Chemistry of Life Flashcards
What is an Acid?
A compound that released H+ ions into solution. pH < 7
What is a Base?
A compound that takes up H+ ions into solution. pH > 7
What is a buffer?
A solution that resists change in pH. Usually a combination of a weak acid and one its soluble salts
What is the pH of blood?
Between 7.35 - 7.45
What is the formula for carbohydrates?
Cx(H2O)y
What does dissociation mean?
Separates into constituent ions
99% of all living matter consists of which four atoms?
Nitrogen, hydrogen, carbon, oxygen
How many elements make up the cell?
16
Which elements make up lipids?
Carbon, Hydrogen, Oxygen
HCl is an example of an acid or a base?
Acid
How is HCl dissociated in solution?
H+ and Cl-
Positively charged ion is
Cation
Cation is…
a positively charged ion
Negatively charged ion is
Anion
Anion is…
Negatively charged ion
Forumla for pH
-log10 (H+ concentration)
Sodium hydroxide formula
NaOH
Sodium hydroxide dissociates into
Na+ and OH-
Ethnic acid formula
C3H3COOH
How does ethanoic acid dissociate in water?
C2H5COO- and H+
How is blood buffered?
Phosphate ions, hydrogen carbonate, blood proteins
Why is it important to use buffers in laboratory experiments?
To keep the pH of a solution under control when diluting or adding acids or bases.
Metabolism is…
All the chemical reactions that occur within an organism
The role of (nitrate) NO3- in plant metabolism is…
Required for DNA, RNA and protein synthesis
The role of calcium (Ca2+) in plant metabolism is…
Used to synthesize calcium pectate
What is calcium pectate?
Forms the lamella, a layer between the walls of adjacent plant cells
The role of magnesium (Mg2+) in plant metabolism
Used in chlorophyll production
The role of phosphate (PO4 3-) in plant metabolism
For energy in the synthesis of ATP from ADP, and in DNA and RNA replication/transcription.
A human cells consists of **% water
80%
What type of bond does water use?
Covalent
Charge of a H2O molecule
Neutral
Which atom(s) in H2O are electro negative?
Oxygen
Which atom(s) in H2O are electro positive?
Hydrogen
Why is Oxygen electro-negative in H2O?
Because the large nuclei of oxygen pulls the electrons away from the small nuclei of hydrogen
Why is hydrogen electro-positive in H2O?
Because the large nuclei of oxygen pulls the electrons away from the small nuclei of hydrogen, therefore giving oxygen additional elections and hydrogen fewer
What is a polar molecule?
The unequal distribution of electrical charge across a molecule
What is a polar molecule?
The unequal distribution of electrical charge across a molecule
How are water molecules bound?
Hydrogen bonds
What is a covalent bond?
A bond between two atoms in which electrons are shared between them.
What is a hydrogen bond?
A link between two polar molecules which combines using the weak positive of one and weak negative charge of the other to form a bond.
How strong is a covalent bond?
Kinda strong, but not the strongest
How strong is a hydrogen bond?
Weak
What is cohesion?
The force that attracts hydrogen bonds between polar molecules or other charged surfaces together
What kind of molecule is water?
Polar
Name some examples of solutes that water is a good solvent for:
- ionic substances i.e. sodium chloride (NaCl-)
2. Organic molecules with ionized groups (COO-, NH3+)
NaCl- is added to water. Which is the solvent and which is the solute?
Solvent = NaCl- Solute = water
A polar molecule that can dissolve in water is known as
Hydrophilic
Are non-polar molecules hydrophilic or hydrophobic?
Hydrophobic
What does hydrophilic mean?
Dissolves in water
What does hydrophobic mean?
Does not dissolve in water
Give an example of a hydrophobic substance
Oil
Give an example of a hydrophilic substance
NaCl-
What does the term “Specific Heat Capacity” mean?
The heat needed to break bonds
What is the specific heat capacity of water?
4.184 kj / kg /^celcius.
This means that it takes 1.184 kj of heat to increase the temperature of 1kg of water by 1 degree Celsius
Why is the specific heat capacity important for humans?
Because it means humans can tolerate large fluctuations in environmental temperature without changing internal temperature.
What is the force by which charged molecules stick together?
Cohesion
Are ionic substances hydrophilic or hydrophobic?
hydrophilic
Are alcohols and sugars hydrophilic or hydrophobic?
hydrophilic
Are oils hydrophilic or hydrophobic?
hydrophobic
Are oils polar or non-polar molecules?
non-polar?
The term used to describe the heat needed to break bonds
The specific heat capacity
A link between two polar molecules which combines using the weak positive of one and weak negative charge of the other to form a bond.
Hydrogen bond
A bond between two atoms in which electrons are shared between them.
Covalent bond
4.184 kj / kg /^celcius is…
The specific heat capacity for water
The intramolecular bonds in water
covalent
The intermolecular bonds in water
hydrogen
Surface tension is..
The cohesion of water at the water-air interface. Occurs because more molecules of H2O are present here.
Is water compressible?
No
Is water incompressible?
Yes
What does it mean if water is incompressible?
The distance between molecules is very small and can therefore not be shortened (or, compressed)
Maximum density of Water is at what temperature?
4^C
Is H2O-ice more or less dense than liquid water?
less
Why does it mean that ice floats on water?
Because ice is less dense than water
Water is at its maximum density at 4^C, what is a consequence of this to living organisms?
In rivers and lakes, the floating layer of ice insulates the large mass of water so that it can’t freeze solid. Therefore the aquatic life in such spaces can survive.
