Topic 1 Flashcards
1
Q
What is the structure of a water molecule
A
It has an oxygen molecule with 2 hydrogen molecules that are at a 104.5 degree angle from the oxygen
2
Q
What bonds do water molecules have
A
Hydrogen bonds
3
Q
What are the 8 properties of water
A
- water is a polar solvent making it excellent at dissolving ionic substances
- an excellent transport medium
- ice is less dense than water
- water molecules are cohesive
- water molecules are adhesive
- water is slow to absorb and release heat
- water can’t be compressed
- water has a very high surface tension
4
Q
What is every carbohydrate made up of
A
Carbon, hydrogen and oxygen
5
Q
What are the 3 main groups of carbohydrates
A
Monosaccharides, polysaccharides and disaccharides
6
Q
What is a monosaccharide
A
They are simple sugars in which there is 1 oxygen atom and 2 hydrogen atoms for each carbon atom present in the molecule. The general formula for this is CH2O
7
Q
What is the structure of alpha and beta glucose
A
Look on page 19 for answer
8
Q
What are disaccharides
A
Disaccharides are made up of two monosaccharides joined together in a condensation reaction
9
Q
What is the link between two monosaccharides called
A
Glycosidic bond
10
Q
What are oligosaccharides
A
Molecules with a 3-10 chain
11
Q
How is the glycosidic bond between 2 monosaccharides split
A
By a hydrolysis reaction ( the breaking of water)
12
Q
What 2 compounds is starch made up of
A
Amylose and amylopectin
13
Q
What molecule is starch made up of
A
Many alpha glucose molecules
14
Q
What is the difference between amylose and amylopectin
A
Amylose is made up of purely alpha glucose molecules joined by 1-4 glycosidic bonds whereas amylopectin is joined by 1-4 glycosidic bonds with a few 1-6 glycosidic bonds which results in branching chains
15
Q
Why do athletes like starchy foods
A
Because they have both amylopectin and amylose and amylopectin releases glucose for respiration rapidly whereas amylose releases glucose more slowly over a long period to keep you going
16
Q
Where is glycogen stored
A
It is stored in the muscles and liver
17
Q
What is the structure of glycogen
A
They have 1-4 and 1-6 glycosidic bonds giving it many side branches
18
Q
What is the structure of cellulose
A
They have beta glucose molecules and are held together by 1-4 glycosidic bonds where one of the monomers has been inverted (turned over) so the bonding can take place. They also have many hydrogen bonds
19
Q
What is the difference between fats and oils
A
Fats are solid at room temp and oils are liquid at room temp
20
Q
What do all lipid molecules contain
A
Oxygen, carbon and hydrogen however they have fewer oxygen atoms than carbohydrates
21
Q
What are the 2 organic chemicals that fats and oils are made up of
A
Fatty acids and glycerol
22
Q
What bond combines fatty acids and glycerol
A
Ester bonds
23
Q
What is the chemical formula for glycerol
A
C3H8O3
24
Q
What do all fatty acids have
A
They have a long hydrocarbon chain a pleated backbone of carbon atoms with hydrogen atoms attached and a carboxyl group (COOH) at the end
25
What is the difference between saturated and unsaturated fatty acids
In saturated fatty acids each carbon atom is joined to the next one by a single covalent bond whereas unsaturated fatty acids have one or more double covalent bonds in them
26
How are Ester bonds formed
A fat or oil results when glycerol combine with 1,2 or 3 fatty acids .A bond is formed in a condensation reaction between the carboxyl group and one of the hydroxyl groups of the glycerol (-OH). A molecule of water is removed and the resulting bond is an Ester bond
27
What is the structure for an amino acid
They always have an amino group (-NH2), and a carboxyl group attached to a carbon atom. They also have an r group which depends on the amino acid
28
How are proteins formed from amino acids
Amino acids react between there amino group and carboxyl group of another. They join in a condensation reaction. A peptide bond is formed when they join and a dipeptide is formed. When more amino acids join this forms a polypeptide chain and this folds to form a protein
29
What other bonds can there be in proteins
Hydrogen bonds, disulfide bonds and ionic bonds
30
How are hydrogen bonds formed in proteins
There are tiny negative charges on the oxygen of the carboxyl group and positive charges on the hydrogen atoms of the amino group. The opposite charges attract forming a hydrogen bond
31
How are disulfide bonds formed in proteins
