unit 1 cells and cell processes
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Unit 1 Cells and Cell Processes
1.1 Characteristics of living organisms
What you need to be able to do:
• List and describe the characteristics of living organisms
• Define nutrition, excretion, respiration, sensitivity, growth, reproduction and movement
Starter
Read the definition and name the life process
MOVEMENT
An action by an organism or part of an organism causing a change of position or
place
The chemical reactions that break down nutrient molecules in living cells
to release energy
RESPIRATION
The ability to detect or sense changes in the environment (stimuli) and to make responses
SENSITIVITY
A permanent increase in size and dry mass by an increase in cell number or cell size or both
GROWTH
The processes that make more of the same kind of organism
REPRODUCTION
Removal from organisms of toxic materials, thewaste products of metabolism and substances
in excess of requirements
EXCRETION
The taking in of nutrients which are organic substances and mineral ions, containing rawmaterials or energy for growth and tissue
repair, absorbing and assimilating them
NUTRITION
Characteristics of living things
A mnemonic to help you remember:
eSay what you see!
MRSGREN
ovementespirationensitivityrowtheproductionxcretionutrition
Tasks
1. Match up the pictures and descriptions of the life processes in your booklet.
2. Complete the Living Things crossword.
1.2 Classification systems
What you need to be able to do:• Define and describe the binomial system of
naming species • List the main features of the following
vertebrate groups - bony fish, amphibians, reptiles, birds and mammals
• Know of other classification systems, e.g.cladistics
• List the main features used in the classification of viruses, bacteria and fungi
StarterWatch the BrainPop video "Classification"
Biological Classification
Binomial Nomenclature
While you watch the video write down the rules for naming organisms
What does binomial mean?
Two names
Rules for binomial classification
1. All organisms have a two part name2. The first part of the name is the Genus and
starts with a capital letter3. The second part of the name is the species
and starts with a lowercase letter4. If the name is written by hand it is underlined5. If the name is typed it is italicised.
Taxomomic Hierarchy
The binomial system gives each organism a two part name showing the genus and species
Genus species Genus species Genus species
Panthera leo Panthera tigris Panthera onca
Other classification systemsCladistics
A method of classification that relies upon lines of descent (evolutionary history) rather than physical similarities
Other classification systems
Previously scientists used the morphology (observable features) of organisms to put them into groups.
Now many species are being reordered because of similarites and differences in their DNA
Tasks
1. Write a mnemonic to help you remember the order of the taxonomic groups
2. Find the classification and the binomial name for modern man
3. Complete past paper question 1
StarterWatch BrainPop "The Six Kingdoms"
Tasks
1. Use your textbook and what you saw in the video to complete the Key Features of the Kingdoms table in your booklet.
Viruses
Watch the BrainPop video "Viruses"
Viruses are not included in the 5 kingdom classification. Can you think why?
Viruses
Consist of:
• An outer protein coat or capsid
• Genetic material - a nucleic acid (DNA or
RNA)
• May be helical, icosahedral in shape or
phages
• e.g. HIV, influenza, measles, herpes simplex
Viral Structure
Tasks
1. Label the diagrams of the two viruses
2. Watch this video
3. Draw a storyboard to explain how viruses
use human body cells to replicate
Kingdom Fungi Watch the BrainPop video "Fungi"
• Fungi were originally classified as plants.
• Why was this classification incorrect?
• Fungi are eukaryotes with cells similar to plants and animals.
• They are usually saprophytes and feed on dead or decaying plant and animals
Yeast• Single celled• Reproduces by
budding (asexual reproduction)
• Used in brewing and baking
Sacchcaromyces cerevisiae
Yeast Structure
Mucor hiemalis• Consist of tubes called hyphae• Many hyphae make a mass called a mycelium• Secrete enzymes to digestfood externally
Fungal Structure
Edible mushroom
• Reproduce sexually using fruiting bodies which can be large (and edible!)
