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YEAR 1 BIO > DNA > Flashcards

DNA Flashcards

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1
Q

who discovered dna

A

watson and crick in 1953

but rosalind franklin worked out the structure

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2
Q

what does DNA stand for

A

deoxyribose nucleic acid

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3
Q

DNA is a polymer, what is a polymer

A

long chain of molecules made of the same units

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4
Q

what are the individual units of DNA

A

nucleotides

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5
Q

what is a single nucleotide made up of in DNA

A

phosphate, deoxyribose (pentose) sugar and a nitrogenous base

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6
Q

how are nucleotides joined together

A

in a condensation reaction

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7
Q

what bonds do sugar and phosphate form when nucleotides join together

A

phosphodiester bond

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8
Q

what are the 4 bases (complimentary pairs)

A

adenine and thymine

guanine and cytosine

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9
Q

what are the bases made up of

A

rings of carbon and nitrogen

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10
Q

what is a purine and which bases are purines

A

double rings

guanine and adenine

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11
Q

what is a pyrimidine and which bases are pyrimidines

A

single rings

cytosine and thymine

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12
Q

a purine always pairs……

A

with a pyrimidine

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13
Q

what is synthesis

A

making something

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14
Q

what is replicating

A

copying somethig

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15
Q

what do nitrogen bases act like

A

oxygen in what making the bases polar which allows hydrogen bonds to form

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16
Q

are the hydrogen bonds formed weak or strong and why

A

weak

essential for replication

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17
Q

what is DNA replication

A

chromosomes must make copies of themselves so that when cells divide each daughter cell receives an exact copy

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18
Q

what is protein synthesis

A

the sequence of bases represents the information carried in DNA and determines the sequence of amino acids in a protein

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19
Q

what are the 3 theories of DNA replication

A

conservative
semi conservative
dispersive

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20
Q

what is conservative theory

A

the original DNA is completely conserved and a whole new copy is created

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21
Q

what is semi conservative theory

A

one strand of the original goes to each daughter strand and one copy strand

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22
Q

what is dispersive theory

A

the original is fragmented and is split between the copies

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23
Q

what is the DNA replication process

A

1) helicase enzyme breaks the hydrogen bonds and the DNA unzips
2) free nucleotides bond to both DNA strands by complimentary base pairing
3) DNA polymerase enzymes joins the nucleotides between the sugar and phosphate groups
4) this results in two identical double stranded molecules

