2.2 Biological Molecules Flashcards
(124 cards)
1
Q
Primarily, what are the 4 main elements all living things are made of?
A
Carbon, hydrogen, nitrogen and oxygen.
2
Q
What is the bonding rule for carbon?
A
Carbon atom can only form 4 bonds with other atoms.
3
Q
What is the bonding rule for nitrogen?
A
Nitrogen can only bonds to 3 other atoms.
4
Q
What is the bonding rule for oxygen?
A
Oxygen can only bond to 2 other atoms.
5
Q
What is the bonding rule for hydrogen?
A
Hydrogen can only bond to 1 other atom.
6
Q
Cation
A
When atoms loses 1 or more electrons, so has a positive charge.
7
Q
Anion
A
When an atoms gains 1 or more electrons, so has a negative charge.
7
Q
What are calcium ions responsible for? (important cations)
A
Nerve impulse transmission and muscle contraction.
7
Q
What are sodium ions responsible for? (important cations)
A
Nerve impulse transmission and kidney function.
7
Q
What are potassium ions responsible for? (important cations)
A
Nerve impulse transmission and stomata opening.
8
Q
What are hydrogen ions responsible for? (important cations)
A
Catalysis of reactions and PH determination.
9
Q
What are ammonium ions responsible for? (important cations)
A
Production of nitrate ions by bacteria.
10
Q
What are nitrate ions responsible for? (important anions)
A
Nitrogen supply to plants, amino acids and protein formation.
11
Q
What are hydrogen carbonate ions responsible for? (important anions)
A
Maintenance of blood PH.
12
Q
What are chloride ions responsible for? (important anions)
A
Balance of positive charge of sodium and potassium ions.
12
Q
What are phosphate ions responsible for? (important anions)
A
Cell membrane formation, nucleic acid, ATP formation and bone formation.
13
Q
What are hydroxide ions responsible for? (important anions)
A
Catalysis of reaction and
PH formation.
14
Q
What are biological molecules made up of?
A
Polymers-made up of multiple monomers joined together to form a chain.
15
Q
What are monomers that are used to make the polymer carbohydrates?
A
Monomers are sugars.
16
Q
What monomers are used to make polymer proteins?
A
Monomers are amino acids.
17
Q
What are polar molecules?
A
Molecules that have areas of positivity and negativity. One atom has greater share of electrons so is negative.
18
Q
Does water have high boiling point?
A
Yes. This is unusual for small molecules however the hydrogen bonding takes a lot of energy to break.
19
Q
Is water a polar molecule?
A
Water is a polar molecule. Oxygen has greater share of electrons compared to hydrogen, so oxygen is negative and hydrogen is positive.
20
Q
Density of water
A
Water becomes less dense when it is in solid state due to hydrogen bonds, which fix position further apart than average, so ice floats.
21
What does cohesive mean?
Moves as one mass because molecules are attracted to one another.
22
What does adhesive mean?
Where water molecules are attracted to other molecules.
23
Is water a solvent?
Yes. Water dissolves solutes.
24
Why does water act as a medium?
Acts as a medium for chemical reactions and transports dissolved substances.
25
Does water act as a coolant?
Yes. It helps buffer temperature in cells. This is important because cells need to remain at a constant temperature for enzymes.
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Why is water being stable useful?
Stable so doesn't change temperature or become a gas easily, so provides a constant environment. Surface tension is strong enough to support small insects.
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Method of Benedict's test for reducing sugars
1) Add sample into test tube ensuring it is in liquid form.
2)Add equal volume of Benedict's reagent.
3) Heat the mixture gently for 5 minutes.
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Results of Benedict's test for reducing sugars
+ = Brick red colour.
- = Blue colour.
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Why do reducing sugars change colour?
Reducing sugars change colour in Benedict's reagent because they react with copper ions in the reagent.
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Method for Benedict's test for non-reducing sugars
1) Add sample to test tube.
2)Heat non-reducing sugar with dilute hydrochloric acid.
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Results for Benedict's test for non-reducing sugars
Non-reducing sugar do not react with Benedict's reagent, so the solution remains blue after heating.
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What has happened to non-reducing sugar?
Non-reducing sugar has been hydrolysed by the acid to glucose and fructose, both are reducing sugar.
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Method for iodine test for starch
Add few drops of iodine dissolves in potassium iodide solution to the sample.
