Biology Unit 1Chapter 2- The chemical composition of cells
Cell EnvironmentsAll cells exist in a very watery environment. Eg blood, water etc
Extracellular fluid• As the plasma
membrane is semi-permeable the extracellular fluid is critical for all cells.
External environment• For unicellular
organisms the extracellular fluid is the extracellular environment it lives in.
• It can’t control the extracellular fluid, it can only move to a different environment.
Internal environment• Because multicellular
organisms are part of a larger organisation they are able to have an extra barrier against the external environment.
• This creates an internal environment that can be controlled.
• More or less independent of external environmentIntracellular fluid
The environment within a cell.
Internal environment Regulated so that cells can function at their
optimum levels◦ Aspects regulated: -ion concentration
-temperature -pH-Nutrients, water and waste levels and
removal
What happens when the above aspects are not regulated?Some of the major bodily systems are involved in this regulation process:
• Respiration• Digestion• Circulation
Plants and Animals
The chemicals in cells
Organic and Inorganic compounds Compounds are
organized into 2 types:◦ Organic compounds –
These are complex chemical compounds which contain Carbon and Hydrogen.
◦ Inorganic compounds- These are all non-organic compounds. e.g. water, oxygen, nitrogen.
INORGANIC COMPONENTS
Water- most organisms are 70-90% water
Surface tension Heat capacity Cohesiveness
Oxygen and carbon dioxide Oxygen is needed for cells to
release energy from food molecules Carbon is the key molecule in organic
molecules. Nitrogen
Nitrogen is needed to make proteins.
Minerals Are needed for the structural part of
cells, the body and in enzymes and vitamins
ORGANIC MOLECULESCarbohydrates
Important source of energy Made of carbon, hydrogen and oxygen
Lipids fats and oils important for energy stores and some
structures. Proteins
Vital for all sorts of functions!Nucleic Acid
Genetic material for all organismsVitamins
Required for normal functioning.
All cells are made of 4 Biomacromolecules
These are really big molecules that make up 99% of most organisms.
These are: LIPIDS CARBOHYDRATES PROTEINS NUCLEIC ACID
Because of their size... Biomacromolecules are made up of subunits;
meaning they are made of smaller parts that can be broken down or built up. The smaller parts are called subunits.Why do you think they need to be built up or
broken down?
Lipids are made of a glycerol and 3 fatty acids
Carbohydrates are made of glucose chains
Proteins are made of amino acid chains
Nucleic acids are made of nucleotide chains
Lipids in cells• The most important functions of lipids •Storage of energy • The plasma membrane is made up of lipids.
Most lipids are made of fatty acids tails and one glycerol.
Lipids can either be saturated or unsaturated.
Lipids
Saturated Fats
• Coconut oil• Butter• Beef• Pork
• Cheese
Unsaturated fats
• Olive oil• Peanut oil• Almonds
• Sunflower oil• Corn oil• Fish
• Mayonnaise• Margarines
Phospholipids Special types of lipids, that
have a phosphate head and 2 fatty acid tails.
The phosphate head is hydrophillic (water loving) and the fatty acid tails are hydrophobic (water hating)
The plasma membrane• The plasma membrane separates the cells internal environment from the external environment.
•Controls the movement of substances into and out of the cell.
•The membrane that surrounds cell organelles controls the movement of substances into and out of different organelles.
The phospholipid bilayer is made up of many phospholipid molecules that have a hydrophilic (water loving) head and hydrophobic (water hating) tail.
They are arranged as a double layer with all the tails facing inwards and the heads around the outside.
Phospholipid bilayer
Lipids and the plasma membrane Lipids are
important components of membranes.
Lipids are the fluid part of the membrane.
Cholesterols give flexibility when cold and stability when hot.
Fats are needed in our diet for the absorption of many vitamins.
Lipids and vitamins
Proteins are made up of subunits called amino acids. There are 20 different types of amino acids. Different combinations can made different types of proteins.
Proteins
AA AA AA AA AA AA
CLASS FUNCTIONCatalytic proteins Catalytic proteins (enzymes) control
and regulate chemical reactions in the cell
Structural proteins Proteins provide support and shape the cell. They are components of many structures.
Mobility proteins Proteins are involved in the movement of cells.
Regulatory proteins Proteins regulate the movement of substances across the plasma membrane, act as signals between cells, are components of the immune response.
Proteins in the plasma membrane
Structural proteins
Keratin and Collogen
Catalasts- meaning they speed up chemical reactions!
Metabolic proteins- ENZYMES
Enzymes break things down or build things up.
http://www.youtube.com/watch?v=CZD5xsOKres
Proteins are made in the ribosomes
These are made up of sugar chain. They can be 1 sugar – monosaccharide, 2 sugar- disaccharide or longer – polysaccharide.
Carbohydrates are the biggest source of energy. Cells break down carbs into glucose and use it to
make ATP.
Carbohydrates
Carbohydrates in Cell Walls
CELLULOSE
The mitochondria is the site where carbohydrates or glucose is used to make ATP. It is the power supply of the cell.
The mitochondria
WHAT IS THIS PROCESS CALLED?
Other organelles important to biomacromolecules
TRANSPORTATION
Endoplasmic reticulum Folded membranes and
tubules within the cytoplasm.
2 kinds of endoplasmic reticulum rough ER and smooth ER.
▪ Rough ER is caused by the ribosome being present on the surface
Proteins produced by the ribosomes enter the ER and are then transported about the cell, they are finally exported out of the cell.
Recieves protein products via the ER. Protein products are modified and stored in this structure before they are placed in vesicles for transport to the plasma membrane and released from the cell.
Golgi Body (Golgi apparatus)
DNA and RNA They are information
molecules. The hold the instructions for everything that is made by an organism’s body.
The DNA is located in the Nucleus of a eukaryotic cell. Why?
Nucleic Acids
Complete a DNA model.
DNA Modelling!
Water is the main liquid in your body because:◦ It doesn’t boil at low temperatures or freeze at
higher temperatures.◦ It keeps the temperature stable enough for
chemical reactions.◦ It has a high surface tension meaning all the
molecules stick together this allows cells to hold their shape by being filled up with water. Water is INCOMPRESSIBLE!
A few things you should know!
Pigments in animal and plant cells provide the colours in the world around us.
Other interesting chemicals
Chlorophyll
CELLS AND ENERGY
WHERE DOES THE ENERGY COME FROM?
All cells use a form of energy called ATP.
Adenosine Triphosphate is when this molecule is fully loaded with energy.
Adenosine Diphosphate is when it is not fully loaded with energy.
ATP and Cells
ATP is made from glucose in a process called CELLULAR RESPIRATION.
Making ATP
Glucose Cellular respiration ATP
Autotrophs make their own glucose from sunlight. They undergo a process called photosynthesis (some bacteria undergo chemosynthesis instead).
AUTOTROPHS
Heterotrophs get their energy from ...
HETEROTROPHS
BOTH Autotrophs and Heterotrophs
must undergo cellular respiration
to make ATP!
Once the glucose has been made
Making energy with and without oxygen.Aerobic respiration
Occurs in the MITOCHONDRIA
Anaerobic respirationLACTIC ACID STITCH
The products of anaerobic respiration in different organisms:
PHOTOSYNTHESIS
Putting it all together
20 Questions! Chapter 1 and 2
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