• New fungi are produced from spores.
• Spread via water which is why fungi are found in damp places
Mushroom and toadstools
Tasks
1. Draw and label a yeast cell and pin mould
2. Answer the questions in your booklet
3. Answer past paper question 2
Kingdom BacteriaWatch the BrainPop video "Bacteria"
• Prokaryotic organisms - made of simple cells without a nucleus
• Cause infectious diseases
• Can be treated with antibiotics (against life)
• e.g. Escherichia coli, Salmonella sp.
Bacterial Structure
Bacteria
• Can be rods, spirals or spheres
• Reproduce asexuallyby binary fission
Tasks
1. Draw and label a typical bacterial cell
2. Complete past paper question 3
Kingdom Animal - Vertebrate Groups
StarterWatch the BrainPop video "Vertebrates"
Make a list of the features of each vertebrate group
What is the common feature of all vertebrates?
Mammals
Mammals
• Warm blooded (homeotherms)
• Breathe using lungs
• Body covered with hair or fur
• Internal fertilisation
• Viviparous
• Offspring develop internally supported by
placenta
• Feed young using milk (suckle)
• e.g. humans, dogs, cats, dolphins
Birds
Birds
• Warm blooded
• Bodies covered with feathers
• Have beaks
• Breathe using lungs
• Internal fertilisation
• Lay eggs with hard shells
• e.g. penguins, owls, pigeon, sparrow
Reptiles
Reptiles
• Cold blooded (ectotherms)
• Breathe using lungs
• Body covered with hard scales
• Internal fertilisation
• Lay soft shelled (leathery) eggs
• e.g. crocodile, iguana, turtle
Amphibians
Amphibians• Cold blooded
• Have lungs but small and not used much
• Thin moist skin
• External fertilisation
• Eggs covered in jelly
• Have an aquatic stage (tadpoles)
• Metamorphosis (change) into adults
• Adults live on land but breed in water
• e.g. frog, newt, toad
Fish
Fish
• Cold blooded• Live entirely in water• Breathe using gills• Body covered in scales• Have fins for locomotion• External fertilisation• e.g. herring (salt water), trout (freshwater)
Tasks
1. Complete the table of features of the Vertebrate Groups in your booklet.
2. Watch BrainPop "Fish and Gills"
3. Dissect and draw a fish4. Complete past paper question 3
Biological Drawing
• Clear outline - no sketching (single lines, no
crossover)
• Proportion - it should look like the object!
• Size - fill the space given (half a page of A4)
• No shading/colouring
• Label - use a pencil and ruler to draw lines
(no crossed lines)
Spot the difference. What is wrong?
shading
thick lines
lines cross over
label lines cross overl
ReviewWhich vertebrate group(s)?1. Have scales?
2. Breathe using lungs?
3. Lay eggs?
4. Reproduce using internal fertilisation?
5. Feed their young using milk?
6. Are warm blooded?
fish and reptiles (and birds on their legs!
birds, mammals, reptiles, amphibians
birds, reptiles, fish amphibians (and duck billed platypuses)
birds, mammals
mammals
mammals and birds
1.3 Adaptations of organisms
What you need to be able to do:
• List the main features used in the classification of: - flowering plants (monocotyledons/dicotyledons)
- Arthropods (insects/crustaceans/arachnids/myriapods)
- annelids- nematodes- molluscs
Invertebrate Groups
Go to http://ngm.nationalgeographic.com/2011/01/seven-billion/biodiversity-game
and play the diversity game.
Watch BrainPops video "Invertebrates"
Invertebrate = without backbone
Invertebrate Groups
As you have seen, there are many types of invertebrate!
Luckily you only need to know these 4 groups:
Annelids Nematodes
Molluscs Arthropods
INVERTEBRATES
ANNELIDS MOLLUSCS NEMATODESARTHROPODS
ARACHNIDS CRUSTACEANS INSECTS MYRIAPODS
Annelids
• Bodies made of many segments.
