Part A: Cells Need Energy
Where there is life, there must be a source of energy and a supply of matter and organisms gain energy and matter in a variety of ways and from a variety of sources.
AUTOTROPHS:
Some autrotrophs harness energy directly from our Sun, this energy is used to drive chemical reactions for photosynthesis.
Some autotrophs are able to harness energy released by chemical reactions in a process called chemosynthesis.
HETEROTROPHS:
These organisms rely on autotrophs to provide energy (usually via consumption).
REMEMBER: The energy supply is for the entire organism. But the energy needs to be gained and used at the cellular level (by each individual cell).
AUTOTROPHS:
Some autrotrophs harness energy directly from our Sun, this energy is used to drive chemical reactions for photosynthesis.
Some autotrophs are able to harness energy released by chemical reactions in a process called chemosynthesis.
HETEROTROPHS:
These organisms rely on autotrophs to provide energy (usually via consumption).
REMEMBER: The energy supply is for the entire organism. But the energy needs to be gained and used at the cellular level (by each individual cell).
Photosynthesis
![Picture](/uploads/1/2/5/9/125983434/chloroplast-drawing-structure-5_orig.png)
What is photosynthesis?
Carbon Dioxide + Water --Light energy--> Glucose + Oxygen + Water
- Not all cells can harness the suns energy. But...
- Cells that can convert solar energy into chemical energy, such as green plant cells, use a special pigment call chlorophyll.
- Chlorophyll absorbs light energy and makes it available for photosynthesis.
- In some eukaryotes, chlorophyll is contained in chloroplasts.
- Photosynthesis is a series of reactions that occur in the Stroma and thylakoid membrane of chloroplast.
- During these reactions:
Carbon Dioxide + Water --Light energy--> Glucose + Oxygen + Water
- The inner membranes of chloroplast are folded many times to provide a greater surface area for reactions to occur.
- Don't forget: Chloroplast have their own DNA and Ribosomes. Read about Endosymbiotic theory the the bottom of the Cell Structures page here
Respiration
What is Respiration?
- All organisms except for Kingdom Archaea use glucose as the primary source of energy to drive the thousands of chemical reactions that occur in their cell(s).
- When the chemical bonds in glucose are broken, it provides energy in a form that cells can harness and use. This process is called Respiration.
- Like Photosynthesis, Cellular Respiration is a series of chemical reactions.
- At certain stages of cellular respiration, energy is released and that energy is used to build up molecules called Adenosine Triphosphate (ATP).
- ATP is an "energy storage" molecule that is used to power cellular processes.
- The first stage takes place in the cytoplasm
- The final stage occurs in the mitochondria
- The mitochondria have a highly folded inner membrane. The folds are caled cristae and they protrude into the matrix.
- The cristae have two important features:
- They provide the enzymes necessary for cellular respiration
- They have a large surface area to for which chemical reactions can occur.
Complete:
Question Set 8.3 p. 170
Part B: Specialised Organelles Synthesise Complex Molecules
What is an organic compound?
Organic compounds are any chemical compound in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen. The only exceptions are: carbonates, cyanides and oxides of carbon.
Why build large molecules?
Large molecules are what cells are made of (like lego blocks!). Aside from structure, they are also used for:
DEFINITION: Biomacromolecules are molecules that have an important structural or functional role in cells.
Biomacromolecules are broken up into 4 main classes:
How are biomacromolecules made?
Autotrophs build their own organic compounds from inorganic materials.
Plants and algae all produce simple sugars (glucose) through photosynthesis. They then use those simple sugars to build more complex organic compounds such as sucrose, starch and cellulose.
Chemotrophs build their own organic molecules through chemosysnthesis. Chemotrphs are autotrophs who do not photosynthesise. Typically found in extreme conditions without oxygen or sunlight.
Heterotrophs make their own from exisiting organic compounds. They must take in a range of organic compounds like proteins, break them down into amino acids and then rebuild them into new organic compounds as required.
