A&P - Lecture 2 (Cell, Transport) Flashcards
What are the three main parts of the cell?
Plasma membrane; nucleus; and Cytoplasm
What are the general functions of the plasma membrane?
- barrier separates the inside and outside of the cell 2. Controls the flow of substances into and out of the cell 3. Helps identify the cell to other cells (immune cells) 4. Participates in intracellular signaling 5. Cytoplasm
What are the two compontents of cytoplasm?
Cytosol and Organelles
Cytosol
the fluid portion (aka: intracellular fluid) Contains: water; dissolved solutes; suspended particles
Organelles
little organ: structures suspended in the cytosol; all with characteristic shape and function
Examples of Organelles
Examples: golgi complex; mitochondrion; ribosomes; lysosomes; peroxisomes
What is the function of the nucleus?
- Houses the cell’s DNA; which controls most aspects of cellular structure and function.
Chromosome
a single molecule of DNA associated with several proteins and contains thousands of hereditary units called genes.
What is the plasma membrane?
flexible; yet sturdy barrier that surrounds and contains the cytoplasm of a cell
Fluid-Mosaic Model
model used to describe the plasma membrane
What are the features of the fluid-mosaic model
- Molecular arrangement resembles a continually moving sea of fluid lipids containing a mosaic of many different proteins. 2. Some proteins float freely like icebergs in the lipid sea 3. Membrane lipids allow passage of several lipid-soluble type proteins, but restrict charged or polar substances 4. Some proteins allow movement of polar molecules and ions; in and out of the cell 5. Some proteins act as signal receptors 6. Some proteins can link the plasma membrane to intracellular and extracellular proteins
What are the three types of molecules in the plasma membrane?
Phospholipids (75%) Cholesterol (20%) Glycolipids (5%)
Three molecules - largest to smallest
Phospholipids; Cholesterol; Glycolipids
What molecule give rigidity?
Glycolipids
What makes a bilayer?
Amphipathic nature of the lipids. Lipids have both polar and nonpolar regions; specifically phospholipids.
Integral protein
Goes from one side of the bilayer to the other
Preferal protien
On both sides of the bilayer but does not go all the way through
What are the parts an Amphipathic Phospholipid?
Head and two fatty acid tails
Is the head polar or non-polar?
Polar: head (hydrophilic-loves water)
Is the tail polar or non-polar?
Non-polar: two long fatty acid tails (hydrophobic-hates water)
What are the characteristics of a choelesterol molecule?
- Weakly amphipathic 2. Dispersed among the other lipids 3. Found in both layers of the bilayer 4. There is a tiny ?OH region on the cholesterol. This is the only region that is polar. This forms hydrogen bonds with the polar heads phospholipids and glycolipids. 5. Steroid ring and hydrocarbon tail of cholesterol is stiff and nonpolar and associates with the nonpolar; hydrophobic tails
What are the characteristics of glycolipids?
- Carbohydrate groups form a polar ?head? 2. Fatty acid tails are nonpolar 3. Appear only in the membrane layer that faces the extracellular fluid (one reason the bilayer is considered asymmetric)
Types of Membrane Proteins
Integral Proteins and Peripheral Proteins
Integral Proteins
extend into or through the lipid bilayer and are firmly imbedded in it