• May have a head and/or antennae
• Chaetae (tiny hairs) for locomotion
• e.g. earthworm
If all the material that has
ever passed through earthworms was piled up, the heap would be 30 miles tall - more than 5x the height
of Everest!
Molluscs
• Soft unsegmented bodies
• Internal or external hard shell (calcium
carbonate)
• Muscular foot
• Secretes mucus (for locomotion)
• e.g. slug, snail, clam, octopus
The giant squid is the world's
largest invertebrate - it can grow to over 50 feet with eyes
the size of basketballs!
Nematodes
• Bodies are not segmented
• No obvious head
• Long and thin
• Never have chaetae
• Many are parasites of the digestive system!The 3 main human diseases caused by nematodes are
ascariasas, hookwork
infection and elephatiasis!
Arthropods
Watch BrainPop "Arachnids" and "Insects"
Arthropod =
(Arthritis = inflammation of the joints)
All arthropods share three characteristics.Look at the pictures on the next slide and tell me what they are...
jointed legs
Did you get them?
• Jointed legs
• Exoskeleton
• Body of two or more segments
How is each of these features beneficial to arthropods?
Crustaceans
• e.g. crabs, prawns, woodlice
• Extra strong exoskeleton (calcium salts)
• Many pairs of legs (5+)
• 2 pairs of antennae
• 2 main body parts- cephalothorax (joined head and thorax)- abdomen
Arachnids
• e.g. spiders, scorpions, mites and lice
• 2 body parts (like crustacea)
• 4 pairs of legs
• No antennae
MyriapodsMyria = ? Pod =
?
• e.g. centipedes and millipedes
• Many body segments
• Many pairs of legs
• 1 pair of antennae
Insects
• e.g. ants, butterflies, bees, beetles
• The biggest group of invertebrates
• 3 body segments
- head, abdomen and thorax
• 3 pairs of legs
• 1 pair of antennae
• Many have wings (not an identifying
feature!)
Tasks
1. Annotate the diagrams of each of the invertebrate animals with their main features.
2. Complete the table of the arthropods groups.
3. Answer past paper questions 5 and 6.
Kingdom Plants - Flowering Plants
StarterWatch BrainPops "Seed Plants"
Compare the two specimens you have in front of you. Make a list of differences.
DicotyledonMonocotyledon
Monocotyledon Dicotyledon
Monocotyledon
Dicotyledon
Tasks
1. Complete the table of differences between monocots and dicots in your booklet.
2. Include some examples of each.
1.4 Simple Keys
What you need to be able to do:
• Use simple dichotomous keys based on easily identifiable features
http://www.district158.org/sdelorenzo/Biology/Foundations/making_a_dichotomous_key.htm
Simple Dichotomous Keys
Dichotomous = two branches
The key to keys!Observable features (what you can see!)
EitherQuestions with yes/no answersAnswer questions and follow branches to the
end
orPairs of statementsChoose the most appropriate statementFollow the instruction (go to...) until you get to
the answer
Making a key1. Look at the drawings of the beetles.2. Choose ONE observable characteristic and sort the beetles
into two groups based on whether they have the characteristic or not.
3. Record the chosen characteristic and write the numbers of the beetles under either Group 1 or Group 2 on your diagram.
4. Select another characteristic of each subgroup, and repeat step 3.
5. Repeat this process until you have only one beetle in each group.
6. Once the diagram is complete, use it to create a dichotomous key for the beetles.
1. Create a series of numbered steps with the first step showing the first characteristic you used.
2. At each step, offer two choices for classifying the beetle based on a single characteristic.
3. e.g. you may have used the characteristic “antennae longer than front legs” as your first dividing characteristic.
