Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of...

62
Cell Structure Cells are the basic units of life. All living things, whether plant, animal, fungus or bacteria, are made up of cells. Plant and animal cells have a cell membrane, cytoplasm, nucleus, mitochondria and ribosomes. In addition, plant cells possess a cell wall made of cellulose, a permanent vacuole and may contain chloroplasts. Animal and Plant Cell Structure Insert and complete the Animal and Plant Cell Ultrastructure diagram from your pack into your notes. Copy & complete the table below: Cell Struct ure In plant or animal cell or both Function site of protein synthesis controls cell division and cell chemistry controls the movement of materials into and out of cells site of photosynthesis 1

Transcript of Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of...

Page 1: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Cell StructureCells are the basic units of life. All living things, whether plant, animal,

fungus or bacteria, are made up of cells.

Plant and animal cells have a cell membrane, cytoplasm, nucleus,

mitochondria and ribosomes.

In addition, plant cells possess a cell wall made of cellulose, a permanent

vacuole and may contain chloroplasts.

Animal and Plant Cell Structure

Insert and complete the Animal and Plant Cell Ultrastructure diagram

from your pack into your notes.

Copy & complete the table below:

Cell Structure

In plant or animal cell or both Function

site of protein synthesis

controls cell division and cell chemistry

controls the movement of materials into and out of cells

site of photosynthesis

site of aerobic stages of respiration

supports the cell

site of chemical reactions

Carry out Practical 1 (Observing Cells Under The Microscope)

Research

Use http://www.cellsalive.com/cells/cell_model.htm to find out about cell

structures and their functions in plant and animal cells.

1

Page 2: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Structure of Bacterial and Fungal CellsBacterial Cell structure

Bacterial cells are different from plant and animal cells as they do not contain

a membrane bound nucleus or mitochondria but they do have a circular

bacterial chromosome and they have ribosomes. Some bacterial cells contain

an extra ring of DNA called a plasmid. Bacterial cells are enclosed in a

membrane, a cell wall and a capsule and some have flagella for movement.

Insert the Bacterial cell diagram from your pack into your notes.

Fungal Cell Structure

Yeast is a single-celled fungus. Penicillium is a multicellular filamentous

fungus. Fungal cells do not contain chlorophyll and therefore cannot make

their own food – they have to be supplied with food in the form of sugar.

Except for yeasts which are unicellular, the bodies of fungi are constructed of

units called hyphae. Hyphae are minute threads composed of cell walls (made

of chitin) surrounding a plasma membrane and cytoplasm. The cytoplasm

contains many organelles including mitochondria, nucleus, ER and ribosomes.

Carry out Practical 2 (Observing Fungal Cells)

Insert and complete the Bacterial and Fungal Cell Structure diagram

from your pack into your notes.

2

Page 3: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Copy and complete the table below.

3

Cell organelles present (√)or absent (x)Type of

cellCell wall

Cell membrane

Nucleus Chloroplasts Ribosomes Mitochondria

Animal

Plant

Bacteria

Fungi

Page 4: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Transport across Cell MembranesPlasma Membrane

The plasma membrane consists of a double layer of lipids with proteins on,

in and through the lipid bilayer. The membrane is selectively permeable.

Insert and complete the Cell Membrane diagram from your pack into

your notes.

Name the 2 main components of the cell membrane.

State the name given to this model of the plasma membrane.

Explain the meaning of the word fluid in this context.

Explain the meaning of the term mosaic in this context.

Carry out Practical 3 (Chemical Nature of The Plasma Membrane)

Passive Transport in Plant & Animal Cells

Diffusion

Diffusion is the movement of molecules from an area of high concentration

to an area of low concentration, down a concentration gradient and it does

not require energy.

Your teacher will demonstrate some different examples of diffusion.

Explain what is meant by the term concentration gradient.

Insert and complete the Diffusion & Cells diagram from your pack into

your notes.

4

1

Page 5: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

The Importance of Diffusion

Animal and plant cells depend on diffusion for the movement of substances

into and out of cells. Substances can only diffuse if they are dissolved in

water first.

Explain why diffusion is important to living cells.

Name 2 substances which enter cells by diffusion.

Name 1 substance which leaves cells by diffusion.

