B3

ANIMAL CELLS

• NUCLEUS - CONTAINS DNA IN THE FORM OF CHROMOSOMES
• CELL MEMBRANE - HOLDS CELL TOGETHER AND CONTROLS WHAT GOES IN AND OUT
• RIBOSOME - WHERE PROTEINS ARE SYNTHESISED
• CYTOPLASM - GELL LIKE SUBSTANCE WHERE MOST OF CELLS CHEMICAL REACTIONS HAPPEN
• MITOCHONDRIA - MOST REACTIONS INVOLVED IN RESPIRATION TAKE PLACE (PROVIDES ENERGY FOR CELL PROCESSES) E.G. LIVER CELLS CARRY OUT ENERGY DEMANDING METABOLIC REACTIONS, MUSCLE CELLS NEED ENERGY TO CONTRACT

PLANT CELLS

CHLOROPLASTS - WHERE PHOTOSYTHESIS HAPPENS

CELL WALL - MADE OF CELLULOSE - SUPPORTS CELL

VACUOLE - RELATIVELY LARGE STRUCTURE - CONTAINS CELL SAP (WEAK SOLUTION OF SUGGAR AND SALTS

BACTERIA CELLS

NO CHLOROPLASTS OR MITOCHONDRIA

NO TRUE NUCLEUS - SINGLE CIRCULAR STRAND OF DNA - FLOATS FREELY IN CYTOPLASM

CHROMOSOMES - LONG MOLECULES OF COILED UP DNA

• GENES - SHORT SECTIONS OF DIVIDED DNA
• DNA - DOUBLE HELIX - TWO STRANDS MADE UP OF LOTS OF SMALL GROUPS CALLED NUCLEOTIDES
• NUCLEOTIDE - CONTAINS SMALL MOLECULE CALLED A BASE - DNA HAS FOUR DIFFERENT BASES - A, C, G, T
• COMPLEMENTARY BASE PAIRINGS - A AND T, C AND G - EACH BASE CROSS LINKS AND BINDS TO A BASE ON OTHER STRAND TO KEEP CHROMOSOME TIGHTLY TOGETHER - A AND T ALWAYS BIND - C AND G ALWAYS BIND

WATSON AND CRICK

• FIRST SCIENTISTS TO COME UP WITH STRUCTURE OF DNA - 1959
• USED DATA FROM OTHER SCIENTISTS TO HELP THEM UNDERSTAND STRUCTURE - X RAY DATA SHOWING DOUBLE HELIX WITH TWO STRANDS WOUND TOGETHER AND DATA SHOWING THAT BASES OCCURED IN PAIRS
• PUT INFORMATION TOGETHER - BUILT MODEL OF DNA - NOT WIDELY ACCEPTED STRAIGHT AWAY - OTHER SCIENTISTS NEED TO REPEAT WORK TO MAKE SURE RESULTS ARE RELIABLE

PROTIENS

• DNA CONTROLS PRODUCTION OF PROTIENS (PROTIEN SYNTHESIS) IN A CELL
• GENE - SECTION OF DNA THAT CODES FOR A PARTICULAR PROTEIN
• MADE UP OF CHAINS OF MOLECULES CALLED AMINO ACIDS - EACH DIFFERENT PROTEIN HAS ITS OWN PARTICULAR NUMBER AND ORDER OF AMINO ACIDS
• GIVES EACH PROTEIN A DIFFERENT SHAPE - EACH A DIFFERENT FUNCTION
• ORDER OF BASES IN GENE DECIDES ORDER OF AMINO ACIDS IN PROTEIN
• EACH AMINO ACID CODED FOR BY SEQUENCE OF THREE BASES IN A GENE
• AMINO ACID ARE JOINED TOGETHER TO MAKE A PROTEIN, FOLLOWING ORDER OF BASES IN GENE
• EACH GENE CONTAINS DIFFERENT SEQUENCE OF BASES - ALLOWS IT TO CODE FOR UNIQUE PROTEIN

mRNA - CARRIES CODE TO RIBOSOMES

• PROTEINS MADE IN CELL CYTOPLASM BY TINY STRUCTURES CALLED RIBOSOMES
• RIBOSOMES USE CODE IN DNA TO MAKE PROTEINS
• DNA FOUND IN CELL NUCLEUS - CAN'T MOVE OUT OF IT - CELL NEEDS TO GET CODE FROM DNA TO RIBOSOMES
• DONE USING mRNA - MADE BY COPYING CODE FROM DNA
• mRNA - ACTS AS MESSENGER BETWEEN DNA AND RIBOSOME - CARRIES CODE BETWEEN THEM

CONTROL OF CELL 

• PROTEINS IN CELL AFFECT HOW IT FUNCTIONS - SOME DETERMINE CELL STRUCTURE - OTHERS E.G. ENZYMES CONTROL CELL REACTIONS
• ONLY MAKE CERTAIN PROTEINS - ONLY SOME OF THE FULL SET OF GENES IS USED IN ANY ONE CELL - REST ARE 'SWITCHED OFF' - PROTEINS THEY CODE FOR AREN'T PRODUCED IN THAT CELL
• GENES THAT ARE SWITCHED ON DETERMINE FUNCTION OF CELL