4. The first numbered step in your key would be:
(1a) antennae longer than front legs................Go to 2(1b) antennae not longer than front legs...........Go to 3
1.5 Cell Structure and Organisation
What you need to be able to do:
• State that living organisms are made of cells• Identify and describe the structure of a plant
cell (palisade cell) and an animal cell (liver cell) as seen under a light microscope
• Describe the differences in structure between typical animal and plant cells
• Relate the structures seen under the light microscope in the plant cell and the animal cell to their functions
Starter Label the parts of the light microscope.
What does each part do?eyepiece lens
revolving mountneck
coarse focusfine focus
base
diaphragm
light source
slide clips
objective lens
stage
Try the echalk microscope
labelling activity
Tasks
http://www.kscience.co.uk/animations/animal_cell.htm
http://www.kscience.co.uk/animations/plant_cell.htm
Watch BrainPop video "Cells"
Cell Structure
Parts common to all cells
Nucleus - contains genetic material which controls the activities of the cell
Cytoplasm - chemical reactions take place here, controlled by enzymes
Cell membrane - partially permeable, controls what comes in and out of the cell
Mitochondria - aerobic respiration occurs here to release energy
Plant cells have these extra features
Cell wall - strengthens the cell and provides support
Chloroplasts - contain chlorophyll which absorbs light energy for photosynthesis
Large permanent vacuole - contains cell sap to keep the cell turgid
Note: animal cells may contain small, temporary food vacuoles
Looking at animal cellsPreparing a temporary mount of cheek cells
Try the echalk activity - preparing cheek cells
Looking at plant cellsPreparation of onion skin temporary mount
Look at the echalk activity - preparing onion cells
Tasks
1. Make biological drawings of each of your
slides.
2. Remember the rules!
3. Add a title and label the parts you can see.
4. Answer past paper question 7.
Review Cells Revision Video
1.7 Size of Specimens
What you need to be able to do:
• Calculate the magnification and size of biological specimens using millimetres as units
Starter
In Biology we study molecules to habitats. The size of these things varies enormously!
Look here: http://www.cellsalive.com/howbig.htm
and here: http://scaleofuniverse.com/
In the last lesson we used microscopes to look at cells. You used 10x and 40x lenses to magnify them.
Magnification
How much an object is magnified under the microscope is calculated as follows:
total magnification = eyepiece lens x objective lens
So, if we use a 10x eyepiece lens and a 10x objective lens the total magnification is:
10 x 10 = 100x magnification
Calculating magnification of biological drawings
• The drawing you make of an object under a microscope is usually much larger than the object’s actual size
• You need to indicate how much bigger• There are three things involved in magnification
calculations;- the size of the drawing- the actual size of the object- the magnification of your drawing
(how much bigger your drawing is compared to the real thing)
Magnification formula
To find the magnification of your drawing, the formula is:
magnification = size of drawing (mm) size of the real thing
(mm)
To find the size of your drawing is easy – just measure it with a ruler (in mm)
The size of the real thing is usually given to you. BUT, you must convert to mm to use the formula
Estimating Cell SizeWe can use a clear plastic ruler to estimate the
size of cells.
Appearance of ruler at 100x magnification
Appearance of onion cells at 100X magnification
Estimating the size of cells
Average cell length5 cells = 1 mmso 1 cell = 0.2 mm
Average cell width12 cells = 1mmso 1 cell = 0.083 mm1
2
5
Imagine the ruler lines!
Count the number of cells in 1 mm
Remember it is only an estimate!
Tasks
1. Prepare an onion skin slide and estimate the average length and width of the cells
2. Answer past paper question 8.
1.6 Level of Organisation
What you need to be able to do:• Relate the structure of the following
to their functions:- ciliated cells - root hair cells- xylem vessels - muscle cells - red blood cells
• Define: tissue, organ and organ system
Starter Describe the cell shape and say how it helps it do it's job
Describe the cell's shape and say how it helps it do it's job
Describe the cell's shape and say how it helps it to do its job
Describe the cell's shape and say how it helps it to do its job
Describe the cell's shape and say how it helps it do its job
Describe the cell's shape and say how it helps it do its job
Describe the cell's shape and say how it helps it do its job
TasksComplete the specialised cell card sort and
complete the table.
