Cell Structure and Function Flashcards
What was the first disease understood at the molecular level and who founded it?
Sickle cell anemia and Linus Pauling
What defines the structure of hemoglobin?
Hemoglobin is a protein that is a polypeptide that has 4 chains ( 2 alpha and 2 beta)
In sickle cell, the mutation is an incorrect amino acid at position 6 in the B chain where Glutamine is changed to Valine, where it can not carry oxygen to its potential
Each hemoglobin molecule can bind 4 oxygens
There are 100s of hemoglobin molecules in a red blood cell, the nucleus is shed to make room for a large, this can happen since the nucleus is only needed for the DNA blueprint
What is a disease that is the result of misfolding?
Cancer, Tay-Sachs
What is a disease that is the result of toxic folding?
Alzheimer’s disease
The Cell
“A cell is the smallest unit of life”
Humans have ~ 100 trillion (10^14) cells
All cells of an organism carry the same genome
Highly specialized and are biochemical factories
Cells make DNA, RNA, and protein, so cells contain simple sugars, nucleotides, and amino acids
Cells require ATP for DNA and RNA synthesis and also freee energy for chemical reactions in the cell
A Nucleotide is the monomeric subunit fir DNA, and denaturation is not the same as degradation, where denaturation does not always mean bad as we have to denature to make copies of DNA
Do we eat DNA?
Yes we take in DNA when we eat plants and meat
What are the features of a prokaryotic cell?
Unicellular organism
Cell membrane is protected by a cell wall
Do NOT have organelles
Do not contain nucleus or nucleolus
DNA organized into single, circular chromosome
Very small (2-3 micrometer)
Come in different shapes and sizes
What are the features of Eukaryotic cells?
Part of a multicellular organism “compartmentalization”
Cell membrane is exposed to external environment
Contain many membrane-bound organelles
Possess both membrane-bound nucleus and nucleolus
DNA organized into many linear chromosomes
Average size ~ 10 micrometers
Come in different shapes and sizes
What is the Cell Membrane (Plasma Membrane)?
Selectively permeable to ions and organic molecules
“Selective barrier” that allows cells to concentrate nutrient from environment for use, while also excepting waste products
Without it cells could not maintain their integrity as coordinated chemical systems
Describe the phospholipid bilayer?
Molecules that form most of the cell membrane and are amphipathic
A phospholipid molecule has a hydrophilic head and a hydrophobic tail, where the tails line up against each other to form the membrane.
Lipids
Phospholipids ~ 75%
Cholesterol ~ 20%
Glycolipids ~ 5%
Proteins - make up approximately 50% of membrane volume
What describes a phospholipid?
Most abundant class of lipids in cell membrane
Amphipathic
Consist of five parts:
1. Hydrophilic head
2. Linked to glycerol
3. via a phosphate group
4-5. Two long, non polar hydrocarbon tails, originating from fatty acids
What are the four major phospholipids in the cell membrane?
Phosphatidylethanolamine
Phosphatidylserine
Phosphatidylchloline
Sphingomyelin
*phosphoinositides - are a phospholipid that are not as abundant, but perform important function in cell signaling and transport vesicle targeting within the cell
What are Glycolipids?
Glycolipids are lipids attached to a sugar in the cell membrane
Backbone is a sphingosine molecule
Short carbohydrate molecule
Found on outer leaflet of cell membrane
Important in cell recognition
Antigenic determinants of ABO blood groups
What is cholesterol in the cell membrane?
~ 20% of the lipid composition o the cell membrane
Fills in the spaces between phospholipids
Makes cell membrane more rigid and less permeable
In order for cells to grow and reproduce what must be able to happen?
Cells must be able to import raw materials and export waste across its plasma membrane
Cells have specialized protein embedded in the phospholipid bilayer that transport specific molecules form one side to the other. They also posses reporter proteins that enable them to revive and respond to stimuli
