Molecular & Cell Biology For Dummies, 2nd Edition
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Studying molecular and cell biology can be challenging, but it’s necessary if you want to pursue microbiology, biotechnology, or genetics. Understanding molecular and cell biology entails knowing the four groups of macromolecules; the processes of central dogma and cellular respiration; and essential components of eukaryotic cells.

cells under microscope ©Anna Kireieva/Shutterstock.com

Four groups of macromolecules

Macromolecules are just that — large molecules. The four groups of macromolecules, shown in the table below, are essential to the structure and function of a cell.

Group (Building Block) Large Molecule Function To Identify, Look for . . .
Carbohydrate (Monosaccharide) Polysaccharide Energy storage, receptors, structure of plant cell wall Made of C,H, and O; –OH’s on all carbons except one
Protein (Amino acid) Polypeptide or protein Enzymes, structure, receptors, transport, and more Contain N, have N-C-C backbone
Nucleic acid (Nucleotide) Polynucleotide or nucleic acid Information storage and transfer Contain N in rings, nucleotides made of sugar, phosphate and nitrogenous base
Lipid * (Glycerol, fatty acids) Fats, oils, waxes, phospholipids, steroids Membrane structure, energy storage, insulation Made of C,H, and O; lots of C-H bonds; may have some C=C bonds (unsaturated); steroids have 4 rings

*Lipids are not polymers.

Central dogma of molecular biology

In molecular and cell biology, central dogma is the passage of information from DNA to RNA to protein. Here’s a brief breakdown of central dogma’s process:

Process What Is Made? What Is Template? Important Molecules Starts At
Ends When
Replication DNA DNA DNA polymerase, primase, helicase, DNA ligase, topoisomerase Origin of replication (ORI) Replication forks meet
Transcription RNA DNA RNA polymerase Promoter Termination sequence
Translation Polypeptide (protein) mRNA Ribosome, tRNA Start codon (AUG)
Stop codon (UAA, UGA, UAG)

 

Important parts of eukaryotic cells

All eukaryotic cells have organelles, a nucleus, and many internal membranes. These components divide the eukaryotic cell into sections, with each specializing in different functions. Each function is vital to the cell’s life.

  • The plasma membrane is made of phospholipids and protein and serves as the selective boundary of the cell.
  • The nucleus is surrounded by a nuclear envelope with nuclear pores. The nucleus stores and protects the DNA of the cell.
  • The endomembrane system consists of the endoplasmic reticulum, the Golgi apparatus, and vesicles. It makes lipids, membrane proteins, and exported proteins and then “addresses” them and ships them where they need to go.
  • Mitochondria are surrounded by two membranes and have their own DNA and ribosomes. They transfer energy from food molecules to ATP.
  • Chloroplasts are surrounded by two membranes, contain thylakoids, and have their own DNA and protein. They transform energy from the sun and CO2 from atmosphere into food molecules (sugars).
  • The cytoskeleton is a network of proteins: microfilaments (actin), microtubules (tubulin), and intermediate filaments (keratin, laminin, and others). Cytoskeletal proteins support the structure of the cell, help with cell division, and control cellular movements.

Cellular respiration in molecular biology

Cellular respiration is your body’s way of breaking down food molecules (carbohydrates, proteins, and fats) and making their stored energy available to the cell. Here’s a brief overview:

Phase Location in Eukaryotic Cell? Molecules That Enter? Molecules Produced? Links to Other Phases?
Glycolysis Cytoplasm Glucose, 2 NAD+, 2 ADP + P 2 pyruvate, Net 2 ATP, 2 NADH + H+ Pyruvate to pyruvate oxidation; NADH to ETC
Pyruvate oxidation Matrix of mitochondrion 2 pyruvate, 2NAD+ 2 NADH + H+, 2 CO2, 2 acetyl-coA NADH to ETC, acetyl-coA to Krebs
Krebs cycle (TCA cycle, citric acid cycle) Matrix of mitochondrion 2 Acetyl-coA, 6 NAD+, 2 FAD 6 NADH + H+, 2 FADH2, 2 ATP, 4 CO2 NADH to ETC, FADH2 to ETC
Electron transport chain (ETC) Inner membrane of mitochondrion NADH, FADH2, ADP + P 3 ATP per NADH, 2 ATP per FADH2 NAD+ to glycolysis, pyruvate oxidation and Krebs, FAD to Krebs

 

About This Article

This article is from the book:

About the book author:

René Fester Kratz, PhD, teaches biology at Everett Community College. Kratz has a doctorate in botany from the University of Washington. She works with other scientists and K–12 teachers to develop science curricula that align with national learning standards and the latest research on human learning.

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