ReviewWatch BrainPop "Cell Specialisation"
Tissue, Organs and Organ Systems
StarterBody organs gameWork in groupsOn the large piece of paper draw around the
smallest personDraw in the main body organs1 point for position, 1 point for shape
Tasks
Define these terms:
Tissue
Organ
Organ system
a group of cells with similar structure working together to perform a shared function
a structure made up from a group of tissues, working together to perform specific functions
a group of organs with related functions, working together to perform body functions
A tissue is a group of cells of similar structure that perform a shared function
Plants have tissues too!
Organs are structures made of a group of tissues, working together to perform specific functions
Organ systems are groups of organs with related functions, working together to perform body
functions
Levels of organisation
smallestlargest
cell tissue organ organ system organism
alpha and beta
cells
pancreatic tissue
pancreas digestive system
human being
Tasks1. Name each of the human organ systems A to K
2. Using the example on the previous slide, draw a flowchart starting with a nerve cell.
ReviewPlay the game!http://www.bbc.co.uk/science/humanbody/body/interactives/3djigsaw_02/index.shtml?organs
1.8 Diffusion
What you need to be able to do:
• Define diffusion
• Describe the importance of diffusion in gases and of water as a solvent
What substances need to go in and out of a cell and why?
Respiring animal cell:oxygen
glucose
carbon dioxide
water
Photosynthesising plant cell:
carbon dioxide
water
glucose
oxygen
Substances can move in and out of cells in 3 waysdiffusion, osmosis and active transport
Diffusion
StarterWatch BrainPops "Passive Transport"
Add potassium permanganate to hot and cold water and observe
Tasks
Can you describe what happens using the following words?
particles, low, concentration, down, high, movement, random, concentration gradient.
Describe and explain how temperature affects diffusion.
Watch the echalk diffusion animation
The importance of diffusion
Diffusion is the random movement of particles from a region of high concentration to a region of low concentration down a concentration gradient.
Where in the human body is this important?
ReviewApart from temperature, what other factors affect the rate of
diffusion, how and why?
Particle size
Diffusion distance
Concentration gradient
Bigger difference = faster rate
Shorter distance = faster rate
Smaller size = faster rate
Smaller particles move faster than larger ones (less energy needed)
Greater net movement down concentration gradient
Less distance takes shorter time to travel
What other important feature is often seen in parts of the body where dffusion occurs?
A LARGE SURFACE AREA
1.10 Osmosis
What you need to be able to do:
• Define osmosis • Describe the importance of osmosis in the
uptake of water by plants and its effects on plant and animal tissues
• Describe and explain the importance of a water potential gradient in the uptake of water by plants
StarterDefine the following and give an example:
Solute
Solvent
Solution
the substance that dissolves in a liquid to form a solution e.g. salt
the liquid in which a solute dissolves e.g. water
the mixture formed when a solute has dissolved in a solvente.g. salt water
Water potential• Usually in cells/body fluids water is present
as part of a solution.e.g. blood plasma is mostly water with dissolved salts. gases and proteins.
• The more water in the solution (the more dilute) the higher the water potential and the greater the tendency for water to leave.
Water potential is the tendency for water to leave a solution
Water potential
Concentrated solution
High solute concentration
Low water potential
Dilute solution
Low solute concentration
High water potential
NET movement of water from left to right
partially permeable membrane
Osmosis
• A partially permeable membrane will let water (and other small molecules) pass through but not solute molecules.
• Cell membranes are partially permeable and this allows cells to control what goes in and out.
Osmosis is the diffusion of water molecules from a region of high concentration to a region of low concentration through a partially permeable membrane.