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Results of iodine test for starch
-If starch is present, solution turns a purple/black colour. This is a positive reaction.
-If there is no starch present, solution remains a yellow colour. This is a negative reaction.
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What is a reagent strip?
Reagent strip is manufactured to test the presence of reducing sugars.
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What is an advantage of using a reagent strip?
Concentration of the solution can be determined using a colour-coded chart.
37
What are carbohydrates made of?
Made from only carbon, hydrogen and oxygen.
38
What are carbohydrates ?
Most carbohydrates are polymers made up of monomers called monosaccharides. E.g. glucose and ribose.
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What is glucose made up of ?
Made up of 6 carbons in a hexose monosaccharide (hexose sugar). There are two structural variations of glucose: alpha and beta.
40
Properties of glucose
-It is a polar molecule.
- It is soluble in water due to hydrogen bonds formed between hydroxyl groups and water molecules. Bonds contain lots of energy.
This is important as glucose is dissolved in cytosol of cell.
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What is the cytosol?
Area of cytoplasm not held by organelles. Cytoplasm minus the organelles.
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What is ribose ?
Monosaccharide with 5 carbon atoms (pentose monosaccharide). Ribose is the sugar components of RNA nucleotides.
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How are polysaccharides formed ?
When 2 or more monosaccharides form together. Monosaccharides are joined together by glycosidic bonds. Hydrogen bonds from with hydroxyl group, which forms water leaving oxygen.
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What is hydrolysis reaction ?
Reverse of condensation when adding water to glycosidic bond to break it apart.
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Disaccharide
Formed with 2 monosaccharides joined together.
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What is starch ?
Main energy store in plants obtained from glucose. Excess glucose is stored as starch.
Made up of 2 polysaccharides: amylose and amylopectin
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Properties of starch
-Insoluble in water and is good storage as water doesn't enter via osmosis.
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Amylose
long, unbranched chain of alpha glucose, Angles of glycosidic bonds make it coil and compact, so good for storage.
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Amylopectin
long branched chain of alpha glucose, Side branches allow enzymes, that break down molecules, to access glycosidic bonds easily so glucose can be released quickly.
50
What is glycogen ?
Main energy store in animals, from glucose which in excess, is stored as glycogen. Has many branches do can be released quickly. Compact so good for storage.
51
Cellulose
Main component in plant cell walls. Long unbranched chains of beta glucose that form straight chains linked together by hydrogen bonds to form strong fibres called microfibrils. Strong fibrils means cellulose provides structural support for plant walls.
52
What are lipids ?
Lipids are macromolecules and are made up of carbon, hydrogen and oxygen. They are commonly known as fats or oils.
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What is a triglyceride ?
A type of lipid made up of one molecule of glycerol with 3 fatty acids attached to it. These are synthesised by the formation of an ester bond between each fatty. acid and glycerol molecule.
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How are ester bonds used in triglycerides ?
One triglyceride molecule has 3 ester bonds. Each bond is formed by a condensation reaction. The process in which triglycerides are synthesised is called esterification.
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When an ester bond is broken, what happens to the triglyceride ?
Triglycerides break down when ester bonds are broken. Each ester bond is broken in a hydrolysis reaction.
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What are fatty acid tails ?
Fatty acid tails are made up of hydrocarbons. The tails are hydrophobic (repel water) and make lipids insoluble in water.
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What are saturated fatty acid tails ?
Saturated fatty acid tails have no double bonds between carbon atoms in their hydrocarbon tails. Fatty acid is saturated with hydrogen.
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What are unsaturated fatty acid tails ?
Unsaturated fatty acid tails have at least 1 double bonds between carbon atoms. This causes the chain to kink, leading to a kink in the tail.
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What are phospholipids ?
Like triglycerides, except one of the fatty acid molecules is replaced by a phosphate group. Phosphate group is hydrophilic and fatty acid tails are hydrophobic.
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What is cholesterol ?
Cholesterol is another type of lipid, with a hydrocarbon ring structure attached to a hydrocarbon tail. The ring structure has a polar hydroxyl group attached to it.
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What is the structure of a triglyceride ?
Made of one glycerol molecule and 3 fatty acid tails. Hydroxyl groups between triglycerides interact and form an ester bond between glycerol and fatt acid.
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What is the function of a phospholipid ?
