biochemistry Flashcards
Cohesion
the sticking together of particles of the same substance.
surface tension
A measure of how difficult it is to stretch or break the surface of a liquid
water properties
-High heat capacity
-molecules of water cling together (high cohesion)
-high surface tension
-frozen water is less dense than liquid water (water anomaly)
Monomer
a small chemical unit that makes up a polymer
Polymer
A long molecule consisting of many monomers linked together.
Carbohydrates
a family of molecules that are made mainly of oxygen, hydrogen and carbon.
suffix: “OSE”
general formula: (CH₂O)n
Monosaccharides
the monomers that compose all carbohydrates.
general formula: (CH₂O)n
n is a number between 3 to 6, therefore there are three types of monosaccharides:
Triose: 3 carbons in the backbone
pentose- 5 carbons in the backbone
hexose- 6 carbons in the backbone
How many fast acids chains are found in phospholipids?
2
Water polarity
Negative dipole on the oxygen atom
Portage dipole on the hydrogen atoms
How many hydrogen bonds can a water molecule form?
4 bonds
1 from each hydrogen
2 from the oxygen
Why does the cohesion in water very high?
Because of the dipole-dipole forces and the hydrogen bonds they form.
What are macromolecules?
Built by repetitive molecules called monomer, and are linked together to form a large molecule called polymer.
Monomers are not always identical to each other
Polymers can be in different lengths
What types of macromolecules exist in biochemistry?
4 kinds:
- proteins
- nucleic acid
- carbohydrates/ polysaccharides (sugar)
- lipids
What type of monomers form protein?
Amino acids
What type of monomers form nucleic acid?
Nucleotides
What type of monomers form carbohydrates?
Monosaccharides
What type of subunits form lipids?
Fatty acids
Which of the macromolecules is not a polymer?
Lipids
What is the general formula of carbohydrates?
( CH2O )n
What are the main functions of carbohydrates?
- Energy source
- mechanical support
- building blocks
What are the main types of monosaccharides?
- Trioses (3 carbon sugar)
- Pentoses (5 carbon sugar) → ribose, deoxyribose
- Hexoses (6 carbon sugar) → glucose
What is the structure of monosaccharides?
Ketone or aldehyde
Depends on their location on the carbonyl
What are structural isomers?
Same chemical composition, but differ in the place of the carbonyl group and in the place/ orientation of the OH group
What are stereo isomers in saccharides?
Mirror image of one another
2 forms:
D- form
L-form
What happens to monosaccharides in water?
They will always close to a ring.
The ring will always dose by the oxygen.
The carbon outside of the ring will always be last!
What is the difference between a-glucose and b-glucose?
A-glucose → OH below carbon no. 1
B -glucose → OH above carbon no. 1
A- bond (alpha bond)
our body can break this bond
A band between to A- glucose
B-bond (beta-bond)
A bond between a beta - glucose
# our body cannot break this bond
What is glucose?
C6H12O6
# Most impotent building block
# all living organisms can break it during cellular respiration for energy
What differ glucose from galactose?
Their OH group on carbon number 4 is in different location
What is fructose?
Fruit sugar
# differ in the location of the carbonyl group.
What is a condensation reaction?
A molecules connect by releasing a smaller molecule (like water).
Usually requires energy.
What is a glycosidic bond?
Is Made by a condensation reaction
Covalent band between 2 cyclic monosaccharides.
# an oxygen losing A hydrogen
# carbon is losing OH group
What is a Hydrolysis?
The reverse reaction to a condensation reaction.
Water is consumed to break glycosidic bond & form 2 monomers
Release energy
What are disaccharides?
Two monosaccharides linked by glycosidic bond
What are oligosaccharide?
Composed of 2-10 monosaccharides linked together
Where are the main types of disaccharides?
- Lactose ( C12H22O11 )
- maltose ( C12H22O11 )
- sucrose ( C12H22O11 )
What Latin lactose?
Disaccharide
“Milk sugar”
Contain a molecule of galactose & one of glucose linked by condensation relation
Found in milk, catabolized by the enzyme lactase.
What is sucrose?
Most common disaccharide
“Table sugar”
Contains one glucose & one fructose
What is maltose?
Disaccharide
Found in germinating seeds
2 glucose molecules linked together.
What are the main functions of polysaccharides?
- Energy storage ( starch: plants, glycogen: animals)
- building strong cellular structures
What are the most common polysaccharides?
- Glycogen
- starch
- cellulose
Whet is the structure of glycogen?
Branched chains, each comprised of 8-12 glucose monomers
- bonds making the chains→ a (1-4) linkage
- bonds within the branches → a (1-6) linkage
What is the main function of glycogen?
Energy storage
Found in the liver and muscle tissue & fungi and bacteria.
What are the main functions of starch?
Energy storage in plants
# may be consumed by animals
What is starch composed of?
Composed of 2 types of glucose polymers:
1. Amylose ( straight chain )
2. Amylopectin (branched chain)
Is starch soluble?
- it becomes soluble in water when it’s heated
- through the activity o amylases
What type of bond form cellulose?
B( 1 → 4) glycosidic bonds
Thee glucose chains are bonded to each other by hydrogen bonds.
Where can we find cellulose?
Cell walls of green plants
Is cellulose soluble?
No!! (Water insoluble )
Non digestible dietary fiber
What are glycoprotein?
Small oligosaccharides covalently bonded to protein.
What are glycolipids?
Small oligosaccharides covalently bonded to lipids
What are proteoglycans?