Insert and complete the Importance of Diffusion diagram from your

pack into your notes.

Osmosis

Osmosis is a special kind of diffusion, involving only water molecules.

Osmosis is the movement of water molecules from a high water

concentration to a low water concentration, across a semi-permeable

membrane down a concentration gradient.

Describe the role of the cell membrane in osmosis.

Describe a 0.5M sucrose solution compared to a 1.0M sucrose solution,

with reference to:

water concentration

solute concentration.

Carry out Practical 4 (Osmosis in Plant Tissue)

5

A Step AheadThe water concentrations of two solutions can be compared using the expressions:

Hypotonic Hypertonic Isotonic

Use any resources available to you to find out what they mean and make notes.

Page 6: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Osmosis and Cells

Insert and complete the Osmosis & Cells diagram from your pack into

your notes.

Carry out Practical 5 (Plasmolysis in Plant Tissue)

6

Page 7: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Active Transport in Plant and Animal Cells

Active transport requires energy for membrane proteins to move molecules

against the concentration gradient.

Active transport is the mechanism by which plant root hair cells take up

nutrients such as nitrates from the soil against the concentration gradient.

In animals, nerve cells depend on active transport of sodium and potassium

ions to maintain a concentration difference across the membrane.

Watch http://www.youtube.com/watch?v=dPKvHrD1eS4&feature=player_embedded to find out more about active transport.

Energy is needed for active transport to take place.

Describe the conditions which are needed for energy to be released in

cells.

7

Active (needs energy)

Passive (doesn’t need energy)

Page 8: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Producing New Cells

Each cell in an organism has two matching sets of chromosomes in the nucleus,

the diploid chromosome complement. All cells in an organism, except

gametes, have exactly the same number and type of chromosomes in the

nucleus so that they will have a complete set of genetic information for their

species.

Every species has its own characteristic chromosome complement. This means

it has the same number and type of chromosomes e.g. humans have 46

chromosomes, fruit flies have 8 chromosomes and pea plants have 14

chromosomes.

Multicellular organisms begin as a single fertilised egg cell but grow with an

increase in cell number by a type of division called mitosis. This division is

controlled by the nucleus.

Insert and complete the Producing New Cells diagram from your pack into

your notes.

Observe prepared microscope slides of root tip cells using the

microscope or Bioviewer.

Examine the photographs of mitosis.

Sort the cards to show the sequence of events in mitosis.

Insert and complete the Mitosis diagram from your pack into your

notes.

Carry out Practical 6 (Mitosis in Root Tips)

8

Cell division

Page 9: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Cell Production by Cell Culture Techniques

Some cells may be grown on a small scale in medical labs for diagnosis or

treatment of various conditions e.g. tissue from a biopsy.

Cells can also be grown on an industrial scale in fermenters to produce food

products such as yoghurt or mycoprotein, alcoholic drinks such as beer or

wine, hormones such as insulin or antibiotics such as penicillin.

These cells must be grown using aseptic techniques to ensure that only the

required cells are present.

The cells must be grown in an appropriate medium which may be solid or

liquid e.g. agar jelly or nutrient broth. Cells need energy to grow and divide.

The medium provides the soluble food, water and essential nutrients for

this.

Insert and complete the Cell Production Using an Industrial Fermenter

diagram from your pack into your notes.

Use the information on the next page to help you interpret the diagram of

an industrial fermenter and explain suitable conditions for

fermentation.

9

Page 10: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Aseptic technique: a pipe filled with steam is fed into the fermenter in

between sessions to sterilise the fermenter.

Nutrients: at the start of the process, nutrients are fed in through pipes

which can be opened or closed using valves.

Optimum Temperature and pH: (detected by probe and data logger)

During fermentation heat is given off, so to prevent the

contents overheating, a cooling water jacket surrounds the

fermenter maintaining the optimum temperature for

growth.

The pH of the contents can be kept constant by adding acid or

alkali as needed.

Stirring paddles mix the contents to keep the microbes in the liquid

exposed to the nutrients that are fed in. This agitation helps keep the

temperature uniform throughout the fermenter.

10

Page 11: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

DNA and the Production of Proteins

Inside The Nucleus

From the drawing of a fruit fly body cell above, what is the chromosome

complement of the fruit fly, Drosophila?

