Biochem Exam 1 Chapter 1

Why is carbon suitable for life?

It has 4 covalent bonds-great for large molecule construction

C-C bonds are strong which results in greater stability and more energy released when C-C bonds are broken in combustion

CO2 is soluble in H2O and exists as gas in biochemical circulation

Proteins

Translations of genetic information composed of amino acids

Proteins are constructed from amino acids linked by peptide bonds.

Include signal molecules and receptors, structural elements, mobility, defense, and catalysts- enhance the rate of chemical reaction

Nucleic acids

Functional and informational molecules composed of nucleotides

store and transfer information

composed of nucleotides linked by phosphodiester linkages

Nucleotides

5 C ribose or deoxyribose sugar attached to a nitrogen containing heterocyclic ring structure and 1-3 phosphoryl groups.

Can store energy that is transformed upon nucleotide hydrolysis

Lipids

Lipids are a storage form of fuel, serve as a barrier, and are often composed of both hydrophilic and hydrophobic regions

most diverse of the key biomolecules, no common structure

water insoluble, soluble in organic solvents

Not polymers made of repeating units

duel chemical nature- part of the molecule is hydrophilic and part is hydrophobic

Used as fuel, serve as barriers, signal molecules

Have non-covalent association that can form membranes

Carbohydrates

Carbohydrates are fuels as well as structural and recognition molecules that can form branched structures

Fuel sources, cell recognition- components of cell exterior may be modified with carbohydrates to help cells recognize each other

monosaccharides make up polysaccharides linked by glycosidic bonds

Central dogma (be able to illustrate)

within an organism, information flows from DNA to RNA and then to protein.

DNA replication- the process of copying the genome, catalyzed by DNA polymerase

Transcription- makes genes accessible, DNA transcribed to mRNA by RNA polymerase

• mRNA- carry information required for protein synthesis

• functional RNAs- act in cell as RNA molecules and are not transcribed into proteins

Selective gene expression defines the function of a cell or tissue

translation- renders protein coding genetic information into a functional form, ribosomes

What 2 biochemical features minimally constitute a cell?

1. a barrier that separates the cell from its environment (plasma membrane)

2. An inside chemically different from the environment (cytoplasm)

How would you describe the major differences between prokaryotic and eukaryotic cells?

eukaryotic cells- membrane bound organelles and nucleus, more complex and often multicellular, linear DNA in nucleus

Prokaryotic cells- no membrane bound organelles, less complex, typically a single circular chromosome (nucleoid)

What are the distinguishing features of living organisms?

• high degree of complexity and microscopic organization (made of cells)

• systems for extracting, transforming, and using energy from the environment (energy and metabolism)

• mechanisms for sensing and responding to alterations in their surroundings (respond to stimuli)

• a capacity for precise self-replication and self-assembly (reproduce)

• a capacity to change over time by gradual evolution (evolution)

High degree of complexity and microscopic organization

Cells have a structural hierarchy

• chromatin made of DNA made of nucleotides

• Plasma membrane made of protein made of amino acids

• Cell wall made of cellulose made of sugars

Basic building blocks of life/functions

amino acids, nucleotides, monosaccharides, lipids

intimate relationship between structure and function

• Proteins- major- cary out metabolic interactions and support cellular structure, minor- store energy

• Nucleic acids- major- encode information, minor- carry out metabolic interactions and support cellular structures

• polysaccharides- major- store energy and support cellular structures, minor- encode information

Energy and metabolism

Cells require energy for all the functions of living, growing, and reproducing

• Gibbs free energy, exothermic- release heat vs exergonic- absorb heat

• Spontaneity

Non-spontaneous reactions can occur in vivo because they can be coupled to spontaneous processes.

• redox reactions of carbon involve reduction- unfavorable, coupled with oxidation- favorable

Mechanisms for sensing and responding to alterations in their surroundings

Living organisms are open systems- exchange matter and energy with their environment

Cells remain in a steady, non-equilibrium state

• homeostasis- the process by which living organisms maintain a stable internal environment despite their external surroundings

  • temperature, blood sugar, hydration all in a narrow range

A capacity for precise self-replication and self-assembly

Genetic information encoded in DNA

Describe basic monomer, structure, linkage, and oligomers

• Proteins, amino acids, peptide bond, hemoglobin

• Nucleic acids, nucleotides, phosphodiester bond, DNA

• Polysaccharides, monosaccharides, glycosidic bond, sucrose

• membranes, lipids, noncovalent association

Enthalpy

• exothermic- negative delta H, release heat: stabilizing interactions bond forming (H bonds)

• Endothermic- absorb heat, positive delta H, bond breaking

Entropy

• exergonic- spontaneous, negative delta S

• endergonic- nonspontaneous, positive delta s