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?

Watch this video and complete the table in your booklet:

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!