Practical 2 ~ Flashcards
What are macromolecules?
The universal occurrence of certain classes of large biopolymers such as polysaccharides, nucleic acids, lipids, and proteins
What do macromolecules do?
They are largely responsible for common features of cellular structures and functions
What are micromolecules?
they serve as building blocks for the synthesis of macromolecules
what is the rule of macromolecules?
They are composed of a limited number of repeating subunits (monomers) bound by the elimination of water (dehydration reaction) which form long chains (polymers)
Polysaccharides
Simplest of the macromolecules
Important polysacs: starches & glycogen (made up of repeating glucose)
Polysaccharides vary due to the type of linkage between subunits and the branching degree of the chains
Nucleic acids
Composed of nucleotide units (unbranched chains)
A cell can synthesize an enormous variety of NA by varying the arrangements on the nucleotide chain
The sequence of nucleotides in the NAs encode the cell’s genetic information
Proteins
Composed of 20 different amino acids, which are joined together by peptide bonds
Protein can contain 100s of amino acids in a chain
Account for much of the internal structure and function as enzymes
Lipids
Make up cell membrane’s structure with proteins
Not generally composed of repeating subunits
Dehydration synthesis
subunits of macromolecules are bound to one another by the elimination of water between each unit
“To put together while losing water”
Hydrolysis
Macromolecules can be broken down by the insertion of a molecule of water between each pair of subunits
If the number of monomers in a macromolecules is n, why is the quantity off water eliminated no greater than (n-1)?
since one water molecule is formed for every bond present in between a macromolecule, there will always be one less since the number of bonds will always be one less than the amount of macromolecules present
Centrifugation
Tube of suspensions swings in a circular motion, suspended particles that are denser than the suspending fluid will settle at the bottom of the container (faster than the norm. Force of gravity)
Max rate: 3000 rpm , force: 1000 g
Dialysis
A dialysis sac of cellulose membrane possesses tiny pores that allow water and small molecules to pass through, blocks macromolecules
Useful for separation of large mols from small mols
Macromols will remain in sac, small mols refuse across the membrane
chromatography
Separates compounds on the basis of different rates of migration on the filter paper
Dependents: relative affinity to the solvent flowing on the paper, relative strengths of absorption of the substance to paper
Water mixtures separate low molecular weight materials
Iodine test
Iodine reagent (iodine potassium iodide solution ; Gram’s iodine): stains glycogen red-brown. Used to determine the fractions in which glycogen is demonstrated
Benedict’s Test Reducing Sugar
+ Benedict’s test: all sugars contains reducing groups (aldehyde / ketone) that can reduce the blue cupric ions to red
Weak + Benedict’s test: a change of color from blue to green
- Benedict’s test: for glycogen or starch since the aldehyde groups are used up in glucose-glucose linkages
Analysis of Nucleic Acid Fraction
The characteristic green color obtained when ribose reacts with Bials’s orcinol reagent indicates for ribose (hydrolysis of RNA)
The characteristic blue color obtained when deoxyribose reacts with the Disce diphenylamine reagent indicates for deoxyribose (hydrolysis of DNA)
Dissecting microscope
Simple microscopes with low magnification
Large FOV
Excellent resolution because it produces 3D images
Often used to observe large specimens in great detail
Compound microscope
Higher magnification
Smaller FOV
Poorer resolution because field depth decreases as magnification increases
Parfocal
Once there are cells in focus with one objective, we can click on another objective and the cell remains in focus
Oil immersion
Allows for a significant increase in magnification by using a small drop of oil that increases the light gathering ability of the lens which increases resolution
Electron microscopes
Resolve at the nm level
Used to see eukaryotic cells, viruses, and large molecules such as DNA
Angstrom
A tenth of a nm
Useful for discussing atoms
Rules for microscope usage
Do’s:
Carry with 2 hands (one for arm and one for base)
Set it down gently
Begin examination with the scanning power objective in place
Cover before putting it away to stop dust accumulation
Don’t’s:
Turn it upside down or sideways
Remove lenses for any reason
Touch lenses with anything but a lens paper folded twice over it
Examine a slide without a coverslip
Bacteria / Cyanobacteria
Prokaryotic cells
Cyanobacteria (blue green bacteria - algae)
Lacks a nucleus with a nuclear membrane, as well as organelles with membranes
Nucleoid: Each cell has a region of DNA in the cytoplasm
Saprotrophic Bacteria
Nutrition from decaying dead organisms
Parasitic bacteria
Nutrition from living organisms
Mutualistic bacteria
Nutrition from living inside other organisms and providing benefits in return
Chemosynthetic bacteria
Nutrition from getting energy by breaking down inorganic nitrogen, sulfur or hydrogen
Photosynthetic bacteria
Nutrition by getting energy from the sun
Bacteria shapes
The most common shapes are coccus (round) and bacillus (rod shaped)
Interphase
DNA is replicated (copied)
Cell grows
Cell prepares to divide
What is G_0 stage?
When cells have reached their final, mature size and function
What is the cell cycle?
All the processes involved in cellular replication
What are chromosomes?
DNA molecules that are a place for the genetic information of eukaryotic organisms to reside in
How many chromosomes does a human cell have vs an onion cell?
Human cell: 46 chromosomes
Onion cell: 8 chromosomes
What is DNA replication?
DNA double helix separates to 2 strands
A complementary strand is created for each
2 identical DNA molecules are produced
What are sister chromatids?
The identical pair of DNA molecules created in replication
What happens in mitosis?
Each daughter cell receives a copy of each of the replicated chromosomes
Stages of mitosis
PMAT (prophase, metaphase, anaphase, telophase)
Prophase
Chromosomes supercoil
Fibers of spindle apparatus forms between centromeres (not attached yet)
Nuclear envelope disintegrates
Chromosomes are free in the surrounding cytoplasm
Prometaphase
Some of the spindle fibers attach tot he centromeres of sister chromatids and begin to move towards the center of the cell
Metaphase
Chromosomes rest along the center plane of the cell
Anaphase
Centromeres split
Sister chromatids migrate toward the opposite poles of the cell
Telophase (animal cell)
Chromosomes at either end of the cell being to cluster together
Clustering facilitates the formation of a new nuclear membrane
Cytokinesis occurs
Telophase (plant cell)
The formation of a cell plate (a new cell wall forming in between 2 cells)
How many regions are there on an onion root tip?
3 regions (root cap, region of cell division, region of cell elongation)
Root cap (onion cell)
Contains cells that cover and protect underlying growth region as roots are pushed into the soil
Region of cell division (onion cell)
Aka meristem
Cells actively divide but are not growing
Region of cell elongation (onion cell)
Cells increase inside but are not dividing