Found in membranes of all eukaryotes and prokaryotes. They make up the phospholipid bilayer. Cell membranes control what enters in and out of the cell. Centre of the bilayer is hydrophobic, so water soluble substances cannot easily pass through it.
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What is the general function of cholesterol ?
In eukaryotic cells, cholesterol molecules help regulate the fluidity of the cell membrane by interacting with phospholipid bilayer. Has small size and flattened shape, so it can fit between phospholipid molecules in the membrane.
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What is the function of cholesterol at higher temperatures ?
At higher temperatures, they bind to hydrophobic tails of phospholipids, causing them to pack more closely together. This helps to make the membrane less fluid and more rigid.
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What is the function of cholesterol at lower temperatures ?
At lower temperatures, cholesterol prevents phospholipids from packing too closely together, so increases membrane fluidity.
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What are proteins ?
Proteins are polymers made up of monomers of amino acids. Proteins are made up of one or more polypeptide.
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What is a dipeptide ?
Formed when 2 amino acids are joined together.
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What is a polypeptide ?
Formed when more than 2 amino acids join together.
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What is the structure of amino acids ?
Amino acids have the same general structures. A carboxyl group (COOH) and an amino acid group (NH3) attached to a carbon atom.
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What is the difference between amino acids ?
The variable group (the thing that changes)
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What does the general structure of amino acids look like ?
R (Variable group)
I
H2N-C-COOH
I
H
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How are amino acids linked together to form dipeptides and polypeptides ?
Linked by peptide bonds. One molecule of water is released during this reaction as it is a condensation reaction. The reverse of this is a hydrolysis reaction.
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What is the primary protein structure ?
When amino acids join together. Different proteins have different sequences of amino acids in their primary structure and this sequence influences how the protein will fold. Only has peptide bonds.
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What does a change in an amino acid result in ?
A change in 1 amino acid may change a whole structure of proteins. It is held together by peptide bonds between amino acids.
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What is the secondary protein structure ?
Polypeptide chain does not stay flat. Hydrogen bonds form between NH and CO groups of the amino acids This causes a chain to coil or fold.
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What is the tertiary structure of a protein ?
Coiled or folded chain of amino acids is often coiled further. More bonds form between different parts of polypeptide chains as R groups are closer so can interact. Can form hydrogen, ionic and disulphide bonds.
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What are disulphide bonds ?
Whenever 2 molecules of amino acids cysteine come close together. Sulphur joins with sulphur forming disulphide bonds.
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What affects how proteins fold up ?
When hydrophobic variable groups are close in a protein, they clump so hydrophilic groups are more likely to be pushed outside affecting how protein folds up.
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What is the quaternary proteins structure ?
Some proteins are made of several different polypeptide chains held together by bonds. Is the way quaternary structure and polypeptide chains are assembled.
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What is a globular protein ?
It is round and compact as hydrophilic r groups on amino acids tend to be pushed to outside of the molecule. It is soluble so are easily transported. Have a range of functions in living organisms.
E.g., haemoglobin
81
What are fibrous proteins ?
Tough and roped shaped. Insoluble, strong and fairly unreactive. E.g., collagen, keratin, elastin.
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What is chromatography used for ?
Used to separate mixtures E.g., biological molecules. There is paper chromatography and thin layer chromatography( solid, glass, plastic).
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What is the mobile phase ?
Molecules can move.
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What is the stationary phase ?
Molecules cannot move.
85
How to work out Rf value (retention factor) ?
Distance moved by solute/ distance moved by solvents.
(Spots/solute)
Call has to be between 0 and 1.
86
What are DNA and RNA made up of?
Essential to function of living organisms and are both made up of nucleotides.
87
What is a nucleotide ?
Biological molecule made up of a pentose sugar, nitrogen containing base and a phosphate group. (Elements C, O , N, H, P)
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What is the function of DNA, RNA, ADP and ATP ?
-DNA = stores genetic information.
-RNA = Makes up proteins from DNA.
-ADP +ATP = Store and transport energy.
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What are the bases and how many bonds are formed between them?
Adenine, guanine, cytosine and thymine.
A-T = double hydrogen bond
C-G = Triple hydrogen bond
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What does RNA contain ?
Contains ribose sugar (not deoxyribose)
Phosphate group and bases : adenine, guanine, cytosine and uracil.
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Purines
Adenine and guanine are purines.
They contain 2 carbon-nitrogen rings.
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Pyrimidines
Cytosine, thymine and uracil are pyrimidines.