Tasks
1. Watch the echalk osmosis animation
2. Complete the potato chip experiment
Aim: to practically demonstrate osmosis at work
1. Take 6 boiling tubes and a test tube rack2. Label the tubes 100%, 80%, 60%, 40% , 20% and 0%.3. Measure out 20 ml of each solution into the appropriate
test tube.4. Cut six equal sized pieces of potato, record the mass of
each one and add to the tubes.5. Seal each tube with a bung.6. Label your test tube rack and leave on the bench. 7. Results will be collected later in the week.
Osmosis in potatoes experiment
Tasks
Answer these questions about the practical1. Write a hypothesis (what you think will happen
and why)
2. List the ways you have made it a fair test
3. What variables have you controlled?
4. What variable have you changed?
5. Why did we seal the tubes with a bung?
6. How could you make your results more reliable?
Sample resultsConcentration
of sugar solution (%)
Mass at start (g)
Mass at end (g)
Change in mass (g)
Percentage change (%)
0 3.90 3.27
20 3.50 3.71
40 3.30 2.55
60 3.40 2.63
80 3.70 2.7
100 2.40 1.41
Describe and explain your results.You should start by thinking about why some potato chips got heavier and some got lighter.Use the words: osmosis, water potential, water particles
Review
Answer past paper question 11.
What is the significance of osmosis in plant and animal cells?
Starter
Watch this animation:http://www.kscience.co.uk/animations/turgor.htm
andhttp://www.kscience.co.uk/animations/plasmolysis.htm
Task
http://www.nuffieldfoundation.org/practical-biology/observing-osmosis-plasmolysis-and-turgor-plant-cells
A plant cell is placed in the following solutions:a) one that is the same concentration as the cytoplasm b) one that is more dilute c) one that is more concentratedDraw diagrams to predict what will happen. Add arrows to show water movement.
More concentratedSame concentrationMore dilute
The presence of the cell wall prevents a plant cell from being damaged by water leaving and entering.
What do you think happens when an animal cell is placed in same three solutions?
More dilute Same concentration More concentrated
Review Use the idea of water potential to explain what
happens with these visking osmometers
ExplanationIn the first osmometer: The water potential in the beaker is high while the
water potential in the visking tubing is low.
Water moves by osmosis down the concentration gradient from the beaker into the visking tubing through the selectively permeable membrane.
Now write your own explanation for the second osmometer.
1.9 Active Transport
What you need to be able to do:
• Define active transport
• Discuss the importance of active transport, e.g. ion uptake by root hair cells and the uptake of glucose by epithelial cells of villi
StarterOsmosis and diffusion both occur when
substances move down the concentration gradient.
What happens when the cell needs to move substances in the opposite direction (against the concentration gradient)?
Can you think of any places where this might occur?
Active Transport
Examples of active transport include the uptake of mineral ions by root hair cells and the absorption of glucose in the small intestine
Active transport is the movement of ions in or out of a cell through the cell membrane, from a region of low concentration to a region of high concentration against their concentration gradient using energy released from respiration (in the form of ATP)
Where is active transport important?
Mineral ions
Soil particle
There is a low concentration of mineral ions dissolved in soil water. The plant needs a constant supply of minerals (why?). There is a higher concentration of minerals inside the root hair cell than in the soil.
Where is active transport important?Villus of small intestine
Initially, glucose is absorbed by diffusion. The concentration of glucose in the small intestine is high and the concentration in the capillaries of the villi is low.
As glucose is absorbed the concentration in the capillaries increases. Active transport is used to ensure that all of the glucose is absorbed.
glucose molecule
Tasks
1. Watch BrainPop video "Active Transport"
2. Look at the animation here :http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/homeostasis/importancerev6.shtml
3. In your booklet produce a labelled diagram to explain how active transport works.
1.11 Enzymes (1)
What you need to be able to do:• Define the term catalyst• Define enzymes• Investigate and describe the effect of
changes in temperature and pH on enzyme activity
• Explain enzyme action in terms of the 'lock and key' model
• Explain the effect of changes in temperature and pH on enzyme activity
Starter Enzymes take part in these reactions.Where do they occur? Can you name the enzymes?
