1
Q
what are nucleotides
A
- monomers of nucleic acids (RNA and DNA)
- carbon, hydrogen, oxygen, nitrogen and phosphorus
- component of coenzyme NAD and FAD
- ATP, ADP AMP all contain adenine base
2
Q
what are the components of a nucleotides
A
- pentose (5 carbon) sugar - deoxyribose (DNA), ribose (MA + ATP)
- a phosphate group
- nitrogenous base
3
Q
what are the three parts of a nucleotide
A
- pentose sugar
- nitrogenous base
- negatively charged phosphate group
4
Q
what are the four different bases in DNA nucleotides
A
- Adenine
- thymine
- guanine
- cytosine
5
Q
what are purines
A
double ring carbon structure
6
Q
what are pyrimidines
A
single ring carbon ring
7
Q
what is the base for RNA
A
Uracil
8
Q
what is the bond between two adjacent nucleotides called
A
a phosphodiester bond
9
Q
what are the stages, Chargaff’s ratios of bases in DNA
A
stage 1 - extract DNA - needs detergent, salt, proteases and ethanol
stage 2 - add protease enzyme - digests the histone proteins.
stage 3 - heat, with a strong acid, to hydrolyse DNA, plus release nucleotide base.
stage 4 - separated bases, using paper chromatography
stage 5 - used a spectrophotometer, allows, determination, of the amount of each base - bands extracted, into solution, results read using UV light
10
Q
what does antiparallel mean
A
- 2 strands, run in opposite directions
- each strand, has a phosphate group, attached to carbon 5’ at one end and a hydroxyl group, attached to 3’ at the other end.
11
Q
what does adenine pair with
A
thymine ( 2x hydrogen bonds)
12
Q
what does Guanine pair with
A
cytosine ( 3x hydrogen bonds)
13
Q
what type of bond join nucleotides together in polynucleotides
A
phosphodiester bond
14
Q
what is DNA replication
A
- occurs in the nucleus, during interphase, of the cell cycle - specifically the synthesis or S phase
- 1 chromosome into 2 sister chromatids
- occurs in mitochondria + chloroplasts just before the cell divides
15
Q
what materials are required for DNA replication
A
- DNA polymerase enzyme, helicase enzyme, gyrase enzyme and ligase enzyme.
- free DNA nucleotides (a, c, g, t)
- intact DNA -> this is because both strands, act as a template for replication
- energy source (ATP), to phosphorylase nucleotides, which activates them.
16
Q
why is DNA semi - conservative
A
in each new DNA molecule, one old strand is conserved and paired with 1 new strand.
17
Q
how many base pairs are there in the human genome?
A
10x10(to the power of 9)
18
Q
the semi - conservative model of DNA replication
A
- DNA molecule, unwinds (gyrase) and unzips (helicase) -> unzips the double helix, by breaking the hydrogen bond between the two strands
free nucleotides in the nucleus, + 2 extra phosphate groups are added to nucleotides, to active them (involves ATP) - bases of the activated nucleotides pair up, with complementary bases. on each of the old strands.
- DNA polymerase, catalyses the formation of phosphodiester bonds, joining the nucleotides together, 5’ to 3’ direction
- on the lagging strand, or Okazaki fragments form, which leaves gaps in the new strand, these gaps are later filled in using ligase enzymes.
- 2 additional phosphate groups are broken off the activated nucleotides and Okazaki fragments are released.
19
Q
what are the 3 things that a mutation can be?
A
- neutral
- harmful
- beneficial
20
Q
what is the semi - conservative model for DNA replication
A
21
Q
summarise Meselson and Stahl experiment on DNA replication
A
- scientist, grew many generations, e.g. in heavy N15 all bacterial DNA was heavy
- took a sample -> span in centrifuge -> heavy band N0
- then placed N0 in to N14, medium after 20 mins, took N1 sample -> hybrid intermediate band
- then allowed N1 to divide -> N2 -> results intermediate band + light
- over more generations, light band becomes thicker
22
Q
what is the function of DNA ligase
A
DNA ligase catalyses condensation reactions between the new nucleotides to create a polynucleotide chain.
23
Q
what is the function, of the enzyme gyrase
A
catalyses the ATP-dependent negative super-coiling of double-stranded closed-circular DNA
24
Q
what is the function of the enzyme helicase
A
unwinds the DNA by breaking the hydrogen bonds between complementary base pairs on the two strands of DNA.
25
what is the function of DNA polymerase
to accurately and efficiently replicate the genome in order to ensure the maintenance of the genetic information and its faithful transmission through generations.
26
name 2 purines
adenine and guanine (double ring)
27
name 2 pyrimidines
thymine and cytosine (single ring)
28
a purine always pairs with a pyrimidine
TRUE
29
why do we say that the two strands in DNA are antiparallel
because they run in opposite directions
30
what does carbon 5 attach to
the phosphate
31
what does carbon 3 attach to
the hydroxyl group
32
why is the proportion of Adenine - thymine and cytosine - guanine the same
due to complementary paring
33
what structure, do the two polynucleotide strands, form when they twist around each other
a double helix
34
what sugar is found in DNA
deoxyribose
35
what sugar is found in RNA
ribose
36
state some facts about DNA
- in chromosomes in the nucleus
- extremely long molecule
- two polynucleotide strands in a double helix
37
state some facts about RNA
- in the cytoplasm
- relatively short molecule
- one polynucleotide strand
38
what happens when a cell undergoes cell division
all of its DNA is copied
39
what is DNA replication
40
what is the difference between a normal nucleotide and an activated nucleotide
- an activated nucleotide contains 3 phosphate groups
- a nucleotide only contains one phosphate group
41
what happens in semi - conservative DNA replication
- the DNA helix, separates into two polynucleotide strands.
