Study Questions #3 Flashcards
September 10-14
What is a lipid, and what function do lipids perform?
Lipids are hydrophobic organic macromolecules. Functions:
- energy storage
- membrane
- signaling
- light absorption
What are glycerolipids?
fatty acids bonded to glycerol
Why do fats store more energy than carbohydrates?
fats have more C-H bonds and are very reduced
Why should you avoid eating fats with trans double bonds?
they fool cells into thinking they’re unsaturated but act like they’re saturated making them hard to digest
Why do unsaturated fatty acids melt at lower temperatures than saturated fatty acids?
The intermolecular interactions are much weaker than saturated molecules. As a result, the melting points are much lower for unsaturated fatty acids.
Why does soap clean up grease?
Hydrophobic ends of soap molecule all attach to the oil. Hydrophilic ends stick out into the water. This causes a drop of oil to form:These drops of oil are suspended in the water. This is how soap cleans your hands - it causes drops of grease and dirt to be pulled off your hands and suspended in water. These drops are washed away when you rinse your hands.
Why do membrane such as phosphatidylcholine form bilayers?
They have two charges so the hydrophilic sides point out and the hydrophobic sides point in
What do triacylglycerols and phospholipids have in common and how do they differ?
Triacylglycerols have fatty acids on all three C’s whereas phospholipids have fatty acids on two and a phosphate on the other. Tricylgylycerols store energy and phospholipids form bilayers.
What are steroids, and what function do they perform?
4C rings
Functions:
-cholestrol in membranes determine structure
-hormones
What are prostaglandins, and what functions do they perform?
They’re altered fatty acid signals
Functions:
-protect stomach lining
-trigger uterine contractions
What are isoprenoids, and what functions do they perform?
two or more units of hydrocarbons, with each unit consisting of five carbon atoms arranged in a specific pattern. range in function from pigments and fragrances to vitamins and precursors of sex hormones
What is the cell theory?
- life is made of multiple cells
- cell is smallest unit of life
- cells come from cells
Why did it take so long for biologists to recognize the importance of cell life?
.
Why are microscopes such important tools for biologists?
they can observe things that are not visible to the eye
How do microscopes work?
light up a specimen, which absorbs certain wavelengths, which is how you can see them
What is the difference between resolution and magnification?
magnification is bending image through lenses and resolution is telling two objects apart
What is the most important property of a microscope?
resolution
Why can we see nuclei with a light microscope, but need an electron microscope to see objects like ribosomes?
light microscopes can’t resolve two objects less than 200 nm apart because the photons overlap
Why are cells so small?
- many things get in and out of cells by diffusion, and if it was too big it would take too long
- if surface area to volume ratio is too small, things can’t be exchanged
What are prokaryotic cells?
Cells without a nucleus
What are the key differences between archeabacteria and eubacteria?
- archaebacteria has no peptidoglycan and eubacteria do.
- archaebacteria have ethers and eubacteria have esters.
- archaebacteria have complex genes and eubacteria have simple genes
What are eukaryotic cells and what is the difference between eukaryotic and prokaryotic?
eukaryotes have organelles
Why can eukaryotic cells grow larger than prokaryotic cells?
they divide the work which reduces diffusion problems, so they have room to grow more
Why can multicellular organisms grow larger then single celled organisms?
they have more things specialized and doing certain work so they can grow easier and still support themselves
What are the two main types of eukaryotic cells and what are the main differences between them?
Plant and animal cells.
- Plant has wall
- animal has no wall
- plant has vacuoles as largest organ
- animals have nucleus as largest organ
- plants divide on cell plate
- animals divide on cleavage
- plants want to be hyper osmotic
- animals want to be in equilibrium
What do the two types of Eukaryotic cells have in common?
The primary cell organelles such as the nucleus, mitochondria, ribosomes, etc., are present in both types of cells.
What are the three main functions of the nucleus?
- protect DNA
- copy DNA before cell division
- make a copy of DNA pieces (genes) when needed
What are nucleoli and what are their functions?
dark spheres within the nucleus that assembles ribosomes
What is the endoplasmic reticulum and what is the difference between RER and SER?
