Biological Molecules Flashcards
Glucose + _____ makes maltose
Glucose + glucose makes maltose
Glucose + fructose makes _____
Glucose + fructose makes sucrose
Glucose + _____ make lactose
Glucose + galactose makes lactose
What is a reducing sugar?
A sugar that donates electrons
Glucose + glucose –> maltose
What type of reaction is this?
Condensation
Fill in the blank:
Polymers are molecules made from a large number of _____
joined together.
Monomers
Fill in the blank:
Monosaccharides, amino acids and nucleotides are examples of
____.
Monomers
A condensation reaction involves the elimination of what molecule?
A water molecule
What is hydrolysis?
Breaking a chemical bond with water
Two monosaccharides are formed in what type of reaction?
A condensation reaction
Two monosaccharides are joined together in a reaction. What type of bond is formed?
A glycosidic bond.
Glucose has two isomers: alpha and beta. What is the difference in their structures?
In alpha glucose both OH groups are at the bottom/top whereas in beta glucose one OH group on top, one of bottom
Glycogen and starch are formed by the condensation reactions of which glucose isomers?
Alpha glucose
Cellulose is formed by the condensation of which glucose isomer?
Beta glucose
Triglycerides are formed in what type of reaction?
A condensation reaction
Triglycerides are formed in a condensation reaction from which molecules?
One molecule of glycerol and three molecules of fatty acid.
The condensation reaction between a glycerol and a fatty acid forms which type of bond?
An ester bond
What is the difference between a phospholipid and a triglyceride?
In phospholipids, one of the fatty acids of a triglyceride is substituted
by a phosphate-containing group.
What is the general structure of a amino acid?
A central carbon with an R group, an H, a carboxylic acid group (COOH) and an amine (NH2) group attached to it.
What is the bond between two amino acids called?
A peptide bond
How are peptide bonds formed?
A condensation reaction between two amino acids.
How do enzymes catalyse a reaction?
By lowering the activation energy
Is starch a monosaccharide, disaccharide or polysaccharide?
Polysaccharide
Is sucrose a monosaccharide, disaccharide or polysaccharide?
Disaccharide
Is fructose a monosaccharide, disaccharide or polysaccharide?
Monosaccharide
Is glycogen a monosaccharide, disaccharide or polysaccharide?
Polysccharide
What are the monomers of DNA called?
Nucleotides
Nucleotides are formed from three key parts. What are they?
A phosphate group, pentose sugar and a nitrogen containing base.
A condensation reaction between two nucleotides form what type of bond?
A phosphodiester bond
What are the key components of a DNA nucleotide?
A deoxyribose sugar, a phosphate group, and one of the organic bases: adenine, cytosine, guanine or thymine.
What are the key components of a RNA nucleotide?
A ribose sugar, a phosphate group, and one of the organic bases: adenine, cytosine, guanine or uracil.
What are three differences between DNA and RNA?
DNA has deoxyribose sugar, whereas RNA has ribose sugar
DNA is larger/longer than RNA/RNA is shorter
DNA contains thymine, RNA contains uracil instead
DNA is double stranded, RNA is single stranded
What are 3 features of a fibrous molecule?
Insoluble
Roles tend to be structural
Remains as a long chain
Very strong and stable
What are 3 features of a globular molecule?
Compact, spherical Soluble (hydrophilic side chain) Not very stable Range of function Usually shape specific
How does temperature affect rate of reaction?
Increasing temperature increase the kinetic energy of the molecules therefore increasing the number of collisions and so increasing the rate of reaction. However, this only to an extent –> will denature if too hot
How does pH affect rate of reaction?
pH can alter tertiary structure and therefore active site, thus halting reactions from occurring.
How does DNA replicate?
DNA is unwound
Helicase breaks the H bonds b/wn bases to unwind strands
Free nucleotides H bond w/ exposed complementary bases
DNA polymerase joins nucleotides on 1 strand together to make a new strand forming phosphodiester bonds
Hydrogen bonds b/wn strands reform
Rewinds
Why is DNA replication known as semi-conservative?