Draw the fruit fly body cell and label a pair of matching chromosomes.

How many chromosomes are present in a human liver cell?

How many pairs of matching chromosomes are present in a human skin cell?

11

Drosophila body cell

Page 12: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Chromosomes & Genes

The threadlike chromosomes in the nucleus of a cell are made from tightly coiled

molecules of a complex chemical called DNA. DNA is a double stranded helix

(spiral).

Each of the two strands has a chainlike backbone structure to which

molecules called bases are attached.

There are four different types of bases within a DNA strand. A – adenine

T – thymine

G – guanine

C - cytosine

It is useful to think of them as shapes and letters which

make up a code. The diagrams show ways in which

the shapes can be drawn.

The two strands are held together by

complementary base pairs.

A always pairs with T

C always pairs with G

12

Page 13: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

The DNA carries pieces of coded genetic information. An individual section

of DNA with a single piece of genetic information is called a gene.

Chromosomes can therefore be thought of as chains of information called

genes.

What does DNA stand for?

Draw the shape of a DNA molecule.

Name the bases found within a strand of DNA.

Name the complementary bases that pair together to hold the 2 strands of

the DNA molecule together.

Describe what a gene is.

Insert and complete the Chromosomes & Genes diagram from your pack

into your notes.

Carry out Practical 7 (Isolating DNA from Kiwi Fruit)

13

A Step AheadThe DNA molecule has a chemical backbone structure

to which the bases are attached.

Use any resources available to you to learn more about the backbone structure and

make notes. Why do you think this structure is called a ‘backbone’?

Consolidate your learning here:

http://www.nobelprize.org/educational/medicine/dna_double_helix/index.html

Have some fun with this at home!

Cell division

Page 14: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

The Function Of DNA

The genetic information coded into DNA in the genes gives the cells the

instructions to make a whole range of protein molecules. Some of these

proteins form the structures of cells and organisms while others form

enzymes which control activities in cells and organisms.

DNA molecules in the nucleus carry the genetic instructions which allow the

cell to make specific proteins for its own structure and function and also that

of the organism as a whole.

Specific proteins are made from amino acid units linked together to form

long chains. There are about 20 different types of amino acids and the

differences between proteins are due to the different amino acids they

contain.

The base sequence on the DNA molecule determines the amino acid

sequence in the protein.

State what the genetic instructions of a DNA molecule code for.

Name the sub-units which are joined together to make this molecule.14

peptide

Page 15: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Describe the genetic code carried on a DNA molecule, with reference to:

the sequence of chemical bases

why these are in a particular sequence

the number of bases coding for an amino acid

the number of different amino acids

how these amino acids are linked together.

Insert and complete the Function of DNA diagram from your pack into

your notes.

Insert and complete the Genetic Code diagram from your pack into your

notes.

15

Page 16: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

DNA to Protein Task to demonstrate secure learning.

Use all you know (and the extra help information in Student Favourites

/Biology /Nat5 /Unit 1/DNA to protein task) to make a poster to show how DNA

codes for proteins by following these instructions:

1. Choose one of these DNA sequences (or make up your own)

2. Arrange the DNA sequence into triplets

3. Use the protein decoder (see below or in class) to identify the amino acids

coded for by your triplets

4. Arrange the amino acids in the correct order to form a protein

Your poster must be colourful, informative and in easy to follow steps to show

you understand how DNA codes for a protein.

16

TACTCGAATCGATTTATC

TACTTAGGCCATGGGACT

TACAGCCGTGTCCCAATT

Page 17: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

The Role of mRNA

DNA remains in the nucleus as the molecule is too large to get out. Proteins

are assembled from amino acids on the ribosomes in the cytoplasm. A

copy of the code for a single protein must be carried from the nucleus to the

cytoplasm by a smaller molecule called messenger RNA (mRNA).

Use any resources available to you to find out about one of these scientists

and the work they did to discover the structure and function of DNA:

Watson and Crick, Rosalind Franklin, Maurice Wilkins, Chargaff.

Present your findings as a two minute talk or presentation

Include a note of the sources of your information.

Starter: http://www.favscientist.com/video_rosalindfranklin.html

17

A Step Ahead

The production of proteins in cells is called Protein Synthesis and this is divided

into two stages.