A core protein bonded to many saccharide chains.
What is differ proteoglycans from glycoprotein?
Size of the sugar compared to the protein groups.
Glycoprotein → small saccharide chains, most of the molecule is composed of the peptide.
Proteoglycans → small protein core, most of the molecule is composed of oligosaccharides and polysaccharides.
What are the monomeric units in DNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
What are the monemeric units in RNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U)
What defines the classification of nucleotides?
The number of nitrogenous rings:
Purines → contain 2 ring of 5 and 6 atoms ( A, G)
Pyrimidines → contain one ring of 6 atoms ( T, C, U)
What is a nucleoside?
The complex of sugar attached to one of the nitrogenous bases without the phosphate group
Which bond forms the nucleotide chains?
Phosphodiester bond.
Condensation reaction → the phosphate group is linked to the sugar
Does the nucleotide backbone has directionality?
Yes.
5’ end → free phosphate group
3’ end → free OH group
What are fatty acids?
Amphoteric molecule → long carbon tail and an OH group
What are are the most familiar lipids?
Oils & fats
In what way do fatty acids differ from one another?
- No. Of carbons in their hydrophobic chain (14 - 20 carbons)
- Degree of unsaturation
According to what is the degree of saturation depends on?
→ no C = C: fully saturated
→ one C = C: monoustaturated
→ many C = C: highly unsaturated.
How does the degree of saturation affect the packing of the molecule?
Double bonds form “kinks” in the molecule.
The more “kinks”, the less packed it can be with other molecules.
In what way do oils and fats differ from each other?
Their state at room temp.
Fats → solid
Oil → liquid
What type of link is between alcohol and fatty acids?
Condensation reaction creating an ester bond (r- coor)
What is glycerol?
Simple organic molecule
# part of the alcohol family - contains 3 hydroxyl groups
# C3H8O3
What are triglycerides?
Most common lipid
#fats & oils
# composed of one glycerol molecule and 3 fatty acids by individual ester bonds.
# hydrophobic & water insoluble
# their fatty acids tails can be of different length
What are the main roles of triglycerides?
- ** energy storage** - when the body doesn’t have available sugar to use it can break the fatty acid and make glucose for use.
- ** insolation** - homeostasis ( core temp.)
- Water source - during respiration , triglycerides can be converted to carbon dioxide and water.
What are phospholipids?
Amphoteric molecule → hydrophilic region (phosphate group bonded to glycerol ), hydrophobic area (2 fatty acids )
What is the west important role of phospholipids?
Form the double layered lipid membrane het surrounds all living cells.
What happens to phospholipids in aqueous environment?
The fatty herds organize in two layers.
The hydrophobic layer point award one another, the hydrophilic areas point outward ( micelle)
What are sterols?
Structural lipids.
Found in many eukaryotic cell’s membrane.
What are the functions of sterols?
- Structural lipids
- Precursors for other products - hormones, bile acids, etc…
Wet is the structure of sterols?
All sterols contain carbon skeleton (steroid nucleus )→ 4 fused carbon rings ( planar rigid plane)
How different steroids are distinguished ?
By the chemical groups attached to the steroid rings.
What are steroids?
A family of hormones ( sterol derivatives)
# cholesterol is the most common steroid, serves as a precursor
What do steroids affect?
Gene expression & metabolism
What is the structure of amino acids?
** Central carbon ** (alpha carbon ) connected to:
1. Amine group - NH2
2. Carbonyl head group - COOH
3. Hydrogen atom
4. R group
What determines the amino acid type?
The R group
How many types of amino acids are there?
20
What are essential amino acids?
9 amino acids that cannot be synthesized in the body, and therefore must be consumed from external sources, mainly through nutrition.
To what groups can the amino acids be classified into?
Most important → polar vs. Non-polar
Also,
Hydrophobic & hydrophilic, acidic & basic…
What is a zwitterion?
The head - base reaction will form it
both positive and negative charges in the some molecule →
carbonyl end (-)
Amine end (+)
Whet is a peptide bond?
Covalent bond between amino acids to form a protein chain.
The bond forms by a condensation reaction.
The bond forms between a carboxylic acid and an amino group.
Forms the protein backbone.
What is the directionality of the polypeptide chain?
N - terminus - free amino acid, always on the left side
C - terminus - free carboxylic group
How many peptide bond can each amino acid form?
2!
What is a dipeptide ?
Two amino heads only linked to each other.
How many levels does the protein structure has?
4 levels.
Primary, secondary, tertiary and quaternary
What does the primary structure refer to?
The amino acid sequence (their type and the order in which they are joined).
Only proteins of the same kind will have the same primary structure.
What does the secondary structure refer to?
The formation of local substructures, based on hydrogen bonds.
# Results from the coiling (folding) of the amino acid chain because of the hydrogen bonds between the carboxylic acid and the amine group.
What are the most common secondary structures?
AIpha-helix ( a- helix)
Beta pleated sheet (b- pleated sheet)
What is the shape of the alpha helix structure?
A helical structure, reminds a corkscrew.
Held in place by multiple hydrogen bonds.
How much space is created between amino acids in an alpha helix structure?
4 positions apart
Amino acid 1 will bond to amino acid 5
What is the shape of a beta - pleated sheet structure?
Looser & straighter than a-helix.
Can be classified to two structures:
1. Anti-parallel beta sheet
2. Parallel beta sheet.
What is a coiled coil structure?
Two alpha helixes can combine to form a coiled coil.
The structure is held by R group interactions.
