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YEAR 1 BIO > DNA > Flashcards

DNA Flashcards

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Biology 101 flashcards
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
Q

how did meselson and stahl conduct their experiment

A

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

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26
Q

what is the correct DNA replication theory

A

semi conservative

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27
Q

what is the function of DNA

A

contains the instructions for protein synthesis

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28
Q

what are codons

A

the section of a molecule that codes for one amino acid (in mRNA)

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29
Q

what did NIRENBERG discover

A

that there was 4 bases and 20 possible amino acids

so said that there codons must be at least 3 bases long

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30
Q

what is the triplet code

A

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

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31
Q

what is a redundant code

A

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

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32
Q

what is non overlapping

A

when you convert DNA into an amino acid sequence you more along three bases each time you read a codon

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33
Q

why is the genetic code described as the universal code

A

all living organisms use the same 4 bases and the same codons for the same amino acids

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34
Q

what are exons

A

the section of a gene that code for one amino acid

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35
Q

what are introns

A

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
Q

what does RNA stand for

A

ribose nucleic acid

37
Q

what does RNA consist of

A

phosphate, ribose sugar and nitrogenous bases

38
Q

list three difference between RNA and DNA

A 
RNA- single stranded
contains uracil 
ribose sugar
DNA- double stranded
contains thymine 
deoxyribose sugar
39
Q

what are the three types of RNA molecules

A

rRNA ribosomal rna
mRNA messenger rna
tRNA transfer rna

40
Q

what is stage 1 of protein syntheiss

A

transcription

41
Q

describe transcription

A

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
Q

what is stage 2 of protein synthesis

A

translation

43
Q

describe translation

A

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
Q

describe the structure of tRNA

A

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
Q

what is the one gene one polypeptide theory

A

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
Q

why do we need cells to divide

A

mitosis - cell growth, replacement and asexual reproduction

meiosis - sexual reproduction

47
Q

what does the cell cycle consist of

A

interphase and mitosis and cytokinesis

48
Q

how much of the cell cycle does interphase take up

A

about 90%

49
Q

what is interphase

A

the phase between division

50
Q

what happens during interphase

A

the DNA is unwound as chromatin so the genes are accessible for transcription
the cell is metabolically active
cell growth and DNA replication

51
Q

what are the three sections of interphase

A

G1,G2 AND S phase

52
Q

what happens during G1+G2

A

cell growth

new protein synthesis and new organelles produced

53
Q

what happens during S phase

A

dna replication

to form two identical sister chromatids

54
Q

what are the four sections of mitosis

A

prophase, metaphase, anaphase and telophase

55
Q

what happens during prophase

A

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
Q

what happens during metaphase

A

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
Q

what happens during anaphase

A

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
Q

what happens during telophase

A

nnuclear membrane forms around each group of newly divided chromosomes
nucleolus reforms
spindle disappears
chromosomes extend into chromatin becoming ‘invisible’

59
Q

what is cytokinesis

A

the cytoplasmic division of other materials (cytoplasm, cell membrane and other organelles)

60
Q

what does cytokinesis result in

A

the formations of two new daughter cells

61
Q

What are the two energy laws

A

Energy cannot be created or destroyed

Energy can be transferred from one form to another

62
Q

Why do we need energy

A 
Muscular contraction
Active transport
Growth 
Thermoregulation
Catabolism
63
Q

What is bioluminescence

A

Converting chemical energy into light energy

64
Q

What does ATP stand for

A

Adenosine triphosphate

65
Q

What is ATP made up of

A

Adenine
Ribose
3 phosphate groups

66
Q

Adenine + ribose =

A

Adenosine

67
Q

What is the role of ATP

A

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
Q

What are the advantages of ATP

A 
Small
Soluble
Universal 
Quick 
Releases energy in small amount when and where it's needed
69
Q

What is ATPase

A

The enzyme that removes the end phosphate groups one at a time

70
Q

What does breaking bonds require

A

Energy

71
Q

How much energy is needed in the case of ATPase to break a bond

A

A small amount

72
Q

What is the equation for the breaking down of ATP

A

ATP—-> ADP + Pi

73
Q

What happens to the Pi bonds and how much energy does it release

A

Bonds with water and becomes hydrated

Releases more energy than was required to split ATP

74
Q

What is the net energy release when ATP is broken down

A

30.6 KJ mol^-1

75
Q

What is phosphorylation

A

The addition of phosphate to ADP

76
Q

What is cancer

A

A breakdown in the cellular control mechanism that slows down cell division
Cells that should be stable begin to divide forming a tumour

77
Q

What is a tumour

A

A swelling that can occur almost anywhere in the body

A MASS OF ABNORMAL CELLS THAT DIVIDE UNCONTROLLABLY

78
Q

What are malignant tumours

A

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
Q

What are benign tumours

A

grow very large but don’t destroy the surrounding tissue

80
Q

Why is cancer so dangerous

A

Tumours interfere with the activity of cells in the tissues if the organs that surround them

81
Q

Why are benign tumours dangerous

A

Can compress tissues preventing normal blood flow or nerve function

82
Q

Why are malignant tumours so dangerous

A

Invade surrounding tissues and kill normal cells

83
Q

How can you control the division of cells

A

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
Q

What is a haploid cell

A

Has half the number of chromosomes of a normal body/semantic cell

85
Q

What are homologous chromosomes

A

Have the same structural features and patterns of genes

86
Q

What does independent assortment help to do

A

Increase variation

87
Q

What is different about meiosis compared to mitosis

A

In meiosis it has two stages of pro,met, ana and telo phase

YEAR 1 BIO (16 decks)

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