Use any resources available to you to find out the names of the two

stages and make a short note stating what happens in each stage.

Page 18: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Proteins and Enzymes

Protein Structure & Function

In proteins the amino acids are folded and twisted to give the molecules three

dimensional shapes. The sequence of amino acids, determined by the

sequence of bases on DNA, is important in the creation of these shapes. The

overall shape of the protein molecule is important in determining the

molecule’s function. In enzymes, the folding of the chains forms the active

sites which make enzymes specific to their substrates.

Describe the structure of a protein, with reference to:

a description of the 3-D shape

what the shape depends on

why this shape is important in the functioning of the molecule.

Insert and complete the table Some Proteins and their Functions from

your diagram pack into your notes.

18

Page 19: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Enzyme Action

Enzymes as Catalysts

Catalysts speed up chemical reactions by lowering the energy required to

start the reaction and they allow reactions to take place at lower

temperatures. Catalysts are unchanged by the reaction so they can be

used over and over again.

All living cells in all living organisms contain biological catalysts which

they make themselves. These catalysts are called enzymes and are made of

proteins.

State three properties of a catalyst.

State the general name which is given to biological catalysts.

Explain what enzymes are made of and where they are found in a living

organism.

Explain why enzymes are needed for the functioning of all living cells.

Your teacher will demonstrate an example of a catalyst in action.

19

2

Page 20: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Specificity of Enzymes for their Substrates

An enzyme molecule acts on a specific substrate by binding with it at its

active site to form an enzyme-substrate complex. A product (or

products) is formed but the enzyme remains unchanged.

The active site is the part of the enzyme molecule into which the substrate

fits to allow the reaction to take place. The active site is complementary to

the substrate as a key is complementary to a lock.

Explain the meaning of the following terms:

substrate

product

active site.

Explain the meaning of the term specific, with reference to:

enzyme

substrate

active site.

Insert and complete the Lock and Key diagram from your pack into your

notes.

Carry out Practical 8 (Investigating Enzyme Specificity)

20

A Step AheadThe Lock and Key model helps to explain some features of enzymes.

Another model of enzyme action is ‘the induced fit’ model.

Use any resources available to you to find out how

this model differs from the lock and key model and

make notes.

Page 21: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Types of Enzyme Reactions

The chemical reactions in a cell involve either breaking down (degrading)

large molecules or building up (synthesising) large molecules.

Breakdown reactions convert large molecules into small molecules. For

example the carbohydrate starch is a very large molecule which cannot pass

through the membranes of cells. To be used as an energy source the starch

must be broken down to smaller soluble molecules. In the digestive system

of humans this process starts in the mouth when the food is mixed with

saliva containing the enzyme amylase.

Amylase breaks down starch molecules into smaller, soluble molecules of

a sugar called maltose. Starch is the substrate in this reaction, maltose is

the product and amylase is the enzyme which is involved in the reaction

but which is not changed by the reaction.

amylase

starch molecule maltose molecules

Name the 2 different types of reaction which enzymes control.

Describe an example of a breakdown reaction, with reference to:

the name of the enzyme involved

the site of production of this enzyme

the name of the substrate

the molecular size of the substrate

the name of the product

the molecular size of the product

the effect of the reaction on the enzyme.

Draw a diagram to illustrate this breakdown reaction.

21

Page 22: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

But where does starch come from in the first place?

Green plants convert light energy from the sun into chemical energy in

glucose.

Glucose is a small soluble molecule which can easily diffuse in and out of

cells so it is unsuitable as a storage molecule. To overcome this, the

glucose molecules can be combined to form starch for storage as in the

potato plant.

Describe an example of a synthesis reaction, with reference to:

the name of the enzyme involved

the site of production of this enzyme

the name of the substrate

the molecular size of the substrate

the name of the product

the molecular size of the product

the effect of the reaction on the enzyme.

Draw a diagram to illustrate the synthesis reaction described above.

22

The leaves make glucose.

Some glucose is used by the leaf cells for

energy.

Some is transported to the roots for storage.

Once in the roots the glucose is converted to glucose-1-phosphate. (G-1-P)

The potato enzyme, phosphorylase, joins many G-1-P molecules together with the

loss of the phosphate group to form starch.

