Biochemistry 2

Catabolic reactions

• break down larger molecules, such as carbohydrates, lipids, and proteins from ingested food, into their constituent smaller parts.

Anabolic Reactions

• reactions that build smaller molecules into larger molecules

Lock and key

• a biological analogy describing the high specificity of enzyme-substrate interaction, where the enzyme's active site (the lock) has a specific shape that perfectly fits only a specific substrate (the key)

Induced Fit

• Describes the dynamic between an enzyme and its substrate, proposing that the enzyme’s active site undergoes a confrontational (shape) change upon binding to the substrate

Mitochondrion

• Produces Adenosine Triphosphate

• It has a double membrane, the inner layer being folded inward to form layers (cristae)

• an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur.

• Singular form

Mitochondria

• Produces Adenosine Triphosphate

• It has a double membrane, the inner layer being folded inward to form layers (cristae)

• acting as the "powerhouses" that generate energy through cellular respiration

• Plural Form

Nucleus

• Control center of the cell

• Houses and Protects the DNA

• Regulates gene expression and coordinating cell activities like growth and division

• Site of DNA replication and transcription

Lysosomes

• a membrane-bound cell organelle that contains digestive enzymes that help in phagocytosis

• Known as suicidal bag because it can destroy its own cell

Golgi Apparatus

• A cell organelle that modifies, sorts, and packages proteins and lipids received from Endoplasmic Reticulum

• Known as the shipping and receiving center

Rough Endoplasmic Reticulum

• A network of interconnected sacs of cisternae that is filled with ribosomes

• Its main function is that of protein synthesis

Smooth Endoplasmic Reticulum

• A network of interconnected sacs of cisternae that is not filled with ribosomes

• Its 3 functions include synthesizing lipids like steroid lipids and phospholipids, detoxifying harmful substances like drugs or poison, and storing and regulating calcium ions

Peroxisomes

• A membrane bound organelle that participates in metabolic practices like the oxidation of various compounds such as fatty and amino acids.

• It also helps in metabolizing drugs.

Fixed Ribosome

• The ribosomes that are located within the Rough Endoplasmic Reticulum

• They synthesize proteins that are meant to be delivered to organelles, inserted into membranes, or secreted by the cell

Free Ribosomes

• The ribosomes that are located in the cytosol

• They synthesize proteins for the cytoskeleton, metabolic enzymes, and proteins for the mitochondria

Cytosol

• the watery, gel-like liquid matrix within a cell, containing dissolved ions, small molecules, and proteins, that surrounds organelles but excludes the nucleus and the organelles themselves

Cell membrane

• a selectively permeable, fluid barrier that encloses cells and their internal organelles, composed primarily of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates

Lipid droplets

• ubiquitous cellular organelles found in all kingdoms of life, acting as dynamic compartments for storing neutral lipids like triacylglycerols (TAGs) and sterol esters (SEs)

Glycoproteins

• Proteins with carbohydrates attached.

• Underwent a process known as glycosylation wherein the protein is modified for crucial functions.

Glycolipids

• Lipids with carbohydrates attached via glycosidic bond

• is vital for maintaining cell membranes and facilitating cellular recognition, immune responses, and cell-to-cell communication.

Peripheral membrane protein

• Proteins that are attached loosely to the cell membrane’s surface

Integral membrane protein

• Is permanently anchored to a biological membrane, requiring hydrophobic interactions with lipid bilayer to embed within it.

Transmembrane proteins

• The most common type, these proteins span the entire lipid bilayer, having segments exposed on both the inside and outside of the cell.

Integral monotropic proteins

• These proteins are embedded in one leaflet (side) of the membrane but do not span the entire bilayer.

Cholesterol

• A crucial component of the phospholipid bilayer in animal cell membrane, playing a key role in maintaining membrane structure and function.

Channel proteins

• It forms selective, hydrophilic pores across cell membranes to facilitate the rapid transport of ions and water through facilitated diffusion or, in some cases, active transport.

Phospholipid bilayer

• the fundamental structure of all cell membranes, composed of two layers of phospholipid molecules arranged with their hydrophilic (water-loving) heads facing outward and their hydrophobic (water-fearing) tails facing inward

Normal Plasma Membrane

• the outermost barrier of a cell, a fluid mosaic of phospholipids, cholesterol, proteins, and carbohydrates that regulates the passage of substances into and out of the cell

Lipid rafts

• are distinct, dynamic subdomains within cellular membranes, particularly the plasma membrane, enriched in cholesterol and sphingolipids that create a more ordered environment compared to surrounding membranes

Diffusion

• Movement down concentration gradient; no energy required.

Simple Diffusion

• Nonpolar molecules; No protein required

Facilitated Diffusion

• Polar molecules; Protein required

Active Transport

• Movement against concentration gradient; requires energy input and a protein pump

Facilitated Diffusion

• Channel Proteins and Carrier Proteins

Active Transport

• Protein pumps

Facilitated Diffusion or Active Transport

• Pores

Typically Active Transport

• Endocytosis and Exocytosis