It’s a network of membranes attached outside the nucleus. RER has ribosomes attached to it while SER doesn’t.
What are the functions of the SER and what are the functions of the RER?
Smooth:
- makes lipids and steroids
- drug detox
- stores calcium
- glycogen catabolism
Rough
-makes ribosomes
What us the Golgi apparatus and what are their functions?
Flat membrane sacks derived from the ER
Functions:
-determines where proteins and lipids should go
What are transport vesicles?
Vesicles in transit from one part of the cell to another.
What are lysosomes and what are their functions?
Lysosomes are vesicles derived from the Golgi containing hydrolytic enzymes that digests things like food and viral/bacterial particles.
How do we prevent lysosomes from digesting cells?
The membrane surrounding a lysosome prevents the digestive enzymes inside from destroying the cell. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents.
What is the difference between lysosomes and vacuoles?
lysosomes are used for digestion and vacuoles are used for storage
What additional functions are preformed by vacuoles?
.
What is the endomembrane system and what organelles does it consist of?
system coming from the ER Organelles: -ER -Golgi -Lysosomes -Nuclear Envelope -Plasma membrane -Endosomes
What do all organelles of the endomembrane system have in common?
- derived from the er
- have transport vesicles
- glycosylated proteins and lipids from Golgi
Which organelles are probably derived from endosymbiotic bacteria?
- Peroxisomes
- Mitochondria
- Plastids
What are peroxisomes and what are their functions?
single membrane organelle present in all eukaryotes that destroys oxygenous poisons, changes fat to CH2O and destroys ethanol
What are mitochondria and what are their functions?
double membrane organelles present in almost all eukaryotes that supplies energy by oxidizing food and makes a lot of biochemicals
What are plastids and what are their functions?
organelles present only in plants
- chloroplasts do photosynthesis
- amyloplasts store starch
- chromoplasts store pigments
What do plastids and mitochondria have in common?
double membrane
have their own DNA, RNA and ribosomes
symbiosis-organisms of different specieis living together
What is the endosymbiotic theory and what evidence supports it?
eukaryotes arose by engulfing other bacteria and making them symbionts
- size and shape are similar to bacteria
- divide by fission
- cardiolipin in membrane
- similar proteins and lipids to bacteria
- DNA also similar to bacteria
What gives cells their shape?
cytoskeleton
What are the three types of fibers which make up the cytoskeleton?
microtubules, intermediate filaments, microfilaments
Which types of cytoskeleton fibers are used for movement?
microtubules
Which types of cytoskeleton fibers are used to move objects inside cells?
Microtubules
What are intermediate filaments and what do they do?
filaments 8-12 nm in diameter that act as support
What are microfilaments and what do they do?
actin filaments 7 nm in diameter.
- present in all eukaryotes
- function: motility
- works with myosin
Why are poisons which interfere with actin, such as cytochalaisin and phalloidin, so deadly?
Cytochalisin stops addition and eventually they’re all only subunits and can’t function.
Phalloidin stops the falling off so they keep growing and there’s no subunits left to start new strands
What are microtubules and what do they do?
25 nm diameter tubes made of 13 strands of protofilaments.
- in all eukaryotes
- polar alpha and beta tubulin subunits form protofilament
- add to positive end fall off negative end
- assemble at mtoc
- give shape to cell, holds organelles in place, movement within cell
How are microtubules used to move organelles inside cells?
they form “tracks” that motor proteins carry the cargo on
Why is taxol used for treating cancer patients?
it stops falling off on microtubules, prevents cell division
What is a MTOC and why do microtubules radiate outwards from MTOC?
microtubule organizing center- the positive end “moons” the mtoc and the negative end faces it so it grows away from the mtoc
What is a centrosome?
microtubule organizing center found only in animals
- replicate before mitosis, move to poles
- organizes complex that divides chromosomes
Why did we have to stain the potato and human cells?
.
Why do we need to provide a scale for drawings made using a microscope?
so we know how big they actually were