PROTEINS - FOUR EXAMPLES

• ENZYMES
• CARRIER MOLECULES  - USED TO TRANSPORT SMALLER MOLECULES - HEAMOGLOBIN - BINDS TO OXYGEN MOLECULES AND TRANSPORTS THEM AROUND BODY
• HORMONES - CARRY MESSAGES AROUND BODY - INSULIN - HOURMONE RELEASED INTO BLOOD BY PANCREAS TO REGULATE BLOOD SUGAR LEVEL
• STRUCTURAL PROTEINS - PHYSICALLY STRONG - COLLAGEN - STRUCTURED PROTEIN THAT STRENGTHENS CONNECTIVE TISSUES

ENZYMES - BIOLOGICAL CATALYSTS

• CELLS HAVE THOUSANDS OF REACTIONS E.G. RESPIRATION, PROTEIN SYNTHESIS GOING ON INSIDE THEM - NEEDS TO BE CAREFULLY CONTROLLED - GET RIGHT AMOUNTS OF SUBSTANCES TO KEEP EACH ORGANISM WORKING PROPERLY
• RAISING TEMP SPEEDS REACTIONS - CELLS START GETTING DAMAGED AT CERTAIN TEMP
• ENZYMES WORK TO SPEED UP CELL REACTIONS - BIOLOGICAL CATALYSTS - REDUCE NEED FOR HIGH TEMP
• EVERY BIOLOGICAL REACTION HAS OWN ENZYME, EACH CODED BY SPECIFIC GENE - UNIQUE SHAPE

SPECIFICITY OF ENZYMES

• SUBSTRATE - MOLECULE CHANGED IN CELL REACTION
• ACTIVE SIGHT - PART THAT JOINS ONTO SUBSTRATE TO CATALYSE REACTION
• ENZYMES HAVE A HIGH SPECIFICITY FOR THEIR SUBSTRATE - ACTIVE SIGHT OF AN ENZYME ONLY FITS TO ONE PARTICULAR SUBSTRATE
• FOR ENZYME TO WORK, SUBSTRATE HAS TO FIT ACTIVE SIGHT - REACTION WON'T BE CATALYSED IF SUBSTRATE SHAPE DOESN'T MATCH ACTIVE SIGHT SHAPE - 'LOCK AND KEY' MECHANISM

ENZYMES - pH

• TOO HIGH OR TOO LOW - INTERFERES WITH BONDS HOLDING ENZYME TOGETHER - CHANGES SHAPE OF ACTIVE SITE - DENATURES ENZYME
• ENZYMES HAVE OPTIMUM pH THEY WORK BEST AT - OFTEN NEUTREL (pH 7)

CONDITIONS - TEMPERATURE

• HIGHER TEMPERATURE = FASTER REACTION UP TO CERTAIN POINT
• MORE HEAT MEANS MORE KINETIC ENERGY - PARTICLES MOVE MORE - MORE COLLISIONS
• WHEN TEMPERATURE REACHES CERTAIN POINT, ENZYME IS DENATURED - LOSES SHAPE AND DOESN'T FIT SUBSTRATE ANYMORE - REACTION CAN'T BE CATALYSED
• EACH ENZYME HAS OWN OPTIMUM TEMP - MOST HUMAN ENZYMES IT'S ABOUT 37 DEGREES CELSIUS

Q10 = RATE AT HIGHER TEMPERATURE / RATE AT LOWER TEMPERATURE

• Q10 VALUE FOR REACTION - SHOWS HOW MUCH RATE CHANGES WHEN TEMP IS RAISED BY 10 DEGREES
• Q10 VALUE OF 2 MEANS THAT RATE DOUBLES WHEN THE TEMPERATURE IS RAISED BY 10 DEGREES
• Q10 VALUE OF 3 MEANS RATE TREBLES

GENE MUTATIONS - CHANGE IN DNA BASE SEQUENCE 

• IF MUTATION OCCURS WITHIN GENE, COULD STOP PRODUCTION OF THE PROTEIN THE GENE NORMALLY CODES FOR - MAY MEAN A DIFFERENT PROTEIN IS PRODUCED INSTEAD

HARMFUL MUTATIONS

• PRODUCING WRONG PROTEIN OR NO PROTEIN - DISASTER IF IMPORTANT ENZYME
• MUTATION OCCURS IN REPRODUCTIVE CELLS - OFFSPRING MAY DEVELOP ABNORMALLY OR DIE IN EARLY STAGE OF DEVELOPMENT
• MUTATION IN BODY CELLS - MUTANT CELLS START TO MULTIPLY IN UNCONTROLLED WAY - CANCER

BENEFICIAL OR HARMLESS MUTATIONS

• PROTEIN PRODUCED AFTER MUTATION COULD BE IMPROVEMENT TO PROTEIN IT'S SUPPOSED TO BE
• GIVES ORGANISM SURVIVAL ADVANTAGE - PASSES ON QUALITY TO OFFSPRING - BECOMES COMMON
• THIS IS NATURAL SELECTION - EVOLUTION E.G. RESISTANT STRAIN BACTERIA
• SOME MUTATIONS DON'T CHANGE PROTEIN BEING CODED FOR - NO EFFECT ON ORGANISM