The starch molecules are stored in the potato tuber to be used later.

Page 23: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Carry out Practical 9 (A Synthesis Reaction)

The build up of starch from glucose is one example of a synthesis reaction,

but there are many others. Some are important because they let an organism

build up storage chemicals which will be broken down later on when they

are needed. Others allow the organism to make the structural chemicals

that will be used to build its body.

23

Some synthesis reactions in human cells

Page 24: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Factors Affecting Enzyme Activity

Two factors which can affect the activity of an enzyme are pH and

temperature.

Effect of pH

State what is meant by the symbol pH.

State the pH number range for acid, alkali and neutral solutions

Explain what happens when an enzyme is exposed to extremes of pH.

Explain what is meant by optimum pH.

Describe the effect on the rate of reaction of pepsin when:

the pH is 2.5

the pH becomes more acidic (less than 2.5)

the pH becomes less acidic (greater than 2.5).

Carry out Practical 10 (pH and Enzyme Activity)

Effect of Temperature

Enzymes are made of proteins. Like all proteins, the rate at which an enzyme

works depends on the temperature.

Describe the activity of an enzyme at:

very low temperatures

a temperature of about 40oC.

higher temperatures

Explain what is meant by the term optimum temperature.

Insert and complete the Effect of pH & Temperature diagram from your pack into your notes.

Carry out Practical 11 (Temperature & Enzyme Activity)

24

Page 25: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

A Step Ahead

Enzyme activity can be affected by factors other than temperature

and pH.

Use any resources available to you to find out about poisons that affect enzyme

activity. How do they work?

Explain what happens to enzymes at temperatures of above 40oC, with

reference to:

chemical bonds which hold the amino acids together

active sites

ability to form enzyme-substrate complexes

term used to describe enzymes in this state

activity of the enzyme.

Explain the rate of reaction of an enzyme at a temperature of 55-60oC.

Insert and complete the Denaturing Enzymes diagram from your pack into

your notes.

Summary of Enzymes …so far!

Copy & complete the table below which summarises all the enzymes you have met in this topic.

Type of Reaction

(synthesis or breakdown)Enzyme Where it is

foundoptimum

pH substrate products

pH 6 glucose-1-phosphate starch

breakdown mouth

pepsin Protein peptides or amino acids

25

Page 26: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Genetic EngineeringThe bacterium Agrobacterium is harmful to plants and useful to scientists. It

transfers DNA into plant genomes. Found in soil worldwide, this bacterium

causes disease in plants by transferring its own DNA into plant cells – it acts

as a natural genetic engineer. However scientists use this bacterium in the

laboratory to move all sorts of genes into plants and this makes the

bacterium the standard tool for investigating plant genetics and modifying

crops.

o Listen to your teacher’s talk on genetic engineering then use all the

information you have to make your own notes:

Name an organism used in genetic engineering.

Name the material upon which normal control of bacterial activity

depends.

Give an example of a product manufactured using genetic engineering.

Describe the use of this product in humans.

Describe what a plasmid is.

State 2 advantages in using bacteria for genetic engineering.

Insert and complete the Genetic Engineering diagram from your pack

into your notes.

Carry out Practical 12 (Genetic Engineering Simulation)

Genetic engineering appears to have many advantages when it comes to

producing bacteria capable of carrying foreign genes, however, inserting genes

into plants and animals to improve a characteristic has proved more difficult

and can be controversial.

26

Page 27: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

In your group, choose one of these genetically engineered products or

another of your choice and research it using the Internet.

Making sure everyone has a role, prepare a 5 minute presentation for the

rest of the class including:

A statement of what the product is – include whether it is available or

being developed now

Information about the host organism

Information about the source of the added genetic material

The case for the product

The case against the product

The group’s opinion of the product

A list of References to show that the information you present is from a

reliable source.

27

Golden Rice - an effective source of vitamin A

Less toxic rape seed oil

Tomatoes with a longer shelf life

Blight resistant potatoes

Humulin - effective

control of diabetes

Page 28: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

PhotosynthesisPhotosynthesis Revision Summary

State the name of the raw materials needed for photosynthesis.

State the name of the products of photosynthesis.

State what other essential requirements are needed for photosynthesis to

take place.

Copy and complete the equation for photosynthesis, using the word

bank.