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24
Q

what did meselson and stahl do

A

devised an experiment to deduce which was the correct theory

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25
how did meselson and stahl conduct their experiment
1 - e coli were grown for several generations in a medium with N-15 present 2 - the n 15 e coli were transferred to a n14 medium to allow the e coli to divide 3- dna was extracted periodically and compared to the density of a pure sample of n14 and n15, they used a centrifuge to compare densities
26
what is the correct DNA replication theory
semi conservative
27
what is the function of DNA
contains the instructions for protein synthesis
28
what are codons
the section of a molecule that codes for one amino acid (in mRNA)
29
what did NIRENBERG discover
that there was 4 bases and 20 possible amino acids | so said that there codons must be at least 3 bases long
30
what is the triplet code
three bases code for one amino acid there are at least 64 possible codons but only 20 amino acids 3 of the codons are stop codons which ends protein synthesis
31
what is a redundant code
many of the amino acids are coded for by more than one code so the ones that aren't used are described as redundant or degenerate
32
what is non overlapping
when you convert DNA into an amino acid sequence you more along three bases each time you read a codon
33
why is the genetic code described as the universal code
all living organisms use the same 4 bases and the same codons for the same amino acids
34
what are exons
the section of a gene that code for one amino acid
35
what are introns
sections f DNA in the gene that DO NOT code for amino acids so they need to be removed before it can be translated
36
what does RNA stand for
ribose nucleic acid
37
what does RNA consist of
phosphate, ribose sugar and nitrogenous bases
38
list three difference between RNA and DNA
``` RNA- single stranded contains uracil ribose sugar DNA- double stranded contains thymine deoxyribose sugar ```
39
what are the three types of RNA molecules
rRNA ribosomal rna mRNA messenger rna tRNA transfer rna
40
what is stage 1 of protein syntheiss
transcription
41
describe transcription
1- helicase enzyme breaks the hydrogen bonds in the DNA where the gene is so the DNA unwinds 2 - free RNA nucleotides line up against the DNA template strand by complimentary base pairing 3 - RNA polymerase moves along the molecule joining the nucleotides in a condensation reaction to form the phosphodiester bond 4 - the mRNA molecules detaches from the DNA 5 - the DNA reforms as a double helix 6 - the mRNA leaves the nucleus through a nuclear pore
42
what is stage 2 of protein synthesis
translation
43
describe translation
1 - a ribsome attaches to the start codon of the mRNA 2 - a tRNA binds with its specific amino acid as determined by the anti codon 3 - the tRNA binds to the mRNA 4 - a second tRNA binds to the next mRNA codon bringing its amino acid 5 - a peptide bonds forms between the adjacent amino acids 6 - the ribosome move along the mRNA the new tRNAs bind to the mRNA and a polypeptide chain is formed until a stop codon is reached
44
describe the structure of tRNA
single stranded has hydrogen bonds which form between complimentary base pairs has three bases which are anti codon has an amino acid bonding site
45
what is the one gene one polypeptide theory
each gene is a sequence of nucleotides that are translated into a chain of amino acids which form a polypeptide polypeptides need modifying to become functional proteins this means that polypeptide sequences of one gene might produce more than one protein
46
why do we need cells to divide
mitosis - cell growth, replacement and asexual reproduction | meiosis - sexual reproduction
47
what does the cell cycle consist of
interphase and mitosis and cytokinesis
48
how much of the cell cycle does interphase take up
about 90%
49
what is interphase
the phase between division
50
what happens during interphase
the DNA is unwound as chromatin so the genes are accessible for transcription the cell is metabolically active cell growth and DNA replication
51
what are the three sections of interphase
G1,G2 AND S phase
52
what happens during G1+G2
cell growth | new protein synthesis and new organelles produced
53
what happens during S phase
dna replication | to form two identical sister chromatids
54
what are the four sections of mitosis
prophase, metaphase, anaphase and telophase
55
what happens during prophase
preparation chromatids condense nucleolus disappears nuclear envelope starts breaking own spindle apparatus forms centrioles migrate to the poles of the cll chromatids combine with HISTONE to become shorter and thicker
56
what happens during metaphase
nuclear membrane has broken down chromosomes align in the centre of the cell each chromosome is attached to a spindle fibre by its centromere
57
what happens during anaphase
centromere of each chromatin splits one chromosome from each chromatid moves to centrioles at poles of cells the chromatid which are now separate are chromsomes
58
what happens during telophase
nnuclear membrane forms around each group of newly divided chromosomes nucleolus reforms spindle disappears chromosomes extend into chromatin becoming 'invisible'
59
what is cytokinesis
the cytoplasmic division of other materials (cytoplasm, cell membrane and other organelles)
60
what does cytokinesis result in
the formations of two new daughter cells
61
What are the two energy laws
Energy cannot be created or destroyed | Energy can be transferred from one form to another
62
Why do we need energy
``` Muscular contraction Active transport Growth Thermoregulation Catabolism ```
63
What is bioluminescence
Converting chemical energy into light energy
64
What does ATP stand for
Adenosine triphosphate
65
What is ATP made up of
Adenine Ribose 3 phosphate groups
66
Adenine + ribose =
Adenosine
67
What is the role of ATP
short term energy store of the cell Often called the energy currency because it picks up energy from food in respiration and passes it on to power cell processes
68
What are the advantages of ATP
``` Small Soluble Universal Quick Releases energy in small amount when and where it's needed ```
69
What is ATPase
The enzyme that removes the end phosphate groups one at a time
70
What does breaking bonds require
Energy
71
How much energy is needed in the case of ATPase to break a bond
A small amount
72
What is the equation for the breaking down of ATP
ATP----> ADP + Pi
73
What happens to the Pi bonds and how much energy does it release
Bonds with water and becomes hydrated | Releases more energy than was required to split ATP
74
What is the net energy release when ATP is broken down
30.6 KJ mol^-1
75
What is phosphorylation
The addition of phosphate to ADP
76
What is cancer
A breakdown in the cellular control mechanism that slows down cell division Cells that should be stable begin to divide forming a tumour
77
What is a tumour
A swelling that can occur almost anywhere in the body | A MASS OF ABNORMAL CELLS THAT DIVIDE UNCONTROLLABLY
78
What are malignant tumours
Destroys the surrounding tissue and their cells can break away and spread through the BLOOD AND LYMPH into other sites where they form secondary tumours
79
What are benign tumours
grow very large but don't destroy the surrounding tissue
80
Why is cancer so dangerous
Tumours interfere with the activity of cells in the tissues if the organs that surround them
81
Why are benign tumours dangerous
Can compress tissues preventing normal blood flow or nerve function
82
Why are malignant tumours so dangerous
Invade surrounding tissues and kill normal cells
83
How can you control the division of cells
PROTO-ONCOGENES regulate cell growth and differentiation but if they mutate can become ONCOGENES (form cancer) TUMOUR SUPPRESSOR GENES inhibit the cell cycle for instance if DNA is damaged Can mutate and lead to cancer
84
What is a haploid cell
Has half the number of chromosomes of a normal body/semantic cell
85
What are homologous chromosomes
Have the same structural features and patterns of genes
86
What does independent assortment help to do
Increase variation
87
What is different about meiosis compared to mitosis
In meiosis it has two stages of pro,met, ana and telo phase

YEAR 1 BIO (16 decks)

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