CAUSES OF MUTATIONS

• IONISING RADIATION - E.G. X-RAYS, ULTRAVIOLET LIGHT, RADIATION FROM RADIOACTIVE SUBSTANCES - GREATER DOSE OF RADIATION - GREATER CHANCE OF MUTATION
• MUTAGENS - CERTAIN CHEMICALS KNOWN TO CAUSE MUTATIONS - IF MUTATIONS PRODUCE CANCER, CHEMICALS ARE OFTEN CALLED CARCINOGENS - CIGARETTE SMOKE CONTIANS CHEMICAL MUTAGENS

RESPIRATION 

• GOES ON IN EVERY CELL IN BODY - PROCESS OF RELEASING ENERGY FROM GLUCOSE
• ENERGY FROM RESPIRATION CAN'T BE USED DIRECTLY BY CELLS - USED TO MAKE SUBSTANCE CALLED ATP
• ATP ACTS AS ENERGY SOURCE FOR MANY CELL PROCESSES AND TRANSPORTS ENERGY TO WHERE IT'S NEEDED IN CELL
• RESPIRATION CONTROLLED BY ENZYMES - EFFECTED BY TEMP AND pH

AEROBIC RESPIRATION 

• GLUCOSE + OXYGEN ---> CARBON DIOXIDE + WATER (+ ENERGY)
• C6H12O6  +      O2      --->           CO2              +    H2O   (+ ENERGY)
• HAPPENS WHEN THERES PLENTY OF OXYGEN AVAILABLE - MOST EFFICIENT RELEASE OF ENERGY FROM GLUCOSE
• TYPE OF RESPIRATION USED MOST OF THE TIME
• WHEN RESPIRATION INCREASES, OXYGEN CONSUMPTION AND CARBON DIOXIDE PRODUCTION INCREASE
• RATE OF OXYGEN CONSUMPTION USED TO ESTIMATE METABOLIC RATE (AMOUNT OF ENERGY BEING USED)

ANAEROBIC RESPIRATION

• GLUCOSE ---> LACTIC ACID (+ENERGY)
• WHEN ONE DOES VIGOROUS EXERCISE, THEIR BODY CAN'T SUPPLY ENOUGH OXYGEN TO THEIR MUSCLES EVEN THOUGH HEARTRATE AND BREATHING RATE INCREASE AS MUCH AS THEY CAN
• MUSCLES HAVE TO START RESPIRING ANAEROBICALLY ASWELL
• NOT THE BEST WAY TO CONVERT GLUCOSE TO ENERGY - RELEASES MUCH LESS ENERGY PER GLUCOSE MOLECULE THAN AEROBIC RESPIRATION
• GLUCOSE ONLY PARTIALLY BROKEN DOWN - LACTIC ACID PRODUCED
• LACTIC ACID BUILDS UP IN MUSCLES - LEADS TO PAIN AND MUSCLE FATIGUE
• ADVANTAGE - ALLOWS YOU TO KEEP USING MUSCLES WHEN OXYGEN IS USED UP
• AFTER RESORTING TO ANAEROBIC RESPIRATION, WHEN YOU STOP EXERCISING YOU'LL HAVE AN OXYGEN DEBT - NEED EXTRA OXYGEN TO BREAK DOWN LACTIC ACID BUILT UP IN MUSCLES TO ALLOW AEROBIC RESPERATION TO BEGIN AGAIN - NEED TO KEEP BREATHING HARD AFTER EXERCISE - REPAY DEBT
• LACTIC ACID - CARRIED TO LIVER TO BE BROKEN DOWN - HEART RATE HAS TO STAY HIGH FOR THIS

RESPIRATORY QUOTENT = AMOUNT OF CO2 PRODUCED / AMOUNT OF O2 USED - TELLS WHETHER SOMEONE IS RESPIRING ANAEROBICALLY (>1) OR AEROBICALLY (0.7 - 1)

MULTICELLULAR AND SINGLE CELLED ORGANISMS

• HUMANS ARE MULTICELLULAR - ADVANTAGES - 
• CAN BE BIGGER - CAN TRAVEL FURTHER, GET NUTRIENTS IN A VERIETY OF DIFFERENT WAYS, NOT GET SQUASHED OR STEPPED ON ETC.
• ALLOWS FOR CELL DIFFERENTIATION - CAN HAVE DIFFERENT TYPES OF CELLS THAT DO DIFFERENT JOBS - CELLS CAN BE SPECIALLY ADAPTED TO THEIR PARTICULAR JOB
• THIS MEANS THEY CAN BE MORE COMPLEX - SPECIALISED ORGANS, DIFFERENT SHAPES AND BEHAVIOUR - CAN BE ADAPTED SPECIFICALLY TO THEIR PARTICULAR ENVIRONMENT
• DISADVANTAGES - HAVE TO HAVE SPECIALIST ORGAN SYSTEMS E.G.
• - SYSTEM TO COMMUNICATE BETWEEN DIFFERENT CELLS - NERVOUS SYSTEM
• - SYSTEM TO SUPPLY CELLS WITH NUTRIENTS THEY NEED - CIRCULATORY SYSTEM
• - SYSTEM THAT CONTROLS EXCHANGE OF SUBSTANCES WITH ENVIRONMENT - RESPIRATORY SYSTEM
• SINGLE CELLED ORGANISMS INCLUDE BACTERIA

