Biochemistry and Cells

The Building Blocks of Life

Stardust

• Hydrogen and Helium, the first two elements to be created, are not complex enough to create living things.

• It wasn’t until the violent death of stars, supernova, that elements complex enough to create life were formed and scattered across the Universe.

• Every molecule in your body is made of the remnants of one of these long dead stars.

H2O

• All living things require water.• Water is vital for many functions of life.• Many of these functions stem from structure of

water, an oxygen atom attached to two hydrogen atoms, forming a “v” shape.

• The three atoms share electrons unevenly giving oxygen a partial negative charge and the hydrogens a partial positive charge.

• Having partial charges is called polarity.

Hydrogen Bonding

• Opposite charges attract, allowing water to engage in what is called hydrogen bonding with any polar molecule, including itself.

• Cohesion- when water is attracted to itself • Adhesion- when water attracts to other

substances.• Adhesion allows water to flow upwards through

narrow tubes, capillarity

Temperature Moderation

• Water’s hydrogen bonds keep water from changing it’s temperature quickly.

• Energy added to water first needs to break the hydrogen bonds before the molecules can speed up.

• Temperature is just a measure of how fast the individual particles of a substance are moving.

Carbon

• Equally important to life, the molecule carbon can form an immense array of compounds.

• Carbon is able to form four bonds with many different compounds.

• Carbon compounds can form a variety of shapes– Straight chain

– Branched chain

– Rings

Functional Groups• Carbon typically bonds with hydrogen in organic

compounds, hydrocarbons• In place of some hydrogens, special groups of

molecules called functional groups, change the properties of the molecule.

• Alcohol (-OH) is an important functional group, that joins many carbon compounds to change the properties.

• Methanol (methane with an alcohol group) is a deadly poison, while Glycerol is necessary for humans to assemble a number of molecules.

Large Carbon Compounds

• Living things need large carbon compounds.• In order to make these compounds, often many

simple compounds, monomers, are put together to form long chains called polymers

• They form by having one molecule losing an alcohol group and one losing a hydrogen, which makes water. Condensation Reaction

• Hydrolysis is the opposite of that reaction and involves the breakdown of a polymer by adding water.

Energy for Life

• Two important polymers are ADP and ATP.• Cells take ADP with two phosphate groups

and store energy by adding another phosphate groups to make ATP. (condensation)

• When the cell needs to use the energy it breaks the bond (hydrolysis) and is back at ADP.

Carbohydrates

• Carbohydrate are compounds containing C, H, and O in a ration of about 2H for every C and O, basically sugar C6H12O6

• Simple carbohydrates are made of one or two molecules of sugar, monosaccharide and disaccharides.

• Complex carbohydrates like fiber and starch are many of many sugar compounds assembled into a polymer, polysaccharide

Proteins

• Proteins are polymers that are made of amino acids.

• There are 20 amino acids that make up all proteins known to man.

• There are around 2050,000 possible proteins

• Enzymes are proteins that help chemical reactions in cells take place.

Lipids

• Are nonpolar organic molecules, which mean they do not dissolve in water.(hydrophobic)

• Organism store large amounts of energy using lipids (fat).

• Fatty acids are lipids with an end that likes water (hydrophilic)

• Phospholipids are composed of two lipid tails attached to a hydrophilic phosphate group

• These are important because they assemble themselves to form membranes in water.

Nucleic Acids

• Nucleic Acids are the most important of all biological compounds.

• Living things store and transfer information using nucleic acids in the form of DNA and RNA

Cells

• Cells were discovered in the late 1600s as the microscope was being invented.

• After about 150 years of observation Cell Theory was developed– All living things are composed of one or more cells

– Cells are the basic unit of structure and function in an organism

– Cells come only from other cells*

Cells (cont)

• Cells are typically very small to allow chemicals to move around in them quickly.

• Some cells, eggs and nerves, are larger.• Cells come in a variety of shapes

– Flat– Round– Square– Some don’t have a definite shape.

Types of Cells

• Simplest organisms, prokaryotes, have simple cells that lack internal structures called organelles.– Bacteria and Archaea

– Almost always unicellular (one celled org.)

• More complex cells fall into two categories, Plant and Animal, and are called Eukaryotes

• We will be examining the animal cell and how the other cells differ.

Cell Structures

• Eukaryotic cells have many important structures that each have their own functions.

• A few of these structures are also present in prokaryotic cells.

• The internal structures of Eukaryotic cells are called organelles.

Cell Membrane

• The cell membrane is made of two layers of phospholipids.

• It keeps out some things and lets in others. Selectively Permeable.

• Embedded with proteins and carbohydrates that help in cellular interactions.

Cytoplasm

• Cytoplasm is the jelly-like fluid that fills a cell.

• The cytoplasm is made of…– Cytosol - fluid– Dissolved salts, minerals, other organic

molecules.

Cytoskeleton

• The cell is supported by a network of connecting threads and tubes that make up the cytoskeleton.

• They are both made of protein.• The threads are called microfilaments and the

tubes are called microtubules• These structures are the reason the cells in your

feet are not popped by the weight of your body.

Mitochondria

• Relatively large organelle, composed of two layers.• Internal has many folds called cristae which increase

the surface area.• Site of cellular respiration

– Sugar + Oxygen --> CO2 + Water + Energy (ATP)

• Mitochondria have their own DNA and reproduce on their own.

Ribosomes

• Most numerous and smallest of organelles

• Look like little dots in the cell.

• Ribosomes make proteins by reading information from DNA

Endoplasmic Reticulum

• Also known as ER

• Series of interconnected pathways around the nucleus.

• Transport chemicals to and from the nucleus.

• Smooth ER- no ribosomes

• Rough ER- ribosomes

Golgi Apparatus

• Packages chemicals made from the cell in preparation for secretion.

• Membrane of a vesicle gets close to the cell membrane and the two fuse, releasing what’s inside.

• Chemicals usual come from the ER

Lysosomes

• Lysosomes contain digestive enzymes which can do many things.

• Digest old organelles, engulfed bacteria, and the cell itself when the cell has outlived its usefulness.

Vacuole

• The vacuole is the organelle responsible for storage.

• It can store sugars, lipids, and water.

• Found in all plant cells but only some animal cells.

• Fat cells have large vacuoles.

Centriole

• Each cell has two centrioles which separate during cell division in order to organize the cytoskeleton.

• Usually they stay together at right angles in what is known as the centrosome.

Nucleus

• The nucleus is the control center of the cell.

• Surrounded by the nuclear membrane, which contains pores for getting in and out of the nucleus.

• Contains DNA organized into chromosomes

Nucleolus

• Found the nucleus.

• Responsible for making ribosomes.

Plant Cells

• Plant cells are different from animal cells in three main ways.

• Plant cells have a tough outer covering that gives them a permanent shape called a cell wall.

• Plants also have chloroplasts.• Plants have very large vacuoles

Chloroplasts

• Chloroplasts are the site of photosynthesis.– Sunlight + CO2 + water --> Sugar + Oxygen

• Chloroplasts are not made by the cell as they reproduce on their own.

• Like the mitochondria, they have their own DNA.

Endosymbiosis

• Most scientists believe that the mitochondria and the chloroplasts evolved separately and we engulfed by simple cells.

• These simple cells came from bacteria that had begun to organize the cells processes.

• The cells provided a safe place to live and the mitochondria and chloroplast provided food and energy for the cell.

Prokaryotes

• The first cells lacked internal structures, most notably a nucleus.

• These cells fall into two groups.• Bacteria- small cells that fill a variety of

roles on Earth.• Archaea- are very similar to bacteria but

live in extreme places like hot springs or ocean vents.