Large biomacromolecules like nucleic acids (DNA and RNA), proteins and complex carbohydrates are synthesised inside cells. This is done by linking together a string of simple molecules. Each individual molecule is called a monomer, when strung together to form a long chain they are called polymers.
NOTE: Not all biomacromolecules are polymers.
Organic compounds are any chemical compound in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen. The only exceptions are: carbonates, cyanides and oxides of carbon.
Why build large molecules?
Large molecules are what cells are made of (like lego blocks!). Aside from structure, they are also used for:
- Communication
- Energy transformation
- Relaying genetic information
DEFINITION: Biomacromolecules are molecules that have an important structural or functional role in cells.
Biomacromolecules are broken up into 4 main classes:
- carbohydrates
- lipids
- proteins
- nucleic acids
How are biomacromolecules made?
Autotrophs build their own organic compounds from inorganic materials.
Plants and algae all produce simple sugars (glucose) through photosynthesis. They then use those simple sugars to build more complex organic compounds such as sucrose, starch and cellulose.
Chemotrophs build their own organic molecules through chemosysnthesis. Chemotrphs are autotrophs who do not photosynthesise. Typically found in extreme conditions without oxygen or sunlight.
Heterotrophs make their own from exisiting organic compounds. They must take in a range of organic compounds like proteins, break them down into amino acids and then rebuild them into new organic compounds as required.
Large biomacromolecules like nucleic acids (DNA and RNA), proteins and complex carbohydrates are synthesised inside cells. This is done by linking together a string of simple molecules. Each individual molecule is called a monomer, when strung together to form a long chain they are called polymers.
NOTE: Not all biomacromolecules are polymers.
Carbohydrates
![Picture](/uploads/1/2/5/9/125983434/published/glucose-sucrose-starch.gif?1563419602)
What are they?
Molecules made exclusively of carbon, hydrogen, and oxygen in the ration of 1:2:1.
What do they do?
Molecules made exclusively of carbon, hydrogen, and oxygen in the ration of 1:2:1.
What do they do?
- Energy-storage molecule (e.g. glucose).
- Form structural elements (e.g. chitin which is the major part of fungi cell walls and arthropod exoskeletons).
- Cell-cell interaction and recognition.
- Monosaccharides: consist of 3-6 carbon atoms and are relatively small and simple (e.g. glucose, fructose, and hexose).
- Disaccharides: consist of two monosaccharides bonded together (e.g. sucrose, lactose, maltose).
- Polysaccharides: consist of multiple monosaccharides bond together (e.g. starch, glycogen, cellulose, chitin).
HOME STUDY: Watch the video below. The first 7 minutes are important for ATAR Biology. Remaining information is possibly useful for ATAR Human Biology, and definitely useful for everyday life!
Lipids
![Picture](/uploads/1/2/5/9/125983434/triglyceride_orig.png)
What are they?
Triglycerides:consist of a glycerol molecule bonded to three fatty acid molecules (e.g. saturated and unsaturated fats).
- A diverse group of substances that are insoluble in water.
- Mostly consist of C, H, and O, but may also contain nitrogen and or phosphorus
- Much lower proportion of oxygen and are mostly chains of H-C-H.
- energy storage - they have approximately twice the amount of energy as carbohydrates (e.g. triglycerides such as saturated and unsaturated fat).
- structural component of membranes (e.g. phospholipids in cell membranes).
- specific biological functions such as transmission of chemical signals both within and between cells, insulation (e.g. steroids such as cholesterol and testosterone).
Triglycerides:consist of a glycerol molecule bonded to three fatty acid molecules (e.g. saturated and unsaturated fats).
![Picture](/uploads/1/2/5/9/125983434/phospholipid_orig.gif)
Phospholipids: consist of a phosphate group, a glycerol group, and two fatty acid molecules (e.g. phospholipid bi-layer in cell membranes).
![Picture](/uploads/1/2/5/9/125983434/published/steroid.jpg?1563421550)
Steroids: consist of 17 carbon atoms bonded together in four fused rings (e.g. cholesterol, testosterone, cortisol, progesterone, oestrogen).