They form when two cysteine molecules are close together in the structure of a polypeptide. Oxidation reaction takes place between the 2 sulfur containing groups resulting in a strong covalent bond known as a disulfide bond
32
How are ionic bonds formed
They form between strongly positive and negative amino acid side chains found buried deep in the protein molecule
33
What are the 4 structures of proteins
Primary structure, secondary structure, tertiary structure and quaternary structure
34
What is the 1st structure of proteins
The first structure is a chain of polypeptides
35
What is the second structure of proteins
The second structure is alpha helix and beta pleated sheets which have a hydrogen bond
36
What is the third structure of proteins
The 3rd structure has ionic bonds,hydrogen bonds,disulfide bonds and hydrophobic interactions
37
What is the fourth structure of proteins
The 4th structure has different subunits and makes up a quaternary structure
38
What is the structure of nucleotides
They have a 5 carbon penthouse sugar, a nitrogen containing base and a phosphate group
39
How are nucleotides joined together
They are joined by condensation reactions which removes 2 water molecules
40
What are the 2 types of nucleotides
Purine and pyramidine
41
What is a purine base
A purine base has 2 nitrogen containing rings, adenine and guanine and they have a weak base
42
What is a pyrimidine base
A base containing 1 nitrogen containing ring, thymine, cytosine and uracil and they have a weak base
43
What is the structure of ATP
It’s a nucleotide with 3 phosphate groups attached
44
Where do we get the energy from in this atp molecule
The third phosphate bond is broken down in a hydrolysis reaction to get this energy
45
Why is ATP considered the universal energy supplier
Because when there is no ATP then the results are fatal
46
What is the function of nucleic acids
They carry all the info needed to form new cells
47
What is DNA
DNA is a code from which parts are copied into mRNA and used to direct the production of proteins that builds the cell and controls its action
48
What are nucleic acids
They are chains of nucleotides linked together by condensation reactions that produce phosphodiester bonds between the sugar of one nucleotide and the phosphate group of another
49
What are the similarities and differences between the DNA and RNA
DNA has a double helix whereas RNA has a single helix
DNA has the bases ATGC whereas RNA has the bases AUGC
In DNA A-T has 2 hydrogen bonds and G-C has 3 hydrogen bonds in RNA they have the same hydrogen bonds
They both have a backbone
50
How does conservative replication work
Both parent strands split and copy. The two parent strands pair back up and the two new strands pair up to make a DNA copy
51
How does semi conservative replication work
Both parent strands split and copy. Then an original and a new strand of DNA pair up each time
52
Which method out of conservative and semi conservative replication was proven to be correct
Semi conservative
53
How does DNA make copies of itself
- When DNA replicates they 2 strands of the DNA molecule unzip along the line of hydrogen bonds. This is brought about by the enzyme DNA helicase
- the exposed bases attract free DNA nucleotides and new hydrogen bonds are formed between matching base pairs
- DNA polymerase lines up and catalyses the linking up of the nucleotides along the template strand
- DNA Ligase catalyses the formation of phosphodiester bonds between the 2 strands of DNA. The result is two new strands of DNA identical with the original piece
54
What is a gene
A gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain
55
What percentage of our genome is used for coding
1.5-2%
56
What is a cordon
A cordon is a triplet of DNA or RNA bases
57
What is an extron and intron
Extrinsic are sections of coding DNA and introns are sections of non coding DNA
58
What Is non overlapping code
It’s a code where the DNA bases don’t overlap with each other
59
What is degenerate code
It is code when only the first 2 of the 3 nucleotides matter in determining amino acids
60
What are the different types of RNA
mRNA , tRNA , rRNA
61
What is the function of mRNA
It’s found in the nucleus and is a complementary copy of the DNA and it is involved in transcription and translation
62
What is the function of tRNA
It’s found in the cytoplasm and one part has a sequence of 3 bases that is complementary to the mRNA strand. The other end carries a specific amino acid
