Biochemistry Unit

Biochemistry Unit

Target 1

I can list the essential chemical elements of life (carbon, hydrogen, oxygen, nitrogen,

phosphorus, and sulfur), and understand how they join together to form complex organic compounds.

All living organisms are composed of the same chemical elements

(Remember CHNOPS!):

Carbon

Hydrogen Oxygen Nitrogen

Phosphorus, and Sulfur

From bacteria to blue whales, if you chemically analyze ANY organism, they

will be 99% the CHONPS elements!

Carbon

• How important is it, really?

• Small size (atomic number 6); four available bonding electrons

• Carbon can join to other carbon atoms in chains and rings to form large and

complex molecules.

Target 2

I can explain the significance of complex organic molecules (carbohydrates; proteins, including enzymes; lipids; and nucleic acids), and describe their essential functions.

Essential functions of cells…

• …involve water and 1. carbohydrates

2. proteins 3. lipids

4. nucleic acids

Important Compounds:

Water (H

O)

All living organisms need water, and living organisms are composed mostly of water.

Most biochemical reactions occur in water. Can you think of some?

You and I are about 60% water!

Digestion – your body would not be able to break down and absorb nutrients w/o water.

Respiration – you would not be able to absorb O₂ and get rid of CO₂ w/o water.

Important Compounds (cont.):

Carbohydrates

Organic compounds made of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio

(ex: glucose is C₆H₁₂O₆)

Carbohydrates represent the major source of ENERGY for cells!

Carbohydrates, cont.

• They are found in most foods, especially fruits, vegetables, and grains.

• The building blocks of carbohydrates are simple sugars called monosaccharides, such as glucose (C₆H₁₂O₆)

• Disaccharides: double sugars, formed when two monosaccharides are joined.

• Polysaccharides, such as starch, are chains of three or more monosaccharides.

• This is an example of a macromolecule, a large molecule made of smaller molecules.

Polysaccharides

• Some function as storehouses of energy contained in sugars.

1. starch, such as cellulose, made by plants 2. glycogen, made by animals

Important Compounds (cont.):

Proteins

All proteins are made from a combination of 20 different amino acids, the building blocks of proteins.

Proteins carry out a variety of functions within living things, including:

structural proteins – which are the building blocks of muscle tissue, hair, and cartilage

antibodies – which are important components of our immune system

and target invaders for destruction

Important Compounds (cont.):

Proteins

And enzymes, a special type of protein,

which ‘jump-start’ and increase the speed of chemical reactions

For example, the enzyme, amylase, Catalyzes (accelerates) the breakdown of starch into sugar

Important Compounds (cont.):

Lipids

Nonpolar molecules that are not soluble, or mostly Insoluble, in water

Include fats, which are lipids that store energy

Phospholipids, which make up the lipid bilayer of the cell membrane

And waxes, which have important water-repelling qualities

Important Compounds (cont.):

Nucleic Acids

Made up of subunits of nucleotides, consisting of a sugar, a phosphate, and a nitrogen base

Include DNA, the master molecule of hereditary information

And RNA, which plays a key role in protein production

Target 4

I can explain the environmental effects of temperature and pH on molecular form and cell function.

Nearly all living organisms survive within an optimal

‘range of tolerance’ for temperature and pH

Movement outside of this range causes the organism stress at first, but eventually can cause death

Effects of temperature

Can you fill in the blanks?

Heat molecules up and they move _________ and __________ apart

faster further

So in general, higher temperatures would have what effect on the speed of chemical reactions (and therefore metabolic rate)?

It speeds it up!

Effects of temperature

Temperatures that are too high or too low, however, can change the shape of important proteins. With a change in shape, they no longer can perform their function and

become ‘denatured’.

Enzymes, proteins which regulate chemical reactions within cells, can become damaged by temperature

extremes which can easily result in the death of the cell.

Effects of pH

pH extremes can have a similar denaturing effect on enzymes and other proteins.

Because they are so sensitive to pH changes, most living systems are highly buffered (they have

mechanisms that enable them to maintain a pH of about 7). Another example of homeostasis!

Target 4

I can explain the process of diffusion as it relates to homeostasis.

Diffusion

• Molecules move randomly from areas of high

concentration to areas of low

concentration until a balance

(equilibrium) is

achieved.

Simple Diffusion

across the Cell Membrane

• Molecules pass directly through membrane.

• Molecules generally

small with little or no

electrical charge (O

,

CO

, H

O, etc.).

Diffusion

Remember, oxygen and water are essential to ALL living organisms! CO₂ is essential to plants and all other photosynthesizers like algae and certain

bacteria!

Homeostasis

• Remember, homeostasis is another characteristic of all living organisms – “the ability to maintain a stable internal environment despite changes in the external environment”.

For example, your body maintains a blood saturation level of 95-100% oxygen

Target 5

I can explain the concept of osmosis, and

predict the movement of water across the cell membrane in hypotonic, hypertonic, and

isotonic solutions.

Osmosis

• Special type of diffusion where water moves

across a

selectively permeable

membrane until a balance is

achieved.

• During osmosis, water moves from high concentration to low concentration.

• Water is called a solvent, molecules dissolved in water are called solutes.

• There are three terms to describe the direction in which water molecules will move during osmosis:

– Hypotonic – Isotonic

– Hypertonic

Hyper- and Hypotonic

• Hypo = less solute

• Hyper = more solute

• These are relative terms like “greater than”

or “less than”

Water moleclue

Solute molecule

Effects of Tonicity on Cells

Osmosis and Homeostasis

Left unchecked, the swelling caused by a hypotonic solution could cause a cell to burst. Different cells have different adaptations to solve this problem and maintain homeostasis.

Plant and fungi cells have rigid cell walls that keep the

cells from expanding too much.

Osmosis and Homeostasis

Some unicellular eukaryotes called protists have contractile vacuoles which are organelles designed to pump water out of the cell, much like a sump

pump in a basement!

Maintaining stable internal environments relates to the ‘range of tolerance’ we discussed earlier!

Without the ability to do this, living organisms would quickly die!