen here

Chloroplasts (containing chlorophyll) – this is needed for photosynthesis

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4)1)

5)

6)

2)

3)

Plant cells vs. Animal Plant cells vs. Animal cellscells

Both types of cell have these: Only plant cells have these:

Cell wall

Large Vacuole

Chloroplasts

Cell Membrane

Cytoplasm

Nucleus

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BacteriaBacteriaConsider a bacteria cell in more detail:

Bacteria contain cytoplasm and a membrane surrounded by a cell wall. The genes are NOT in a distinct nucleus and bacterial cells do not have mitochondria or chloroplasts.

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Measuring Plant GrowthMeasuring Plant GrowthI’m bored of using

quadrats now. I think I’ll measure the

growth of this plant instead. How can I

do it?

There are a number of ways to measure plant growth, including measuring:

1) Length/height

2) Wet mass

3) Dry mass

What are the advantages and disadvantages of each?

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Measuring Human GrowthMeasuring Human GrowthGrowth rate

(cm/year)

Age

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Adult Stem CellsAdult Stem Cells

White blood cell

Egg cell (ovum)

Ciliated epithelial cell

Nerve cell (neurone)

It is also possible to have adult stem cells – these are unspecialised cells that can become specialised later (but they can’t form ALL types of cell)

Adult stem cells can be found in places like bone marrow.

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Stem cell researchStem cell researchStem cells are cells that have not yet specialised:

Egg and

sperm

Embryo

Cloned embryo

s

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.

The ethical issue:

Should these embryos be treated as humans?

18/04/23Human Growth vs Plant Human Growth vs Plant GrowthGrowthThere are many differences between the way humans

grow and the way plants grow:

1. Humans have two main stages of growth: straight after birth and during adolescence

2. Human growth occurs throughout the human

1. Plants grow continually and won’t 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

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Plant Growth IntroductionPlant Growth IntroductionPlants 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 - MeristemsPlant Growth - MeristemsPlant growth occurs in areas called meristems. These meristems are “mitotically active”:

This meristem causes the plant to grow upwards.

This meristem causes the plant to grow in width.

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 OldB3g New Genes for Old

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Selective breedingSelective 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 I’m reducing the

“gene pool” by doing this.

Friesian

Jersey

Hereford

18/04/23Examples of Selective Examples of Selective BreedingBreeding

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Uses of Genetic EngineeringUses of Genetic Engineering

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.

“Genetic engineering” is the idea of transferring a gene from one organism into another in order to give it extra features, such as:

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An example - InsulinAn example - InsulinStep 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 EngineeringGenetic Engineering

Should genetic engineering

be allowed?

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Gene TherapyGene TherapyGene therapy is when diseases are treated by modifying a person’s 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 CloningB3h Cloning

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Dolly the sheepDolly the sheepMy 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 AnimalsCloning AnimalsHere’s how Dolly the sheep was cloned:

Host mother

Clone

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Applications of CloningApplications 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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CloningCloning

Should cloning be allowed?

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Cloning PlantsCloning PlantsPlants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples:

1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________.

2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop.

Words – clones, damp, independent, roots, identical

18/04/23Cloning Plants by tissue Cloning Plants by tissue cultureculture

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