What our body needs and why

Water

• How long can humans survive without food?

• How long can we survive without water

• All life on Earth depends on Water

Water

• Water absorbs and retains heat

• Hydrogen bonds constantly break and form between water molecules

• Helps organisms maintain constant internal temperature

Water cont…

• Water molecules stick to each other by Hydrogen bonds

• Dew on a flower (Cohesion)

• Stick to other polar substances

• Enables water to move upward through stem of a plant to roots and leaves(adhesion)

pH of water and living things

• In pure water, hydronium & hydroxide ions are present in equal numbers.

• The pH of living things must be stable.• Human blood = pH 7.4• If it goes down to 7 or up to 7.8, an individual will die

within minutes.

Buffers

• For a stable pH to be maintained, the solutions in living things contain buffers.

• A buffer is a substance that reacts to prevent pH changes in a solution.

• Buffers in our blood prevent changes in pH (bicarbonate ion)

Carbohydrates• Carbohydrates are the main energy source

for our body– they are the energy that gets used first (before protein, fat and alcohol).

• about 45-60% of our energy intake should come from carbohydrates.

• Sub unit - monosaccharides

• roles in our body including:• •An energy source that gives us most the

energy that our body needs;• •Providing nutrients for the good bacteria

in our intestines that helps us digest our food; and

• •Protecting our muscles because carbohydrates are the first source of energy for our body, without it, protein from our muscles will be used meaning that our body will effectively eat its own muscles!

Lipids

• Foods like walnuts, eggs, steak, and vegetable oil look very different, but they have something in common, and that is they all contain fats, or lipids, which is another name for fats

• Subunit –Glycerol/ Fatty Acids• Triglycerides. Triglycerides are

the most common type of lipid present in our foods and in our bodies

Why we need lipids

• Hormones and Enzymes

• Fats are a large part of hormone and enzyme production. Without the use of hormones and enzymes everything from digestion of food to sexual reproduction would be disrupted or stopped.

• Protection

• Body fat provides cushioning for the organs, both from outside forces and from bouncing off one another and creating havoc in our systems.

• Stored Energy

• Stored fat allows humans the ability to continue functioning when food is no longer available for up to three weeks.

Lipids you eat

• Through their metabolism, animals tend to produce triglycerides with saturated fatty acids, so foods from animals, like beef and dairy products contain saturated fats.

• Saturated fats have been linked to an increased risk of heart disease. You can recall this fact by thinking of your arteries being saturated or coated with fat.

Amino Acids

• To build a protein, first the amino acids (subunit) are connected into long chains.

• There are nine amino acids that your body can’t make.

• They are called essential amino acids, meaning you must have them to live.

• They are found in foods like milk, eggs and meat and also a wide variety of plants

Proteins• Proteins are essential for growth and

maintenance of your body tissues. • Through digestion and absorption,

proteins from the foods you eat are broken down and then reformulated, via genetic instructions, into many kinds of proteins, each with a unique function.

• Muscles, hormones, enzymes and antibodies are all made of proteins.

• Proteins aid blood clotting, fluid balance, buffering, vision and transportation of vital substances throughout your body.

• Protein can be metabolized for energy when carbohydrate and fat are in short supply.

Proteins you make

What are enzymes?• Enzymes are protein molecules that

are manufactured by all plant and animal cells.

• All cells require enzymes to survive and function.

• Enzymes are catalysts, which means that they make chemical reactions go faster, but are not changed by the reaction.

• For example, digestive enzymes cause food that you eat to be broken down much faster than would occur without them, but they are not broken down in the reaction they are speeding up.

Enzymes cont…• Enzymes are required for your body to

function properly because without enzymes you wouldn't be able to breathe, swallow, drink, eat, or digest your food.

• To do all of these things, your body needs some help. You must have enzymes to help perform these tasks. Enzymes are an absolute necessity to live.

• Enzymes are your body's workers. They are responsible for constructing, synthesizing, carrying, dispensing, delivering, and eliminating the many ingredients and chemicals our body uses in its daily business of living. Your body makes enzymes

Nucleic Acids• A nucleic acid is a long chain of

nucleotide units.• A nucleotide is a molecule made up of

three parts: a sugar, a base, and a phosphate group.

DNA

Deoxyribonucleic Acid

Contains the sugar deoxyribose

Double Helix

Contains genetic information

RNA

Ribonucleic AcidContains the sugar riboseSingle strandedTranscribes DNA & helps build proteins

Functions of Nucleic Acids

• Heredity Information• Energy Carriers Turn to page 63

and read about each of these functions. Fill in your Guided notes with the information you learned

Functions of Nucleic Acids

• Heredity Information• Nucleic acids store and transmit hereditary

information.• DNA molecules act as “instructions” for the processes

of an organism’s life.• RNA also interacts with DNA to help decode the

information.

Functions of Nucleic Acids

• Energy Carriers• Adenosine triphosphate, or ATP, is a nucleotide that has

three phosphate groups and supplies energy to cells.• Energy is released in the reaction that breaks off the third

phosphate group.