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B3A - Molecules of Life

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
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B3A - Molecules of Life

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

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B3A - Molecules of Life

BACTERIA CELLS


NO CHLOROPLASTS OR MITOCHONDRIA

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

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B3A - Molecules of Life

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
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B3A - Molecules of Life

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
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B3A - Molecules of Life

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
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B3B - Proteins and Mutations

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
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B3B - Proteins and Mutations

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          --- next line ---- 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
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B3B - Proteins and Mutations

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)
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B3B - Proteins and Mutations

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

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B3B - Proteins and Mutations

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
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B3B - Proteins and Mutations

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
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B3C - Respiration

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)
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B3C - Respiration

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)
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