Photosynthesis Equation

Circle the raw materials in red

essential requirements in yellow

products in blue.

Chemistry of Photosynthesis

Photosynthesis is a series of enzyme controlled chemical reactions occurring in

two stages:

1. the light reaction

2. carbon fixation

28

+ +chlorophyll

water

Word bankSugar carbon dioxide light energy oxygen

Products raw materials essential requirements

Page 29: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

The Light Reaction

During the light reaction light energy from the sun is trapped by chlorophyll

in the chloroplasts and converted into chemical energy in the form of ATP.

The light energy absorbed by the chlorophyll is used in the photolysis of water

to split water molecules into hydrogen and oxygen. Chemical energy is

released in this reaction and used to combine ADP and phosphate to form

ATP.

Excess oxygen diffuses out of the cells and is released from the leaves.

The ATP and hydrogen are used in the carbon fixation stage of

photosynthesis.

Describe the role of chlorophyll in the light reaction and the energy

change which takes place.

Explain what happens to the hydrogen which is released.

Insert and complete the Light Reaction diagram from your pack into

your notes.

Oxygen is released as a by product. The hydrogen and ATP are used in the

carbon fixation stage.

Carry out Practical 13 (Photolysis of Water)

Carbon Fixation

Carbon fixation is an enzyme controlled series in which sugar is formed

from CO2 plus the hydrogen and energy from the ATP produced during the

light reaction.

State where carbon fixation takes place.

Name the molecule which combines with the CO2.

Name the end product which is formed.

29

Page 30: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Insert and complete the Carbon Fixation diagram from your pack into

your notes.

The fate of the sugar

The sugar made during carbon fixation can be used as an immediate source of

energy in respiration or to make structural carbohydrates such as cellulose for

cell walls or it can be stored as starch. Carbohydrates can then be used in the

production of fats and proteins.

Insert and complete the Fate of Carbohydrates diagram from your pack

into your notes.

Carry out Practical 14 (Observing Starch Grains)

Factors Affecting the Rate of Photosynthesis

Carbon dioxide concentration, light intensity and temperature act as

limiting factors on the rate of photosynthesis. If any one of these factors is in

short supply the rate of photosynthesis will be limited.

Insert and complete the Limiting Factors diagram from your pack into

your notes.

Carry out Practical 15 (Effect of Light on the Rate of Photosynthesis)

30

A Step Ahead :

Use any resources available to you to find out about producing early crops in

horticulture or agriculture.

Explain how early crops can be produced in horticulture, with reference to:

supplementary lighting

carbon dioxide enrichment

heating.

Page 31: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

RespirationAerobic Respiration Revision Summary

Respiration is the series of enzyme-controlled reactions going on in all cells

by which chemical energy is released from glucose.

State the name of the raw materials needed for aerobic respiration.

State the name of the products of aerobic respiration.

Copy and complete the equation for aerobic respiration, using the word

bank.

Aerobic Respiration Equation

Carry out Practical 16 (Release of Carbon Dioxide in Respiration)

31

+ + water

Word bankglucose carbon dioxide energy oxygen

products raw materials

+

Page 32: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Chemistry of Aerobic Respiration

Aerobic Respiration is a series of enzyme controlled chemical reactions in

which oxygen is needed to release chemical energy from glucose to form ATP.

There are 2 main steps to this process:

Glycolysis

Breakdown of pyruvate to carbon dioxide and water

Role of ATP

ATP is a molecule which acts as an immediate chemical energy store.

When energy is released from the breakdown of glucose it is used to form

ATP from ADP and phosphate. The chemical energy stored in the ATP can

be released when the ATP breaks down to ADP and phosphate again. The

energy is used for a range of cellular activities including muscle cell

contraction, cell division, protein synthesis and transmission of nerve

impulses.

ATP is regenerated during respiration when more glucose is broken down

and the energy released combines ADP and phosphate.

Describe 3 uses of ATP in cells.

Briefly describe how ATP is formed and write the word equation for

this.

Insert and complete the ATP diagram from your pack into your notes.

32

Page 33: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Glycolysis

The first stage in aerobic respiration involves glycolysis. This is the

breakdown of glucose, in the absence of oxygen, to form pyruvate. This

process occurs in the cytoplasm of all cells. During this process one

molecule of glucose breaks down to form two molecules of pyruvate and

enough energy is given out to produce 2 molecules of ATP.

