Unit 4- Biochemistry, Energy, & Enzymes 4a- Chemistry + Carbon Compounds

Chemistry Review What makes an atom stable? 8 valence electrons; full outer energy level, or shell What can an atom do to become stable? Form bonds with other atoms

Chemistry Review Two types of bonds? Ionic Bonds: attraction of oppositely charged ions Covalent Bonds: form by sharing electrons; causes the outer energy levels to overlap

Chemistry Review Bonds between atoms are built and broken causing substances to combine and recombine as different molecules during chemical reactions. Essential functions of a cell involve chemical reactions that take place between many different types of molecules All of the chemical reactions within a cell are referred to as the cell’s metabolism.

Building Blocks of Cells Living things are organized… All organisms are composed of organic molecules Organic Molecules- contain carbon atoms

The Role of Carbon A carbon atom has 4 electrons in its valence shell. Carbon can form covalent bonds with as many as 4 other atoms. Can also bond with other carbon atoms to form a single, double or triple bond (sharing 1, 2, or 3 electrons) Allows carbons to form straight chains, branched chains, or rings Tendency of carbon to bond with itself results in enormous variety of organic compounds

Large Carbon Molecules (Biomolecules, Macromolecules) Most organic molecules are made of smaller units (monomers) that bond to form larger molecules (polymers) Energy is stored in the bonds that link these units together The amount of energy varies with the type of molecule formed. Polymer: a molecule that consists of repeated, linked units. Units may be identical or structurally related Lipids are not polymers, carbs, proteins, Nacids are Polymer- identical units- like a metal watch wristband, or similar- like the beads that make up a multicolored necklace

Large Carbon Compounds Example: Starches are complex carbohydrates formed by long chains of simple sugars, like glucose Glucose= monomer; Starch= polymer Different functional groups

Molecules of Life There are four types of organic compounds necessary for life (aka biomolecules) Carbohydrates Lipids Proteins Nucleic Acids

Carbohydrate Structure Contain: Carbon, Hydrogen, & Oxygen Structures: Monosaccharides – 1 ring (simple sugars) Glucose (cell’s primary source of energy) Disaccharides – 2 rings Sucrose (table sugar) Polysaccharides – 3 or more rings (complex carbohydrates) Amylose (component of starch) Cellulose (structural carbohydrate in plants) Simple sugars can bond together to make larger, more complex carbohydrate molecules

Role of Carbohydrates In Plants Carbohydrates are synthesized during the process of photosynthesis The plants then: Use them as a source of energy Store them in the cells. Carbs are important as an energy source for all organisms

Role of Carbohydrates In Animals Consumed as sugars, starches, and fiber When complex carbohydrates are consumed, digestion breaks the bonds between the larger carbohydrate molecules so that individual simple sugars can be absorbed into the bloodstream through the walls of the intestines. The bloodstream carries the simple sugars to cells throughout the body Once inside the cells, they are used as fuel in the process of cellular respiration, releasing energy that is stored as ATP. If an organism has a greater supply of carbohydrates than needed for its energy requirements, the extra energy is converted to fats and stored by the body.

Functions of Carbohydrates Energy Source Glucose in cells is the primary source of energy - fuel for cellular respiration Energy Storage (short term) Glycogen in the liver of animals Starch in the structures of plants Structural Support Cellulose forms cell walls in plants An important source of fiber for animals to stimulate the digestive system The C, H, & O that make up carbohydrates serve as raw materials for the synthesis of other small organic molecules, such as amino acids & fatty acids. Our bodies cant breakdown cellulose into individual sugars. Helps move food along by stimulating contractions of the smooth muscles that form walls of digestive organs

Lipids Contain: Carbon, Hydrogen, & Oxygen Includes fats (triglycerides), phospholipids, steroids, & waxes A triglyceride is a lipid made up of a glycerol & 3 fatty acids The high number of C-H bonds makes lipids very energy rich. glycerol three fatty acids

Role of Lipids Fats Important to organisms for energy when carbohydrates are scarce, but when there is no shortage of food, stored fat accumulates. Functions: providing long-term energy storage cushioning of vital organs insulation for the body Fats are insoluble in water.

Role of Lipids Phospholipids Steroids Waxes Major component of cell membranes. Steroids Can serve as raw materials necessary for the production of some vitamins, some hormones, and cholesterol Waxes Lipids that form waterproof coatings for plants and animals Phospholipid- hydrophilic phosphate head, hydrophobic fatty acid tail

Proteins Proteins are molecules composed of chains of amino acids Contain: Carbon, Hydrogen, Oxygen, & Nitrogen & sometimes Sulfur 20 different amino acids 10 amino acids are made in the human body Humans need to consume the other 10 amino acids from sources such as nuts, beans, or meat. Failure to obtain enough of even 1 of the 10 essential AA’s results in degradation of the body’s proteins. 20 standard amino acids= encoded directly by codons in genetic code Body doesn’t store excess AA’s like it does fat and starch—AA’s must be in food everyday If the essentials arent included in our diet it can lead to organ damage & failure due to not being able to maintain and repair. Also will break down bodys proteins, like muscle, to obtain the one AA that is needed

Protein Structure Two amino acids bond to form a dipeptide. This covalent bond is called a peptide bond Polypeptide: long chain of amino acids Proteins are composed of one or more polypeptides. The sequence of amino acids determines the proteins shape & function. ~100,000 different proteins in the human body Proteins are involved in almost every function in the human body

Role of Proteins Proteins are the major structural & functional material of body cells. (workhorse molecules) Because of the variety of shapes & structures of protein molecules, proteins have a wide variety of functions Involved in almost every function in the human body Functions: Structural proteins- used for support such as connective tissue & keratin that forms hair & finger nails. Transport proteins- move many substances throughout the body Example: hemoglobin transports oxygen from the lungs to the other parts of the body to be used by cells in cellular respiration.

Hormone proteins- coordinate body activities Example: insulin regulates the amount of sugar in the blood. Contractile proteins- help control movement Example: proteins in the muscles which help control contraction. Enzymatic proteins- accelerate the speed of chemical reactions Example: digestive enzymes break down food in the digestive tract.

Nucleic Acids Nucleic Acids are long chains of nucleotides Nucleotides contain: Carbon, Hydrogen, Oxygen, Nitrogen, & Phosphorus Nucleotides are made up of three parts Five carbon sugar Phosphate group Nitrogen base

Function of Nucleic Acids Carry and transmit genetic information Two Types: DNA – holds genetic code for an organism RNA – makes a copy of DNA in order to make a protein

Calorie Comparison Energy stored in organic molecules determines the caloric value Lipids have the greatest chemical bond energy over carbohydrates & proteins Calorie comparisons: Proteins 4 Calories per gram Lipids 9 Calories per gram Carbohydrates 4 Calories per gram