They only have one carbon-nitrogen ring.
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ATP structure
ATP is a phosphorylated nucleotide.
Contains base adenine, sugar ribose, base and 3 phosphate groups.
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ADP structure
ADP is a phosphorylated nucleotide.
Contains base adenine, sugar ribose and 2 phosphate groups.
95
How does a cell get energy (not directly from glucose)?
Cell does not get energy directly from glucose. Energy from glucose makes ATP and provides energy for chemical reactions. ATP is synthesised from ADP, an inorganic phosphate, to form ATP and a phosphate bond is formed. Energy is stored in phosphate bond and is broken bak down when needed.
96
What is DNA made up of ?
Made up of 2 nucleotide chains that are joined together to form polynucleotides.
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Where does polynucleotide join up between ?
They join between phosphate group and sugar via condensation. This forms a phosphodiester bond.
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What is the chain of sugars and phosphate known as ?
Known as sugar phosphate backbone. The polynucleotides can be broken down by hydrolysis.
99
Why does DNA replicate ?
-So each new cell has same amount of DNA.
-Important for making new cells and passes genetic information from generation to generation.
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What is the first step into DNA replication ?
DNA helicase enzyme breaks hydrogen bonds between polynucleotide DNA strands and forms 2 strands.
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What happened during DNA replication once the strands have separated?
Each strand act as a template for a new strand. Free floating DNA nucleotides join to exposed bases on each original template strand by complimentary base pairing.
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What is the 3rd step in DNA replication once template has been made ?
DNA polymerase joins a together nucleotides on a new strand. Forms sugar-phosphate backbone and hydrogen bonds forms between bases on original strand and bases on new strand. Strands twist together.
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How accurate is DNA replication ?
Very accurate to make sure generic information is conserved.
Spontaneous mutations can occur.
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What is a mutation ?
Change in sequence of DNA bases.
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What is a gene ?
Sequence of DNA nucleotides that code for a polypeptide.
106
What forms a protein ?
Sequence of amino acids in a polypeptide form primary structure of a protein. Different proteins have different number and order of amino acids. Order of nucleotide bases in a gene that determines order of amino acids.
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What is each amino acid coded by ?
Coded by 3 bases called a triplet in a gene. Sequence of bases in a section of DNA is a template that is used to make proteins during protein synthesis.
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What is mRNA ?
Copied section of DNA that can move out of nuclear pores and into cytoplasm, where it is used to make a protein during translation.
Made in nucleus during transcription.
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What is transcription ?
Section of DNA is copied, called mRNA and can leave nucleus.
First stage of protein synthesis.
Occurs in the nucleus.
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What is translation ?
Occurs in cytoplasm.
Where mRNA joins with ribosomes, where it can be used to synthesis a protein.
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What is RNA ?
It is a single polynucleotide strand that contains uracil instead of thymine, which pairs with adenine during protein synthesis.
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What is tRNA ?
Single polynucleotide strand that is folded into a clover shape, which is held together by hydrogen bonds.
Specific sequence of bases have an anticodon on one end, and an amino acid on the other.
Found in cytoplasm, where it carries amino acids for translation.
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What is rRNA ?
Forms 2 sub-units in a ribosome, along with proteins. Ribosome moves along mRNA strand.
rRNA in ribosome, catalyses formation of peptide bonds between amino acids.
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What is the genetic code ?
Sequence of base triplets in DNA or mRNA, that code for a specific amino acid.
Also degenerate, as there are more codons than amino acids, so some codons code for the same amino acid.
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What enzyme breaks double helix in transcription ?
-RNA polymerase separates DNA strands due to hydrogen bonds breaking.
-One strand is used as template.
-Complementary strand is made (mRNA) - uracil instead of thymine.
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What enzyme joins together strands in transcription ?
-RNA polymerase passes by strands and hydrogen bonds reform and double helix re-assembles.
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How does transcription stop ?
When RNA polymers reaches a stop codon, it stops making mRNA and detaches from DNA. mRNA can move out of nucleus via nuclear pores.
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What does mRNA do when left the nucleus (translation) ?
mRNA attached to ribosomes in cytoplasm and tRNA molecules carry amino acids to ribosomes.
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What does tRNA molecule have in translation ?
Has anticodon that is complementary to start of codon on mRNA. Attaches by complementary base pairing. Second tRNA molecule attaches in same way.
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