DNA REPLICATTION

• DNA HAS TO REPLICATE ITSELF PRIOR TO CELL DIVISION SO EACH NEW CELL HAS FULL AMOUNT OF DNA
• DNA DOUBLE HELIX 'UNZIPS' - FORMS TWO SINGLE STRANDS
• NEW NUCLEOTIDES (FLOATING FREELY IN NUCLEUS) JOIN ON USING COMPLIMENTARY BASE PAIRINGS - MAKES EXACT COPY OF DNA ON OTHER STRAND
• RESULT - TWO DOUBLE STRANDED MOLECULES OF DNA IDENTICAL TO ORIGIONAL MOLECULE OF DNA

MITOSIS - WHEN A CELL REPRODUCES ITSELF BY SPLITTING TO FORM TWO IDENTICAL OFFSPRING

• HAPPENS WHEN YOU WANT IDENTICAL CELLS E.G. GROWTH
• BEFORE IT STARTS, DNA IS REPLICATED
• DNA COILS UP INTO DOUBLE ARMED CHROMOSOMES - BOTH ARMS CONTAIN EXACT SAME INFORMATION
• CHROMOSOMES LINE UP IN CENTRE OF CELL - DIVIDE AS CELL FIBRES PULL THEM APART - TWO ARMS OF EACH CHROMOSOME GO TO OPPISITE POLES (ENDS) OF CELL 
• MEMBRANES FORM AROUND NEW SETS OF CHROMOSOMES
• CYTOPLASM DIVIDES - TWO NEW CELLS WITH THE EXACT SAME GENETIC MATERIAL

MEIOSIS - TYPE OF CELL DIVISION WHICH CREATES GAMETES

• GAMETES - SEX CELLS - EGGS AND SPERM - FORMED BY MEIOSIS IN THE OVARIES AND TESTES 
• DIPLOID - BODY CELLS - EACH OF THE ORGANISMS BODY CELLS HAVE TWO COPIES OF EACH CHROMOSOME IN IT'S NUCLEUS - ONE FROM MUM, ONE FROM DAD
• HAPLOID - GAMETES - ONLY HAVE ONE COPY OF EACH CHROMOSOME - EGG AND SPERM COMBINE TO FORM DIPLOID NUMBER OF CHROMOSOMES         

PROCESS OF MEIOSIS

• DNA REPLICATES ITSELF, CURLS UP INTO DOUBLE ARMED CHROMOSOME (LIKE MITOSIS)
• CHROMOSOMES ARRANGE THEMSELVES INTO PAIRS - HUMANS HAVE 23 PAIRS OF CHROMOSOMES - 46 ALTOGETHER - BOTH CHROMOSOMES IN A PAIR CONTAIN INFORMATION ABOUT SAME FEATURES, ONE FROM MUM AND ONE FROM DAD
• FIRST DIVISION - PAIRS SPLIT UP - CHROMOSOMES IN EACH PAIR MOVE TO DIFFERENT POLES OF CELL - IN EACH OF THE TWO NEW CELLS THERE ARE NO PAIRS - MIXTURE OF MUM AND DADS CHROMOSOMES - 23
• SECOND DIVISION - LIKE MITOSIS - CHROMOSOME SPLITS IN HALF - ONE ARM ENDS UP IN EACH NEW CELL
• FOUR NEW CELLS - TWO AFTER FIRST DIVISION, EACH OF THOSE SPLIT AGAIN - CELLS GENETICALLY DIFFERENT - CHROMOSOMES GET SHUFFLED UP - EACH GAMETE GETS HALF AT RANDOM

GENETIC VARIATION

• FERTILISATION - MALE AND FEMALE GAMETES COMBINE TO FORM DIPLOID CELL - ZYGOTE
• CHARACTERISTICS OF ZYGOTE CONTROLLED BY COMBINATION OF GENES ON IT'S CHROMOSOMES
• ZYGOTE INHERITED CHROMOSOMES FROM BOTH PARENTS - SHOW FEATURES OF BOTH PARENTS BUT WON'T BE EXACTLY LIKE EITHER OF THEM

ADAPTATIONS OF SPERM CELL

• FUNCTION - TRANSPORT MALES DNA TO FEMALE EGG
• SMALL AND HAVE LONG TAILS - SWIM TO EGG
• LOTS OF MITOCHONDRIA - PROVIDE ENERGY NEEDED TO SWIM DISTANCE
• ACROSOME AT FRONT OF HEAD - RELEASE ENZYMES NEEDED TO DIGEST WAY THROUGH MEMBRANE OF EGG CELL 

BLOOD PLASMA - PALE YELLOW LIQUID WHICH CARRIES EVERYTHING THAT NEEDS TRANSPORTING AROUND BODY:

• RED BLOOD CELLS, WHITE BLOOD CELLS (IMMUNITY) AND PLATELETS (USED IN BLOOD CLOTTING)
• WATER
• DIGESTED FOOD PRODUCTS LIKE GLUCOSE AND AMINO ACIDS FROM GUT TO BODY CELLS
• CARBON DIOXIDE - FROM BODY CELLS TO LUNGS
• UREA FROM LIVER TO KIDNEYS WHERE IT IS REMOVED IN URINE
• HOURMONES - ACT LIKE CHEMICAL MESSENGERS
• ANTIBODIES - PROTEINS INVOLVED IN BODY'S IMMUNE RESPONSE

RED BLOOD CELLS - CARRY OXYGEN FROM LUNGS TO ALL CELLS IN BODY

• SMALL, BICONCAVE SHAPE - LARGE SURFACE AREA TO VOLUME RATIO FOR ABSORBING/RELEASING O2
• CONTAIN HEAMOGLOBIN - GIVES BLOOD COLOUR - CONTAINS IRON - COMBINES WITH OXYGEN IN LUNGS TO BECOME OXYHEAMOGLOBIN - REVERSE HAPPENS IN BODY CELLS TO RELEASE OXYGEN
• NO NUCLEUS - MORE SPACE FOR HEAMOGLOBIN - CARRIES MORE OXYGEN
• VERY FLEXIBLE - EASILY PASS THROUGH TINY CAPILLARIES

ARTERIES - CARRY BLOOD AWAY FROM HEART

• HEART PUMPS BLOOD OUT AT HIGH PRESSURE - ARTERY WALLS STRONG AND ELASTIC TO COPE WITH IT
• WALLS ARE THICK COMPARED TO SIZE OF LUMEN 
• WALLS CONTAIN THICK LAYERS OF MUSCLE TO MAKE THEM STRONG

CAPILLARIES - INVOLVED IN EXCHANGE OF MATERIALS AT TISSUES

• ARTERIES BRANCH ONTO CAPILLARIES - REALLY TINY - TOO SMALL TO SEE
• USES - CARRY BLOOD REALLY CLOSE TO EVERY CELL TO EXCHANGE SUBSTANCES WITH THEM
• SUPPLY FOOD AND OXYGEN AND TAKE AWAY WASTES LIKE CO2 
• ADAPTIONS - PERMEABLE WALLS - SUBSTANCES CAN DIFFUSE IN AND OUT
• WALLS ONE CELL THICK - ICREASES RATE OF DIFFUSION BY DECREASING DISTANCE OVER WHICH IT OCCURS

VEINS - CARRY BLOOD TO THE HEART

• CAPILLARIES JOIN UP EVENTUALLY TO FORM VEINS
• BLOOD AT LOWER PRESSURE IN VEINS - WALLS NOT AS THICK - BIGGER LUMEN THAN ARTERIES - HELP BLOOD FLOW DESPITE LOWER PRESSURE - VALVES - KEEP BLOOD FLOWING RIGHT WAY

DOUBLE CIRCULATORY SYSTEMS

• FIRST SYSTEM - CONNECTS HEART TO LUNGS - DEOXYGENATED BLOOD PUMPED TO LUNGS TO TAKE IN OXYGEN - BLOOD RETURNS TO HEART
• SECOND SYSTEM - CONNECTS HEART TO REST OF BODY - OXYGENATED BLOOD PUMPED OUT TO BODY - GIVES UP OXYGEN - DEOXYGENATED BLOOD RETURNED TO HEART TO BE PUMPED TO LUNGS AGAIN
• ADVANTAGES - RETURNING BLOOD TO HEART AFTER BEING OXYGENATED MEANS IT CAN BE PUMPED TO REST OF BODY AT MUCH HIGHER PRESSURE - INCREASES RATE OF BLOOD FLOW TO TISSUES - MORE OXYGEN DELIVERED TO CELLS - IMPORTANT FOR MAMMALS - USE UP A LOT OF OXYGEN MAINTAINING BODY TEMP

THE HEART

• RIGHT ATRIUM RECEIVES DEOXYGENATED BLOOD FROM BODY THROUGH VENA CAVA
• DEOXYGENATED BLOOD MOVES THROUGH RIGHT VENTRICLE WHICH PUMPS IT TO LUNGS THROUGH PULMONARY ARTERY
• LEFT ATRIUM RECEIVES OXYGENATED BLOOD FROM LUNGS THROUGH PULMONARY VEIN
• OXYGENATED BLOOD MOVES THORUGH TO LEFT VENTRICLE WHICH PUMPS IT AROUND WHOLE BODY VIA AORTA
• LEFT VENTRICLE - MUCH THICKER WALL THAN RIGHT VENTRICLE - NEEDS MORE MUSCLE - HAS TO PUMP BLOOD AROUND WHOLE BODY, NOT JUST TO LUNGS
• SEMILUNAR, BICUSPID AND TRICUSPID VALVES PREVENT BACKFLOW OF BLOOD