What shape does the water molecule take? (almost)
Tetrahedron
What symptoms would be shown by a plant grown in magnesium deficient soil?
Lack of chlorophyll production
In plants, what is chlorophyll?
Great pigment found in the chloroplasts of cells. It is essential in photosynthesis and allowing plants to absorb energy from plants
What are 5 properties of water that make it essential for life?
1.
What is xylem tissue?
One of two types of transport tissue in vascular plants
Phloem is?
One of two types of transport tissue in vascular plants
Why can a pond skater walk on water but humans can’t
because the surface tension of the water is strong enough to hold the tiny weight of the pond skater, and because this weight is distributed across a large diameter relative to its size and weight.
Carbon is the — most abundant element in cells and living organisms
Third
What is the third most abundant element in cells and living organisms
carbon
What is an organic compound?
A large carbon compound which carbons are covalently linked to each other and to hydrogen molecule
What bonds are used between carbons are organic compounds?
covalent
Organic compounds are made up (mostly) from which two elements?
Carbon and Hydrogen
Properties of carbon
- Can form four strong, stable, covalent bonds (four lone pairs of electrons)
- Carbon atoms can react with one another ro form extended chains, or skeletons
- Can form covalent bonds with other atoms too, e.g. oxygen, nitrogen, hydrogen and sulfur.
How many covalent bonds does carbon form? And why?
Four, because it has four lone pairs
What shape does methane form?
Tetrahedron.
What are the four families of organic molecules?
Lipid, nucleic acid, carbohydrate, protein
Examples of carbohydrates
sugars, starch, glycogen, cellulose
Types of carbohydrate
Monosaccharide, disaccharide, polysaccharide
Features of a monosaccharide
Smalll molecules, soluble in water and sweet in taste Simple sugars e.g. 1. trioses (C3-H6-O3) 2. Pentoses (C5-H10-O5) 3. Hexoses (C6-H12-O6) *Numbers should be sub-script
What is the formula for a Triose?
C3-H6-O3
*Numbers should be sub-script
What is the formula for Pentoses?
C5-H10-O5
*Numbers should be sub-script
What is the formula for hexoses?
C6-H12-O6
*Numbers should be sub-script
Triose, pentose and hexose are all types of what?
Monosaccharide
C3-H6-O3 is the formula for…
*Numbers should be sub-script
Triose - monosaccharide
C5-H10-O5 is the formula for…
*Numbers should be sub-script
Pentose - monosaccharide
C6-H12-O6 is the formula for…
*Numbers should be sub-script
hexose - monosaccharide
Features of a disaccharide…
Two simples sugars chemically linked by a glycosidic bond during a condensation reaction e.g.
Sucrose = glucose + fructose
lactose = glucose + galactose
Maltose = glucose + glucose
Sucrose =
glucose + fructose
glucose + fructose =
Sucrose
lactose =
glucose + galactose
glucose + galactose =
lactose
Maltose =
glucose + glucose
glucose + glucose =
Maltose
Features of polysaccharides
Lots of simple sugars in a chain chemically linked by glycosidic bonds, e.g.
Starch (Fuel storage in plants)
Glycogen (energy storage in animals)
Cellulose (major component of plant cell walls)
Importance of monosaccharides
All green leaves produce glucose using light and glucose is important in respiration
Glucose is which type of monosaccharide?
Hexose (C5-H10-O5)
What is the chemical formula for glucose?
C6-H12-O6
What shape does glucose take?
Cyclic
How many carbons does glucose have?
6 (hexose)
What is an isomer?
Molecules that have the same molecular formula but different structural formula
What is the molecular formula?
Shows the name and number of atoms in a molecule
What is the structural formula?
shows the way atoms are arranged in the molecule
Alph-glucose and beta-glucose differ by…
The positions of the H and the OH bound to the carbon-1.
In solution, glucose transitions between both structures
What is Benedict’s test?
When heated with Benedicts solution, the COOH group from the sugar reduces Cu2+ ions of copper(II) sulfate to Cu+ ions, which then form a brick-red precipitate of copper(I) oxide. In this process, the aldehyde group is oxidized to a carbonyl group (C=O).
If no reducing sugar is present the solution remains blue after heating.
The greater the sugar content, the bigger the color change.
blue -> green -> yellow –> brown -> red
What is Benedict’s solution?
An alkaline solution of copper(II) sulfate
What color is the solution in Benedicts test if there is no reducing sugar present?
Blue
What is the color sequence in Benedicts test if there is reducing sugar present?
blue -> green -> yellow –> brown -> red
blue -> green -> yellow –> brown -> red
is the sequence for which test? And what does it measure?
Benedicts test.
Measures the concentration of reducing sugar in a solution
Examples of hexose sugars
Glucose, fructose and galactose
Glucose, fructose and galactose are examples of what type of monosaccharide?
hexose
Ribose is what type of monosaccharide?
pentose. C5
Glyceraldehyde is what type of monosaccharide?
triose
What is the purpose of glyceraldehyde?
An intermediate in respiration and photosynthesis
What is the purpose of ribose
basic building block of RNA, ATP, NAD and NADP
Where would you find deoxyribose?
DNA
Where would you find deoxyribose?
DNA
What is the byproduct of the formation of disaccharides?
H2O
When two monosaccharides come together to form a disaccharide, what reaction occurs between the two macromolecules?
condensation
Because a H2O is produced
The bond between two monosaccharides in a disaccharide is known as a…
glycosidic bond