Lecture 6-10 Flashcards
Name the 4 lipids.
1) fatty acids
2) triacylglycerols
3) phospholipids
4) steroids
How can fatty acids vary?
- chain length
- presence, number, position of double bonds
- isomers
Compare saturated and unsaturated fatty acids.
- saturated: single bonds causing the molecule to be fairly straight and packed together
- unsaturated: cis double bonds present that put a bend in the molecule (polyunsaturated fatty acids have multiple double bonds)
What is the structure of fatty acids?
has a carboxyl and methyl end
What is the structure of triacylglycerols and its bonding?
- three fatty acids attached to a glycerol backbone
- ester linkages are formed between glycerol and fatty acid from dehydration reaction
Identify the differences between plant and animal lipids. Name the exceptions.
plants:
-rich in unsaturated fatty acids and are liquid at room temperature
-coconut oil
animals:
-rich in saturated fatty acids and solid at room temperature
-duck fat
What are the characteristics of trans fats?
- produced by hydrogenation of vegetable oils
- unsaturated fats with trans double bonds
- solid at room temperature
What is the structure of phospholipids?
- two fatty acids
- a phosphate group with a charged molecule attached
- glycerol backbone
How are phospholipids oriented in a two layered bilayer?
- hydrophilic head interact with themselves and water, facing the outside
- hydrophobic tails interact with themselves and face the inside of the bilayer
What is the structure of steroids?
-carbon skeleton with 4 rings
What is cholesterol and what is its role?
- steroid
- maintains structure and fluidity
- component of cell membranes
- precursor of sex hormones
All cells must be able to…
1) keep internal environment different from external
2) expel wastes
3) make proteins with ribosomes
4) divide and replicate (reproduction)
Explain the fluid mosaic model.
- phospholipid bilayer where hydrophobic tails are on the inside and hydrophilic heads are facing the outside
- proteins embedded in bilayer and are unequally distributed (proven by freeze fracturing)
- glycoproteins are on the outside of the bilayer
Where are the integral, peripheral, and transmembrane proteins located?
integral: within the bilayer
peripheral: attached to the surface
transmembrane: span the whole bilayer
Identify the 6 functions of membrane proteins.
1) transport of solutes and molecules
2) enzymatic activity in metabolic reactions
3) signal transduction
4) cell to cell recognition
5) intercellular joining
6) attachment to cytoskeleton and extracellular matrix
How do you explain the movement of phospholipids in the fluid mosaic model?
- mostly move laterally in bilayer
- flip flop rarely
What is the role of cholesterol in membrane fluidity?
- stabilizes membrane fluidity
- reduces movement and prevents packing
Explain the permeability of the plasma membrane.
- permeable to small non polar molecules
- not permeable to large charged molecules
Explain the importance of cell size.
- volume must be large enough to contain all material necessary for functions of life
- volume must be small enough so the surface area can maximize its capabilities to control inputs and outputs
Which are the first eukaryotes to evolve?
Protists- unicellular eukaryotes
What are the differences between prokaryotes and eukaryotes?
- eukaryotes are larger
- prokaryotes have no membrane bound organelles
- genetic information is free in a nucleoid in prokaryotes; in a nucleus in eukaryotes
- prokaryotes don’t have mitochondria or chloroplasts
What are the similarities between prokaryotes and eukaryotes?
have extracellular structures (outside of plasma membrane)
List the order in which organisms evolved.
1) prokaryotes
2) atmospheric oxygen
3) single-celled eukaryotes
4) multicellular eukaryotes
5) animals
6) colonization of land
7) phanerozoic eon
What happened before the oxygen revolution in the Earth’s history?
earliest prokaryotes generated ATP without oxygen, used other molecules instead, due to low levels of oxygen in the atmosphere
How did oxygen accumulate during the oxygen revolution?
early prokaryotes had specialized cell membranes for photosynthesis where oxygen was a byproduct
Where are free and bound ribosomes located in prokaryotes and eukaryotes?
prokaryotes: in the cytosol
eukaryotes: free ribosomes in the cytosol
bound ribosomes are attached to the endoplasmic reticulum
What is the function of the free and bound ribosomes?
carry out protein synthesis
free: make cytosolic proteins
bound: make proteins that are inserted into membranes
What is the structure of ribosomes?
composed of protein and rRNA (ribosomal RNA) that are made in the nucleus