ANIMAL AND PLANT GROWTH

• PLANTS - GROW CONTINUOUSLY - GROWTH IN HEIGHT MAINLY TO DO WITH CELL ELONGATION - CELL DIVISION HAPPENS IN TIPS OF ROOTS AND SHOOTS
• ANIMALS - GROW UNTIL THEY RRERACH A FINITE SIZE THEN STOP GROWING - GROWTH HAPPENS BY CELL DIVISION IN TIPS OF ROOTS AND SHOOTS

STEM CELLS

• DIFFERENCIATION - THE PROCESS IN WHICH CELL CHANGES TO BECOME SPECIALISED FOR ITS JOB
• ABILITY TO DIFFERENTIATE LOST AT EARLY STAGE IN HUMANS - PLANTS NEVER LOSE IT
• MOST CELLS IN BODY SPECIALISED FOR A PARTICULAR JOB
• STEM CELLS - UNDIFFERENTIATED CELLS - CAN DEVELOP INTO DIFFERENT TYPES OF CELLS TISSUES AND ORGANS DEPENDING ON INSTRCTIONS GIVEN
• FOUND IN EMBYOS - HAVE ABILITY TO TURN INTO ANY CELL, TISSUE OR ORGAN
• ADULTS HAVE STEM CELLS - ONLY FOUND IN BONE MARROW - AREN'T AS VERSITILE AS EMBRTO STEM CELLS - CAN ONLY TURN INTO CERTAIN CELLS

STEM CELL RESEARCH - BENEFITS

• BLOOD CANCER - CURED WITH BONE MARROW TRANSPLANTS - CONTAINS CERTAIN ADULT STEM CELLS - TURN INTO NEW BLOOD CELLS TO REPLACE OLD ONES
• EARLY HUMAN EMBRYOS - CONTAINS LOTS OF STEM CELLS - SCIENTISTS CAN EXTRACT THESE CELLS AND GROW THEM - WILL EVENTUALLY BE ABLE TO GROW TISSUES TO TREAT MEDICAL CONDITIONS

STEM CELL RESEARCH - ARGUMENTS FOR AND AGAINST

• FEEL THAT HUMAN EMBRYOS SHOULDN'T BE USED FOR EXPERIMENTS - EACH ONE POTENTIAL LIFE
• OTHERS THINK PATIENTS WHO ALREADY EXIST AND SUFFERING ARE MORE IMPORTANT THAN EMBRYOS
• EMBRYOS USED IN RESEARCH - ONES WHUCH HAVE BEEN DISCARDED IN FERTILITY CLINICS - WOULD HAVE BEEN THROWN AWAY ANYWAY
• CAMPAIGNERS FOR EMBRYO RIGHTS PROTEST THIS TOO
• NOW 'STOCKS' OF STEM CELLS - SCIENTISTS CAN USE THEM FOR RESEARCH
• SOME COUNTRIES E.G. USA WON'T FUND RESEARCH TO MAKE NEW STEM CELL STOCKS - UK ALLOWS IT UNDER STRICT GUIDELINES

METHODS OF MEASURING GROWTH

• LENGTH - MEASURING LENTH OR HEIGHT OF PLANT OR ANIMAL - EASY TO MEASURE - BUT DOESN'T TELL YOU ABOUT CHANGES IN WIDTH, DIAMETER, NUMBER OF BRANCHES ETC.
• WET MASS - WEIGHING PLANT OR ANIMAL - EASY TO MEASURE - BUT CHANGABLE - PLANT IS HEAVIER WHN IT'S RECENTLY RAINED, ANIMALS HEAVIER WHEN BLADDER FULL ETC.
• DRY MASS - DRYING OUT ORGANISM BEFORE WEIGHING IT - NOT AFFECTED BY AMOUNT OF WATER ORGANISM HAS HAD - BUT ORGANISMS HAVE TO BE KILLED BEFORE BEING WEIGHED

PHASES OF HUMAN GROWTH

• INFANCY - ROUGHLY FIRST TWO YEARS OF LIFE - RAPID GROWTH
• CHILDHOOD - PERIOD BETWEEN INFANCY AND PUBERTY - STEADY GROWTH
• ADOLESCENCE - BEGINS WITH PUBERTY - CONTINUES UNTIL BODY GROWTH AND DEVELOPMENT COMPLETE - RAPID GROWTH
• MATURITY/ADULTHOOD - PERIOD BETWEEN ADOLESCENCE AND OLD AGE - GROWTH STOPS
• OLD AGE - USUALLY CONSIDERED BETWEEN AGE OF 65 AND DEATH

MAIN PHASES OF RAPID GROWTH

• JUST AFTER BIRTH AND DURING ADOLESCENCE
• TYPICAL HUMAN GROWTH CURVE - STRETCHED S SHAPE - STEEPER CURVE - MORE RAPID GROWTH

GROWTH RATES OF DIFFERENT BODY PARTS

• BODY DOESN'T GROW EVENLY
• DIFFERENT PARTS OF BODY GROWS AT DIFFERENT RATES AT DIFFERENT TIMES
• E.G. IN EMBRYOS, BRAIN GROWS FASTEST - GIVES HUMANS BEST SURVIVAL ADVANTAGE - BEST TOOL HUMANS HAVE FOR FINDING FOOD, AVOIDING PREDETORS ETC.

