Chapter 1 Flashcards
Protein functions
Signal molecule - hormones
Receptors for molecules - hemoglobin transport oxygen.
Biological catalysts - enzymes
Structural building blocks - keratin (hair/nails)
Motors - myosin in muscle
Four major classes of biomolecules
Proteins
Carbs
Nucleic acids
Lipids
Carbohydrate function
Fuel source - glucose
Store energy - glycogen
Signal molecules
Nucleic acids function
Store and transmit genetic information (Dna)
Enzymes, structural, signaling
Energy currency of cell - nucleotide triphosphate
DNA
double strand on nucleotide polymers form a helix • Anti parallel (strands run opposite direction)
Sugar: 2’ deoxyribose • (missing 2 hydroxyl group)
Four bases: Adenine (A) Guanine (G) Cytosine (C) Thymine (T)
RNA
Typically a single strand polymer of nucleotides , but can also be double stranded and form complex structures. •
Sugar: ribose • Contains 2 hydroxyl group
Four bases: Adenine (A) Guanine (G) Cytosine (C) Uracil (U)
Dna has thyme, RNA has Uracil
Central dogma
Sequence of the proteins is encoded by the sequence of the DNA
Dna (transcription) > RNA (translation) > protein
The Central Dogma describes the flow of gene9c informa9on •
DNA is the inherited gene9c material of most organisms (the genome). • Excep9on include some types of virus that have RNA genomes. •
The genome contains the “blueprints” of an organism in the form of genes that encode proteins. •
Gene expression: “DNA makes RNA which makes Protein”
ReplicaXon: DNA is copied each 9me a cell divides into two new cells. • TranscripXon: DNA is transcribed into an RNA copy. •
TranslaXon: The informa9on in RNA is translated into Proteins.
Dna replication
The process of DNA replica9on is catalyzed by a special type of enzyme called DNA polymerase. •
DNA polymerase creates new polymers of DNA by joining 2’-‐deoxy nucleo9des. •
The DNA sequence is copied precisely
Replicated strands are identical to starting strands
Transcription
During the process of transcrip9on, a special type of enzyme called RNA polymerase makes a new RNA by copying the informa9on contained in DNA. •
RNA polymerase creates polymers of RNA from nucleo9des. •
Each cell in an organism expresses specific types of RNA.
Gene expression and specialized cell function
Every cell contains all DNA, but only certain genes are expressed
Based on what genes are expressed, proteins are synthesized
This is why there are specialized cells, only certain proteins expressed in cells and this determines function
Translation of proteins
Transla9on converts the informa9on in RNA into a protein. •
The nucleo9de sequence of the RNA specifies the amino acid sequence of the protein being translated. •
Transla9on occurs on enzymes called Ribosomes. •
Cells produce thousands of different proteins. •
Each cell produces a specific set of proteins that are necessary for its func9on.
Lipid function and properties
Func-ons of Lipids •
Form barriers referred to as Membranes •
Serve as a Fuel – lipids contain hydrocarbon chains that are rich in energy. •
Serve as a Signal – lipid deriva-ves are used by cells to transmit signals.
Proper-es of Lipids
Hydrophilic – dissolve in water •
Hydrophobic – cannot dissolve in water
Membrane
A membrane is a lipid bilayer. •
The plasma membrane forms a barrier that separates the outside from the inside of the cell. •
The plasma membrane is impermeable to most biomolecules.
Proteins within membrane
Transmembrane protein - protein extends across bilayer
Membrane associated protein - associated with Hydrophilic group or associated with transmembrane proteins
Prokaryotic cell membrane
2 membranes within cell - inner and outer
Also have cell wall
Extra membranes allow bacteria to survive harsh environment, extra rigidity
Lack organelles (intracellular membranes)
Chromosomes located in the nucleoid
Eukaryotic cell membrane
Have organelles
Biochemical functions sequestered in organelles
No cell wall unlike Prokaryotes
Cytoplasm
The cytoplasm is the part of the cell surrounded by the plasma membrane but not enclosed by any intracellular membranes. •
The cytoplasm is organized by a series of structural filaments called the cytoskeleton.
Cytoskeleton
Made up of microtubules, actin, and intermediate filament
These can also serve as transport pathways within the cell
Nucleus
organelle containing the DNA genome in eukaryo-c cells. DNA replica-on and transcrip-on occur within the nucleus.
Mitochondria
–the powerhouses of cells where fuel undergoes combus-on to produce adenosine triphosphate (ATP)
Chloroplasts
the sites of photosynthesis in plant cells.
Endoplasmic reticulum
A series of membranous sacs in the cytoplasm.
Rough ER -has ribosomes associated with it and is involved in processing new proteins
Smooth ER - lacks ribosomes and plays a variety of biochemical roles.
Golgi apparatus
complex of stacked membranes that sort proteins. Proteins are shuVled from the endoplasmic re-culum to the Golgi apparatus by vesicles.
Lysosome
contain a variety of enzymes that digest material brought into the cell, as well as damaged organelles such as mitochondria. •
Tay-‐Sachs Disease results from a defect in lysosome func-on and leads to muscle weakness, dementia, and early childhood death.
Cellular export
Proteins from Endoplasmic reticulum travel to golgi
Proteins are packaged in vesicles and fuse with membrane, expelling proteins via exocytosis
Exocytosis - proteins deposited outside the cell
Cellular import
Endocytosis - mechanism for bringing molecules in
An endosome is the structure that forms when the plasma membrane invaginates and buds off. •
Familial Hypercholesterolemia -‐ defec-ve endocytosis of cholesterol from the blood leads to high blood cholesterol levels and heart aVacks.
Phagocytosis - for large objects to be taken into the cell
Macrophages are an example
