bacterial cell – genetic information not contained within a nucleus
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CELLS
Bacterial cell – genetic
information not contained
within a nucleus
Diffusion is the net movement of particles
from a high concentration to a low
concentration down the concentration gradient until an equilibrium is
reached
Cell
Tissue
Organ system
Organ
Organs are made of tissues. The stomach is an organ that contains:
■ muscular tissue, to churn the contents■ glandular tissue, to produce digestive juices■ epithelial tissue, to cover the outside and the inside of the stomach.
PLANTS
Examples of plant tissues include:
• epidermal tissues, which cover the plant
• mesophyll, which carries out photosynthesis
• xylem and phloem, which transport substances around the plant
FOOD (GLUCOSE) OXYGEN+WATERCARBON
DIOXIDE +
We know that plants make their own food from sunlight. They are the producers in the food chain. This is done in the green parts of the plant, e.g. upper surface of the leaves.
Made by photosynthesis and stored as
starch in leaves, roots, stems,
etc.
Taken in through holes in the leaves
as a gas in air
waste product exhaled
Taken in through
the roots from soil
With light and
chlorophyll
LIMITING FACTORS?• LIGHT INTENSITY
• TEMPERATURE
• CARBON DIOXIDE
Paraffin lamps have traditionally been used in greenhouses. Their use increases the rate
of photosynthesis because as well as the
light generated from the lamps, the burning
paraffin produces heat and carbon dioxide too
The use of artificial light allows photosynthesis to continue beyond daylight hours. Bright lights also provide a higher-than-normal light intensity.
The use of artificial heating allows photosynthesis to continue at an increased
rate.
GLUCOSE
Converted into insoluble starch
for storage
Used in respiration
To produce fats and oils for storage
To produce proteins
To produce cellulose for cell walls
To produce proteins, plants also use nitrate ions that are absorbed from the soil.
DISTRIBUTIONOF
ORGANISMS
ENZYMES
• Proteins act as:– structural components of tissues such as
muscles– hormones– antibodies– catalysts
• Catalysts increase the rate of chemical reactions. Biological catalysts are called enzymes. Enzymes are proteins.
Enzymes are protein molecules, and so are made up of long chains of amino acids. Most enzymes contain between 100 and 1,000 amino acids.
These long chains are folded to produce a unique 3D shape which enables other molecules to fit into the protein.
• The shape of an enzyme is vital for the enzyme’s function. High temperatures change the shape. Different enzymes work best at different pH values.
This is what happens at the active site
enzyme
reactant
+enzyme-reactant
complex↔products
enzyme
+↔
+ ↔ ↔ +
If the temperature and pH changes sufficiently beyond an enzyme’s optimum, the shape of the enzyme irreversibly changes.
normal denatured
heat
pH
This affects the shape of the active site and means that the enzyme will no longer work.
When this happens the enzyme is denatured.
Effect of pH…
A change in the pH changes the shape of the protein molecule, the enzyme loses its active site and so can no longer act as a catalyst.
Effect of temperature…
QUIZ!1. What are biological catalysts called?2. What are enzymes made of?3. What is the place on the enzyme
where the reactant molecule binds called?
4. What does it mean when an enzyme is denatured?
5. What two factors can affect enzyme action?
Some enzymes work outside the body cells.
The digestive enzymes are produced by specialised cells in glands and in the lining of the gut. The enzymes then pass out of the cells into the gut where they come into contact with food molecules.
They catalyse the breakdown of large INSOLUBLE molecules into smaller
SOLUBLE molecules.
Name Where it is made
The nutrient it catalyses
What it breaks down into
Where the break down occurs in the body
Amylase Salivary glandsPancreasSmall Intestine
Starch(carbohydrates)
Glucose MouthSmall Intestine
Protease StomachPancreasSmall Intestine
Proteins Amino acids
StomachSmall Intestine
Lipase PancreasSmall Intestine
Lipids (fats
Fatty acids and glycerol
Small Intestine
The stomach produces
hydrochloric acid to create the optimum conditions for the protease
enzymes in the stomach
Bile neutralises the acid that was added to
food in the stomach. This
provides alkaline
conditions in which enzymes
in the small intestine work
most effectively.
QUIZ!1. Name the enzyme that breaks down fats?2. Name the enzyme that breaks down proteins?3. Name the enzyme that breaks down carbohydrates?4. What are fats broken down into?5. What are proteins broken down into?6. What are carbohydrates broken down into?7. Where is amylase made?8. Where is protease made?9. Where is lipase made?10. Where is bile produced?11. Where is it stored?12. What does it do?