SELECTIVE BREEDING - HUMANS ARTIFICIALLY SELECT PLANTS OR ANIMALS TO BREED TO HAVE THEIR GENES STAY IN THE POPULATION ACCORDING TO WHAT WE WANT FROM THEM

• ORGANISMS ARTIFICIALLY SELECTED TO DEVELOP FEATURES SUCH AS:
  • MAXIMUM YEILD OF MEAT, MILK, GRAIN ETC.
  • GOOD HEALTH AND DISEASE RESISTANCE
  • SPEED, ATTRACTIVENESS ETC.
• PRCESS OF SELECTIVE BREEDING INVOLVES:EXAMPLE - AGRICULTURE - IMPROVE YEILD - E.G. FARMERS BREED ANIMALS WITH BEST CHARACTERISTICS FOR PRODUCING MEAT TOGETHER FOR HIGHER MEAT YEILD
  • SELECT ONES FROM EXISTING STOCK WHICH HAVE BEST CHARACTERISTICS
  • BREED THEM WITH EACHOTHER
  • SELECT BEST OFFSPRING - BREED THEM TOGETHER
  • CONTINUE PROCESS OVER SEVERAL GENERATIONS

REDUCTION IN GENE POOL

• GENE POOL - NUMBER OF DIFFERENT ALELLES PRESENT IN POPULATION
• INBREEDING - FARMER BREEDS BEST ANIMALS - CLOSELY RELATED 
• HEALTH PROBLEMS - MORE CHANCE OF ORGANISM DEVELOPING GENETIC DISORDERS - LOTS OF GENETIC CONDITIONS RECESSIVE - NEED TWO ALLELES TO BE SAME TO HAVE AN EFFECT - RECESSIVE ALLELES MORE LIKELY TO BUILD UP IN POPULATION IF CLOSELY RELATED ANIMALS ARE BREEDED TOGETHER
• NEW DISEASE APPEARS - SERIOUS PROBLEM - NOT MUCH VARIATION IN POPULATION - STOCK CLOSELY RELATED - ONE OF THEM IS KILLED THEN OTHERS LIKELY TO BE KILLED

GENETIC ENGINEERING - MOVING GENES FROM ONE ORGANISM TO ANOTHER SO THAT IT PRODUCES USEFUL BIOLOGICAL PRODUCTS

• GENE RESPONSIBLE FOR PRODUCING DESIRABLE CHARACTERISTIC SELECTED 
• CUT FROM DNA USING ENZYMES AND ISOLATED
• USEFUL GENE INSERTED INTO DNA OF ANOTHER ORGANISM
• ORGANISM REPLICATES - LOADS OF SIMILAR ORGANISMS PRODUCTING USEFUL PRODUCT

EXAMPLES OF GENETIC ENGINEERING

• VITAMIN A - TAKE GENES FROM CARROTS THAT CONTROL BETA CAROTINE PRODUCTION - PUT THEM IN RICE - RICE EATEN THROUGHOUT WORLD - HUMANS CHANGE BETA CAROTINE INTO VITAMIN A
• INSULIN - GENE FOR HUMAN INSULIN PRODUCTION PUT INTO BACTERIA - CULTURED IN FERMENTER - HUMAN INSULIN EXTRACTED FROM MEDIUM AS THEY PRODUCE IT
• RESISTANCE TO HERBICIDES, FROST DAMAGE AND DISEASE - CUT OUT OF PLANTS THAT WE DON'T WANT TO GROW AND PUT INTO USEFUL ONES

ADVANTAGES AND RISKS OF GENETIC ENGINEERING

• ADVANTAGE - CAN PRODUCE ORGANISMS WITH NEW AND USEFUL FEATURES VERY QUICKLY
• RISK - INSERTED GENE MAY HAVE UNEXPECTED, HARMFUL EFFECTS - E.G. GENETICALLY ENGINEERED BACTERIA MAY MUTATE AND BECOME PATHOGENETIC - FOREIGN GENES MAY MAKE THEM MORE HARMFUL AND UNPREDICTABLE
• RISK - GENES MAY ESCAPE - E.G. WEEDS GAIN PESTICIDE RESISTANT GENES FROM USEFUL PLANT

ETHICAL ISSUES

• WRONG TO GENETICALLY ENGINEER ORGANISMS PURELY FOR HUMAN BENEFIT - PARTICULAR PROBLEM WITH GENETIC ENGINEERING OF ANIMALS, PARTICULARLY IF ANIMAL HARMED
• WON'T STOP AT PLANTS AND ANIMALS - RICH MAY BE ABLE TO PAY FOR BABY TO BE GENETICALLY ENGINEERED TO HAVE GOOD CHARACTERISTICS - THOSE WHO CAN'T AFFORD IT WILL BE 'GENETIC UNDERCLASS'
• EVOLUTIONARY CONSEQUENCES UNKNOWN - IRRESPONSIBLE IF WE DON'T KNOW THE IMPACT ON FUTURE GENERATIONS

GENE THERAPY - ALTERING A PERSONS GENES TO CURE GENETIC DISORDERS - TWO TYPES:

