biology 2201 ch 2.1 notes.notebook

1

October 08, 2011

May 20­1:37 PM

Biology 2201 Unit 1Chapter 2

2.1 – The Molecular Basis of Life

May 20­1:37 PM

• biochemistry – the study of the chemistry of living things, including the chemical substances and processes involved. • There are countless numbers of chemical reactions going on inside living things every second, and there are several classes of important molecules that allow life on Earth to exist. • Organic compounds – molecules that contain both carbon and hydrogen • Ex. Sugar, fats, proteins, vitamins • Inorganic compounds – any compound that is not organic • Ex. Water, minerals, carbon dioxide

What is biochemistry?

biology 2201 ch 2.1 notes.notebook

2

October 08, 2011

May 20­1:37 PM

• 1) water • 2) carbohydrates • 3) lipids • 4) proteins • 5) nucleic acids

Important molecules for life:

May 20­1:37 PM

• most abundant molecule in any cell • has several important chemical properties: • (1) remains liquid over a wide temperature range, including temperatures at which most small molecules are gases (such as room temperature) • (2) dissolves most substances involved in living processes such as oxygen, carbon dioxide, glucose, amino acids, and sodium chloride • (3) changes temperature gradually when heated or cooled, so it protects cells from rapid temperature changes and provides a stable environment for cell reactions • (4) is one of the only pure substances that expands when it becomes a solid, which means it floats when it freezes

Water

biology 2201 ch 2.1 notes.notebook

3

October 08, 2011

May 20­1:37 PM

Carbohydrates • includes sugars and starches • contain carbon, hydrogen and oxygen atoms in the ratio 1:2:1 • larger carbohydrates are made of units called monosaccharides. Most monosaccharides have 6 carbon atoms. These sugars have a ring structure. • Monosaccharide – a simple sugar such as glucose, fructose, or galactose (see fig. 2.6, p. 43)

May 20­1:37 PM

• disaccharide – sugar that contains two monosaccharide subunits; for example maltose, sucrose and lactose (see fig 2.7, p. 43) • glucose + glucose = maltose • glucose + fructose = sucrose • glucose + galactose = lactose

Carbohydrates (disaccharides)

biology 2201 ch 2.1 notes.notebook

4

October 08, 2011

May 20­1:37 PM

• →polysaccharide – complex carbohydrate consisting of many simple sugars linked together • ex. Starch (plants), glycogen (animal starch), cellulose (wood) (see fig. 2.8, p. 44) • → simple sugars are used by living organisms as a quick source of energy; larger polysaccharides are used mostly for energy storage (starch and glycogen) or can be structural (cellulose)

Carbohydrates (polysaccharides)

May 20­1:37 PM

• lipids – organic molecules that do not dissolve in water • contain carbon, hydrogen, and oxygen in varying proportions • most lipids consists of 3 chains of fatty acids all connected to a glycerol molecule (see fig. 2.10 and 2.11, p. 45) • fatty acid – molecule that contains a hydrocarbon chain with COOH (acid) groups at one end

Lipids

biology 2201 ch 2.1 notes.notebook

5

October 08, 2011

May 20­1:37 PM

• saturated fatty acids – fatty acids where there are no double bonds in the fatty acid chain • unsaturated fatty acids – fatty acids where there is one or more double bonds in the fatty acid chains (see fig. 2.12, p. 45) • mono = one • poly = many • lipids have many functions: • (1) energy storage • (2) insulation • (3) makes up structure of cell membranes

Lipids (cont…)

May 20­1:37 PM

• consist of carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur atoms • have many functions in the body: • (1) can be used as an energy source (only in emergencies) • (2) structural (like muscle, keratin, ligaments, tendons) • (3) they function as enzymes to facilitate chemical reactions • (4) help transport substances across cell membranes or to different parts of an organism • (5) act as chemical messengers

Proteins

biology 2201 ch 2.1 notes.notebook

6

October 08, 2011

May 20­1:37 PM

Proteins (cont…)→ made of units called amino acids 

amino acid – any of a group of organic compounds containing both the carboxyl (COOH) and the amino (NH2) group, occurring naturally in plant and animal tissues and forming the basic building blocks of proteins → all amino acids are identical except the remainder group (R group) → humans need 20 amino acids to make all the proteins you need. However, the body can make 12 of those. The other 8 must be present in food and are called essential amino acids.→ peptide bond – chemical linkage that joins individual amino acids together in a protein molecule dipeptide = two amino acids polypeptide = many amino acids → protein molecules are very sensitive to environmental conditions (temperature, pH, etc.) 

May 20­1:37 PM

Proteins (cont…)

biology 2201 ch 2.1 notes.notebook

7

October 08, 2011

May 20­1:37 PM

• complex organic molecules that carry the hereditary information • contain carbon, hydrogen, oxygen, nitrogen, phosphorous and • examples include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) • nucleotides – the monomers of nucleic acids. Each nucleotide is composed of a five-carbon sugar, a phosphate group (phosphoric acid), and one of the four nitrogen-containing bases (see fig 2.17, p. 48) • DNA and RNA have somewhat similar structures, but there are differences

Nucleic Acids

May 20­1:37 PM

DNA­ two chains of nucleotides (see fig 2.19) ­ have the sugar deoxyribose ­ contain the bases adenine (A), thymine (T), cytosine (C) and guanine (G) 

biology 2201 ch 2.1 notes.notebook

8

October 08, 2011

May 20­1:37 PM

• only one chain of nucleotides • have the sugar ribose • contain the bases A, C, G and uracil (U)

RNA