Starch
Glucose
Protein Amino acids
Fats Fatty acids and glycerol
+ water
+ water
+ water
amylase
protease
lipase
TaskCarry out this experiment:
10 mlhydrogen peroxide
raw potato
boiledpotato
manganese (VII) oxide
copper (II) oxide
1 2 3 54
Read this information
• Hydrogen peroxide is a toxic waste product found in living things.
• It has to be broken down (decomposed) to prevent it from harming cells and tissue.
• This is a chemical reaction (metabolism).
• Look at the results of your experiment, and describe what happened.
hydrogen peroxide water + oxygen
Description of results
• Decomposition of hydrogen peroxide normally happens very slowly (tube 1).
• Manganese (VII) oxide makes the reaction happen faster (tube 5).
• Copper (II) oxide does not make the reaction faster (tube 4).
• The raw potato makes hydrogen peroxide decompose quickly (tube 2).
• The boiled potato does not make the reaction faster (tube 3)
Information
Catalyst
Enzyme
Both catalysts and enzymes are usually specific (they will only speed up one type of reaction)
A substance which speeds up chemical reactions and is not changed by the reaction
A protein which functions as a biological catalyst (i.e. it is found in living things)
Tasks
Look back at your results.
Can you explain what is happening using the information given to you?
• The manganese (VII) oxide is a catalyst for the decomposition of hydrogen peroxide.
• Copper (II) oxide is not a catalyst for this reaction.
• The potato is a living thing and so contains enzymes.
• The boiled potato is no longer living, therefore no enzymes.
• Tube 1 contains neither catalyst or enzyme (it is a control) and the reaction is very slow.
Tasks1. Watch this and make your own notes.
2. Now complete the paragraph on the next slide by adding the key words.
Review - Properties of enzymesEnzymes are_________ ____________.They speed up chemical reactions in _________ things. Each
enzyme catalyses one reaction, we say they are ____________, e.g. protease breaks down ___________ and ________ breaks down lipids (fats and oils). Their names end in "___". The enzymes are not ______ ___ but can be used many times to catalyse the same reaction.
The substance that the enzyme breaks down is called the __________. The substance that is made is called the ________. They work by the ________ ____ _____ mechanism. Enzymes are affected by ___ and ____________. They have an ___________ temperature and pH at which they work best.
At low temperatures enzyme work ________ but at high temperatures they may become ______________.
biological catalysts
living
specific proteinslipase
ase used up
substrateproduct lock and key
pHtemperature optimum
slowlydenatured
Factors affecting enzymesStarter
• Go to the kscience animation:http://www.kscience.co.uk/animations/model.swf
• Change each of the following conditions and then write a few sentences to describe what is happening:
- temperature- pH- enzyme concentration- substrate concentraion
Factors affecting enzymesTaskDescribe and explain the shape of these
graphs:
Experiments involving enzymes
1. Amylase and starchhttp://www.nuffieldfoundation.org/practical-biology/investigating-effect-ph-amylase-activity
2. Catalase and hydrogen peroxidehttp://www.nuffieldfoundation.org/practical-biology/investigating-enzyme-controlled-reaction-catalase-and-hydrogen-peroxide-concentrat
1.11 Enzymes (2)What you need to be able to do:• Describe the role of enzymes in the
germination of seeds, their uses in biological washing products and in the food industry (including pectinase and fruit juice)
• Outline the use of microorganisms and fermenters to manufacture the antibiotic penicillin and enzymes for use in biological washing products
• Describe the role of the fungus Penicillium in the production of antibiotic penicillin
StarterWhat is the difference between a biological and
a non biological washing powder?
