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 environment

Intracellular fluidThe 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 MOLECULES

Carbohydrates 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 organisms

Vitamins 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 AAAA

AA AA AA

CLASS FUNCTION

Catalytic 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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