Introduction to Molecular Biology

What is life?

The ability to reproduce, metabolize, consume, and contain information content (DNA); living things can grow and change by taking energy from the environment and transforming it for growth, tend to be complex, adapt to equilibrium with the environment, respond to stimuli, and require macromolecules.

What are the major biological requirements mentioned in the notes?

Macromolecules are a biological requirement for life.

What are the macromolecules of life?

Carbohydrates, lipids, nucleic acids, and proteins; they are found in all living organisms and are the building blocks of all cells.

Which six atoms make up combinations found in macromolecules of life?

Carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S).

What are carbohydrates?

Macromolecules whose basic unit is sugar and whose atoms are C, H, and O; they provide energy and support to cells through structure and cushioning and are found mainly around the cellular membrane.

What are lipids?

Macromolecules whose basic unit is a fatty acid or fatty acid chain and whose atoms are C, H, and O; they provide energy, structure, and cushioning, are found mainly around the cellular membrane, and prevent heat loss.

What are nucleic acids?

Macromolecules made from nucleotides; they contain C, H, O, N, and P, direct and control all activities of the cell, and are the only macromolecule not found in the plasma membrane.

What is a nucleotide?

The basic unit of nucleic acids, composed of a sugar, phosphate, and a base.

What are the two types of nucleic acids?

DNA and RNA.

How do DNA and RNA differ?

DNA contains deoxyribose and thymine and is double-stranded; RNA contains ribose and uracil and is typically single-stranded.

What roles do nitrogen and phosphorus play in nucleic acids?

Nitrogen and phosphorus act as part of the nucleic acid backbone according to the notes.

What are proteins?

Macromolecules made of amino acids containing C, H, O, N, and S; they have a vast array of cellular functions including metabolism, transport, and stimulus response and must interact with something to function.

Why were proteins originally believed to be the source of genetic material?

They were considered the most complex macromolecules and were originally believed to be the source of genetic material because of their complexity.

How variable are proteins in size?

Proteins vary greatly in size.

What was recognized about macromolecules in the late 17th century?

A class of macromolecules was recognized by its ability to coagulate under heat, such as egg whites.

What happened in the 1830s regarding proteins?

Elemental analysis was carried out and a protein was described; all elements were recognized.

What happened in 1838 regarding DNA?

DNA was identified inside the nuclei of white blood cells and called nuclein.

What happened in 1878 regarding nuclein?

A non-protein component of nuclein called nucleic acid was identified, containing five bases.

What happened in 1919 regarding nucleic acids?

The three components of a nucleotide were identified and a polynucleotide model was developed.

What did Frederick Griffith study during World War I?

He studied pneumonia in soldiers affected by trench warfare and isolated rough and smooth strains of pneumonia.

What was Griffith's transforming principle?

Something from a heat-killed smooth strain transferred to a rough strain and made the rough strain lethal; this process was called transformation.

What did Avery, MacLeod, and McCarty investigate?

They set out to determine whether DNA was the hereditary material.

What did Avery, MacLeod, and McCarty conclude?

Transformation cannot occur unless DNA is present; protein is not the transforming agent, and S cells appear when DNA is present and R cells are added.

What did Hershey and Chase investigate?

They tested whether DNA or protein was the genetic material using radioactive isotopes in bacteriophages.

How did Hershey and Chase distinguish DNA from protein?

They used radioactive sulfur (S) to label proteins and radioactive phosphorus (P) to label DNA in phages that invaded cells.

What did Hershey and Chase find?

Only phages with radioactive DNA entered the cell, confirming that DNA was the source of genetic material.

Why is DNA important in genetics?

DNA is the material of heredity and the most important macromolecule in genetics; proteins are made from DNA, and DNA is involved in heredity, genes, gene interactions, chromosomes, and modern genetic research.

How is DNA used in biotechnology?

DNA allows researchers to largely synthesize proteins used for research, including production in E. coli.

How is DNA used in pharmaceuticals?

DNA can be used to synthesize specific proteins or to target DNA within a cell.

How is DNA used in diagnostics?

PCR can be used for disease detection.

How is DNA used in agriculture?

GMOs are widespread; examples include herbicide-resistant plants, which can transfer resistance to weeds, and bigger fish, which can contribute to lack of food supply.