Cell Structure, Organelles & Biochemistry

Cell Structure and Function

• Diagrams should label organelles in prokaryotic and eukaryotic cells
• Diagrams should compare plant and animal cells

Functions of Organelles

• Nucleus stores genetic material (DNA)
• Mitochondria is the powerhouse of the cell and produces ATP
• Ribosomes are responsible for protein synthesis
• Endoplasmic Reticulum: Smooth ER handles lipid synthesis, Rough ER handles protein synthesis
• Golgi Apparatus modifies and packages proteins
• Lysosomes digest waste and cellular debris
• Cell Membrane is a semi-permeable barrier controlling substance movement

Biochemistry

• There are four categories of organic molecules: carbohydrates, lipids, proteins, and nucleic acids

Organic Molecule Identification

• Carbohydrates are monosaccharides (glucose, fructose), disaccharides (sucrose), polysaccharides (starch, cellulose)
• Lipids are fatty acids, triglycerides, phospholipids, steroids
• Proteins are made of amino acids, perform enzymatic and structural functions
• Nucleic Acids: DNA & RNA store and transfer genetic information

Enzyme Action & Dehydration Synthesis

• Enzymes lower activation energy and function via a lock-and-key model
• Dehydration synthesis joins monomers by removing water, hydrolysis breaks them apart by adding water

Protein Structure

• Primary structure is the amino acid sequence
• Secondary structure includes alpha helices and beta sheets
• Tertiary structure is the 3D structure due to side-chain interactions
• Quaternary structure involves multiple polypeptides interacting

Introduction to Proteins

• Proteins are essential macromolecules responsible for growth, repair, and maintenance in the body
• Proteins are composed of long chains of amino acids, which are the building blocks of proteins
• Proteins are also referred to as polypeptides, consisting of multiple amino acids linked together by peptide bonds
• The monomers of proteins are amino acids
• 20 different amino acids are all necessary to form a functional protein

Why Are Amino Acids Important in the Diet?

• A complete diet must contain all 20 amino acids because they are essential for the body to synthesize proteins effectively
• Essential amino acids must be obtained through diet, while others can be synthesized by the body

The 20 Amino Acids

• Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamine, Glutamic acid, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine, Threonine, Tryptophan, Tyrosine, Valine
• The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

Proteins and Nitrogen

• Proteins contain the element nitrogen, which is not found in all carbohydrates and lipids
• Nitrogen is essential for the structure of amino acids and their ability to form peptide bonds

Peptide Bonds and Protein Formation

• When amino acids are linked together, they form peptide bonds through a process of removing a water molecule called dehydration synthesis
• A dipeptide forms when two amino acids join together
• A polypeptide is a longer chain of amino acids linked by multiple peptide bonds, which eventually folds into a functional protein

Why Is a Protein Called a Polypeptide

• Proteins are called polypeptides because they consist of multiple amino acids joined together by peptide bonds
• The term "poly-" means "many," and "peptide" refers to the bond that links amino acids

Protein Structure Levels

• Primary structure is the specific sequence of amino acids in a polypeptide chain
• Tertiary structure is the three-dimensional shape of a protein, which results from interactions between amino acids, including hydrogen bonds, ionic bonds, and hydrophobic interactions

Evolution and Adaptation

• Natural Selection is the process where favorable traits become more common in populations
• Evidence of Evolution includes the fossil record, comparative anatomy, molecular biology, embryology
• Adaptations can be structural (camouflage), behavioral (migration), or physiological (temperature regulation)

Genetics & DNA Structure

• DNA’s Role in Genetic Information Transfer: includes DNA replication which follows a semi-conservative model
• Transcription converts DNA to mRNA, and translation converts mRNA to a protein

Structure of DNA

• Double helix, nucleotides (A-T, G-C pairing)
• RNA differences: single-stranded, uracil replaces thymine

Scientific Method

• Steps: Observation, Question, Hypothesis, Experiment, Data Collection, Conclusion

Interpretation of Experiments

• Experiments must consider independent vs. dependent variables, controls
• Outcomes must involve graph analysis and data interpretation

Inorganic/Organic Aspects of Water & Complexity of Life

• Water’s Role in Life includes cohesion, adhesion, high specific heat, solvent properties
• Biological Organization (Simple to Complex): Atom -> Molecule -> Organelle -> Cell -> Tissue -> Organ -> Organ System -> Organism -> Population -> Community -> Ecosystem -> Biosphere

Prokaryotes vs. Eukaryotes

• Prokaryotic Cells: Do not have a nucleus, are unicellular (bacteria, archaea), and have a simple structure
• Prokaryotic cells have DNA in the nucleoid region, with no membrane-bound organelles
• Eukaryotic Cells: Nucleus is present, and can be unicellular or multicellular (plants, animals, fungi, protists)
• Eukaryotic cells have membrane-bound organelles