ENZYMES IN INDUSTRY
From microorganisms
More effective at low
temperatures than other washing powders
Isomerase – converts glucose
into fructose
• In industry, enzymes are used to bring about reactions at normal
temperatures and pressures that would otherwise require
expensive, energy-demanding equipment.
• However, most enzymes are denatured at high temperatures and many are costly to produce.
QUIZ!1. What type of organisms produce
enzymes that are used in industry?2. What enzymes are found in washing
powders?3. What enzyme converts glucose into
fructose?4. Why is fructose used in slimming
foods rather than glucose?
RESPIRATION
from the digestive system
from the breathing system
useful!waste product exhaled
waste product exhaled
AEROBIC Respiration is the process that the body uses to release energy from digested food (glucose):
carbondioxideglucose oxygen water energy
Happens in all cells all the time in plants & animals inside mitochondria
Which cells contain more mitochondria? Why?
• Muscles, liver and kidneys
• They require more energy
• They use energy at a higher rate, especially during exercise
The folded layers produce a large surface area for the chemical reactionsThe large surface area means more enzymes can attach to the substrates to catalyse the reactions
REASONS• Respiration releases energy from the food we
eat so body cells can use it• Builds large molecules up from smaller
ones to make new cell material (synthesis reactions) – example – sugars and nitrates are built into amino acids which are then used to make proteins
• Makes your muscles contract – whether aware of or not – e.g. sleeping – heart beats, breathe, gut churns!
• On cold days we use energy to keep warm and on hot days use energy to sweat and keep cool – WARM BLOODED
QUIZ!1. Write the equation for aerobic
respiration2. Where does respiration occur?3. Which cells contain more
mitochondria?4. Give two reasons for respiration
•What changes happen during
exercise?
What do these changes mean?
• Increase the blood flow to the muscles and so
increase the supply of glucose and oxygen and
increase the rate of removal of carbon
dioxide.
If insufficient oxygen is available during exercisewhat type of respiration
happens?
• Anaerobic respiration is the incomplete
breakdown of glucose and
produces lactic acid
HIGHER LEVEL!• As the breakdown of glucose is
incomplete, much less energy is released than during aerobic respiration.
• Anaerobic respiration results in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
EXTRA!• If muscles are subjected to long
periods of vigorous activity they become fatigued, i.e. they stop contracting efficiently.
• One cause of muscle fatigue is the build-up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid.
QUIZ!1. What does anaerobic mean?2. What is produced in anaerobic
respiration?3. Why is more energy produced with
aerobic than anaerobic respiration?4. What is the ‘oxygen debt’?5. What is one cause of muscle
fatigue?
GENETICS
• In body cells the chromosomes are normally found in pairs. Body cells divide by mitosis. The chromosomes contain the genetic information
MITOSIS MEIOSISOccurs during growth or
to replace body cellsProduces gametes
Occurs in every cell in body
Occurs only in ovaries/testes
Cell divides once Cell divides twiceProduces 2 daughter
cellsProduces 4 daughter
cellsAsexual Sexual
2 sets of chromosomes (46)
One set of chromosomes (23)
Produces genetically identical copies
Produces variation
• When a cell divides to form gametes:–copies of the genetic
information are made–then the cell divides
twice to form four gametes, each with a single set of chromosomes.
QUIZ!1. How do body cells divide?2. Where are the chromosomes found?3. How many daughter cells does mitosis
produce?4. How many daughter cells does meiosis
produce?5. Where does meiosis occur?6. What does meiosis produce?
• Most types of animal cells differentiate at an early stage whereas many plant cells retain the ability to differentiate throughout life.
• In mature animals, cell division is mainly restricted to repair and replacement
STEM CELLS• Cells from human embryos and
adult bone marrow, called stem cells, can be made to differentiate into many different types of cells, e.g. nerve cells.
• Human stem cells have the ability to develop into any kind of human cell.
• Treatment with stem cells may be able to help conditions such as paralysis.
• Sexual reproduction gives rise to variation because, when gametes fuse, one of each pair of alleles comes from each parent
Each gene may have different forms called
allelesDomina
nt Recessi
ve
Gene is a small section of DNA
Chromosomes are made of DNA
Each gene codes for a particular combination of
amino acids which make a
specific protein
Each person (apart from identical twins)
has unique DNA. This can be used to
identifyindividuals in a
process known as DNA fingerprinting
QUIZ!1. What is a stem cell?2. Where are they produced?3. What is an allele?4. What is a gene?5. What are chromosomes made of?6. Why does sexual reproduction give rise to
variation?
Polydactyly
Cystic fibrosis
Embryo screenin
g?
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