exam 1: lecture 1 Flashcards
what 3 branches of study in cell biology a combination of?
Cytology
Biochemistry
Genetics
what is cytology
the study of cells
the beginning of cell biology
-an observation where it is just looking- not experiment or interaction.
not until biochemistry and genetics that there were interactions or experiments
what is cell biology?
a cell-level zoology
what does a zoologist do? study how the animal functions
-> cell biology is the same: how they move, make energy, reproduction, organelles, and different types of cells
micrometer
1/1,000,000th meter (million)
ex. bacteria (prokaryotes), nucleus, mitochondria
nanometer
1/1,000,000,000th meter (billion)
ex. mycoplasma, viruses, ribosomes,proteins, lipids, small molecules, atoms
uses electron microscope
number of electron in each shell orbital
1st: 2
2nd: 8
3rd:8
what is valence number
the number of electrons that are needed to fill the orbitals
what are covalent bonds
bonds that are made by sharing of electrons of molecules ( missing valence electrons)
-strong: takes energy to break (heat from fire, electricity)
the importance of carbon: organic chemistry
the study of all classes of carbon-containing compounds
the importance of carbon: biochemistry
the study of chemistry of living systems
what is the most important atom in biological molecules?
carbon
specific bonding properties of carbon account for the characteristics of carbon-containing compounds
bonding properties of carbon
carbon has 4 valance electrons, which means it can form 4 bonds
most likely to form covalent bonds with C,H,O,N,S
what is a covalent bond
the sharing of a pair of electrons
stable
why are strong covalent bonds necessary for life
high energy such as UV light is more hazardous to the molecules (nucleic acids are sensitive)
->the visible light is lower in energy than C bonds
=>visible light cannot break of he bond of covalent bonds
what are ionic bonds
weaker than covalent bonds
ions: imbalance between protons and electrons (have a charge)
cation: loss of electron (+) ~ Na+
anion: gain of electron (-) ~ Cl-
structure of sodium chloride
a crystal
how to break ionic bonds? water (the molecules will dissociate)
what are hydrogen bondings
The bonding of H with other charged atoms
ex.h2o
H has a smaller nucleus-spends more time around the oxygen
->uneven electrons sharing=> polar charged
what makes water molecules polar?
- unequal distribution of electrons
- geometry: bent, not linear
- the O atom has a slight negative charge that draws H atoms around it
what bonds water molecules tgt?
hydrogen bond
=1/10 as strong as covalent bonds
How are water molecules cohesive?
due to their polarity, they are attracted to each other as the electronegativity of oxygen draws other electropostive H nearby
what are the effects hydrogen bonds have on water
- surface tension
- boiling point
- specific heat
- heat of vaporization
- freezing point: salt content plays a role in water not freezing
what are the two weak molecular interactions
- van der waals
- hydrophobic interaction
what are van der waals interactions
the weak attraction between two atoms ONLY IF THE ATOMS ARE VERY CLOSE TGT AND ORIENTED CORRECTLY
-atoms that are too close will repel
-van der Waals radius: defines how close other atoms can come to it= the basis for space-filling models
=explains why molecules are certainly distanced
what are hydrophobic interactions
the behavior of nonpolar groups- will try to minimize contact with water
-> cause nonpolar groups to be found in the inside of a protein or a membrane
Building block of the cells
- sugars (carbohydrates)-> polysaccharides
2.fatty acids (lipids)-> fats, membranes - amino acids-> proteins
- nucleotides (DNA/RNA)-> nucleic acids
+WATER
why is water so important biochemically?
- Most nutrients are dissolved in water
- water heps the transport of food and wastes in/out of cells
- water is the medium for most reactions
- water makes up on avg. to 65-75% of a cell’s mass
How do hydrogen bonds make water a special molecule
- being able to form hydrogen bonds, this allows it to have a high boiling point and a low freezing point
->water freezes from the top down unlike other nonpolar molecules - its polarity makes it an excellent solvent
- can act as a donor of hydroxide (OH-) and hydrogen (H+)
H2O–dissociates–> H+ & OH_ - makes water an excellent temp. buffer
-small scaled: slow exchange of heat
-large scale: during the summer, water will stay cold for a while due to the cold climate of winter has heat is lost during the summer