Cell Bio

Chapters 1-8 for exam 1. 2/2/26

Central Dogma

The Central Dogma of molecular biology describes the flow of genetic information within a biological system, specifically the process of DNA being transcribed into RNA, which is then translated into proteins.

What are the basic requirements of a cell?

Sequence information to aa to proteins and leads to catalytic activity. It requires a stable environment, energy sources, and essential nutrients for structure and function.

Eukaryotes:

Organisms with complex cells containing a nucleus and organelles, including plants, animals, fungi, and protists. 200um seen w unaided eye. (ALL have MITOCHONDRIA from endosymbiotic theory)

Endosymbiotic heory

Mitochondria derive from early prokaryotic symbiotes.

Chloroplasts

another example of endosymbiotic theory. Uses photosynthesis to harvest energy from sunlight and store it in the bonds of sugar. Have own circular DNA. Fission. Widespread in plant cells, enabling glucose production.

LUCA

Ancestral prokaryote from which all life on Earth descends, representing the last universal common ancestor.

Endoplasmic reticulum

Produces cel membrane (double mem) components and molecules to be exported. rough has ribosomes.

Golgi Apparatus

Modifies proteins and molecules for transport or secretion. (vesicles are sorted to transport everywhere)

Lysosomes and peroxisomes

sequester degradative enzymes from the cytosol to prevent damage to the cell, facilitating the breakdown of waste and cellular debris. (Intracellular digestion)

Peroxisomes

Where reaction uses hydrogen peroxide to inactivate toxic molecules.

Cytosol

Full of proteins and molecules. ex: actin filaments thin movement/contraction, microtubules -thick chromosomes separation and movement, and intermediate filaments- strength and shape without cell walls.

Atomic number

=number of protons= number of electrons

What are covalent bonds?

Reaction is needed to build or break. Polar-shared unequally between atoms, resulting in a stronger intermolecular force. O/N high electronegative (polar). C/H less and (nonpolar. )

What are ionic bonds?

Ionic bonds are chemical bonds formed through the electrostatic attraction between oppositely charged ions, typically resulting from the transfer of electrons from one atom to another.

Noncovalent ionic

In vaccum 335. in water. 12.

What are the different types of non-covalent interactions found between molecules?

1) Hydrogen Bonds (electron hogs). 2) Electrostic Interactions (±). 3) Van der Waals Attractions. 4) Hydrophobic Forces

Fatty acids

are the basis of most lipids and membranes. They are long hydrocarbon chains with a carboxylic acid group at one end.

Condensation reactions

form covalent bonds between monomers to build larger polymers

What are the most basic chemical and physical characteristics that all cells share?

All cells are composed of a plasma membrane, contain genetic material (DNA or RNA), exhibit metabolic activity, and have the ability to grow and reproduce.

What are the relative sizes of different types of cells and their components?

Cell sizes vary significantly, with prokaryotic cells typically ranging from 0.1 to 5.0 micrometers, eukaryotic cells ranging from 10 to 100 micrometers, and organelles being even smaller. For instance, ribosomes are about 25 nanometers in diameter.

How can you use microscopy to see these different structures?

Microscopy techniques like light microscopy and electron microscopy allow visualization of cells and their organelles by magnifying their structures, revealing details such as cell membranes and internal components.

What are the important organelles of a eukaryotic cell?

Important organelles of a eukaryotic cell include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and ribosomes, each with specific functions essential for cell operation.

What are the important elements in cell biology?

Key elements in cell biology include carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. These elements are crucial for forming biomolecules like proteins, nucleic acids, carbohydrates, and lipids that make up living cells.

What’s so special about water? Types of bonds/molecular interactions and their properties

Water is vital for life due to its unique properties, such as being a polar solvent, allowing for biochemical reactions, aiding in temperature regulation, and contributing to cellular structure and function. Additionally, its hydrogen bonds give water a high surface tension and specific heat capacity, making it essential for sustaining life.

What are the four important macromolecules in cells? Where are they found in the cell?

proteins, nucleic acids, carbohydrates, and lipids. Each plays a crucial role in biological functions, including structure, energy storage, and information transfer.

These macromolecules are found throughout the cell: proteins perform various functions in membranes and organelles; nucleic acids like DNA and RNA are primarily located in the nucleus; carbohydrates are found in the cell membrane and as stored energy; lipids, including phospholipids and fats, are present in membranes and as energy reserves.