In each DNA, one strand is old, one strand is new
Why is ATP an ideal short term energy currency? Give three reasons
Very quickly broken down (quicker than glucose)
Small amounts released (minimal wastage)
Easy to remake
Can’t move in/out of cells so therefore is always available in the cell
Why is glucose a more ideal long term energy currency than ATP?
Glucose releases more energy, and at a slower rate. It is also larger
Carbs can be stored as glycogen
What are the 3 components of an ATP molecule?
An adenine molecule, a ribose sugar, and three phosphate groups
The hydrolysis of ATP is catalysed by which enzyme?
ATP hydrolase
ATP is hydrolysed to what?
ADP (adenosine diphosphate) and an inorganic phosphate group (Pi)
The inorganic phosphate released in the hydrolysis of ATP can be used to reform ATP. What else can it be used for?
To phosphorylate other compounds, often making them more reactive
ATP is resynthesised by the condensation of ADP and Pi. This reaction is catalysed by what enzyme?
ATP synthase
ATP hydrolase catalyses what reaction?
The hydrolysis of ATP into ADP and Pi
Give 4 key properties of water
Water:
Is a metabolite in many metabolic reactions (inc hydrolysis and condensation reactions)
Is an important solvent in which metabolic reactions occur
Has a relatively high specific heat capacity, buffering changes in temp.
Has a relatively large latent heat of vaporisation, providing a cooling effect w/ little loss of water through evaporation
Has a strong cohesion b/wn water molecules; supports columns of water in the tube like transport cells of plants and produces surface tension where water meets air
What makes up cell walls in plants?
Cellulose
Which microscope has the best resolution?
TEM
What are triglycerides used for?
Energy storage
What is the structure of a nucleotide?
A pentose sugar, an nitrogenous base and a phosphate group
What type of bond joins the phosphate group and pentose sugar in a nucleotide?
An ester bond
What type of bond joins the pentose sugar and the nitrogenous base in a nucleotide?
Glycosidic bond
What is the name of the monomers that make up DNA?
Nucleotides
What are the three basic components that make up RNA?
Ribose sugar, nitrogenous base and a phosphate group
How is DNA adapted for its function?
Stable - Able to pass from generation to generation with no change
Strands may be separated to allow replication
Large - able to carry lots of information
Base pairs with helix
Genetic information protected by strong sugar-phosphate backbone
What type of bond forms between DNA nucleotides?
Phosphodiester
What are the key differences between DNA and RNA?
RNA has uracil, DNA has thymine
RNA has ribose, DNA has deoxyribose
RNA is single stranded, DNA is double stranded
What enzyme breaks the hydrogen bonds between the complementary bases?
DNA helicase
What is the role of DNA polymerase in DNA replication?
Joins the nucleotides on one strand together
Describe the process of DNA replication
Helicase breaks bond between complementary base pairs, allowing helix to be unwound
Free nucleotides form hydrogen bonds with their complementary exposed bases
DNA polymerase joins the nucleotides on one strand together
Name the chemical elements in a non-reducing sugar
Carbon, hydrogen and oxygen
The condensation of alpha glucose leads to the formation of what polysaccharide?
Glycogen
Starch
The condensation of beta glucose leads to the formation of what polysaccharide?
Cellulose
Which type of saccharides form insoluble or colloidal structures?
Polysaccharides
Which two polymers of glucose make up starch?
Amylose and amylopectin
Which glucose isomer forms branched chains?
Alpha glucose
Which glucose isomer forms unbranched chains?
Beta glucose
What is the main role of starch?
Energy storage
What is the animal equivalent of starch?
Glycogen
What is the plant equivalent of glycogen?
Starch
How is the structure of starch related to its function?
Insoluble - doesn’t affect water potential so water not drawn in by osmosis
Large and insoluble - doesn’t diffuse out of cells
Helical/spiral/coiled - compact, lots stored in small space (from MS)
(When hydrolysed forms ⍺ glucose - easily transported and readily used for respiration
Branched form has many ends - glucose monomers released rapidly)
What is the key difference between the structure of starch and the structure of glycogen, and why is it necessary?
Glycogen has more branching - animals use more energy generally, so can be more rapidly broken down to release glucose
Where is glycogen primarily found in animals?