![Picture](/uploads/1/2/5/9/125983434/wax-lipid_orig.jpg)
Waxes: A simple lipid which is an ester of a long-chain alcohol and a fatty acid. Waxes are found in nature as coatings on leaves and stems to prevent water loss.
HOME STUDY: Watch The following explanation of lipids:
HOME STUDY: Watch The following explanation of lipids:
Proteins
What are they?
What do they do?
- A diverse group of large molecules made up of 100s or 1000s of amino acids.
- Are also mostly carbon, hydrogen, and oxygen but ALWAYS contain nitrogen and sometimes contain sulfur and or phosphorus.
- Amino acids all join together to form a "polypeptide chain".
- A protein consists of one or more of these polypeptide chains twisted, folded, and coiled in a precise way to form a molecule with a unique shape and function.
What do they do?
- The most complex biomacromolecule and the most abundant in our body (approximately 17-20% of our weight).
- An essential component of all body structures (muscles, hair, skin, bone, blood, etc.).
- Control what goes in and out of cells.
- Enzymes are proteins. Enzymes facilitate essential reactions in the body such as digestion and DNA replication.
Nucleic Acid
What are they?
- A molecule composed of a series of nucleotides bonded together.
- A nucleotide consists of a ribose or deoxyribose sugar, a phosphate group, and a nitrogenous base a molecule primarily composed of nitrogen.
- The molecules in which information regarding cell structure and function is stored and transferred from generation to generation.
- Nucleic acids are like the instruction manual for an organism.
- DNA (contains a deoxyribose sugar and the following 4 nitrogenous bases (Adenine, Thymine, Guanine, and Cytosine).
- RNA (contains a ribose sugar and the following four bases (Adenine, Uracil, Guanine, and Cytosine) – U replaces T.
To summarise, you should watch...
You should complete...
Question Set 7.4 on p. 174
PART C: Specialised structures for the removal of wastes
![Picture](/uploads/1/2/5/9/125983434/er-to-membrane_orig.jpg)
Cells need to be able to move nutrients and wastes around the cell and even across the cell membrane. In order to study how cells do this, scientists "label" molecules like proteins with flourescent or radioactive "dyes" in order to track their movements.
The result of these studies? The realisation that specific organelles are in charge of trasportation. These organelles are:
Return to the Cell Structures Page to refresh your memory of these organelles.
From the ER to the Cell Membrane:
The result of these studies? The realisation that specific organelles are in charge of trasportation. These organelles are:
- Endoplasmic Reticulum
- Golgi Apparatus
- Lysosomes
- Plasma Membrane
Return to the Cell Structures Page to refresh your memory of these organelles.
From the ER to the Cell Membrane:
Step 1: RNA is copied from DNA in nucleus and moves through nuclear pores.
Step 2: The RNA is read by ribosomes and amino acids are joined together to form proteins based on the RNA code.
Step 3: Some proteins move through the lumen of the Endoplasmic reticulum and are altered.
Step 4: The proteins escape the ER via "transport vesicles" which bud off of the ER.
Step 5: The Golgi apparatus is reached and the transport vesicles unite to become a part of the cisternae.
Step 6: Any unwanted proteins are packaged into "secretory vesicles" to be released via the cell membrane in a process called "exocytosis".
Step 2: The RNA is read by ribosomes and amino acids are joined together to form proteins based on the RNA code.
Step 3: Some proteins move through the lumen of the Endoplasmic reticulum and are altered.
Step 4: The proteins escape the ER via "transport vesicles" which bud off of the ER.
Step 5: The Golgi apparatus is reached and the transport vesicles unite to become a part of the cisternae.
Step 6: Any unwanted proteins are packaged into "secretory vesicles" to be released via the cell membrane in a process called "exocytosis".
Complete:
Question set 7.5
Chapter 7 Review Questions
Question set 7.5
Chapter 7 Review Questions
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