• CHANGING BODY CELLS - PARTICULARLY CELLS MOST AFFECTED BY DISORDER - E.G. CYSTIC FIBROSIS - LUNGS WOULD BE TARGETED - WOULDN'T AFFECT GAMETES - DISEASE COULD STILL BE INHERITED
• CHANGING GENES IN GAMETES - EVERY CELL IN BODY OF OFFSPRING AFFECTED - WON'T INHERIT DISEASE - CURRENTLY ILLEGAL

ETHICAL ISSUES OF GAMETE THERAPY

• UNEXPECTED CONSEQUENCES - CAUSE NEW SET OF PROBLEMS - HARMFUL GENES INHERITED BY OFFSPRING
• COULD LEAD TO CREATION OF 'DESIGNER BABIES' - PARENTS CHOOSE GENES THEY WANT CHILDREN TO HAVE

CLONES - GENETICALLY IDENTICAL ORGANISMS

CLONING OF ADULT ANIMAL - DONE BY TRANSFERRING THE NUCLEUS - NUCLEAR TRANSFER - E.G. DOLLY SHEEP

• NUCLEUS OF SHEEPS EGG CELL REMOVED - LEFT EGG WITHOUT ANY GENETIC INFORMATION
• ANOTHER NUCLEUS INSERTED IN IT'S PLACE - DIPLOID NUCLEUS FROM UDDER CELL OF SHEEP BEING CLONED - HAD ALL OTHER SHEEPS GENETIC INFORMATION
• CELL GIVEN ELECTRIC SHOCK - STARTED DIVIDING MY MITOSIS
• DIVIDING CELL )NOW AN EMBREO) PLANTED INTO UTERUS OF SURROGATE MOTHER SHEEP TO DEVLOP UNTIL READY TO BE BORN
• RESULT - DOLLY - CLONED SHEEP FROM WHICH THE UDDER CELL CAME

CLONING HUMANS - ETHICAL ISSUES

• LOTS OF SURROGATE PREGNANCIES - HIGH RATES OF MISCARRIAGE AND STILLBIRTH
• CLONES OF OTHER ANIMALS HAVE BEEN UNHEALTHY - OFTEN DIE PREMATURELY
• CLONE MAY BE PSYCOLOGICALLY DAMAGED TO KNOW THAT IT'S JUST A CLONE OF ANOTHER HUMAN

BENEFITS OF CLONING

• ALLOWS PRODUCTION OF ANIMALS WITH DESIRABLE CHARACTERISTICSHUMAN EMBREOS PRODUCED BY CLONING ADULT BODY CELLS - EMBREOS USED TO SUPPLY STEM CELLS FOR STEM CELL THERAPY - EXACTLY THE SAME GENETIC INFORMATION AS PATIENT - REDUCED RISK OF REJECTION
  • ANIMALS WHICH PRODUCE MEDICINES IN THEIR MILK DEVELOPED BY GENETIC ENGINEERING AND CLONED - USEFUL HUMAN GENES TRANSFERRED TO SHEEP AND COWS AND PUT INTO HUMANS WITHOUT USEFUL GENE E.G. BLOOD CLOTTING AGENT PUT INTO PEOPLE WITH HAEMOPHILIA
  • ANIMALS WITH ORGANS SUITABLE FOR TRANSPLANTATION CLONED - CONSTANT SUPPLY OF ORGANS FOR TRANSPLANT - SOLVE PROBLEM OF LIMITED SUPPLY (ALTHOUGH THERE ARE ISSUES E.G. VIRUSES PASSED FROM ANIMALS TO HUMANS)

RISKS OF CLONING

• CLONES NOT AS HEALTHY AS NORMAL ANIMALS
• NEW SCIENCE - MAY HAVE CONSEQUENCES WE'RE NOT YET AWARE OF

COMMERCIAL CLONING OF PLANTS - EASIER THAN CLONING ANIMALS

• PLANT WANTED IS CHOSEN BASED ON CHARACTERISTICS
• REMOVE SEVERAL SMALL PIECES OF TISSUE FROM PARENT PLANT - BEST RESULTS IF TISSUE TAKEN FROM FAST GROWING SHOOTS OR TIPS
• GROW TISSUE IN GROWTH MEDIUM CONTAINING NUTRIENTS AND GROWTH HORMONES - DONE UNDER ANTISEPTIC CONDITIONS TO PREVENT MICROBE HARMING PLANT
• TISSUES PRODUCE SHOOTS AND ROOTS - MOVED TO POTTING COMPOST TO CARRY ON GROWING

COMMERCIAL USE OF CLONED PLANTS - PROS AND CONS

• PRO - CAN BE FAIRLY SURE OF CHARACTERISTICS OF PLANT - GENETICALLY IDENTICAL TO PARENTS - DON'T WASTE TIME OR MONEY GROWING BAD PLANTS
  • POSSIBLE TO MASS PRODUCE PLANTS THAT ARE HARD TO GROW FROM SEEDS
• CON - SUFFER FROM DISEASE DUE TO CHANGE IN ENVIRONMENT - ALL PLANTS WILL SUFFER - SAME GENES
  • LACK OF GENETIC VARIATION