Cell Processes Biology Unit 3

MCAS Objectives Identify the reactants and products in the general reaction of photosynthesis. Identify how cellular respiration is important for the production of ATP Explain the interrelated nature of photosynthesis and cellular respiration.

Cell Review A cell is the smallest unit of life It retains characteristics of the entire organism Take in fuel Convert it to energy Eliminate wastes

What are the two types of cells? Prokaryotic Eukaryotic

Cell Membrane Review Cell/Plasma membrane encloses and defines cells as separate from their environment The membrane is made up of a phospholipid bilayer Hydrophilic Polar heads – water loving Points towards the watery environments outside and inside the cell Hydrophobic Lipid tails – water fearing In between the two hydrophilic polar heads

Cell Membrane Review Cell Membranes are selectively permeable = choosy about what substances can pass through Passive Transport – requires no energy from cell Diffusion Facilitated Diffusion Osmosis Active Transport - requires energy from cell Protein pumps/carrier proteins Endocytosis Exocytosis High to low concentration Low to high concentration

Comparing Photosynthesis & Respiration Cellular Respiration Function Energy Storage Energy Release Location Chloroplasts Mitochondria Reactants CO2 and H2O C6H12O6 and O2 Products Equation 6CO2 + 6H2O  C6H12O6 + 6O2 C6H12O6 + 6O2 6CO2 + 6H2O

Terms to know Autotrophs – make their own food Plants, algae, green bacteria Heterotrophs – consume other organisms to get food Animals, fungi, most bacteria

Autotrophs An autotroph or "producer", is an organism that produces organic compounds from simple substances present in its surroundings, generally using energy from light by photosynthesis) . They are the producers in a food chain, such as plants on land or algae in water. They are able to make their own food. Heterotrophs (animals) depends on autotrophs for energy

Heterotrophs Heterotrophs are the consumers in the food chain, particularly the herbivores, carnivores and omnivores. All animals, some fungi and most bacteria are heterotrophs. They are not capable of producing their own food. Therefore, they obtain their energy requirements by feeding on organic matter or another organism.

Photosynthesis & Cellular Respiration are the opposites of each other Obtaining energy Acquiring nutrients is a metabolic process 1. Photosynthesis – only autotrophs 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2 2. Cellular Respiration – both autotrophs & heterotrophs C6H12O6 + 6O2 6CO2 + 6H2O + usable energy Photosynthesis & Cellular Respiration are the opposites of each other

Review - Plant cells What 3 cell parts are found solely in plants? Cell Wall Large Central Vacuoles Chloroplasts

Chloroplasts Specialize in transferring energy from the Sun into the chemical energy in food. Green in color = chlorophyll During Photosynthesis, the energy from sunlight is used to combine the atoms from carbon dioxide and water to produce sugars

PHOTOSYNTHESIS Autotrophic Process: Plants make their energy (glucose) from sunlight. Stored as carbohydrate in their bodies. 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2

Why is Photosynthesis important? Makes organic molecules (glucose) out of inorganic materials (carbon dioxide and water). It begins all food chains/webs. Thus all life is supported by this process. It also makes oxygen!!

Photosynthesis- starts ecological food webs!

Photo-synthesis means "putting together with light." Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. Autotrophs make glucose and heterotrophs are consumers of it.

How do we know that plants make carbohydrates from just carbon dioxide water and light energy? Experiments!

History of Photosynthesis Plants use the water they absorb from the soil to grow... ... because the only thing added to the plants was water This is because plants make their own food in a process called photosynthesis Water is one of the raw materials for photosynthesis

History of Photosynthesis Plants produce something which candles need to burn (oxygen) The mint replaced the oxygen in the bell jar after the candle used it up This happens because the sprig of mint was photosynthesising Photosynthesis produces oxygen as a waste product

History of Photosynthesis Plants need light to produce oxygen The pond weed produced bubbles when placed in the light but not in the dark Plants need light to photosynthesise. Plants absorb light energy and use this energy to combine water and oxygen to make glucose: this produces oxygen as a waste product.

History of Photosynthesis Only the green parts of plants can photosynthesise... ... as only the green parts of the leaf produce bubbles Plants need chlorophyll to be able to photosynthesise Chlorophyll absorbs the light energy which plants need to build sugars from water and carbon dioxide

History of Photosynthesis 1961 – American chemist Melvin Calvin received the Nobel prize for figuring out the chemical pathway used by plants to make sugars

THE BIG PICTURE → These experiments led to work by later scientists who finally discovered that in the presence of light, plants transform CO2 and water into carbohydrates and release oxygen. Carbon dioxide WATER Sugars Oxygen _____________ + ____________ _______________ + ____________ 6 CO2 6 H2O → C6H12O6 6 O2 _____________ + ____________ _______________ + ____________

Photosynthesis 6CO2 + 6H2O + energy  C6H12O6 + 6O2 Carbon dioxide + water glucose + oxygen sunlight absorbed by chlorophyll 6CO2 + 6H2O + energy  C6H12O6 + 6O2

Plants in Action The process that uses the sun’s energy to make simple sugars?

The photograph below is an elodea leaf X 400 The photograph below is an elodea leaf X 400. Individual cells are clearly visible. The tiny green structures within the cells are chloroplasts this is where photosynthesis happens.                                     Elodea’s are aquatic plants with leaves that are only 2 cells thick!

Plants chlorophyll Leaves are green because they contain the pigment: Leaves have a large surface area to absorb as much light as possible "Thanks for the Glucose!"

Stomata Where plants exchange gases!

Photosynthesis Plant roots absorb mineral salts including nitrates needed for healthy growth For healthy growth plants need mineral ions including: nitrate – for producing amino acids which are then used to form proteins magnesium – which is needed for chlorophyll production

Pigments: Absorb different colors of white light (ROY G BIV) PHOTOSYNTHESIS Pigments: Absorb different colors of white light (ROY G BIV) These pigments absorb all wavelengths (light) BUT green!

That’s why leaves LOOK GREEN….. Chlorophyll doesn’t absorb…. it ___________ GREEN light! REFLECTS

Photosynthesis Glucose provides the energy and carbon needed to make other plant materials like wax and proteins.

In plants and simple animals, waste products are removed by diffusion In plants and simple animals, waste products are removed by diffusion. Plants, for example, excrete O2, a product of photosynthesis.

EQUATION FOR PHOTOSYNTHESIS WATER OXYGEN 6CO2 + 6H2O + ENERGY C6H12O6 + 6O2 CARBON DIOXIDE GLUCOSE

Photosynthesis The rate of photosynthesis may be limited by: low temperature shortage of carbon dioxide shortage of light

PHOTOSYNTHESIS Light intensity: as light increases, rate of photosynthesis increases

PHOTOSYNTHESIS Carbon Dioxide: As CO2 increases, rate of photosynthesis increases

PHOTOSYNTHESIS Temperature: Temperature Low = Rate of photosynthesis low Temperature Increases = Rate of photosynthesis increases If Temperature too hot, rate drops

Comparing Photosynthesis & Respiration Cellular Respiration Function Energy Storage Energy Release Location Chloroplasts Mitochondria Reactants CO2 and H2O C6H12O6 and O2 Products Equation 6CO2 + 6H2O  C6H12O6 + 6O2 C6H12O6 + 6O2 6CO2 + 6H2O