In the muscles and in the liver
How is the structure of glycogen related to its function?
Insoluble - doesn’t affect water potential so water not drawn in by osmosis
Large and insoluble - doesn’t diffuse out of cells
Compact - lots stored in small space
When hydrolysed forms ⍺ glucose - easily transported and readily used for respiration
Branched form has many ends - glucose monomers released rapidly (more so than starch)
What is the key difference in the structure of cellulose when compared to starch and glycogen?
Cellulose is made from ϐ glucose, starch and glycogen made from ⍺
Describe the structure of cellulose
ϐ glucose form straight, unbranched chains that are parallel to each other
H bonds form between chains forming cross-linkages
Cellulose molecules grouped to form microfibrils
Which of these are found in plants: cellulose, starch, glycogen
Cellulose and starch
How is the structure of cellulose related to its function?
ϐ glucose –> long, straight, unbranched molecules
Chains run parallel to each other to form H bonds - collectively add strength
Molecules grouped to form microfibrils, which in turn form - collectively add strength
What are the two main groups of lipids?
Triglycerides and phospholipids
What are some of the key roles of lipids?
Source of energy
Waterproofing - insoluble in water
Insulation - slow conductors of heat
Protection
Hydrolysis of a triglyceride produces what?
Glycerol and three fatty acids
What chemical group do all fatty acids contain?
-COOH attached to a hydrocarbon chain
What is the main difference between fats and oils?
Fats = solids at room temp, oils = liquids
What bond is formed between the fatty acid and glycerol in a triglyceride?
Ester bond
Esterification is what type of reaction?
Condensation
Describe how the structure of a triglyceride is related to its properties
High ratio of energy storing C-H bonds : C atoms - good energy source
Low mass to energy ratio - good storage molecules
Insoluble in water (large and non-polar) - don’t affect water potential of cells or osmosis
High ratio of O to H - release H2O when oxidised - important source
Describe how the structure of a phospholipid is related to its properties
Polar (hydrophobic tail, -philic head) - form a bilayer
Phosphate ‘heads’ - help to hold at surface of cell surface membrane
Structure allows them to form glycolipids - combine w/ carbs within the cell surface membrane
What term describes a fatty acid with more than one C double bond?
Polyunsaturated
What term describes a fatty acid with one C double bond?
Monounsaturated
What term describes a fatty acid with no C double bonds?
Saturated
Describe and explain what having C double bonds does to the melting point of a fatty acid
Lowers it - creates a kink which means chains can’t pack as closely together
‘A single polypeptide chain’ describes what structure of a protein?
Primary
Describe the primary structure of a protein
Many amino acid monomers which have reacted to form a single polypeptide chain
Describe the secondary structure of a protein
Can either form an alpha helix (twist into helix) or beta pleated sheet (‘fold’)
Describe the tertiary structure of a protein
Different parts of the polypeptide chain are attracted to each other, causing the secondary structure to fold and twist into more complex and specific 3D shapes.
What are the three main types of bond found in the tertiary structure of a polypeptide?
Disulfide bridges
Ionic bonds
Hydrogen bonds
What is the strongest type of bond found in the tertiary structure of a protein?
Disulfide bridges
Describe the quaternary structure of a protein
Multiple polypeptide chains combine to form one larger, more complex 3D molecule
Not all proteins have this
Which type of inhibitor binds to the allosteric site of an enzyme?
Non-competitive
Which type of inhibitor binds to the active site of an enzyme?
Competitive
Describe the induced fit model of enzyme action
The active site has a certain general shape, which alters in the presence of a substrate to fit around the substrate
The active site is complementary to an extent
Describe the lock and key model of enzyme action
The active site is a specific shape. It is also rigid, and so the substrate must be the exact complementary shape.
Describe the structure of proteins (5) PPQ
- Polymer of amino acids;
- Joined by peptide bonds;
- Formed by condensation;
- Primary structure is order of amino acids;
- Secondary structure is folding of polypeptide chain due to hydrogen bonding;
- Tertiary structure is 3-D folding due to hydrogen bonding and ionic/disulfide bonds;
- Quaternary structure is two or more polypeptide chains;