A biological washing powder contains enzymes
• Enzymes are important in many processes• The germination of seeds is one example• They have been used by man for thousands of
years in brewing, baking and leather tanning• They can also be used in industry to make
foods and biological washing powder
Seed germination
Starch
Will grow into plant
Amylase breaks down starch into maltose. Maltose is broken down into glucose by maltase.Glucose is used for respiration.
Water is needed for germinationIt activates the enzyme amylase.
STARCH
GLUCOSE
amylase
MALTOSEmaltase
Industrial uses of enzymes
• Biological washing powders
• Making soft centred chocolates
• Pre-digesting baby food so babies can eat it more easily
• Making diet foods
• Lactose free milk
Soft centred chocolates• A chocolate coating is poured over a solid
mixture which contains sucrose
• The enzyme sucrase is injected into the centre
• Sucrase breaks down sucrose into glucose and fructose
Baby foods• Proteins can be difficult for babies to digest
• Proteases are added to baby food to pre-digest the proteins
• Babies can get the aminoacids they need withoutan upset stomach
Diet foods
• Carbohydrases are used to convert starch into glucose syrup.
• Starch is very cheap as it is made by plants like corn.
• Using enzymes to convert starch into sugar is a cheap source of sweetness
Diet foods• Glucose syrup can be converted to fructose
syrup by the enzyme isomerase
• Glucose and fructose contain exactly the same amount of energy but fructose is much sweeter
• Smaller amounts of fructose are needed to make food taste sweet
Biological washing powders
• In the past, people boiled and scrubbed clothes to get them clean
• Now we use biological detergents
• These contain enzymes which work at quite low temperatures
Biological washing powders
Are considered to be more "environmentally friendly" - why?
What type of stains do we get on clothes?
What enzymes might biological detergents contain?
Why is it recommended to wash at 30 degrees?
Apple juice• Plant cell walls are
made of cellulose
• Cellulose fibres are held together by pectin
• Pectinase enzymes are added to apple juice
• This helps to produce a nice clear product
Immobilised Enzymes
• Enzymes are expensive to manufacture.
• They also need to be removed from the product.
• To solve this problemenzymes can be immobilised.
• The enzyme is trappedin a jelly bead
Lactose free milk
• Lactose is a sugar found in milk
• Lactose is digested using lactase
• Many adults are unable to make the enzyme lactase
• Drinking milk causes nausea and diarrhoea
• Milk is passed over immobilised lactase to produce lactose free milk
Medical Uses
• Thrombosis - blood clot
• Build up in damaged blood vessels.
• Danger of travelling to the heart (resulting in a heart attack) or the brain (resulting in a stroke).
• Digested away by proteases which dissolve fibrin, from which the clot is built up.
Review
TasksMake a list of advantages and disadvantages of
using enzymes in industry.
Advantages DisadvantagesSpecific - produce only wanted product
Can be denatured easily - need to carefully control conditions
Biodegradable - less environmental pollution
May contaminate the product - product needs processing
Work at low temperatures - use less energy
Expensive to produce initially
Efficent - only a small amount needed and can be reused
Making enzymes for industry
• Many enzymes are made by microbesCan you think of a reason why?
• Most industrial enzymes are made by a process called fermentation in a piece of apparatus called a fermenter (or bioreactor)
• Other useful products, such as medicines can also be made in this way.
Making penicillin in a fermenter
Bubbles of oxygen
Steam or cold water in
Mixture of carbohydrates and amino acids
Penicillium mould
air supply
Steam or cold water out
Mixture removed and processed
Tasks
1. Label the diagram of the fermenter in your booklet.
2. Explain why each of the labelled items in the diagram is necessary.
3. Complete past paper question 12.
Topic Review1. Look back at the learning outcomes.
2. Use them to produce a revision booklet or mind map.
3. Make sure you include the keywords and their definitions.
4. If you are not sure about anything you have studied ASK the teacher!
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