- each strand is then replicated into a complementary new strand
- one molecule of DNA, is thus copied into 2 molecules of DNA
- each of the two copies of DNA, contains one strand from the original DNA molecule and one new strand.
42
what is conservative replication
- a DNA double helix is formed containing two new strands of DNA
- one strand, comprises of old DNA
- one strand, comprises of completely new DNA
43
what do all bases in DNA contain
hydrogen
44
what are the two main forms of nitrogen
- N14 ( light nitrogen )
- N15 ( heavy nitrogen )
45
what does the position of the DNA band in the test tube depend on
it depends on how heavy the DNA is
46
what is the structure of RNA
single stranded, ribose sugar, with uracil instead of thymine
47
what is the function of RNA
involved in protein synthesis
48
what is messenger RNA
- single stranded molecule, forms a helical shape
- product, of transcription in the nucleus.
- copy of the DNA coding strand (sense) or complementary to the DNA template strand (antisense) (except U replaces T)
- moves out of the nucleus, via nuclear pore. (using microtubules, for movement attaches to a ribosome)
49
what is transfer RNA
- smaller molecule, than mRNA (80nts comparted to ~1000nts)
- made in the nucleus + transported, into the cytoplasm
- clover leaf shape
- can attach, to a specific amino acid
- 3 exposed bases -> anti codon, determining which amino acid is attached, + binds to the codon of mRNA, to ensure that a sequence of amino acids forms in the correct order.
50
what is ribosomal RNA
- produced in the nucleolus
- produced, from DNA
combined with ribosomal proteins
- 2 sub units ( one larger subunit and one smaller subunit)
- eukaryote -> 80S size (ribosomes)
- archaea + bacteria -> 70S size (smaller)(ribosomes)
51
give two places, where you find find ribosome in the cell
- cytoplasm
- RER
52
what does the nucleolus do
produce ribosomal RNA + assembles ribosomes
53
what makes species different from each other
the sequence of amino acids
54
what is the amino acid base code called
the triplet code.
55
what happens, if a base is added or deleted
it causes a frame shift, as every triplet after that is changed and this could affect every amino acid
56
why does protein synthesis occur
because DNA, is to large to leave the nucleus - mRNA, is small enough, to move out of the nucleus, via a nuclear pore.
57
describe the steps of transcription
- in the nucleus the gene unwinds (gyrase) and unzips (helicase) exposing the bases on DNA
- free activated nucleotides (RNA), line up, complementary to the DNA template strand
- RNA polymerase, binds to the promoter region of the gene and joins the RNA nucleotides together, with a phosphodiester bond , forming a sugar phosphate backbone -> primary RNA
- when the RNA polymerase, reaches the stop triplets, it detaches, primary RNA is spliced, to remove introns (non - coding regions)
- exons are joined together by (ligase)
- mature RNA, leaves nucleus + enters cytoplasm.
58
what is RNA polymerase
the enzyme that synthesis mRNA from DNA in transcription
59
what are the 4 requirements, for translation
- mRNA + ribosome
- tRNA (transfer RNA)
- enzymes
- proteins from the cytoplasm
60
what is the initiation codon
the first codon to be translated from the mRNA, is always **AUG**.
61
what is meant, when the triplet code, is said to be non - overlapping
it means, that no base is read more than once
62
what are the 3 triplets, that determine where translation stops
- UAA
- UAG
- UGA
63
what is each triplet in mRNA called
a codon
64
describe the process of translation
https://youtu.be/nekOPRY94aI?t=310
65
what happens, when a ribosome gets to a stop codon, during translation
it detaches and the polypeptide chain is released
66
where does transcription take place
in the nucleus
biology a level OCR
flashcards
Decks in class (32)
# Cards
-
cell structure41
-
Nucleotides and Nucleic acids66
-
biological molecules (carbohydrates, lipids and proteins)67
-
enzymes55
-
biolgical membranes41
-
Exchange surfaces79
-
transport in animals94
-
communicable diseases85
-
biodiversity46
-
classification and evolution78
-
Recycling materials in the ecosystem38
-
transport in plants55
-
communicable diseases SLOP40
-
stages of mitosis and meiosis12
-
exchange surface and transport SLOP2
-
module 3 exchange and transport (booklet 2)12
-
communication and homeostasis41
-
photosythesis71
-
neuronal communication66
-
plant reponses32
-
hormonal communication43
-
respiration62
-
excretion - the liver20
-
cellular control37
-
kidney34
-
patterns of inheritance65
-
Animal responses (the nervous system and the brain)20
-
muscle notes22
-
manipulating genomes72
-
biotechnology33
-
cloning17
-
characteristic of each kingdom of classification6