63
What is the function of rRNA
It makes up about 50% of the structure of the ribosome and it’s made in the nucleus and combined with proteins to form ribosomes
64
How does transcription work
- RNA polymerase binds to the DNA in a non coding region and separates the strands
- it moves along the DNA template strand or anti sense strand and unravels it
- RNA nucleotides Line up alongside the exposed anti sense strand and initially form hydrogen bonds with the DNA bases
- RNA polymerase catalyses the formation of phosphodiester bonds between the sugars and phosphate group. There is a length of mRNA formed
65
How does translation work
- the mRNA strand leaves the nucleus through nuclear pores. The mRNA attaches to a ribosome
- a ribosome moves along the mRNA strand three bases at a time each triplet is a codon
- at each codon a tRNA matches up. Each tRNA carries a specific amino acid. The ribosome joins the amino acids together to form a polypeptide
66
What are the positive effects of gene mutations
They are responsible for genetic variation and can create advantageous proteins which could make an organism have reproductive advantages
67
What are the neutral effects of gene mutations
They can have no effects on the protein produced and they don’t change chance of survival
68
What are the negative effects of gene mutations
The change in amino acid that a triplet codes for can have damaging effects on an organism and could result in a non functioning protein
69
What is a mutation
A permanent change in the DNA of an organism
70
What are the 3 types of point mutation
Substitution, deletion or insertion and triplet insertion or deletion
71
What are substitution mutations
Where you swap one base for another . They can change the amino acid therefore the protein
72
What are deletion/insertion mutations
Where a base is completely lost or added which results in all amino acids changing
73
What are chromosomal mutations
Changes in the positions of genes within the chromosome
74
What are whole chromosome mutations
Where an entire chromosome is either lost or duplicated
75
What are non coding mutations
If there is a mutation in this part it can result in RNA polymerase not binding very well resulting in not enough of a protein. Alternatively it binds too well and you end up with too much protein
76
What are enzymes
Enzymes are biological catalysts that control the rate of reactions that take place in individual cells and in whole organisms
77
What is the structure of enzymes
They are globular proteins and so are made up of amino acids. Their polypeptide folds up to form a unique shape which can catalyses specific reactions
78
What are anabolic reactions
Reactions that build up molecules
79
What are catabolic reactions
Reactions that break down molecules
80
What are intracellular enzymes and extra cellular enzymes
Enzymes that work inside the cell and enzymes that work outside the cell
81
How do enzymes speed up chemical reactions
They lower the activation energy required for a reaction to take place
82
What is the induced fit hypothesis
This is where the active site has a distinct shape but it is still flexible. Once the substrate enters the active site the shape of the site modified to form around it. Once the products have left the active site will revert to its inactive relaxed form
83
What are the factors that affect enzymes
Temperature, substrate concentration and PH
84
How does temperature affect enzymes
Temp causes thermal energy to be converted into kinetic energy causing a higher chance of particles colliding. It then denatures with the bonds breaking causing activity to decrease
85
How does substrate concentration affect enzymes
When there is more substrate than enzymes there is a longer rate of reaction. But when there is either more enzymes or less substrate the reaction takes place quicker
86
How does PH affect enzymes
As PH approaches optimum it increases then it will decrease once past optimum. The h+ ions and OH- ions will take away the electrons which affects the tertiary structure.
87
What is reversible inhibition and what two types are there
This is when an inhibitor affects an enzyme in a way that does not permanently damage it the two types are competitive and non competitive inhibition
88
What is competitive inhibition
This is when the inhibitor molecule is similar in shape to the substrate molecule so it competes with the substrate for binding at the active sites of the enzymes