How are macromolecules built from monomers?

Macromolecules are built through polymerization, where monomers such as amino acids, nucleotides, and simple sugars are chemically bonded together via condensation reactions, forming larger structures like proteins, nucleic acids, and polysaccharides.

Chp. 4 How does an amino acid sequence affect protein structure?

The amino acid sequence determines a protein's three-dimensional structure by dictating how the polypeptide chain folds and interacts with itself. This ultimately influences the protein's function and stability.

What are important properties of amino acid side chains?

Amino acid side chains, or R groups, determine the properties of amino acids, influencing protein structure and function. They can be polar, nonpolar, acidic, or basic, impacting hydrophobicity, charge, and interactions within proteins.

What chemical forces govern protein folding?

Chemical forces governing protein folding include hydrogen bonds, ionic interactions, hydrophobic interactions, and van der Waals forces. These forces contribute to the stability of the protein's tertiary and quaternary structures, ultimately influencing its functionality.

What are primary, secondary, and tertiary structure? What are some examples of each of these structures?

Primary structure refers to the linear sequence of amino acids in a polypeptide chain; secondary structure involves localized folding into alpha helices or beta sheets due to hydrogen bonding; tertiary structure is the overall three-dimensional shape formed by interactions among the side chains of the amino acids. Examples include: primary - insulin's amino acid sequence; secondary - alpha helix in keratin; tertiary - globular shape of enzymes.

Proteins are made of chains of amino acids linked by _______ peptide bonds. ( ribosomes needed for protein synthesis c-N )

covalent

How does structure affect function of the protein?

The structure of a protein is critical to its function, as it determines how the protein interacts with other molecules. Changes in structure, whether due to mutations or environmental factors, can significantly alter activity, stability, and specificity.

How do proteins work?

• What chemical forces govern protein-protein interactions?

Proteins work by interacting with other molecules through various chemical forces such as hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals forces. These interactions are crucial for protein-protein interactions, determining the stability and specificity of protein complexes.

Feedback inhibition

is a regulatory mechanism in metabolic pathways where the end product inhibits an earlier step, preventing overproduction.

Allosteric inhibition

binding of a molecule at a site other than the active site causes a conformational change in structure that reduces enzyme activity and changes function.

Competitive inhibition

a molecule similar to the substrate binds to the active site, preventing the actual substrate from binding and thereby decreasing the rate of the reaction. REPRESSOR.

Regulatory phosphorylation

is the process by which the addition of a phosphate group to a protein alters its activity, often regulating enzymatic function and signaling pathways.

What other bond could you use to fold other than noncovalent?

Disulfide bonds.

What are some h bond between side chains and back bone?

1) backbone-backbone (2 pep bonds) 2) backbone to side chain (h bond bet peptide bond and aa side chain) 3) side chain to side chain (h bond between two aa side chains)

Secondary alpha helix has

3.6 residues and 10 in length amino acids. IT rotates 100 degrees.

Secondary beta pleated sheets has

parallel and antiparallel . 3.5 degrees. It consists of β-strands connected laterally by hydrogen bonds, forming a sheet-like structure. Each strand typically contains 5-10 amino acids.

Amphipathic.

Refers to molecules that contain both hydrophilic and hydrophobic regions, allowing them to interact with both water and lipids. Good to make paths or pass through membrane.

Which stage of protein folding requires an enzyme to occur?

Primary structure. secondary and tertiary use h bonds noncovalent interacts that arent driven by enzymes.

Why is protein folding spontaneous?

Protein folding increases entropy of the water around the proteins by

removing hydrophobic interactions. Makes it more thermodynamic. No enzyme use.

_____ structure is composed of multiple (polypeptide) proteins that function together in a complex

Quaternary structure.

________ structure provides highly selective binding sites for protein-ligand and protein-protein interactions

3D protein

Non-covalent interactions allow for _______

substrate-enzyme interactions

Kinases:

Add phosphate groups. Enzymes that catalyze the transfer of phosphate groups from high-energy donor molecules, such as ATP, to specific substrates, thus modifying their function.

Phosphatase

Catayzes the hydrolytic removal of a phosphate group from a molecule. This process is crucial for regulating cellular functions and signaling pathways.