Describe the process of glycolysis including:

the name of the molecule which is broken down (substrate)

the product formed

the number of molecules of substrate and end products

the number of ATP molecules generated

Insert and complete the Glycolysis diagram from your pack into your

notes.

Breakdown of pyruvate to carbon dioxide and water

This second stage of aerobic respiration goes on in the mitochondria of all

cells. The pyruvate molecules are broken down in the presence of oxygen to

form carbon dioxide and water and 36 molecules of ATP are made. All of

the reactions in respiration are controlled by enzymes.

Calculate the total number of ATP molecules formed during the whole

of aerobic respiration of one glucose molecule.

Explain how you got this total number of ATP molecules with reference

to the number of molecules of ATP formed during each stage of aerobic

respiration.

Describe what would happen if oxygen was absent.

Insert and complete the Aerobic Respiration - The breakdown of

pyruvate diagram from your pack into your notes.

33

Page 34: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

A Step Ahead :

Athletes sometimes have a problem with lactic acid (lactate) build up. What effect

does lactic acid have on muscle?

Using any resources available to you find out what is meant by the term oxygen debt,

with reference to:

whether this process is reversible

the name of the compound formed from the conversion of lactic acid.

Anaerobic Respiration

The Fermentation Pathway in Animal Cells

When there is no oxygen available glucose can still be broken down to

pyruvate in the cytoplasm by glycolysis.

In animal cells, in the absence of oxygen, glucose is broken down to

pyruvate then lactic acid. By this fermentation pathway, enough energy

is released from the glucose to form only 2 molecules of ATP.

Describe the fermentation pathway in animal cells including:

where this takes place in the cells

whether oxygen is required

the breakdown of glucose

the product formed

the number of ATP molecules formed.

34

pyruvate lactic acid

oxygen debt builds up

oxygen debt repaid

Page 35: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

__________ + __________ __________ + __________ +

__________ __________ +

The Fermentation Pathway in Plant and Yeast Cells

When there is no oxygen available in plant and yeast cells glucose can still

be broken down to pyruvate in the cytoplasm by glycolysis.

In plant and yeast cells, in the absence of oxygen, glucose is broken down

to pyruvate then alcohol (ethanol) and carbon dioxide. By this

fermentation pathway, enough energy is released from the glucose to form

only 2 molecules of ATP.

Describe the fermentation pathway in plant and yeast cells including:

where this takes place in the cells

whether oxygen is required

the breakdown of glucose

the products formed

the number of ATP molecules formed.

Carry out Practical 17 (Products of Fermentation)

Copy and complete the summary word equations for the different types of

respiration.

Types of Respiration

35

lots of energy

__________ __________ + __________ +

Anaerobic

Aerobic

Yeast(fermentation

)

Plants &Animals

little energ

ylittle

energy

Animals

Page 36: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Comparison of Respiration via Aerobic and Fermentation Pathways

Copy and complete the following table:

Aerobic Respiration Fermentation

Need for Oxygen

Substrate

End Product(s)Plants

Animals

Energy Yield

Site of respiration in a cell

Cells such as muscle cells, nerve cells and sperm cells in animals and

companion cells in plants have a high energy requirement compared with

other cells. When examined under the electron microscope these cells

have many more mitochondria than other cells.

36

outer membrane

inner membrane

crista

Mitochondrion

Central matrix containing enzymes

Page 37: Investigating Living Cells - Hyndland Secondary School · Web viewThe energy is used for a range of cellular activities including muscle cell contraction, cell division, protein synthesis

Insert the “Mitochondria” diagram from your pack into your notes.

Label it with the following parts:

inner membrane

outer membrane

crista (plural: cristae)

central matrix.

State what is meant by anaerobic conditions.

State what is meant by aerobic conditions.

Glycolysis and fermentation are anaerobic processes and they occur

in the cytoplasm of the cell.

The breakdown of pyruvate to carbon dioxide and water is aerobic and

this occurs in the mitochondria of a cell.

37

A Step Ahead :

Use any resources available to you to find out how the matrix and cristae

of the mitochondria are involved in aerobic respiration.